HR: 0800h
AN: B31B-01    [Abstracts]
TI: Seasonal Water Availability and Mountain Forest Dynamics in the Southwestern U.S.A.
AU: * Brown-Mitic, C M
EM: combrown@indiana.edu
AF: Indiana University, Geography Department 701 E. Kirkwood Ave., Bloomington, IN 47405, United States
AU: Parajuli, K
EM: parajulk@indiana.edu
AF: Indiana University, Geography Department 701 E. Kirkwood Ave., Bloomington, IN 47405, United States
AU: Telewski, F
EM: telewski@beal.cpp.msu.edu
AF: Michigan State University, Department of Plant Biology , East Lansing, MI 48824, United States
AU: Shuttleworth, W J
EM: shuttle@hwr.arizona.edu
AF: University of Arizona, SAHRA Department of Hydrology and Water Resources, Tucson, AZ 85721, United States
AB: Water availability in the semi arid United States varies seasonally, annually, and on multi-year cycles, affecting mountain forest carbon exchange directly by influencing primary production and respiration and indirectly through drought, forest fires and insect infestation. Explicitly quantifying the carbon-water relationship in mountain island ecosystems depends largely on understanding both the temporal distribution of water availability and the response of the vegetation to seasonal inputs. Understanding how ecosystems, particularly those which are positioned along sensitive vegetation ecotones and steep transitional climate zones, function and respond to perturbations in climatic conditions is critical to our understanding of the expected range of changes that are possible with changes to our climate. What are the possible responses in ecosystem composition, diversity and biotic feedbacks, not only to changes in the amount of precipitation, but also shifts in its' seasonal pattern, frequency distribution and intensity? Southern Arizona provides a natural laboratory with an annual bimodal precipitation pattern, steep transitional climatic zones, sensitive ecotones, with clear demarcation resulting from large elevation and precipitation gradients and high water limiting conditions with extreme climate variability. This presentation highlights the seasonal carbon-water relationship of a coniferous mountain island forest in the Santa Catalina Mountains of Southern Arizona. Hydro-micrometeorological observations from an eddy covariance flux tower made over five years encompass periods of severe multi-year drought punctuated by strong El Nino winter seasons. Distinct seasonal water use efficiency and carbon assimilation highlights the unique dynamics of this ecosystem and provide part of the fundamental reasons for the observed northward migration of semi-arid coniferous species.
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0429 Climate dynamics (1620)
SC: Biogeosciences [B]
MN: 2007 Joint Assembly