A review of current hydrologie models indicates that ET is weakly quantified for forested catchments, due to lack of specific information on vegetation data such as leaf area index (LAI), stornata! ...conductance, rooting depth, and soil moisture. Due to the increasing importance of forest hydrologic science and its application to addressing sustainable water resource issues on a much broader scale, ASABE engineers are increasingly challenged to develop innovative technologies and reliable tools and models.
Belowground carbon allocation (BCA) in forests regulates soil organic matter formation and influences biotic and abiotic properties of soil such as bulk density, cation exchange capacity, and water ...holding capacity. On a global scale, the total quantity of carbon allocated belowground by terrestrial plants is enormous, exceeding by an order of magnitude the quantity of carbon emitted to the atmosphere through combustion of fossil fuels. Despite the importance of BCA to the functioning of plant and soil communities, as well as the global carbon budget, controls on BCA are relatively poorly understood. Consequently, our ability to predict how BCA will respond to changes in atmospheric greenhouse gases, climate, nutrient deposition, and plant community composition remains rudimentary. In this synthesis, we examine BCA from three perspectives: coarse-root standing stock, belowground net primary production (BNPP), and total belowground carbon allocation (TBCA). For each, we examine methodologies and methodological constraints, as well as constraints of terminology. We then examine available data for any predictable variation in BCA due to changes in species composition, mean annual temperature, or elevated CO2 in existing Free Air CO2 Exposure (FACE) experiments. Finally, we discuss what we feel are important future directions for belowground carbon allocation research, with a focus on global change issues.
Using forest slash to improve degraded soils Sanchez Felipe, G., USDA Forest Service, (USA). Southern Research Station; Carter Emily, A., USDA Forest Service, (USA). Southern Research Station; Trettin Carl, C., USDA Forest Service, (USA). Southern Research Station
2002
Conference Proceeding
Fifty years of forest hydrology in the southeast Jackson, C. Rhett; Sun, Ge; Amatya, Devendra ...
A century of forest and wildland watershed lessons / George G. Ice and John D. Stednick, editors,
2004
Publication
Hydrology controls the majority of ecosystem functions and ecological services derived from wetlands; it is also the primary regulator of carbon dynamics, which is significant because wetlands ...contain 20-30%\ of the terrestrial carbon. Accordingly, the ability to simulate wetland hydrology is fundamental to assessing ecosystem responses to climate change and other anthropogenic disturbances. We present the application of MikeShe to an Atlantic coastal plain watershed with long-term gauging records from the Santee Experimental Forest. The simulation model was calibrated and validated against stream outflow and water table, and evaluated by the Pearson correlation coefficient (R), and the Nash and Sutcliffe model efficiency metric (E). The E (0.72 and 0.93 for daily and monthly outflows and 0.52 for water table in a 3 year period), R (0.8,0.98 and 0.83) and slope for the regression (0.84, 1.03 and 1.02) of observations vs. simulations showed that MikeShe can perform reasonably well to estimate the overall hydrology of this low-relief watershed (WS80). The calibrated and validated model was then used for assessing the hydrologic response of the watershed to climate changes and land use change, from forest to agriculture. The effects of altered precipitation or temperature on stream outflow and groundwater table may be significant. A simulated 10%\ decrease in precipitation decreased stream outflow 20%\ and the mean water table depth 15%\ (11cm on average within the watershed); a simulated 10%\ increase in precipitation increased stream outflow by 10%\ and mean water table depth 12%\ (8cm). A 2 deg C increase in mean temperature decreased stream outflow by 7%\ and water table by 6 to 22%\ (8cm on average ); this effect was primarily attributable to an increase ET. Simulated land use change from forest to agriculture caused large changes in the hydrology of watershed WS80; stream outflow increased by 29% and the mean water table was raised by 8cm.
We examined the carbon balance of North American wetlands by reviewing and synthesizing the published literature and soil databases as part of the State of the Carbon Cycle Report for North America ...under the auspices of the U.S. Climate Change Program. North American wetlands contain about 220 Pg C, most of which is in peat. They are a small to moderate carbon sink of about 70 Tg C yr-1, although the error around this estimate is greater than 100%, with the largest unknown being the role of carbon sequestration by sedimentation in freshwater mineral-soil wetlands. We estimate that North American wetlands emit 26 Tg CH4 yr-1; however, the error of this estimate is also greater than 100%. With the exception of estuarine wetlands, methane emissions from wetlands may largely offset any positive benefits of carbon sequestration in soils and plants in terms of climate forcing. Historically, the destruction of wetlands through land-use changes has had the largest effects on the carbon fluxes and consequent radiative forcing of North American wetlands. The primary effects have been reduction in carbon sequestration (a small to moderate increase in radiative forcing), oxidation of soil carbon reserves upon drainage (a small increase in radiative forcing), and reduction in methane emissions (a large decrease in radiative forcing). It is uncertain how global changes will affect the carbon pools and fluxes of North American wetlands. We will not be able to accurately predict the role of wetlands as potential positive or negative feedbacks to anthropogenic global change without knowing the integrative effects of changes in temperature, precipitation, atmospheric carbon dioxide concentrations, and atmospheric deposition of nitrogen and sulfur on the carbon balance of North American wetlands.
