HR: 1340h
AN: B43B-1164    [Abstracts]
TI: Fine Root and Aboveground Development and Turnover in a Seasonally Dry Forest
AU: * Gershenson, A
EM: agersh@ucsc.edu
AF: UC Santa Cruz, Dept of Environmental Studies 1156 High St, Santa Cruz, CA 95064, United States
AU: Misson, L
AF: CNRS-CEFE, 1919 route de Mende, Montpellier, 34293, France
AU: Tang, J
AF: Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, United States
AU: Curiel Yuste, J
AF: UC Berkeley, ESPM 330 Hilgard Hall, Berkeley, CA 94720, United States
AU: Goldstein, A
AF: UC Berkeley, ESPM 330 Hilgard Hall, Berkeley, CA 94720, United States
AU: Cheng, W
AF: UC Santa Cruz, Dept of Environmental Studies 1156 High St, Santa Cruz, CA 95064, United States
AB: Terrestrial carbon dynamics are dependent in large part on factors which affect fine root dynamics, as fine roots constitute a significant part of belowground carbon allocation. Differences in factors affecting fine root dynamics under different climatic conditions are not well known. We conducted a three year study of above- and belowground dynamics in a Ponderosa pine plantation in the central Sierra Nevada, examining the overall patterns of fine root production and survival in a seasonally arid montane forest in a Mediterranean climate, as well as the correlations between above- and belowground growth dynamics. Data collected during the 2003- 2005 seasons suggest that fine root development of ponderosa pine-dominated ecosystems of the Sierra Nevada are highly dependent on prevailing climatic conditions, and that belowground phenology is more sensitive to variations in available moisture than is aboveground development. To the best of our knowledge, these findings represent one of the first comprehensive examinations of above- and below-ground growth dynamics in a forest system growing in a Mediterranean climatic zone, and offer a few clues for evaluating the potential difficulties in projecting climate change influences on ecosystem dynamics. We monitored stem diameter growth, shoot and needle elongation, fine root development using minirhizotrons, as well as soil moisture, and soil and air temperature throughout the season. The onset of belowground phenological development in this ecosystem appears to be controlled by the increase of the daily minimum temperatures above 5 ° C, and the end of the active fine root elongation season appears to be controlled by the decrease of soil water potential below -0.3MPa. Root development appears to follow the overall patterns of warming and drying of the soil profile, with surface root growth initiation and mortality occurring earlier than that of subsurface roots. In contrast, aboveground development does not appear to be strongly related to changes in climatic conditions.
DE: 0429 Climate dynamics (1620)
DE: 0438 Diel, seasonal, and annual cycles (4227)
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting