HR: 15:25h
AN: B12E-08    [PDF]
TI: Assessing Biogeochemical Cycling in Forested Ecosystems Through Integration of Remotely-Sensed Forest Structure with an Ecosystem Model
AU: * Dubayah, R
EM: dubayah@geog.umd.edu
AF: Geography Department, 1149 Lefrak Hall University of Maryland, College Park, MD 20740 United States
AB: Forested landscapes are generally composed of a heterogeneous mixture of patches that reflect the complex interaction of processes occurring at many spatial and temporal scales. Whether caused by natural disturbances, such as blow downs and fire, management practices, such as logging and agriculture, or varying climatic factors, both ecosystem structure and carbon fluxes will vary strongly as a result of differences in successional stage. Forest structural measurements, such as canopy characteristics and biomass, are key elements in furthering our understanding of the carbon budgets of forested ecosystems because they provide the observational evidence from which the impacts of various processes may be assessed. They also provide what is often the only means of determining successional status and edaphic controls, and are thus critical for both initialization and validation of carbon modeling approaches. Identifying and tracking these structural differences through space and time has been extraordinarily difficult, given the burden and limited scope of field-based methods, and the limited efficacy of most remote sensing approaches. In this paper we explore the potential for assessments of biogeochemical cycling in forests using a combined field, remote sensing and modeling approach. Our focus is on the fusion of various remote sensing data, including lidar and multispectral methods, with limited field based observations, to provide trajectories of successional status that can then be used to initialize and validate ecosystem models. We provide examples using the Ecosystem Demography (ED) model for both tropical and temperate forests. Our results in these areas show that initialization of the ED model with remotely sensed data on forest structure, in particular canopy height, allows for estimates of carbon stocks within few percent of field-based methods, greatly constrains consequent estimates of carbon flux. This approach thus provides a promising means for observing the effects of various disturbance and management regimes on forested ecosystem structure and associated carbon fluxes.
DE: 1615 Biogeochemical processes (4805)
DE: 1640 Remote sensing
SC: Biogeosciences [B]
MN: 2003 Fall Meeting