RL31432 - Carbon Sequestration in Forests
29-Mar-2007; Ross W. Gorte; 28 p.
Abstract: Widespread concern about global climate change has led to agreements to reduce emissions of carbon dioxide (CO2) and, under certain circumstances, to count additional carbon absorbed in soils and vegetation as part of the emissions reductions. Congress may consider options to increase the carbon stored (sequestered) in forests as it debates this and related issues.
Forests are a significant part of the global carbon cycle. Plants use sunlight to convert CO2, water, and nutrients into sugars and carbohydrates, which accumulate in leaves, twigs, stems, and roots. Plants also respire, releasing CO2. Plants eventually die, releasing their stored carbon to the atmosphere quickly or to the soil where it decomposes slowly and increases soil carbon levels. However, little information exists on the processes and diverse rates of soil carbon change.
How to account for changes in forest carbon has been contentious. Land use
changes — especially afforestation and deforestation — can have major impacts on
carbon storage. Foresters often cut some vegetation to enhance growth of desired
trees. Enhanced growth stores more carbon, but the cut vegetation releases CO2; the
net effect depends on many factors, such as prior and subsequent growth rates and
the quantity and disposal of cut vegetation. Rising atmospheric CO2 may stimulate
tree growth, but limited availability of other nutrients may constrain that growth. [read report]