Post-disturbance aboveground biomass accumulation in global secondary forests

To examine rates of aboveground biomass accumulation (ABA) in global second ary forests following stand-clearing disturbances, we compiled aboveground biomass data from 283 known-age plots drawn from chronosequence and long-te rm studies. We focused on three likely influences on ABA for which data are readily available. climate, soil texture, and forest type. Growing-season degree-years (GSDY, stand age x growing-season length x growing-season temp erature) generally predicted ABA better than stand age alone. Using regress ion analyses and slope homogeneity tests, we determined that broadleaf fore st plots on sandy textured soils exhibited slower GSDY-adjusted ABA than th ose on nonsandy soils. On nonsandy soils, the GSDY-adjusted ABAs of tropica l and nontropical plots were indistinguishable; tropical forest post-distur bance ABA was not particularly slow. Compared to broadleaf forests, needle- leaf forest, GSDY-adjusted ABA was less sensitive to soil texture and was i ntermediate in rate between sandy and nonsandy broadleaf forest ABA. Foliar nutrient concentration did not significantly influence the GSDY-adjusted A BA of a subset of the nonsandy broadleaf forests for which foliar nutrient data were available. At the global scale, differences in climate (represent ed by growing-season length and temperature) and moisture-holding capacity (represented by soil texture) are the principal independent factors influen cing ABA in most post-disturbance secondary forests.