Tag: Sustainable Biomass Program (SBP)

Alabama Cluster Catchment Area Analysis

The area of timberland in the Alabama cluster catchment area has remained stable over the last 20 years, increasing slightly from 4.08 million ha to 4.16 million ha, an increase of 79 thousand hectares.  This area represents 79.6% of the total land area in 2020, up from 78.1% in 2020.  The total area of forestland and woodland was 86% of the catchment area in 2020, with farmland making up 13% and urban areas 1%.  This land base can be considered to be heavily forested and dominated by timberland.

Figure 1: Land Use Type – Alabama cluster

The timberland area is classified by growth rate potential, capable of achieving a minimum of 0.57 m3/ha/year.  More than 95% of the timberland area is in private ownership.  This proportion has remained stable since 2000 as shown in Figure 2.

Figure 2: Timberland Ownership Profile – Alabama cluster

The total standing volume, the amount of carbon stored in the forest area, has increased by 115 million m3 since 2000 an increase of 30%. Most of this increase has occurred since 2010, with 90 million m3 added to the inventory since this time, reflecting the maturing age class of the forest resource as it passes through the peak growth phase.  Almost all of this increase has been in the softwood pine forest area, with a combined increase of 86 million m3 since 2010.  Pine saw-timber and chip-n-saw both increased by 46% since 2010 and pine pulpwood by 25% over the same period. Suggesting that the average tree size is getting larger as the forest matures.

Figure 3: Standing Volume by Product Class – Alabama cluster

One measure of the sustainability of harvesting levels is to compare average annual growth against removals.  This comparison gives a growth drain ratio (GDR).  Where removals are equal to or lower than growth (a GDR of 1 or more) this is a measure of sustainability, where the ratio falls below 1, this can indicate that harvesting levels are not sustainable in the long-term.  Figure 4 shows that all pine product classes have a positive GDR since 2010.  In particular the pine pulpwood GDR ratio is in excess of 2 suggesting that there is a substantial surplus of this product category.  By contrast, the hardwood GDR for both saw-timber and pulpwood are both lower than 1 suggesting that harvesting levels for hardwood species should be reduced until growth can recover.

Figure 4: Growth Drain Ratio by Product Class – Alabama cluster

Figure 5 shows the maturing age class of the forest area, charting the change in annual surplus and deficit in each product class.  The trend shows that harvesting of pine saw-timber from 2000 to 2008 represented a deficit of growth compared to harvesting removals.  This indicates an immature forest resource with a low quantity of forest categorised as saw-timber, therefore harvesting volume in mature stands outweighed the growth in mid-rotation stands.  As the forest aged, and more standing timber grew into the saw-timber category, the surplus of annual growth compared to removals increased.  Saw-timber growth in 2020 was 3 million m3 higher than in 2000.  The surplus of pine pulpwood has remained positive and has increased substantially from 3 million m3 in 2000 to 6.5 million m3 in 2020 despite harvesting levels increasing slightly over this period.

Figure 5: Annual Surplus/Deficit of Growth and Removal by Product Class – Alabama Cluster

Biomass demand began in 2008 at a very small scale, representing just 0.5% of total pulpwood demand in the catchment area.  From around 2013 it began to increase and reached peak in 2015 with a total demand of 724,000 tons of pulpwood in that year, representing 8.1% of total pulpwood demand in the catchment area.  After that time, demand for pulpwood declined as pellet mills switched to mill residuals.  The latest data on pulpwood demand shows that the biomass sectors made up just 2.8% of total pulpwood demand in 2020 with just over 216,000 tonnes of total demand.  This demonstrates that the biomass and wood pellet sector is a very small component of the market in this region and unlikely to influence forest management decision making, as shown in Figure 6.

Figure 6: Pulpwood Demand by Market – Alabama Cluster

Pine pulpwood stumpage prices have declined significantly since a peak in 2013, falling from an annual high of $9.46 when demand was strongest to just $4.12 in 2020 as demand for pine pulpwood declined in 2020.  Pine saw-timber prices have seen a similar decline from a high point in the early 2000’s to a plateau from 2011 onwards.  Saw-timber stumpage more than halved in value over this period from $49 per ton to $22 per ton.  This can have a significant impact on forest management objectives and decision making.

Figure 7: Stumpage Price Change by Product Category – Alabama Cluster

Detailed below are the summary findings from Hood Consulting on the impact of biomass demand on key issues in the Alabama cluster catchment area.

Is there any evidence that bioenergy demand has caused the following:

Deforestation?

No. US Forest Service (USFS) data shows that total timberland area has held steady and averaged roughly 4,172,000 hectares in the Alabama Cluster catchment area since Alabama Pellets-Aliceville started up in late-2012. More importantly, planted pine timberland (the predominant source of roundwood utilized by the bioenergy industry for wood pellet production) has increased more than 75,000 hectares (+4.9%) in the catchment area since Alabama Pellets’ startup in 2012.

A change in management practices (rotation lengths, thinnings, conversion from hardwood to pine)?

Inconclusive. Changes in management practices have occurred in the catchment area over the last two decades. However, the evidence is inconclusive as to whether increased demand attributed to bioenergy has caused or is responsible for those changes.

Clearcuts and thinnings are the two major types of harvests that occur in this region, both of which are long-standing, widely used methods of harvesting timber. TimberMart-South (TMS) data shows that the prevalence of thinnings temporarily increased in the Alabama Cluster market (from 2007-2013) due to the weakening of pine sawtimber markets. Specifically, challenging market conditions saw pine sawtimber stumpages prices decline from an average of $47 per ton from 2000-2006 to just over $23 per ton in 2011, or a roughly 50% decrease from 2000-2006 average levels. This led many landowners to refrain from clearcutting (a type of harvest which typically removes large quantities of pine sawtimber), as they waited for pine sawtimber prices to improve. However, pine sawtimber stumpage prices never recovered and have held between $22 and $25 per ton since 2011. Ultimately, landowners returned to more ‘normal’ management practices by 2014, with thinnings falling back in line with pre-2007 trends.

The catchment area has also experienced some conversion. Specifically, from 2000-2020, planted pine timberland increased more than 460,000 hectares while natural hardwood and mixed pine-hardwood timberland decreased a combined 390,000 hectares. Note that the increase in planted pine timberland and decrease in natural hardwood/mixed pine-hardwood timberland over this period were both gradual and occurred simultaneously. This suggests a management trend in which natural timber stands are converted to plantation pine following final harvest. It’s also important to note that there is little evidence that links these changes to increased demand from bioenergy, as this conversion trend begun years prior to the startup of Alabama Pellets and continued nearly unchanged following the pellet mill’s startup.

Diversion from other markets?

No. Demand for softwood (pine) sawlogs increased an estimated 12% in the catchment area from 2012-2020. Also, there is no evidence that increased demand from bioenergy has caused a diversion from other softwood pulpwood markets (i.e. pulp/paper). Also, even though softwood pulpwood demand not attributed to bioenergy is down 14% since Alabama Pellets-Aliceville’s startup in 2012, there is no evidence that increased demand from bioenergy has caused this decrease. Rather, the decrease in demand from non-bioenergy sources is due to a combination of reduced product demand (and therefore reduced production) and increased utilization of sawmill residuals.

An unexpected or abnormal increase in wood prices?

No. The startup of Alabama Pellets-Aliceville added roughly 450,000 metric tons of softwood pulpwood demand to the catchment area from 2012-2016, and this increase in demand coincided with essentially no change in delivered pine pulpwood (PPW) price over this same period. Ultimately, the additional demand placed on the catchment area following the startup of Alabama Pellets-Aliceville was offset by a decrease in demand from other sources from 2012-2016, and, as a result, delivered PPW prices remained nearly unchanged.

However, the Aliceville facility was shut down for a majority of 2017 due to the catastrophic failure of a key piece of environmental equipment, and this was followed by Alabama Pellets’ strategic decision to transition to residual-consumption only beginning in 2018, which eliminated more than 360,000 metric tons of annual softwood pulpwood demand from 2016-2018. Over this same period, softwood pulpwood demand from other sources also decreased nearly 360,000 metric tons. So, with the elimination of roughly 720,000 metric tons of annual softwood pulpwood demand from all sources from 2016-2018, delivered PPW prices in the catchment area proceeded to decrease more than 6% over this period. Since 2018, total softwood pulpwood demand has increased roughly 4% in the catchment area (due to increases in demand from non-bioenergy sources), and this increase that has coincided with a simultaneous 4% increase in delivered PPW price.

Statistical analysis did identify a positive relationship between softwood biomass demand and delivered PPW price. However, the relationship between delivered PPW price and non-biomass-related softwood pulpwood demand was found to be stronger, which is not unexpected given that pine pulpwood demand not attributed to bioenergy has accounted for 94% of total pine pulpwood demand in the catchment area since 2012. Ultimately, the findings provide evidence that PPW price is influenced by demand from all sources – not just from bioenergy or from pulp/paper, but from both.

Furthermore, note that Alabama Pellets’ shift to residual-consumption only beginning in 2018 resulted in no increase in pine sawmill chip prices, as the price of pine sawmill chips in the Alabama Cluster catchment area rather decreased from 2018-2020, despite a more than 100,000-metric ton increase in pine sawmill chip consumption by the Aliceville mill over this period.

A reduction in growing stock timber?

No. From 2012 (the year Alabama Pellets started up) to 2020, total growing stock inventory increased an average of 2.6% per year (+22% total) in the Alabama Cluster catchment area. Specifically, inventories of pine sawtimber and pine chip-n-saw increased 41% and 40%, respectively, while pine pulpwood (PPW) inventory increased 25% over this same period.

A reduction in the sequestration rate of carbon?

No. US Forest Service (USFS) data shows the average annual growth rate of total growing stock timber in the Alabama Cluster catchment area increased from 6.0% in 2012 to 6.2% in 2020, suggesting that the sequestration rate of carbon also increased slightly over this period.

Note that the increase in overall growth rate (and therefore increase in the sequestration rate of carbon) can be linked to gains in pine timberland and associated changes with the catchment area forest. Specifically, growth rates decline as timber ages, so the influx of new pine timberland (due to the conversion of both hardwood forests and cropland) has resulted in just the opposite, with the average age of softwood (pine) growing stock inventory decreasing from an estimated 35.4 years of age in 2000 to 33.2 years of age in 2010 and to 32.2 years of age in 2020 (total growing stock inventory decreased from 41.9 to 41.0 and to 40.4 years of age over these periods).

An increase in harvesting above the sustainable yield capacity of the forest area?

No. Growth-to-removals (G:R) ratios, which compare annual timber growth to annual timber removals, provides a measure of market demand relative to supply as well as a gauge of market sustainability. In 2020, the latest available, the G:R ratio for pine pulpwood (PPW), the predominant timber product utilized by the bioenergy sector, equaled 3.26 (recall that a value greater than 1.0 indicates sustainable harvest levels).

Moreover, note that the PPW G:R ratio has increased in the catchment area since the Aliceville mill’s startup in 2012, despite the associated increases in pine pulpwood demand. In this catchment area, pine pulpwood demand from non-bioenergy sources decreased more than 860,000 metric tons from 2012 to 2020, and this decrease more than offset any increase in demand from bioenergy.

Impact of bioenergy demand on:

Timber growing stock inventory

Neutral. According to USFS data, inventories of pine pulpwood (PPW) increased 25% in the catchment area from 2012-2020, and this increase in PPW inventory can be linked to both increases in pine timberland and harvest levels below the sustainable yield capacity of the forest area. Specifically, pine timberland (both planted and natural combined) increased more than 185,000 hectares in the catchment area from 2012-2020. Over this same period, annual harvests of PPW were 65% below maximum sustainable levels.

Timber growth rates

Neutral. The average annual growth rate of total growing stock timber increased from 6.0% in 2012 to 6.2% in 2020 in the Alabama Cluster catchment area, despite pine pulpwood (PPW) growth rate decreasing from 15.1% to 12.5% over this period. However, this decrease in PPW growth rate was not due to increased demand attributed to bioenergy but rather to the aging of PPW within its product group and its natural movement along the pine growth rate curve. Specifically, USFS data indicates the average age of PPW inventory in the catchment area increased from an estimated 13.4 years of age in 2012 to 13.6 years of age in 2020.

Forest area

Neutral. In the Alabama Cluster catchment area, total forest (timberland) area remained nearly unchanged (decreasing only marginally) from 2012-2020. However, pine timberland – the predominant source of roundwood utilized by the bioenergy industry for wood pellet production – increased more than 185,000 hectares over this period, and this increase can be linked to several factors, including conversion from both hardwood and mixed pine-hardwood forests as well as conversion from cropland.

Specifically, the more than 185,000-hectare increase in pine timberland from 2012-2020 coincided with a roughly 197,000-hectare decrease in hardwood/mixed pine-hardwood timberland and a more than 8,000-hectare decrease in cropland over this period. Furthermore, statistical analysis confirmed these inverse relationships, identifying strong negative correlations between pine timberland area and both hardwood/mixed pine-hardwood timberland area and cropland in the catchment area from 2012-2020.

Wood prices

Negative/Neutral. Softwood pulpwood demand attributed to bioenergy increased from roughly 80,000 metric tons in 2012 (the year Alabama Pellets-Aliceville started up) to more than 655,000 metric tons in 2015 (the year biomass demand reached peak levels). However, this roughly 575,000-metric ton increase in softwood biomass demand coincided with essentially no change in delivered pine pulpwood (PPW) price – which averaged $26.40 per ton in 2012 and $26.39 per ton in 2015. Ultimately, the additional demand placed on this catchment area following the startup of Alabama Pellets-Aliceville was offset by a more than 680,000-metric ton decrease in demand from other sources over this same period, and, as a result, delivered PPW prices remained nearly unchanged. Also note that Alabama Pellets’ strategic shift to consume residuals only (a transition that begun in 2018 and had been completed by 2019) resulted in a nearly 480,000-metric ton decrease in softwood biomass demand in the catchment area from 2015 to 2020. Over this same period, softwood pulpwood demand from other sources decreased more than 180,000 metric tons. In total, softwood pulpwood demand from all sources decreased more than 660,000 metric tons from 2015 to 2020, and this decrease in demand resulted in delivered PPW prices decreasing 5% over this period.

Statistical analysis did identify a positive relationship between softwood biomass demand and delivered PPW price. However, the relationship between delivered PPW price and non-biomass-related softwood pulpwood demand was found to be stronger, which is not unexpected given that pine pulpwood demand not attributed to bioenergy has accounted for 94% of total pine pulpwood demand in the catchment area since 2012. Ultimately, the findings provide evidence that PPW price is influenced by demand from all sources – not just from bioenergy or from pulp/paper, but from both.

Markets for solid wood products

Positive. In the Alabama Cluster catchment area, demand for softwood sawlogs used to produce lumber and other solid wood products has increased an estimated 12% since 2012, and this increase in softwood lumber production has consequentially resulted in the increased production of sawmill residuals (i.e. chips, sawdust, and shavings) – by-products of the sawmilling process and materials utilized by Alabama Pellets to produce wood pellets.

Moreover, the increased availability of sawmill residuals and lower relative cost compared to roundwood (after chipping and other processing costs are considered) led Alabama Pellets to make a strategic shift to utilize residuals only for wood pellet production beginning in 2019. So, not only has Alabama Pellets benefited from the greater availability of this lower-cost sawmill by-product, but lumber producers have also benefited, as Alabama Pellets has provided an additional outlet for these producers and their by-products.

Read the full report: Alabama Cluster Catchment Area Analysis

This is part of a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. Others in the series can be found here

What is sustainable forest management?

Sustainable forest management is frequently defined in terms of providing a balance of social, environmental, and economic benefits, not just for today but for the future too. It might be seen as the practice of maintaining forests to ensure they remain healthy, absorb more carbon than they release, and can continue to be enjoyed and used by future generations.

To achieve this, foresters apply science, knowledge, and standards that help ensure forests continue to play an important role in the wellbeing of people and the planet.

Managed forests, also called working forests, fulfil a variety of environmental, social, and economic functions. These range from forests managed to attract certain desired wildlife species, to forests grown to provide saw timber and reoccurring revenue for landowners.

How are forests sustainably managed?

How forests are managed depends on landowner goals – managing for recreation and wildlife, focusing on maximising production of wood products, or both. Each forest requires management tailored to its owner’s or manager’s objectives.

There are many ways to manage forests to keep them healthy – there is no ‘one size fits all’ – but keeping track of how they are doing can be tricky. One alternative for monitoring forests is to use satellite imagery.

One common sustainable forestry practice is thinning, which involves periodically removing smaller, unhealthy, or diseased trees to enable stronger ones to thrive. Thinning reduces competition between trees for resources like sunlight and water, and it can also help promote biodiversity by creating more space for other forest flora.

The wood removed from forests through thinning is sometimes not high-quality enough to be used in industries such as construction or furniture. However, the biomass industry can use it to make compressed wood pellets; a feedstock for renewable source electricity.

By providing a market for low-quality wood, pellet production encourages landowners to carry out thinnings. This practice improves the health of the forest, and helps support better growth, greater carbon storage, and creates more valuable woodland.

Fast facts

What are the environmental benefits of sustainably managed forests?

Through their ability to act as carbon sinks, forests are an important part of meeting global climate goals like the Paris Agreement and the UK’s own target of reaching net zero emissions by 2050.

When managed effectively through thinning or active harvesting, and replanting and regeneration, forests can often sequester – or absorb and store – more carbon than forests that are left untouched, increasing productivity and improving planting material.

Harvesting trees before they reach an age when growth slows or plateaus can help prevent fire damage, pests, and disease, so timing of final cutting is important. Though the vast majority of timber from such cutting will go to other markets (construction, furniture etc) and secure higher prices from those markets, being able to sell lower quality wood for biomass provides the landowner with some extra revenue.

Sustainably managed forests also help achieve other environmental goals, such as sustaining biodiversity, protecting sensitive sites and providing clean air and water. Managed forests also have substantial water absorption capacity preventing flooding by slowing the flow of sudden downpours and helping to prevent nearby rivers and streams from overfilling.

Wood from working forests also help tackle climate change in that high-value wood from harvested trees can be used to make timber for the construction or furniture sectors. These wood products lock up carbon for extended periods of time, and the wood can be used at end-of life to displace fossil fuels. Using wood also means materials such as concrete, bricks or steel are not used, and these materials have a large carbon footprint compared to wood.

What are the socioeconomic benefits of sustainably managed forests?

There are also social and economic benefits to managing forests. Sustainably managed working forests make vital contributions both to people and to the planet.

The commercial use of wood in industries like furniture and construction drives revenue for landowners. This encourages landowners to continue to replant forests and manage them in a sustainable way that continues to deliver returns.

Healthy forests can also improve living standards for local communities for jobs and helping to address unemployment in rural regions. Managed forests can also improve access for recreation. On a larger scale, sustainable forestry can offer a valuable export for regions and nations and foster trade between countries.

Go deeper 

Enviva Cottondale pellet plant catchment area analysis

The Enviva Cottondale pellet mill has a production capacity of 760,000 metric tonnes of wood pellets annually. Raw material used by the mill includes a combination of roundwood, chips, and secondary residuals (i.e., sawdust and shavings), with pine accounting for 80‐90% of total feedstock. In October 2018, Hurricane Michael passed through the centre of the Cottondale catchment area, causing significant damage to the forest resource with more than 500,000 hectares (ha) of forestland destroyed and an estimated loss of 42 million m3of timber (equivalent to around 4 times the UK annual production of roundwood).

This event has had an impact on the data trends for forest inventory, growth and harvesting removals – as harvesting levels were increased to salvage as much timber as possible before it became unusable due to decay. This can be clearly seen in many of the charts below. However, these forest areas have been restored and now continue to grow, allowing the catchment area to return to its pre-hurricane trends in the medium term.

Forest Area 

The catchment area around Enviva’s Cottondale pellet mill includes 4.3 million ha of land, based on the historical feedstock sourcing patterns of the mill. Timberland represents 68.7% (2.95 million ha) of the total land area in the Cottondale catchment area, this has increased slightly since 2000 from 67.8% and can be considered to have remained stable over this time period.  There are also around 300,000 ha of woodland (associated with agricultural land) and around 800,000 ha of cropland and pastureland.  Forestry is the dominant land use in this catchment area (Figure 1).

Figure 1: Land area by usage

Planted pine represents 33% of the timberland area, natural pine 20%, with 10% mixed stands and the remainder being hardwood forest of which 94% is naturally regenerated (Figure 2).  The breakdown of forest type and species composition has remained relatively stable and largely unchanged over the last 20 years, in contrast to other parts of the US South where some natural pine stands have been converted to planted pine. The pine and mixed forest areas are actively managed and produce the majority of the timber harvest in the catchment area. Despite the large area of hardwood forest, management and timber production is limited. Much of this area is classified as bottomland hardwood located alongside rivers, streams, and creeks and in streamside management zones (SMZs), which restricts active management. In addition, the proportion of this catchment area located in Florida contains a large area of swampland, which is largely composed of hardwoods and cannot be actively managed for timber production and is recognised as having important ecological value.

Figure 2: Breakdown of forest type

Volume and Growth

The overall trend of volume and growth in the Cottondale catchment area is of a maturing forest resource and an increasing accumulation of standing volume, particularly in the larger forest product classes (saw-timber and chip-n-saw). Figure 3 shows that total standing volume increased by 64 million m3 from 2000 to 2018, with the largest increases in the pine saw-timber and chip-n-saw categories. In 2018, the devastating impact of Hurricane Michael caused a substantial reduction in the standing volume across every product category with the total standing volume being reduced by 42 million m3. This event has had a significant impact on the forest resource and is a primary cause of recent data trends.

However, the overall long-term trend in the catchment area is of maturing forest and increasing inventory. This should continue in the long-term once the impact of the hurricane damage has been managed and replacement forest areas begin to mature.

Figure 3: Standing volume by product category

Pine pulpwood inventory increased steadily by around 8 million m3 from 2000 to 2013, reaching a peak of 49 million m3. This then declined slightly to 46 million m3 in 2018 due to the maturing age class of the forest and pulpwood forest growing into the larger size class of chip-n-saw and saw-timber forest (Figure 4), in addition to an increase in pulpwood demand as biomass markets became operational and ramped up production. Following the hurricane in 2018, the pine pulpwood inventory dropped by more than 10 million m3. 

Replanting and reforestation of damaged areas will ensure that future pine pulpwood production will increase again once these forests start to mature.

In the period from 2000 to 2018 pine sawtimber standing volume increased by 41.5 million m3 (78%) and chip-n-saw by 19.6 million m3 (73%), indicating a maturing age class and a growing forest resource. The 2018 hurricane caused a reduction in standing volume in both of these product categories of 11.6 and 8 million m3respectively (12% and 17% of the 2018 volume). However, the increasing trend is likely to continue once the forest area recovers.

Figure 4: Standing volume by product category

The growth drain ratio (GDR) is the comparison of average annual growth to removals (typically harvesting), where the growth exceeds removals the GDR will be in excess of 1 and this is considered sustainable, where removals exceed growth then the GDR will be less than 1 and this is not sustainable if maintained in the long-term – although in the short-term this can be a factor of large areas of mature forest with low growth rates and high rates of harvesting, short periods of high demand for a particular product or salvage harvesting after a natural disturbance. The GDR should be considered over a longer time period to ensure it reflects the long-term trend. In the period from 2003 to 2020 the combined GDR for pine products averaged 1.52 with a high of 1.84 and a low of 1.08 (Figure 5).

Figure 5: Growth to drain ratio by product category

The maturing forest resources can be clearly seen from the growth to removals data for each product category. Average tree sizes getting larger and more pulpwood class stands moving into the larger saw-timber and chip-n-saw categories. This trend can be seen by comparing the data values from 2003 and 2018 where saw-timber average annual growth increased by 90% (1.6 million m3), and removals by 41% (0.98 million m3).  Chip-n-saw growth increased by 73% (1.3 million m3) whilst removals increased by 160% (1.9 million m3). Pulpwood growth decreased by 7.5% (0.4 million m3) whilst removals increased by 63% (1.6 million m3).  Over this time period the total annual surplus of pine growth compared to removals averaged 3.7 million m3 per year (Figure 6).

Figure 6: Pine growth and removals by product category and year

Hardwood saw-timber and pulpwood removals declined by 20% and 40% respectively between 2000 and 2018, whilst growth increased by 23% for hardwood saw-timber and declined by 16% for hardwood pulpwood. The average annual hardwood surplus over this time period was 1.5 million m3 per year (Figure 7).

Figure 7: Hardwood growth and removals by product category and year

Despite a short-term imbalance in some product categories, the overall surplus of pine growth compared to removals has remained strong, with an average of 3.3 million m3 between 2000 and 2020, which includes the increased salvage harvesting in 2018 (Figure 8).

Figure 8: Cumulative annual surplus of growth compared to removals

Wood Prices

Stumpage price is the value paid to the forest owner for each category of product at the time of harvesting. The variation in prices in the Cottondale catchment area has been significant and shows some interesting trends. The higher value pine products (saw-timber and chip-n-saw) began with high stumpage values in 2000, as markets were strong for construction and furniture grade timber and supply limited at that stage due to the young age class and predominance of pulpwood stands at that time.  In 2008, following the global economic crisis and the crash in housing and construction markets, saw-timber prices declined substantially reaching a low of $23 per ton, a 47% decline from the 2000 price. This stumpage price has never recovered, despite an improvement in the economy and an increase in housing starts and demand for structural timber. The reason for the continued deflated saw-timber stumpage price is a substantial surplus of supply in this catchment area.  As the forest area has matured and more saw-timber grade stands are available, markets have been able to satisfy demand without an increase in price.

Pine pulpwood prices at Cottondale were lower than the US South-wide average in 2000 and remained relatively low until around 2013. A reduction in saw-timber production, and consequent reduction in mill residuals, due to the recession of 2008, led to a shortage of pulp mill feedstock and increased harvesting of pulpwood stands. This caused an increase in pine pulpwood stumpage values alongside an overall increase in demand as biomass and pellet markets began production around this time. The data shows a short-term spike in pine pulpwood stumpage prices in 2013-14, but this returned to a more normal trend as more saw-timber residues became available and pulpwood stumpage values have been around $10-11 per ton since 2015 (Figure 9).

Figure 9: Variation in stumpage value over time

Biomass demand 

Biomass demand in the Cottondale catchment area began in 2008 and has averaged around 800 thousand m3per year since that time with a high of just over 1 million m3 in 2013 to 2015 and a low of 200 thousand m3 in 2008. Other pulpwood markets have had an average annual demand of 3.97 million m3 between 2000 and 2020 with a high of 4.76 million m3 in 2018 and a low of 3.2 million m3 in 2009.  In 2020 the biomass market represented 16% of the total pulpwood demand in the Cottondale catchment area (Figure 10).

Figure 10: Total pulpwood demand

Forest Management

The average size of clear-cut harvesting sites from 2000 to 2020 has been 47 ha, ranging from 38 ha up to 56 ha. The average size of thinning sites has been 65 ha, ranging from 55 ha up to 76 ha. When isolating the period from 2000 to 2010 and 2011 to 2020, the averages and range remain very similar, suggesting that there has been no significant change in harvesting coupe size over this period.

Figure 11: Average size of harvesting sites

The impact of biomass and wood pellet demand on the key metrics in this catchment area are considered below. This is a summary of Hood Consulting’s view on the trends and impacts in the Cottondale catchment area.

Is there any evidence that bioenergy demand has caused the following:

Deforestation?

No. US Forest Service (USFS) data shows a 55,166-hectare (+1.9%) increase in the total area of timberland in the Enviva Cottondale catchment area since the Enviva Cottondale pellet mill commenced production in 2008. Furthermore, a strong positive relationship was identified between biomass demand and timberland area, suggesting that the increase in timberland area since 2008 can be linked, to a degree, to increased demand attributed to bioenergy.

A change in management practices (rotation lengths, thinnings, conversion from hardwood to pine)?

Inconclusive. Changes in management practices have occurred in the catchment area over the last two decades. However, the evidence is inconclusive as to whether increased demand attributed to bioenergy has caused or is responsible for these changes.

Clearcuts and thinnings are the two major types of harvests that occur in this region, both of which are long-standing, widely used methods of harvesting timber. TimberMart-South (TMS) data shows that thinnings accounted for 63% of total reported harvest area in the Cottondale market from 2005-2011 but only 39% of total harvest area reported from 2012-2020. Specifically, the decreased prevalence of thinning since 2012 can be linked to the strengthening of pine pulpwood markets and concurrent weakening of pine sawtimber markets beginning in the mid-2000s.

Prior to the bursting of the US housing bubble in 2006, timber management in this market had been driven to a large degree by pine sawtimber production. However, challenging market conditions saw pine sawtimber stumpages prices decline more than 40% from 2006-2011. At the same time, pine pulpwood markets started to strengthen, with pine pulpwood stumpage prices increasing more than 50% from 2006-2010. So, with sawtimber markets weakening and pulpwood markets strengthening, the data suggests that many landowners decided to alter their management approach (i.e. to take advantage of strong pulpwood markets) and focus on short pulpwood rotations that typically do not utilize thinnings.

Bioenergy has had an impact on this market by adding an average of roughly 680,000 metric tons of additional pine pulpwood demand to this catchment area annually since 2008. However, bioenergy has accounted for only 17% of total softwood pulpwood demand in this market since Enviva Cottondale’s startup. Ultimately, the shift in management approach that occurred in this market can be more closely linked to other factors, such as increased softwood pulpwood demand from non-bioenergy sources (i.e. pulp/paper) as well as the weakening of pine sawtimber markets.

Diversion from other markets?

No. Demand for softwood (pine) sawlogs increased an estimated 23% in the Cottondale catchment area from 2008-2020. Also, there is no evidence that increased demand from bioenergy has caused a diversion from other softwood pulpwood markets (i.e. pulp/paper), as softwood pulpwood demand not attributed to bioenergy has increased 25% since the Cottondale mill’s startup in 2008.

An unexpected or abnormal increase in wood prices?

Inconclusive. The startup of Enviva Cottondale added more than 900,000 metric tons of softwood pulpwood demand to the catchment area from 2008-2013, and this increase in demand coincided with a 28% increase in the delivered price of pine pulpwood (PPW) – the primary roundwood product consumed by the Enviva Cottondale mill. However, since 2013, delivered PPW prices have held flat, despite biomass-related softwood pulpwood demand falling to an average of roughly 635,000 tons per year since 2016, down more than 40% compared to 2013 peak levels. (Note the decrease in roundwood consumption was due to a higher utilization of secondary residuals). It’s also important to point out that the roughly 410,000-metric ton decrease in softwood biomass demand from 2013 to 2020 was offset by a roughly 455,000-metric ton increase in softwood pulpwood demand from other sources.

Statistical analysis did identify a positive relationship between softwood biomass demand and delivered PPW price. However, that relationship was found to be relatively weak. The relationship between delivered PPW price and softwood pulpwood demand from other sources was found to be much stronger, which was not unexpected to find given that softwood pulpwood demand not attributed to bioenergy has accounted for 83% of total softwood pulpwood demand in the catchment area since 2008.

Furthermore, there is some evidence linking the increase in pine sawmill chip prices to increased consumption of secondary pine residuals by Enviva Cottondale. Specifically, consumption of secondary pine residuals by Enviva Cottondale more than doubled from roughly 213,000 metric tons in 2012 to nearly 490,000 metric tons in 2016, and this increased consumption of pine residuals coincided with a nearly 20% increase in the price of pine sawmill chips. However, increased consumption of residuals by the bioenergy sector was only one of several contributing factors that can be linked to the increase in pine sawmill chip prices. Increased consumption of pine residuals by the pulp/paper industry also contributed to higher pine sawmill chip prices. In addition, there is a strong linkage between pine sawmill chip prices and softwood lumber production. Specifically, the increase in softwood lumber production that begun in the early-to-mid-2010s consequently resulted in the increased production of secondary residuals, and the increased availability of this lower-cost material led to greater competition and ultimately higher pine residual prices.

A reduction in growing stock timber?

No. From 2008 (the year Enviva Cottondale commenced production) up until Hurricane Michael struck in late-2018, total growing stock inventory increased an average of 1.8% per year (+19% total) in the Cottondale catchment area. Specifically, inventories of pine sawtimber and pine chip-n-saw increased 58% and 28%, respectively, while pine pulpwood (PPW) inventory decreased 4% over this same period.

However, note that the decrease in pine pulpwood inventory from 2008-2018 was not due to increased demand from bioenergy or increased harvesting above the sustainable yield capacity of the forest area, as annual growth of pine pulpwood exceeded annual removals every year throughout this period. Rather, this slight decrease in PPW inventory levels is more a reflection of the aging of the catchment area forest and the movement of stands classified as pulpwood to stands classified as chip-n-saw.

A reduction in the sequestration rate of carbon?

No. US Forest Service (USFS) data shows the average annual growth rate of total growing stock timber in the Cottondale catchment area decreased from 5.9% in 2008 to 5.2% in 2020, suggesting that the sequestration rate of carbon also declined slightly over this period. However, there is little evidence to suggest that increased demand attributed to bioenergy is responsible for this change.

The reduction in overall growth rate (and therefore reduction in the sequestration rate of carbon) is more a reflection of the aging of the catchment area forest. Specifically, growth rates decline as timber ages, and this is exactly what USFS data shows in the Cottondale catchment area, with the average age of growing stock timber increasing from less than 44 years of age in 2008 to nearly 46 years of age in 2020.

An increase in harvesting above the sustainable yield capacity of the forest area?

No. Growth-to-removals (G:R) ratios, which compare annual timber growth to annual timber removals, provides a measure of market demand relative to supply as well as a gauge of market sustainability. In 2020, the latest available, the G:R ratio for pine pulpwood (PPW), the predominant timber product utilized by the bioenergy sector, equaled 1.26 (recall that a value greater than 1.0 indicates sustainable harvest levels).

Note, however, that the PPW G:R ratio averaged 1.57 in the catchment area from 2013-2017 before falling to 1.20 in 2018 and averaging 1.27 since. This notable drop in 2018 was due to a nearly 35% increase in PPW removals (due to Hurricane Michael). It’s also important to note that while annual removals have moved back in line with pre-Michael levels since 2019, this lower PPW G:R ratio is likely reflective of the new norm (at least over the midterm). Hurricane Michael destroyed an estimated 22% of total pine pulpwood inventory in the Cottondale catchment area, and this loss in inventory will be reflected in reduced growth until the destroyed forests regenerate. However, in spite of this loss, adequate PPW inventory levels still remain and sustainable market conditions are expected to persist moving forward.

Timber growing stock inventory

Neutral. According to USFS data, inventories of pine pulpwood (PPW) decreased 25% in the catchment area from 2008-2020. However, this substantial decrease was due to Hurricane Michael, which destroyed nearly 520,000 hectares of catchment area timberland when it hit the Florida panhandle in late-2018. Prior to this event occurring, PPW inventory levels had held relatively steady, decreasing slightly but averaging 47.2 million m3 in the catchment area from 2008-2018. However, the destruction caused by Hurricane Michael resulted in the immediate loss of more than 10.3 million m3 of PPW inventory, or a 22% decrease compared to pre-hurricane levels.

Moreover, the slight decrease in PPW inventory levels that did occur from 2008-2018 was not due to increased demand from bioenergy. Typically, a reduction in inventory is linked to harvest levels above the sustainable yield capacity of the forest area, but in the Cottondale catchment area, annual growth of PPW exceeded annual removals every year throughout this period. Ultimately, the decrease in PPW inventory from 2008-2018 can be more closely linked to decreased pine sawtimber production beginning in the early to mid-2000s. Specifically, annual removals of pine sawtimber decreased 28% from 2003-2014, and the reduction in harvest levels over this period translated to a reduction in newly-re-established pine stands and ultimately the slight reduction in PPW inventory levels that occurred in the mid-to-late 2010s.

Timber growth rates

Neutral. Overall, timber growth rates declined slightly in the catchment area from 2008 (the year Enviva Cottondale commenced operations) through 2020. However, this decrease in timber growth rates was not due to increased demand attributed to bioenergy but rather to the aging of the catchment area forest. Specifically, USFS data shows the average age timber inventory in the Cottondale catchment area increased from an estimated 43.6 years of age in 2008 to 45.7 years of age in 2020.

Forest area

Positive. In the Enviva Cottondale catchment area, total forest area (i.e. timberland) increased more than 55,100 hectares (+1.9%) from 2008 through 2020, and this increase can be linked to several factors, including increases in softwood pulpwood demand (from both bioenergy and other sources) as well as conversion from farmland.

Specifically, the more than 55,100-hectare increase in catchment area timberland from 2008-2020 coincided with a 1.1-million metric ton increase in annual softwood pulpwood demand (roughly half of which was attributed to bioenergy). While statistical analysis identified moderately strong positive relationships between timberland area and both softwood biomass demand and non-bioenergy-related softwood pulpwood demand, a strong positive correlation was found between timberland and total softwood pulpwood demand – suggesting that the increases in timberland since 2008 can be attributed, in part, to the increase in total softwood pulpwood demand (from both bioenergy and other sources).

The more than 55,100-hectare increase timberland from 2008-2020 also coincided with a roughly 75,000-hectare decrease in farmland (i.e. cropland, woodland, and pastureland) over this period. Specifically, the catchment area experienced a roughly 31,800-hectare loss in cropland, 8,900-hectare loss in pastureland, and 34,300-hectare loss in woodland from 2008-2020. Furthermore, statistical analysis confirmed this inverse relationship, identifying a strong negative correlation between timberland and farmland in the Cottondale catchment area.

Wood prices

Negative / Positive. Total softwood pulpwood demand attributed to bioenergy in the Cottondale catchment area increased from zero tons in 2007 (the year prior to Enviva Cottondale’s startup) to over 1.0 million metric tons in 2013. Over this same period, the price of delivered pine pulpwood (PPW) – the predominant roundwood product utilized by Enviva Cottondale for wood pellet production – increased 42% (from $21.06 per ton in 2007 to $29.82 per ton in 2013).

However, the apparent link between increased softwood biomass demand and increased delivered PPW price is only loosely supported by statistical analysis, which identified a relatively weak positive relationship between these two variables. Furthermore, delivered PPW price has remained nearly unchanged in the catchment area since 2013, despite softwood biomass demand declining and averaging roughly 577,000 metric tons per year since 2016. (Note that the roughly 410,000-metric ton decrease in softwood biomass demand from 2013-2020 was offset by a roughly 455,000-metric ton increase in softwood pulpwood demand from other sources). Ultimately, the increase in delivered PPW prices in the catchment area can be linked to increased demand for softwood pulpwood from all sources, and roughly half of the 1.2-million metric ton increase in softwood pulpwood demand since 2007 can be attributed to bioenergy.

However, it’s also important to note that the increase in bioenergy-related wood demand has been a positive for forest landowners in the Enviva Cottondale catchment area. Not only has bioenergy provided an additional outlet for pulpwood in this market, but the increase in delivered PPW price resulting from increased softwood pulpwood demand from bioenergy has transferred through to landowners in the form of higher PPW stumpage prices. Specifically, over the six years prior to Enviva Cottondale’s startup, PPW stumpage price – the price paid to landowners – averaged roughly $7.40 per ton in the Cottondale catchment area. However, since 2010, PPW stumpage prices have averaged more than $11.15 per ton, representing a more than 50% increase compared to pre-mill startup levels.

Markets for solid wood products

Positive. In the Enviva Cottondale catchment area, demand for softwood sawlogs used to produce lumber and other solid wood products increased an estimated 23% from 2008-2020. This increase in softwood lumber production has consequentially resulted in an increase in sawmill residuals (i.e. chips, sawdust, and shavings) – by-products of the sawmilling process and materials utilized by Enviva Cottondale to produce wood pellets.

Specifically, softwood sawlog demand has increased more than 16% in the catchment area since 2014, and this increase in demand has coincided with a nearly 60% increase in pine residual purchases by Enviva Cottondale. (Note that pine residuals constituted 25% of total raw material purchases by Enviva Cottondale in 2014 but 41% of total raw material purchases in 2020). So, not only has Enviva Cottondale benefited from the greater availability of this sawmill by-product, but lumber producers have also benefited, as Enviva Cottondale has provided an additional outlet for these producers and their by-products.

Read the full report: Enviva Cottondale pellet plant catchment area analysis

This is part of a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. Others in the series can be found here

Evaluating regrowth post-harvest with accurate data and satellite imagery

  • Drax has been using effective post-harvest evaluations, which includes remote sensing technology and satellite imagery

  • Alongside sustainable forest management, monitoring can help support rapid regrowth after harvesting

  • Evidence shows healthy managed forests with no signs of deforestation or degradation

As part of Drax’s world-leading programme of demonstrating biomass sustainability, including ongoing work on catchment area analysis (CAA), responsible sourcing policy and healthy forest landscapes (HFL). We have also been trialling the use of high-resolution satellite imagery to monitor forest conditions on specific harvesting sites in the years after harvesting has taken place, in addition to the catchment area level monitoring of trends and data. Post-harvest evaluations (PHE) are an essential part of an ongoing sustainability monitoring process, ensuring that the future forest resource is protected and maintained and that landowners restore forests after harvesting to prevent deforestation or degradation.

The most effective form of PHE is for an experienced local forester to walk and survey the harvesting site to check that new trees are growing and that the health and quality of the young replacement forest is maintained.

Rapid regrowth

The images below show some of the sites surrounding Drax’s Amite Bioenergy pellet plant in Mississippi, with trees at various stages of regrowth in the years after harvesting.

A full site inspection can therefore enable a forester to determine whether the quantity and distribution of healthy trees is sufficient to make a productive forest, equivalent to the area that was harvested. It can also identify if there are any health problems, pest damage or management issues such as  weed growth or water-logging that should be resolved.

Typically, this will be the responsibility of the forest owner or their forest manager and is a regular part of ongoing forest management activity. This degree of survey and assessment is not practical or cost-effective where a third-party consumer of wood fibre purchases a small proportion (typically 20-25 tonnes per acre) of the low-grade fibre produced at a harvest as a one-off transaction for its wood pellet plant..  It is time consuming to walk every acre of restocked forest and it is not always possible to get an owner’s permission to access their land.

Forests from space

Therefore, an alternative methodology is required to make an assessment about the condition of forest lands that have been harvested to supply biomass, without the need to physically inspect each site.  One option is to use remote sensing and satellite imagery to view each harvested site in the years after biomass sourcing, this helps to monitor restocking and new tree growth.

Drax has been testing the remote sensing approach using Maxar’s commercial satellite imagery.  Maxar has four satellites on orbit that collect more than three million square kilometres of high-resolution imagery every day. Drax accesses this imagery through Maxar’s subscription service SecureWatch.

To test the viability of this methodology, Drax has been looking at harvesting sites in Mississippi that supplied biomass to the Amite Bioenergy pellet plant in 2015 and in 2017.  As part of the sustainability checks that are carried out prior to purchasing wood fibre, Drax collects information on each harvesting tract. This includes the location of the site, the type of harvest, the owner’s long-term management intentions and species and volume details.

This data can then be used at a later date to revisit the site and monitor the condition of the area. Third-party auditors, for instance Through Sustainable Biomass Program (SBP) certification, do visit harvesting sites, however this is typically during the year of harvest rather than after restocking. Maxar has historical imagery of this region from 2010, which is prior to any harvesting for wood pellets.  The image below shows a harvesting site near the pellet plant at Gloster, Mississippi, before any harvesting has taken place.

March 2010 (100m)

Satellite image © 2021 Maxar Technologies.

The image below shows the same site in 2017 immediately following harvesting.

December 2017 (100m)

Satellite image © 2021 Maxar Technologies.

If we look again at this same site three years after harvesting, we can see the rows of trees that have been planted and the quality of the regrowth. This series of images demonstrates that this harvested area has remained a forest, has not been subject to deforestation and that the regrowth appears to be healthy at this stage.

August 2020 (50m)

Satellite image © 2021 Maxar Technologies.

Another site in the Amite catchment area is shown below. The image shows a mature forest prior to harvesting, the site has been previously thinned as can be seen from the thinned rows that are evident in the imagery.

May 2010 (200m)

Satellite image © 2021 Maxar Technologies.

Looking at the same site in the year after harvesting, the clear cut area can be seen clearly. Some green vegetation cover can also be seen on the harvested area, but this is weed growth rather than replanted trees. Some areas of mature trees have been left at the time of harvesting, and are visible as a grey colour in the 2010 image. These are likely to be streamside management zones that have been left to maintain biodiversity and to protect water quality, with the grey winter colouring suggesting that they are hardwoods.

September 2018 (200m)

Satellite image © 2021 Maxar Technologies.

Three years after the harvest, in a zoomed in view from the previous image, clear rows of replanted trees can be seen in the imagery.  This demonstrates that the owner has successfully restocked the forest area and that the newly planted forest appears healthy and well established.

August 2020 (50m)

Satellite image © 2021 Maxar Technologies.

While examining different harvesting sites in satellite imagery, Drax noted that not every site had evidence of tree growth, particularly within the first three years after harvesting. Deliberate conversion of land to non-forest use, such as for conversion to pasture, agricultural crops or urban development, is likely to be evident fairly soon after harvesting.

Preparing for planting

Some forest owners like to leave a harvested site unplanted for a couple of years to allow ground vegetation and weed growth to establish, this can then be treated to ensure that trees can be planted and that the weed growth does not impede the establishment of the new forest, this process can mean that trees are not visible in satellite imagery for three to four years after harvesting.

The image below shows a site three years after harvesting with no evidence of tree growth.  Given that no conversion of land use is evident and that the site appears to be clear of weed growth, this is likely to be an example of where the owners have waited to clear the site of weeds prior to replanting.  This site can be monitored in future imagery from the Maxar satellites to ensure that forest regrowth does take place.

November 2020 (100m)

Satellite image © 2021 Maxar Technologies.

Drax will continue to use Maxar’s SecureWatch platform to monitor the regrowth of harvesting sites and will publish more detailed results and analysis when this process has been developed further.  The platform allows ongoing comparison of a site over time and could prove a more efficient method of analysis than ground survey.  In conjunction with the CAA and HFL work, PHE can add remote sensing as a valuable monitoring and evidence-gathering tool to demonstrate robust biomass sustainability standards and a positive environmental impact.

Go deeper: 

Discover the steps we take to ensure our wood pellet supply chain is better for our forests, our planet and our future here, how to plant more trees and better manage them, our responsible sourcing policy for biomass from sustainable forests and a guide to sustainable forest management of the Southern Working Forest.

Georgia Mill Cluster catchment area analysis

Forest in LaSalle catchment area

The seventh report in a series of catchment area analyses for Drax looks at the fibre sourcing area surrounding a number of compressed wood pellet plants operated by Georgia Biomass (now owned by Enviva) and Fram Renewable Fuels.

The evidence found in the report by Hood Consulting shows a substantial increase in forest inventory (stored carbon) and a relatively stable forest area. However, with continued pressure from urban development, future losses of timberland area are possible.  Despite this, increasing growth rates can maintain and improve wood supply and carbon stock for the foreseeable future.

Increasing forest growing stock and carbon sequestration

The overall inventory of growing stock in the catchment area has increased by 63 million cubic metres (m3) between 2000 and 2018, a growth of 19.3%.  All of this increase has been in the pine area, which increased by nearly 68 million m3, whereas the hardwood species decreased in volume by 4.5 million m3. Overall, the inventory volume split by species in 2018 was 72% to 28% softwood to hardwood. The breakdown by product category is shown in Figure 3 below.

Figure 1: Change in growing stock by major product category and species (USFS)

The pine saw-timber and chip-n-saw product categories, larger dimension and higher value material, showed the largest increase in inventory, whereas pine pulpwood decreased in total volume.  The most substantial change occurred from 2010 to 2018, where pulpwood went from an increasing trend to a decreasing trend and saw-timber increased in volume much more rapidly – this is shown in Table 1 and Figure 2 below.

Change (cubic metres (m3))Pine SawtimberPine Chip-n-sawPine PulpwoodHardwood SawtimberHardwood PulpwoodTotal
2000-201851,301,62822,277,139-5,835,2301,211,110-5,657,11463,297,533
2000-201014,722,99512,707,6745,262,192-3,740,507-5,76989923,182,455
2010-201836,578,6329,569,465-11,097,4224,951,618112,78440,115078
Table 1: Change in growing stock volume by major product category (USFS)

These changes are likely to reflect an increasing age class in the catchment area, with younger stands of pine (previously classed as pulpwood), growing into a larger size class and being reclassified as saw-timber.  This means that the volume of saw-timber availability in future will be significantly higher, but pulpwood availability will be diminished.  For pellet mill markets any loss in pulpwood availability can be compensated by an increase in sawmill residue production if market demand is maintained or increased.

Figure 2: Change in growing stock by major product category and species (USFS)

Growth rates for both softwood and hardwood species have been increasing since 2000 as shown in Figure 3 below. Softwood growth has increased by 18.5% since 2000 and hardwood by 1.4%. The improved softwood growth rate probably resulted from increased investment in the management of pine forests, the superior quality of seedlings and better management practice (ground preparation, weed control, fertilisation etc.). This is a very positive trend for the sequestration rate of carbon and also for providing landowners with the potential to increase revenue per hectare and encourage the retention and improved management of forests, rather than converting to other land uses. The Georgia catchment area is likely split between passive owners that do not actively manage, where growth rates are slower or decline and the incentive to convert land is greater, and owners that actively manage to improve growth and quality, increasing revenue and maintaining productive forest.  There is likely to be a much greater differential in growth rate between these two management approaches than reflected by the trend in Figure 3, highlighting the importance of active management for carbon abatement.

Average annual growth rate per hectare (USFS)

Figure 3: Average annual growth rate per hectare (USFS)

Stable forest area

At a macro scale, the distribution of land use categories has remained relatively stable since 2000, with no apparent major shifts in land use. The timberland area around the seven mills has decreased by around 135 thousand hectares (ha) between 2000 and 2018 (2.3% of the total land area), whilst the area of arable and urban land increased by 98 thousand (1.7% of total area) and 158 thousand (2.7% of total area) ha respectively.  In 2018, timberland represented 67% of total land area and all forest and woodland 80% of total area, down from 69% and 82% respectively in 2000 (Figure 1).

Change in land use category (USDA)

Figure 4: Change in land use category (USDA)

Looking at this change in land use more closely, the timberland area shows the most pronounced decline between 2010 and 2018, a drop of 117 thousand ha. The largest change in other land use categories over this period was an increase of 97 thousand ha in urban and other land, suggesting that a large proportion of the timberland area has been converted to urban areas.

LaSalle Bioenergy forest area

The most significant change in agricultural land occurred prior to 2010, when the timberland area remained relatively stable, this change appears to have involved the transition of pastureland to arable crops. There may also have been some reclassification of forest and woodland types, with a decrease in the area of woodland and an increase in forestland during the period between 2000 and 2010 (Table 2).

Change (hectares (ha))TimberlandOther ForestlandArable CroplandWoodlandPasturelandUrban & Other Land
2000-2018-135,19570,07398,436-77,904-113,725178,315
2000-2010-18,53953,15073,243-73,077-95,63060,852
2010-2018-116,65616,92225,193-4,827-18,09697,463
Table 2: Timing of land use change in Georgia catchment area (USDA)

These trends are also clear and apparent in Figure 3 below which shows the sharp decline in timberland area, albeit small in absolute area relative to the total catchment area size, and the steady increase in urban land.  Georgia ranks 8th in the list of US States and territories by total population with 10.6 million and 17th by population density at 184 per square mile (mi2) compared to just 63 per mi2  in Mississippi where Drax’s Amite Bioenergy (ABE) pellet plant is located and 108 per mi2 in Louisiana where the Morehouse Bioenergy (MBE) and LaSalle Bioenergy (LBE) mills are located (US Census Bureau). This population pressure and increased development can lead to more forest loss and land use change.

Trends in major land use categories (USDA)

Figure 5: Trends in major land use categories (USDA)

Drax’s suppliers in the Georgia catchment area have made a commitment not to source wood from areas where land use change is taking place. This commitment is monitored and verified through the Sustainable Biomass Program (SBP) certification process that is maintained by each mill.  Any land use change in the catchment area is likely to be a result of prevailing economic drivers in the region rather than due to actions being taken by the pellet producers.

Increasing demand and surplus forest growth

Strong markets are essential for ensuring that forests are managed and restocked to optimum benefit, sawlog markets are particularly important as this is highest revenue stream for forest owners. Figure 6 shows the trend in market demand for each major product category since 2000 and demonstrates the recent increase in softwood sawlog demand as the US economy (particularly housing starts) recovered from the global recession at the end of the last decade. Softwood pulpwood demand increased through the 2000s but has remained relatively stable since 2011, with the exception of a peak during 2018 which resulted from an increase in volume generated by salvage operations after hurricane Michael.

Figure 6: Demand for wood products (USFS, TMS)

Figure 6: Demand for wood products (USFS, TMS)

The comparison of average annual growth and removals in the Georgia catchment area is much more tightly balance than in Drax’s other supply regions, as shown in Figure 7. Since 2000 the average annual surplus of growth has been around 3.6 million m3 with both demand and growth increasing in recent years.

Figure 7: Average annual growth, removals and surplus (USFS)

Figure 7: Average annual growth, removals and surplus (USFS)

As shown in Figures 2 & 3, growth rates are strong and inventory is increasing, this is not a problem in the Georgia area.  The relatively small surplus, as compared to other catchment areas in the US South, is due to the higher concentration of wood fibre markets and the more intense forest industry activity in this region.  As of July 2020, there were over 50 major wood-consuming mills operating within the Georgia catchment area and an additional 80+ mills operating within close proximity, overlapping the catchment area.  Total pulpwood demand in 2019 was 12.9 million tons, of which approximately 87% was attributed to non‐bioenergy‐related sources (predominantly pulp/paper) and 13% was attributed to the bioenergy sector.  Given the bio-energy sector’s low ranking position in the market (with the lowest ability to pay for fibre), combined with the relatively small scale in demand compared to the pulp and paper industry, the influence of biomass markets can be considered to be minimal in this region, particular when it comes to impacts on wood prices and forest management practice.

Wood price trends

Pine sawtimber prices suffered a significant decline between 2000 and 2010, dropping almost $21 per ton as a result of the global financial crisis and the decline in demand due to the collapse in housing markets and construction (Table 3).  Since 2010 pine sawtimber has remained relatively stable, with some minor fluctuations shown in Figure 8 below.

Change ($/ton)Pine SawtimberPine Chip-n-sawPine PulpwoodHardwood SawtimberHardwood Pulpwood
2000-2019-$20.92$15.14$5.95$12.55$4.70
2000-2010-$20.92-$21.41$2.11$11.25$5.67
2010-2019$0.00$6.27$3.84$1.30-$0.97
Table 3: Stumpage price trends (TMS)

Pine pulpwood prices have been on a generally increasing trend since 2000, with a more significant increase since 2011.  This increase does not reflect an increase in demand or total volume, which has remained relatively stable over this period, but a shifting of the geographic distribution of the market with some new mills opening and old mills closing, resulting in increased competition in some localised fibre baskets and leading to an overall increase in stumpage price.

Figure 8: Stumpage price trends (TMS)

Figure 8: Stumpage price trends (TMS)

Figure 9 below shows that, with the exception of the hurricane salvage volume in 2018, pulpwood removals have declined or remained relatively stable since 2010, whereas pulpwood stumpage prices increased by 41% from 2010 to 2018.

Figure 9: Pulpwood demand and stumpage price (USFS, TMS)

Figure 9: Pulpwood demand and stumpage price (USFS, TMS)

Comparing this stumpage price trend with other catchment areas of the US South (Figure 10), where Drax sources wood pellets, the Georgia area is on average 35% higher than the next highest area (Chesapeake) and 87% higher than the lowest cost area (Amite Bioenergy in Mississippi).  This price differential is predominantly due to the scale of demand and availability of surplus low-grade fibre.

Figure 10: Comparison of pine pulpwood stumpage prices in Drax supply areas US South (TMS)

Figure 10: Comparison of pine pulpwood stumpage prices in Drax supply areas US South (TMS)

Hood Consulting summary of the impact of the seven pellet plants on key trends and metrics in this catchment area.

Is there any evidence that bioenergy demand has caused the following…

Deforestation?

No. US Forest Service (USFS) data shows a 108,130-hectare (-2.6%) decrease in total timberland in the Georgia catchment area since Georgia Biomass’ first full year of production in 2012. Specifically, this loss in total area of timberland coincided with a more than 21,000-hectare increase in cropland/pastureland and a more than 73,000-hectare increase in urban land and land classified as having other uses.

However, there is little evidence to suggest that increased wood demand from the bioenergy sector has caused this decrease in total timberland. Furthermore, pine timberland – the primary source of roundwood utilized by the bioenergy industry – has increased more than 17,000 hectares in the catchment area since 2016.

A change in management practices (rotation lengths, thinnings, conversion from hardwood to pine)?

No. Changes in management practices have occurred in the catchment area over the last two decades. However, there is little evidence to suggest that bioenergy demand, which accounts for roughly 10-14% of total pulpwood demand (and only 5-7% of total wood demand in the catchment area), has caused or is responsible for these changes.

Clearcuts and thinnings are the two major types of harvests that occur in this region, both of which are long-standing, widely used methods of harvesting timber. TimberMart-South (TMS) data shows that thinnings accounted for 67% of total reported harvest area in the southeast Georgia market from 2000-2010, but only 43% of total harvest area reported from 2012-2019. Specifically, this downward shift was initiated by the bursting of the US housing bubble in the mid-2000s and had been completed by the early 2010s. We’d like to note that this shift coincided with a nearly 50% decrease in pine sawtimber stumpage price from 2006-2012. This is important because the strength of pine sawtimber markets had been a driving force behind timber management decisions in this region in the early and mid-2000s.

Also, contributing to the decreased prevalence of thinnings was the strengthening of pine pulpwood markets in the mid-2000s, as pine pulpwood stumpage prices increased more than 40% in the Georgia catchment area from 2003-2008. So, with sawtimber markets continuing to weaken and pulpwood markets doing just the opposite, the data suggests that many landowners decided to alter their management approach (to take advantage of strong pulpwood markets) and focus on short pulpwood rotations that typically do not utilize thinnings.

Ultimately, the shift in management approach that occurred in this market can be linked to the weakening of one type of timber market and the strengthening of another. In the early and mid-2000s, timber management was focused on sawtimber production – a type of management that utilizes thinnings. However, for more than a decade now, this market has been driven to a large degree by the pulp/paper industry, with a significant portion of the timber management in this area focused on short pulpwood rotations.

Diversion from other markets?

No. Demand for softwood (pine) sawlogs increased an estimated 39% in the Georgia catchment area from 2011-2019. Also, increased bioenergy demand has caused no diversion from other pulpwood markets (i.e. pulp/paper), as pulpwood demand not attributed to bioenergy held steady and remained nearly unchanged from 2012-2017 before increasing in 2018 and 2019 due to the influx of salvage wood brought about by Hurricane Michael.

We’d like to make special note that increased demand for softwood sawlogs since 2011 has not resulted in a full pine sawtimber (PST) stumpage price recovery in this market. Reduced demand for softwood sawlogs in the late 2000s and early 2010s resulted in oversupply, and this oversupply has remained, despite increased demand the last 6-8 years. As a result, PST stumpage prices have held steady and averaged roughly $30 per ton in the catchment area since 2013 – down approximately 35% from the 2000-2006 average of more than $46 per ton, but up roughly 15% from the 2011-2012 average of approximately $26 per ton.

An unexpected or abnormal increase in wood prices?

No / Inconclusive. The delivered price of pine pulpwood (PPW) – the primary roundwood product consumed by both Georgia Biomass and Fram – increased 26% in the Georgia catchment area over the six years directly following the startup of Georgia Biomass, increasing from $29.16 per ton in 2011 to $36.63 per ton in 2017. And while this 26% increase in delivered PPW price coincided with a roughly 1.1 million metric ton increase in annual pine pulpwood demand from Georgia Biomass and Fram, total demand for pine pulpwood (from both bioenergy and other sources) actually decreased 7% over this period. Moreover, evidence suggest that this increase in PPW price is more closely linked to changes in wood supply, specifically, the 9% decrease in PPW inventory from 2011-2017.

However, there is evidence that links increased demand from the bioenergy sector to an increase in secondary residual (i.e. sawmill chips, sawdust, and shavings) prices. Specifically, the price of pine sawmill chips – a residual feedstock utilized by the bioenergy industry for wood pellet production – held steady and averaged approximately $26 per ton in the Georgia catchment area from 2008-2012. However, from 2012-2016, pine sawmill chip prices increased more than 15% (to $29.55 per ton in 2016). This increase in price coincided with annual pine residual feedstock purchases by Georgia Biomass and Fram increasing from roughly 325,000 metric tons to nearly 1.0 million metric tons over this period. However, note that pine sawmill chip prices have held steady and averaged roughly $29.50 per ton in the catchment area since 2016, despite further increases in pine secondary residual purchases by Georgia Biomass and Fram (to more than 1.2 million metric tons in 2019).

Ultimately, the data suggests that any excess supply of pine secondary residuals in the catchment area was absorbed by the bioenergy sector in the early and mid-2010s, and the additional demand/competition placed on this market led to increased residual prices. However, the plateauing of residual prices since 2015 along with the continued increase in secondary residual purchases by Georgia Biomass and Fram further suggest that an increasing percentage of secondary residual purchases by the bioenergy sector is sourced from outside the catchment area. Specifically, Fram confirmed this notion, noting that 35-40% of its secondary residual purchases come from outside the Georgia catchment area (from six different states in the US South).

A reduction in growing stock timber?

No. Total growing stock inventory in the catchment area increased 11% from 2011 through 2018, the latest available. Specifically, over this period, inventories of pine sawtimber and chip-n-saw increased 35% and 13%, respectively. However, pine pulpwood inventory decreased 11% from 2011-2018.

Note that the decrease in pine pulpwood inventory was not due to increased demand from bioenergy (or other sources) or increased harvesting above the sustainable yield capacity of the forest area – as annual growth of pine pulpwood has exceeded annual removals every year since 2011. Rather, this decrease can be linked to the 24% decline in pine sawtimber removals that occurred from 2005-2014 (due to the bursting of the US housing bubble and Great Recession that followed). In this region, timber is typically harvested via clearcut once it reaches maturity (i.e. sawtimber grade), after which the stand is reestablished, and the cycle repeated. However, with the reduced harvest levels during this period also came a reduction in newly reestablished timber stands – the source of pine pulpwood. So, with less replantings occurring during this period, inventories of pine pulpwood were not replenished to the same degree they had been previously, and therefore this catchment area saw a reduction in pine pulpwood inventory levels.

However, according to the US Forest Service, annual removals of pine sawtimber have increased 50% in the Georgia catchment area since 2014, which would suggest higher clearcut levels and increased stand reestablishment. TimberMart-South data also supports this assertion, as clearcut harvests have constituted approximately 60% of the total harvest area reported to TimberMart-South in this region since 2014, compared to 40% from 2005-2014. Ultimately, these increases in clearcut (and stand reestablishment) levels may not be reflected in increased pine pulpwood inventory levels in the short term – as it can take more than 10 years for a pine seedling to become merchantable and reach the minimum diameter requirements to be classified as pulpwood. However, adequate supply levels are expected to remain in the meantime. Furthermore, pine pulpwood inventory levels are expected to increase in the mid-to-long terms as a result of the increased harvest levels and stand reestablishment levels that have occurred in the catchment area since 2014.

A reduction in the sequestration rate of carbon?

No / Inconclusive. US Forest Service data shows the average annual growth rate of total growing stock timber has remained nearly unchanged (holding between 6.0% and 6.1%) in the catchment area since 2011, which would suggest that the sequestration rate of carbon has also changed very little in the catchment area the last 8-10 years. However, the 11% increase in total growing stock inventory since 2011 does indicate that total carbon storage levels have increased in the Georgia catchment area since Georgia Biomass commenced operations in this market.

An increase in harvesting above the sustainable yield capacity of the forest area?

No. Growth-to-removals (G:R) ratios, which compare annual timber growth to annual harvests, provides a measure of market demand relative to supply as well as a gauge of market sustainability. In 2018, the latest available, the G:R ratio for pine pulpwood, the predominant timber product utilized by the bioenergy sector, equaled 1.06 (a value greater than 1.0 indicates sustainable harvest levels). Note, however, that the pine pulpwood G:R ratio averaged 1.44 from 2012-2017. The significant drop in 2018 was due to a 31% increase in removals (due to Hurricane Michael) and is not reflective of the new norm. Specifically, pine pulpwood removals are projected to be more in line with pre-2018 levels in 2019 and 2020, and so too is the pine pulpwood G:R ratio.

Timber growing stock inventory

Neutral. According to USFS data, inventories of pine pulpwood decreased 11% in the catchment area from 2011-2018. However, that decrease was not due to increased demand from bioenergy. Typically, a reduction in inventory is linked to harvest levels above the sustainable yield capacity of the forest area, but in this case, annual growth of pine pulpwood exceeded annual removals every year during this period.

Ultimately, the decrease in pine pulpwood inventory from 2011-2018 can be linked to decreased pine sawtimber production beginning in the mid-2000s. Specifically, annual removals of pine sawtimber decreased 24% from 2005-2014, and the reduction in harvest levels during this period meant fewer new pine stands were reestablished, and that has led to the current reduction in pine pulpwood inventory. (Note that the decrease in pine sawtimber removals from 2005-2014 was mirrored by a 27% increase in pine sawtimber inventory over this same period). However, USFS data shows that annual removals of pine sawtimber have increased 50% in the Georgia catchment area since 2014, which suggests that pine pulpwood inventory levels will start to increase in the catchment area due to increased harvest levels and the subsequent increase in stand reestablishment levels.

Timber growth rates

Neutral. Timber growth rates have increased for both pine sawtimber and pine chip-n-saw but decreased slightly for pine pulpwood in the catchment area since 2011. Evidence suggests that this decrease in pine pulpwood growth rate is not due to increases in bioenergy demand, but rather linked to changes in diameter class distribution and indicative of a forest in a state of transition, where timber is moving up in product class (i.e. pine pulpwood is moving up in classification to pine chip-n-saw).

Forest area

Neutral. In the Georgia catchment area, total forest area (timberland) decreased more than 115,000 hectares (-2.8%) from 2011 through 2018. Note that this decrease coincided with a roughly 19,000-hectare increase in cropland and 93,000-hectare increase in urban land and land classified as having other uses.

Specifically, pine timberland, the primary source of roundwood utilized by the bioenergy industry, decreased over 34,000 hectares from 2011-2016. However, from 2016-2018, pine timberland stabilized and rather increased more than 17,000 hectares in the catchment area (or a net decrease of roughly 17,000 hectares from 2011-2018). Ultimately, there is little evidence that the decrease in pine timberland from 2011-2016 or increase since 2016 is linked to increased bioenergy demand. Rather, the overall decrease in pine timberland since 2011 appears to be more closely linked to the relative weakness of pine sawtimber markets in the Georgia catchment area and the lack of return from sawtimber.

Wood prices

Positive / Negative. Intuitively, an increase in demand should result in an increase in price, and this is what the data shows in the Georgia catchment area as it relates to increased biomass demand from Georgia Biomass and Fram and the prices of the various raw materials consumed by these mills. Specifically, the 1.4-million metric ton increase in softwood pulpwood demand attributed to Georgia Biomass and Fram coincided with a 20% increase in delivered pine pulpwood price and a 10-15% increase in pine chip prices from 2011-2015. Since 2015, biomass demand has held relatively steady, and, overall, so too have delivered pine pulpwood and pine chip prices. The apparent link between increased bioenergy demand and increased pine raw material prices is supported further by statistical analysis, as strong positive correlations were found between softwood biomass demand and both delivered pine pulpwood and pine chip prices. However, note that biomass demand alone is not responsible for these changes in prices, as softwood biomass demand accounts for only 10-15% of total softwood pulpwood demand in the catchment area. Rather, the prices of these raw materials are impacted to a larger degree by demand from other sources (i.e. pulp/paper), which accounts for 85-90% of total softwood pulpwood demand in the Georgia catchment area.

On the other hand, it’s also important to note that the increase in bioenergy-related wood demand has been a positive for forest landowners in the Georgia catchment area. Not only has bioenergy provided an additional outlet for pulpwood in this market, but the increase in pulpwood prices as a result of increased pulpwood demand has transferred through to landowners (improved compensation). Specifically, since 2015, pine pulpwood (PPW) stumpage price – the price paid to landowners – has averaged more than $17 per ton in the Georgia catchment area. This represents a 70% increase over the approximately $10 per ton averaged by PPW stumpage in the catchment area over the last five years prior to Georgia Biomass’ startup in 2Q 2011.

(Note: Pine pulpwood stumpage prices are notably higher in the Georgia catchment area due to a much tighter balance in supply and demand (in comparison to most other markets across the US South). For instance, in all other areas across the US South2, PPW stumpage prices have averaged less than $9 per ton since 2015, or roughly half that of prices in the Georgia catchment area).

Markets for solid wood products

Positive. In the Georgia catchment area, demand for softwood sawlogs used to produce lumber and other solid wood products increased an estimated 39% from 2011-2019, and by-products of the sawmilling process are sawmill residuals – materials utilized by Georgia Biomass and the Fram mills to produce wood pellets. With the increased production of softwood lumber, so too has come an increase in sawmill residuals, some of which have been purchased/consumed by Georgia Biomass and Fram. Not only have these pellet producers benefited from the greater availability of this by-product, but lumber producers have also benefited, as the Georgia Biomass and Fram mills have provided an additional outlet for these producers and their by-products.

Read the full report: Georgia Biomass Catchment Area Analysis.

This is part of a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. Others in the series include: ChesapeakeEstonia, Latvia and Drax’s own, other three mills LaSalle BionergyMorehouse Bioenergy and Amite Bioenergy.

What is biomass?

Illustration of a working forest supplying biomass

What is biomass?

In ecological terms, biomass refers to any type of organic matter. When it comes to energy, biomass is any organic matter that can be used to generate energy, for example wood, forest residues or plant materials.

How is biomass used?  

Biomass used and combusted for energy can come in a number of different forms, ranging from compressed wood pellets – which are used in power stations that have upgraded from coal – to biogas and biofuels, a liquid fuel that can be used to replace fossil fuels in transport.

The term biomass also refers to any type of organic material used for energy in domestic settings, for example wood burned in wood stoves and wood pellets used in domestic biomass boilers.

Biomass is organic matter like wood, forest residues or plant material, that is used to generate energy.

Where does biomass come from?

Biomass can be produced from different sources including agricultural or forestry residues, dedicated energy crops or waste products such as uneaten food.

Drax Power Station uses compressed wood pellets sourced from sustainably managed working forests in the US, Canada, Europe and Brazil, and are largely made up of low-grade wood produced as a byproduct of the production and processing of higher value wood products, like lumber and furniture.

Biomass producers and users must meet a range of stringent measures for their biomass to be certified as sustainable and responsibly sourced.

Key biomass facts

Is biomass renewable?

 Biomass grown through sustainable means is classified as a renewable source of energy because of the process of its growth. As biomass comes from organic, living matter, it grows naturally, absorbing carbon dioxide (CO2) from the atmosphere in the process.

It means when biomass is combusted as a source of energy – for example for heat or electricity production – the CO2 released is offset by the amount of CO2 it absorbed from the atmosphere while it was growing.

Fast facts

  • In 2019 biomass accounted for 6% of Great Britain’s electricity generation, more than 1/6 of the total generation of all renewable sources
  • There is about 550 gigatonnes of biomass carbon on Earth in total. Humans make up around 1/10,000th of that mass.
  • Modern biomass was first developed as an alternative for oil after its price spiked as a result of the 1973 Yom Kippur War
  • The International Energy Agency (IEA) estimates bioenergy accounts for roughly 1/10th of the world’s total energy supply

Biomass is a renewable, sustainable form of energy used around the world.

How long has biomass been used as a source of energy?

Biomass has been used as a source of energy for as long as humans have been creating fire. Early humans using wood, plants or animal dung to make fire were all creating biomass energy.

Today biomass in the form of wood and wood products remains a widely used energy source for many countries around the world – both for domestic consumption and at grid scale through power stations, where it’s often used to replace fossil fuels with much higher lifecycle carbon emissions.

Drax Power Station has been using compressed wood pellets (a form of biomass) since 2003, when it began research and development work co-firing it with coal. It fully converted its first full generating unit to run only on compressed wood pellets in 2013, lowering the carbon footprint of the electricity it produced by more than 80% across the renewable fuel’s lifecycle. Today the power station runs mostly on sustainable biomass.

Go deeper

Read next: What is reforestation and afforestation?

Plant more forests and better manage them

Working forests in the US South

There is an ongoing debate about forests’ contribution to fighting the climate crisis.

Forests can act as substantial and effective tools for carbon sequestration during a high growth phase. They can also function as significant and extensive carbon storage areas during maturity and throughout multiple stages of the age class cycle, if managed effectively at a landscape level. Or, they can be emitters of carbon if over-harvested, subject to fire, storm, pest or disease damage.

Different age class forest stands in Louisiana

In a natural state, forests will go through each of these life phases: rapid early growth; maturity and senescence; damage, decay and destruction through natural causes. Then they begin the cycle again, absorbing and then emitting carbon dioxide (CO2) in a continual succession.

Recently, loud voices have argued against forest management per se; against harvesting for wood products in particular, suggesting that this reduces both forest carbon stocks and sequestration capacity.

Pine cut in into wood for different wood products markets in Louisiana. Big, thick, straight higher value sections go to sawmills and smaller and misshapen low-grade wood not suitable for timber production is sold to pulp, paper or wood pellet mills.

Many foresters consider that this is just not correct. In fact, the opposite is true. Research and evidence clearly support the foresters’ view. Active forest management, when carried out appropriately, actually increases the amount of carbon sequestered, ensures that carbon is stored in solid wood products, and provides substantial savings of fossil fuels by displacing other high carbon materials (e.g. concrete, steel, brick, plastic and coal).

Oliver et al.(2014)[1] compared the impact of forest harvesting and the use of wood products to substitute other high-carbon materials, concluding that: ‘More CO2 can be sequestered synergistically in the products or wood energy and landscape together than in the unharvested landscape. Harvesting sustainably at an optimum stand age will sequester more carbon in the combined products, wood energy, and forest than harvesting sustainably at other ages.’

This research demonstrated that an increase in the use of structural timber to displace concrete and steel could lead to substantial emissions savings compared to unharvested forest. The use of wood for energy is an essential component of this displacement process, although it is important to use appropriate feedstocks. Burning wood that could be used for structural timber will not lead to a positive climate impact.

The message here is to manage working forests for optimum sawlog production for long-life solid wood products and utilise the by-products for energy where this is the most viable market, this provides the best all-round climate benefit.

What happens when you close the gate

Closing the forest gate and stopping all harvesting and management is one option being championed by some climate change campaigners. There is certainly a vital role for the preservation and protection of forests globally: primary and virgin forests, intact landscapes, high biodiversity and high conservation value areas all need to be protected.

That doesn’t necessarily mean that there is no forest management. It should mean careful and appropriate management to maintain and ensure the future of the resource. In these cases, management is with an objective to reduce the risk of fire, pests and disease, rather than for timber production.

Globally, we need better governance, understanding and implementation of best practice to achieve this. Forest certification and timber tracing systems are a good start. This can equally apply to the many hundreds of millions of hectares of ‘working forest’ that do not fall into the protection categories; forests that have been managed for many hundreds of years for timber production and other purposes. Harvesting in these forests can be more active, but governance, controls and the development of best practice are required. Better management not less management.

During the 1970s there was a significant change of policy in the US, aimed at removing massive areas of publicly owned forest from active management – effectively closing the gate. The drivers behind this policy were well meaning; it was intended to protect and preserve the habitat of endangered species, but the unintended consequences have also had a substantial impact. In the 1970s little thought was given to the carbon sequestration and storage potential of forests and climate change was not at the top of the agenda.

The west coast of the US was most substantially affected by these changes, more than in the US South, but the data below looks at the example of Mississippi which is primarily ‘working forest’ and 88% in private ownership.

Pine trees in Mississippi working forest

This is the location of Drax’s Amite pellet mill. The charts below show an interesting comparison of forest ownership in Mississippi where limited or no harvesting takes place and where active management for timber production occurs. In the short term the total volume of timber stored per hectare is higher where no harvesting occurs. This makes sense since the forest will keep growing until it reaches its climax point and succumbs to fire, pest or disease.

Average standing volume per unit area in the private sector, where active management occurs, is the lowest as timber is periodically removed for use in solid wood products. Remember that the Oliver et al. analysis (which does not include re-growth), showed that despite a short-term reduction in forest carbon, the total displacement of high-carbon materials with wood for structural timber and energy leads to a far higher emissions saving. It is better to have a lower stock of carbon in a working forest and to be continually sequestering new carbon for storage in solid wood products.

Average standing volume per acre by ownership class, Mississippi[2]

Comparing the average annual growth rates across all forest types in Mississippi, annual growth in the private sector is almost double that in the unharvested public forest. This differential is increased even further if only commercial species like pine are considered and a comparison is made between planted, well managed forests and those that are left to naturally regenerate.

Average growth rates per acre by ownership class, Mississippi[3]

The managed forest area is continually growing and storing more carbon at a materially higher rate than less actively managed forest. As harvesting removes some forest carbon, these products displace high carbon materials in construction and energy and new young forests are replacing the old ones.

We know that forests are not being ‘lost’ and that the overall storage of carbon is increasing. For example, the Drax catchment area analysis for the Amite biomass wood pellet plant showed an increase in forest area of 5,200 ha and an increase in volume of 11 million m3 – just in the area around the pellet mill. But what happens to protected forest area, the forest reserve with limited or no harvesting?

Over the last 20 years the average annual loss of forest to wildfire in the US has been 2.78 million ha per year (the same as the UK’s total area of productive forest). According to the USFS FIA database the average standing volume of forests in the US is 145 m3 per ha (although in the National Park land this is 365 m3 per ha). Therefore, wildfires are responsible for the average annual combustion of 403 million m3 of wood p.a. (equal to the total annual wood harvest of the US) or 2.5 billion m3 if entirely in National Parks.

One cubic metre equates to a similar quantity of CO2 released into the atmosphere each year, therefore wildfires are responsible for between 407 million and 2.5 billion tonnes of CO2 emissions in the US each year[4].

Wildfires in the US

Starrs et al. (2018)[5] demonstrated that the risk of wildfire was significantly higher in federally owned reserved forest (where harvesting and management were restricted), compared to privately owned forests with active management.

In California, the risk of wildfire in federal forest (2000-15) was almost double the risk in private forests where both had State firefighting resources. The risk of fires in federal lands had increased by 93% since 1950-66, compared to only 33% in non-federal forests, due to the change in forest management practice in the 1970s.

Forest fire in California

Closing the gate means that the carbon stock is maintained and grows in the short term, but there is no opportunity for carbon to be stored in solid wood products, no high-carbon materials are displaced (concrete, steel and fossil fuels) and the rate of sequestration declines as the forest ages. Eventually the forest will reach its natural climax and die, releasing all of that carbon back into the atmosphere. The managed forest, by contrast, will have a lower standing volume at a certain point in time, but will be in a continual cycle of sequestration, storage and regrowth – with a much lower risk of fire and disease. If managed correctly, the rate of growth and standing volume will also increase over time.

How should we manage the forest

Forests are extremely variable, there are a vast variety of tree species, soil, geological features, water regimes, temperature, climate and many other factors that combine to make unique ecosystems and forest landscapes. Some of these are rare and valuable for the exceptional assemblages they contain, some are commonplace and widespread. Some are natural, some man-made or influenced by human activity.

Forests have many important roles to play and careful management is required. In some cases that management may be protection, preservation and monitoring. In other cases, it may be active harvesting and planting to optimise growth and carbon storage.

Cypress forests in the Atchafalaya Basin in Louisiana are an example of a forest landscape where the suitable management practice is protection, preservation and monitoring

For each forest type and area, we need to recognise the highest or best purpose(s) for that land in the objectives set and carefully plan the management to optimise and sustain that value. The primary value could be in species and habitat diversity or rarity; provision of recreation and aesthetic value; production of timber, forest products and revenue generation; carbon sequestration and storage; water management and other ecosystem benefits.

Most likely it will be a combination of several of these benefits. Therefore, best management practice usually involves optimising each piece of forest land to provide the most effective combination of values. Forests can deliver many benefits if we are sensible about how we manage them.

In a recent study Favero et al. (2020)[6] concluded that: Increased bioenergy demand increases forest carbon stocks thanks to afforestation activities and more intensive management relative to a no-bioenergy case. Some natural forests, however, are converted to more intensive management, with potential biodiversity losses…the expanded use of wood for bioenergy will result in net carbon benefits, but an efficient policy also needs to regulate forest carbon sequestration.

[1] CHADWICK DEARING OLIVER, NEDAL T. NASSAR, BRUCE R. LIPPKE, and JAMES B. McCARTER, 2014. Carbon, Fossil Fuel, and Biodiversity Mitigation with Wood and Forests.
[2] US Forest Service, FIA Database, 2020.
[3] US Forest Service, FIA Database, 2020.
[4] Assumes an average basic density of 570kg/m3 and 50:25:25 ratio of cellulose, lignin and hemicellulose.
[5] Carlin Frances Starrs, Van Butsic, Connor Stephens and William Stewart, 2018. The impact of land ownership, firefighting, and reserve status on fire probability in California.
[6] Alice Favero, Adam Daigneault, Brent Sohngen, 2020. Forests: Carbon sequestration, biomass energy, or both?

Changing forest structure in Virginia and North Carolina

Photos: Roanoke Rapids area near the North Carolina, Virginia border, courtesy of Enviva.

Forest owners have responded to the recovery in pine saw-timber markets, since the global financial crisis of 2008, by planting more forest and investing more in the management of their land. The same period has witnessed increased demand from the biomass sector which has replaced declining need for wood from pulp and paper markets.

The area of timberland (actively managed productive forest) has increase by around 89,000 hectares (ha) since 2010. This change is due to three important factors: new planting on agricultural land; the planting of low-grade self-seeded areas with more productive improved pine; and the re-classification by the US Forest Service (USFS) of some areas of naturally regenerated pine from woodland to timberland.

The 2018 data shows that pine forest makes up 46% of the timberland area, of which 61% is planted and the remainder naturally regenerated. Hardwoods cover 43% of the timberland area, with 93% of this naturally regenerated. The remaining area is mixed stands.

Composition of timberland area

Since 2000 there have been some significant changes in the composition of the timberland area with a transition from hardwood to softwood. Pine has increased from 39% of the total area in 2000 to 46% in 2018 and hardwood has decreased from 50% to 43% over the same period.

All pine areas have increased since 2000 with naturally regenerated pine increasing by 13,000 ha and planted pine by 340,000 ha since 2000. Mixed stands have declined by 6,500 ha as some of these sites have been replanted with improved pine to increase growth and saw-timber production.

The biggest change has been in the hardwood areas where there has been a decline of around 314,000 ha, despite the total area of timberland increasing by 31,000 ha.

Change in forest type

This change has been driven by private forest owners (representing 91% of the total timberland area), seeking to gain a better return on investment from their forest land.

Hardwood markets have declined since the 2008 recession and demand for hardwood saw-timber has not recovered. Demand for pine saw-timber has rebounded and is now as strong as pre-crisis.

Pine also offers much faster growth rates and higher total volumes in a much shorter time frame (typically 25-35 years compared to 75-80 years for hardwoods).

The decision to change species is similar to a farmer changing their agricultural crops based on market demand and prices for each product. Where forests are managed for revenue generation then it is reasonable to optimise the land and crop for this objective. This can be a significant positive, from a carbon perspective more carbon is sequestered in a shorter time frame and more carbon is stored in long term wood products, if the quantity if saw-timber is increased.

Increased revenue generation also helps to maintain the forest area (rather than conversion to urban development, agriculture or other uses).

A potential negative is the change in habitat from a pure hardwood stand to a pure pine stand, each providing a different ecosystem and supporting a different range of flora and fauna. There is no conclusive evidence that one forest type is better or worse than the other; there is a great deal of variety of each type.

Some hardwood forests are rich in species and biodiversity, others can be unremarkable. The key is not to endanger or risk losing any species or sensitive habitat and to ensure that any conversion only occurs where there is no loss of biodiversity and no negative impact to the ecosystem.

It is not clear whether all of the lost hardwood stands have been directly converted to pine forests, some hardwood stands may have been lost to other land uses (urban and other land has increased by 400,000 ha). Some may have been directly converted to pine by forest owners encouraged by the increase in pine saw-timber demand and prices.

Whatever the primary driver of this change it is clearly not being driven by the biomass sector.

Change in forest type – timing

The chart above demonstrates that the biggest change, loss of hardwood and increase in planted pine, occurred between 2000 and 2012, prior to the operation of the pellet mills. Since 2012, there has been no significant loss of natural hardwood and only a small decline in planted hardwood.

Read the full report: Catchment Area Analysis of Forest Management and Market Trends: Enviva Pellets Ahoskie, Enviva Pellets Northampton, Enviva Pellets Southampton (UK metric version). Explore Enviva’s supply chain via Track & Trace. This is part of a series of catchment area analyses around the forest biomass pellet plants supplying Drax Power Station with renewable fuel. The series includes: Estonia, Morehouse Bioenergy, Amite Bioenergy, and the Drax forestry team’s review of the Chesapeake report on Enviva’s area of operations.