ECOLOGY/EVOLUTION

Seeing the Deadwood Through the Trees

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Science  23 Jan 2004:
Vol. 303, Issue 5657, pp. 435
DOI: 10.1126/science.303.5657.435c

The death rate of trees is a key parameter for ecologists quantifying and elucidating forest dynamics. Knowledge of this rate, especially in tropical forests, provides important clues about how forests are responding to climate change and whether forests are sources or sinks for carbon. However, data have been in short supply because of the practical obstacles to counting dead trees from the ground. Recent research has shown that high-spatial-resolution satellite images can be used to measure a variety of forest features, such as tree crown size and the frequency of forest gaps across wide areas. Clark et al. show that such techniques can be used to provide reliable measures of tree mortality. In their study area at La Selva Biological Station in Costa Rica, satellite remote sensing at a resolution of <1 m, corroborated by ground-based data from inventory plots, indicated annual mortality rates of 2.8% for canopy trees. Regular collection of similar data from this and other tropical forests will reveal whether mortality rates are stable, increasing, or decreasing. — AMS

Ecol. Lett. 7, 52 (2004)

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