Document: RAY-3-87-18

MC1 LAI and vegetation carbon output compared with its progenitor models and with new satellite LAI estimates.

DRAPEK, R.J.* ¹, R.P.NEILSON ², D.BACHELET ¹, J.M.LENIHAN ¹ and V.MEMBERS ³

Oregon State University, Corvallis, OR 97331 USA ¹
USDA Forest Service, Corvallis, OR 97331 USA ²
Multiple Institutions ³

Abstract:
Leaf Area Index (LAI) is a variable of fundamental importance for determining ecosystem productivity and biosphere-atmosphere fluxes of matter and energy. Vegetation carbon, (vegc) measured in gC m^-2, includes all living tissue, but is generally highly correlated with LAI. In previous ESA sessions, comparisons were between current LAI maps produced by MAPSS, satellite estimates, and phase I VEMAP vegetation models. Since then new satellite-based estimates of LAI have come to be available. and VEMAP phase II dynamic vegetation models have been developed. MC1, is one dynamic vegetation model which weds climatic rules similar to MAPSS to simulate vegetation distribution, a dynamic fire disturbance model, and CENTURY biogeochemistry. A comparison is made of LAI output by MAPSS, CENTURY, and MC1 versus satellite LAI estimates. Spatial and temporal patterns of vegc are compared between MC1 and CENTURY. One notable change of the new satellite LAI estimate over the old, is a more distinct mapping of high LAI values in northeast USA relative to the southeast. This is more in accord with results mapped by MAPSS. MC1 produces LAI patterns more similar to CENTURY, with larger LAI values appearing in the southeast. The MC1 vegc map, on the other hand, produces a pattern similar to a hybrid of MAPSS and CENTURY LAI with high vegc values occurring both in the northeast and in the south along the Gulf Coast. Both spatial and temporal heterogeneity of vegc values are higher in MC1 versus CENTURY, resulting in large part from the dynamic fire disturbance model.

Keywords: Dynamic Vegetation Model, Biogeography Model, Biogeochemistry Model, Leaf Area Index, Vegetation Carbon

This abstract is being presented at: 10:30 AM in session:
REMOTE SENSING