Quantifying forest carbon stocks and change from forest management activities

Photo Credit

USDA photo by Alexis Neukirch

Quantifying above-ground biomass grossly underestimates the total carbon budget in forests and grasslands. Soils contain vast amounts of carbon and other organic material. Soil disturbance associated with beetle kill, mechanical fuel treatments, timber harvest, prescribed fire and wildfire may produce changes in soil temperature and moisture that will affect carbon and nitrogen cycles. Removal of canopy cover could result in warmer soil temperatures and varying soil moisture changes. As a result, soil structure, bulk density, and soil porosity (properties that affect water infiltration, rooting depth, soil erosional losses, and water holding capacity) are likely to change. Warming temperatures without additional moisture may reduce soil organic carbon and the capability of soils to store carbon. Rapidly fluctuating changes in temperature and moisture may disrupt soil physical structure, releasing physically protected soil organic matter, freeing labile organic carbon and increasing the export of dissolved nutrients.

The research approach has three components aimed at developing a comprehensive carbon balance in the priority landscapes:

1. Using the U.S. Forest Service's FIA data, Wildland Urban Interface land cover spatial analyses, and the Forest Vegetation Simulator, this project would estimate the carbon standing stock within the priority firesheds, scaled to PODs where they have been developed, and provide estimates of above-ground carbon sequestration in standing biomass and harvested wood products under different management scenarios. The project would quantify the potential for the implementation of wildfire risk reduction to mitigate greenhouse gas emissions from forest management activities.
2. Soil monitoring and mapping efforts carried out by the Forest Service and Natural Resources Conservation Service will also be evaluated for baseline data on soil carbon pools at depth in the soil profile. This data will provide an estimate of below-ground carbon pools at the time of sampling. Using FIA soil data and other long-term study plots such as the North American Long-Term Soil Productivity, Long Term Ecological Research, and Fire-Fire Surrogate can also be used to establish baseline and, in some cases provide data on soil carbon changes with compaction, various levels of harvesting, and fire. Samples from the Natural Resources Conservation Service mapping of National Forests and Grasslands provide valuable data on the effects of land management and climate change. The sources of the original samples are known, and it is possible to resample those locations and assess the change from the previous sample. Current work has been done with remotely sensed soil data and matching that with the previous analyses.
3. Soil physical structure, soil moisture, and biochemical properties would be measured at gridded experimental plots within the priority firesheds where thinning, harvest, salvage logging, grazing, and prescribed fire would occur, with Forest Service Experimental Forests and Ranges and Research Natural Areas serving as controls, using a Before-After-Control-Impact design.

Objectives

This project will quantify above-ground carbon sequestration in standing biomass and harvested wood products coupled with measurements of soil organic carbon and nitrogen stocks in under different management scenarios. We will quantify the potential for the implementation of wildfire risk reduction to mitigate greenhouse gas emissions from forest management activities. Specifically, the project will quantify how mechanical fuels treatments, prescribed fire and managed wildfire affect above- and below-ground carbon storage and carbon balance.