AGU journal highlights -- July 23, 2008( 1. Fire suppression may have reduce...)

Active fire suppression since the early twentieth century has caused a widespread increase in fire-intolerant trees, smaller trees, and the density of stems growing on trees within western U.S. forests. These factors have created thicker forests and are thought to account for much of North America's carbon sink. To better quantify changes in aboveground biomass, Fellows and Goulden compare California forest inventories from the 1930s with those from the 1990s. To compare these data, interpolation measures are used that result in underestimations of stem density and biomass estimates for data from the 1930s. Nonetheless, the authors find that stem density in these conifer forests increased by 34 percent between 1930 and 1990, reflecting an increase in the number of small trees. However, aboveground carbon stocks decreased by 26 percent because large trees, which contain a disproportionate amount of carbon, experienced a net loss between the surveys. The authors conclude that twentieth-century fire suppression and the resulting increase in stand density may have decreased, rather than increased, the amount of biomass stored in western U.S. forests.

Title: Has fire suppression increased the amount of carbon stored in western U.S. forests?

Authors: Aaron W. Fellows and Michael L. Goulden: Department of Earth System Science, University of California, Irvine, California, U.S.A..

Source: Geophysical Research Letters (GRL) paper 10.1029/2008GL033965, 2008; http://dx.doi.org/10.1029/2008GL033965

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