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Remote Sensing of Coniferous Forest Leaf Area
Author(s) -
Running S. W.,
Peterson D. L.,
Spanner M. A.,
Teuber K. B.
Publication year - 1986
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938532
Subject(s) - citation , spanner , computer science , library science , ecology , information retrieval , database , biology
Many important ecological questions concern eco? system processes occurring over large areas. However, our understanding of ecosystem functions is derived primarily from research executed on small, intensively studied sites, and extrapolation to large areas is diffi? cult. For example, it is not known definitively whether the land biota act as a source or a sink in the global carbon cycle, or whether increases in carbon dioxide concentrations and the subsequent predicted global warming would stimulate or suppress land vegetation (Bolin 1977, Woodwell et al. 1983). Much of this indecision results from our inability to directly measure important vegetation properties on large spatial scales. Estimates of the global carbon content of terrestrial plant biomass range from 450 x 1015 to 1000 x 1015 g. These estimates are derived by extrapolation of data from sites of intensive study to the areal coverage of vegetation assumed to be equivalent; hence no direct means of verification exist. As a consequence, no defensible estimate of energy and mass exchange rates is possible for large areas of terrestrial vegetation. Four recent workshops have evaluated the potential of advanced satellite technology for direct measure? ment of critical vegetation characteristics over large areas (Botkin 1982, 1985,Goody 1982, Wittwer 1983). Each workshop ultimately identified leaf area index (LAI, the area of leaf over a given area of ground) as the single variable both amenable to measurement by satellite and of greatest importance for quantifying en? ergy and mass exchange by plant canopies over landscapes. Characterizing vegetation in terms of LAI, rath? er than species composition, is a critical simplification for regional and global comparison of different terres? trial ecosystems. Previous research in crops and grass? lands has shown leaf area and biomass to be correlated with reflectance values measured by satellite-based sensors (Wiegand et al. 1979). We report here the first attempt to measure the LAI of coniferous forests using optical scanners of satellite resolution.