Forest Sequestration Controversy

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Forest Sequestration has many controversies associated with it because we do not yet know all the factors that contribute to the rates of carbon capture and storage.  We know that old-growth forests contain massive amounts of carbon in their biomass (Leaves, stems, trunk, and surrounded soil). However, when trees expire, they release carbon back into the atmosphere and therefore no longer serve as a sink. 




Above image from: meic.org/.../energy-4.jpg/image_view_fullscreen


Also, certain types of forest cover grow faster than others, and therefore sequester carbon faster. But do you cut down old forest to replace them with younger, faster forests having higher carbon capturing rates? Do all young-growth forests capture and store high levels of carbon or does it depend on what type of forest cover previously occupied the space? Another factor might be how long ago the area contained forest. Reforestation projects, for example, are planted on lands in which there has been forest within the past 50 years, how does this effect the soil and land in which the new trees are planted? 

Does local climate and precipitation amounts effect the sequestration rate?

In addition, should we stride to preserve degraded forests destroyed by human or natural means? Should be plant tree planations with little biodiversity in order sequester carbon? What would ecologist say about having large forests containing only one type of tree? What would that mean for local wildlife?

These are all questions that remain relatively unanswered. 


Why Old VS Young-Growth Forests?

A forest carbon sequestration controversy falls between Old-Growth Forest and Fast-Growth Forests. Which one is better at sequestering carbon? There has been uncertainty in the scientific community whether old growth or fast growth forest sequester carbon more efficiently. Arguments whether different types of trees (i.e. old-growth or fast growing) have lead to controversial debates on what type of forests should be used to capture carbon.

Some wish to plant younger fast growing trees in place of old-growth forests thinking the fast growth rate will capture more carbon. However, stated by M. Harmon, W. Ferrell and J. Franklin, “converting old-growth forests to younger forests reduces carbon storage ” and “the conversion of old-growth forests to younger forests under current harvesting and use conditions has added and will continue to add carbon to the atmosphere”(Harmon, et al., 1990).  Figure 1 shows their research on the high amount of carbon storage that old-growth forests can capture over time.  Research has shown that “Old-growth forests accumulate carbon for centuries and contain large quantities of it” (Luyssaert, S. et al., 2008). Also stated is that “young forests rather than old-growth forests are very often conspicuous sources of Carbon Dioxide because the creation of new forests (whether naturally or by humans) frequently follows disturbance to soil and the previous vegetation, resulting in a decomposition rate of coarse woody debris, litter and soil organic matter (measured as heterotrophic respiration) that exceeds the NPP of the re-growth” (Luyssaert, S. et al., 2008). In addition, the Luyssaert, S. et al. article stated that Old-growth forests are a global carbon sink which is defined by the United Nations Framework Convention on Climate Change that “a ‘sink’ means any process, activity or mechanism which removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere” (UNFCCC, 1992 ).


 

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Carbon storage capacity with (A) having a disturbance and (b) having no distance (Harmon, et al., 1990).


Many argue that fast growing forests would be more effective at capturing carbon. On a Vancouver Island in Canada, has received a $20 million national pilot called the Forest 2020 Plantation Demonstration and Assessment. This pilot, administered by the Canadian Forest Service, states that the “Forest 2020 encourages industry, local governments, First Nations, and other landowners to establish plantations of fast-growing trees on un-forested land” (Canadian Forest Service, 2004).  Similarly, in Costa Rica, the Reforest the Tropics, Inc., (RTT) are focused on planting super-fast growing RTT Deglupta hybrids that showed to capture carbon successfully by “RTT’s selection of tree species is based on more than 40 years of species trials” (Reforest the Tropics Inc., 2009). The RTT stated that it would “improve sustainable carbon-offset forests for efficient carbon capture and farmer income” (Reforest the Tropics Inc., 2009).

To add to the controversy, there are problems associated with the means in which carbon levels are obtained.  One problem we are addressing is a lack of a viable measuring system of obtaining carbon levels within plant biomass, which would aid the policy markers in finding out if forest sequestration is even worth pursuing.  For the most part, remote sensing, field research and land surveying are used to determine forest cover and carbon sequestration numbers.  However, In an article by the Wildlife Society, who is known for their push toward stronger forest sequestration policy, it clearly states: that the land surveys conducted are from different years, in some cases more than a decade apart; that no complete surveys were conducted, rather samples, which resulted in high sampling errors; that different states used different tools for measuring; and that sampling methods were recently changed, and therefore makes comparing difficult. In addition, Ann Ingerson, author of the article, goes on to say that we need more accurate tools to measure sequestered amounts of carbon. (The Wilderness Society, 2007).

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