Reconstructing succession: historical and chronosequence approaches to understanding the assembly of forest communities

Abstract

Historical legacies can be important determinants of the structure, composition and dynamics of secondary forests recovering from agricultural conversion. Tracing the effects of historical processes on secondary tropical forests can lead to a better understanding of successional patterns and ecosystem states. Puerto Rico is an ideal place to study lasting legacies of human disturbance because of the widespread secondary forest growth following large-scale clearing for agriculture more than a century ago and because of the abundance of historical records produced during the recovery period. In this study we combine historical aerial photographs and land use records with tree census data from five forest plots in the El Verde and Sabana Research Areas of El Yunque National Forest differing in successional age to reconstruct forest recovery and identify land use legacies influencing secondary forest composition. We found variation in the type and intensity of land use among the forest plots and over time within agricultural disturbance and forest recovery periods that shaped local forest transformation. Enduring, localized human influences on tree communities include the presence of nonnative species planted for reforestation or silvicultural purposes that contribute to differences in species composition among plots of similar forest age. These findings can help researchers investigating the ecologies of El Verde and Sabana areas to incorporate a historical perspective and inform our understanding and management of secondary forest stands recovering from human disturbance.