HR: 14:35h
AN: B23E-04    [Abstracts]
TI: Effects of Post-fire Succession and Edaphic Conditions on Tree Transpiration in a Boreal Black Spruce Forest
AU: * Angstmann, J L
EM: jangstma@uwyo.edu
AF: University of Wyoming, 1000 East University Avenue, Laramie, WY 82071, United States
AU: Ewers, B E
EM: beewers@uwyo.edu
AF: University of Wyoming, 1000 East University Avenue, Laramie, WY 82071, United States
AU: Kwon, H
EM: hkwon@uwyo.edu
AF: University of Wyoming, 1000 East University Avenue, Laramie, WY 82071, United States
AU: Bond-Lamberty, B
EM: bpbond@wisc.edu
AF: University of Wisconsin, Department of Forest Ecology and Management A127 Russell Laboratories 1630 Linden Dr., Madison, WI 53706, United States
AU: Amiro, B
EM: amirobd@cc.umanitoba.ca
AF: University of Manitoba, Department of Soil Science, Winnipeg, MB R3T 2N2, United States
AU: Gower, S T
EM: stgower@facstaff.wisc.edu
AF: University of Wisconsin, Department of Forest Ecology and Management A127 Russell Laboratories 1630 Linden Dr., Madison, WI 53706, United States
AB: Boreal forest ecosystems play an integral role in global climate change because of their large land area and ability to store large quantities of carbon. Quantifying and explaining tree water use in both well- and poorly- drained soils and across successional development is critical in understanding the influence of physiological processes on carbon, water, and energy cycling. Four black spruce stands burned in 1850, 1930, 1964, and 1989 were chosen for this research because they had been shown in previous studies to represent critical stages of forest development that capture the successional impacts of both leaf area and species composition change. We hypothesized that tree transpiration will differ between well- and poorly-drained areas and with age due to 1) tree size and age and edaphic-related hydraulic adjustments and 2) tree size will be explained by species specific growth differences from edaphic conditions. Sap flux, leaf water potential (\Psi_L), site specific allometric relationships between sapwood area and leaf area and soil properties such as texture and organic matter depth in each of the four burn ages were utilized to test these hypotheses. Results show that sap flux for Picea mariana at the 1964 burn age differed between well- and poorly-drained soils when scaled per unit xylem area with trees located on poorly-drained soils experiencing higher sap flux rates than trees in well- drained areas (101.79 & 83.02 g cm^-2 day^-1 respectively). However, when scaled to transpiration on a per tree basis, taking tree size into account, trees on well-drained soils had higher rates than those in poorly- drained locations (366.96 & 216.82 g tree^-1 day^-1 respectively). The presence of Pinus banksiana and Populus tremuloides in the well-drained areas increased stand transpiration rates for these areas considerably as compared to the poorly-drained areas. Midday \Psi_L for all four burns show no significant difference between well- and poorly-drained (average midday \Psi_L = -1.23 & -1.29 MPa respectively) sites for Picea mariana (t-value = -0.591, df = 6, p-value = 0.576). This indicates that tree size, which is constrained by growth and anaerobic conditions, drives differences in tree transpiration for well- and poorly-drained soils.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0476 Plant ecology (1851)
DE: 0495 Water/energy interactions (1878)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting