HR: 11:50h
AN: B42B-06    [Abstracts]
TI: Beyond Potential Vegetation II: Using Repeat Lidar Data on Changes in Vegetation Height to Test Model Predictions of Ecosystem Dynamics
AU: * Hurtt, G
EM: george.hurtt@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth Oceans and Space, Durham, NH 03824,
AU: Thomas, R Q
EM: rqt2@cornell.edu
AF: Cornell University, Ecology and Evolutionary Biology, Ithaca, NY 14853,
AU: Dubayah, R
EM: dubayah@umd.edu
AF: University of Maryland, Department of Geography, College Park, MD 20740,
AB: Carbon estimates from terrestrial ecosystem models are limited by large uncertainties in the current state of the land surface, as previous disturbances have important and lasting influences on ecosystem structure and fluxes and can be difficult to detect or assess. Previous studies have illustrated how data on the vertical structure of vegetation from lidar can help to provide needed information on successional status for model initialization and constrain estimates of both carbon stock and fluxes. Here, we illustrate how repeat lidar data on vegetation structure can be used to test model predictions of ecosystem dynamics at a tropical forest site at La Selva, Costa Rica (108259 N, 848009 W). Airborne lidar remote sensing was used to measure spatial heterogeneity in the vertical structure of vegetation in 1998 and 2005. The ecosystem demography model (ED) was used to estimate corresponding patterns of carbon stocks, fluxes, and ecosystem dynamics during the interval. Lidar-initialized ED estimates of changes in maximum canopy height) were comparable to but significantly lower than observed (0.85 +/- 0.9 m observed vs. 0.53 +/- 0.4 m modeled) over the whole domain. Most of the model-data difference was due to growth of primary forest trees that exceeded model estimates (0.44 +/-0.9 m observed vs. 0.04 +/-0.1 m modeled), while the model-data comparison was significantly better over secondary forest areas (1.84 +/- 0.18 m observed vs. 1.71 +/-0.9 m modeled). The results of this study provide a promising illustration of the power of using repeat lidar data on changes in vegetation height to test estimates of ecosystem dynamics from height-structured ecosystem models. Extending these capabilities to regional and global scales will require repeat lidar data sets from space, and the continued development of height-structured ecosystem models.
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0466 Modeling
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: 2007 Fall Meeting