Tree Life History Patterns and Forest Dynamics

Abstract

Forest trees are usually classified into broad ecological groups (e.g., pioneers vs. mature-phase species) based on the importance of natural disturbance for their regeneration. These classifications only tie into account a small component of the plant's life-cycle, usually seeds and seedlings, and therefore may over-simplify the role of natural disturbance in the evolution of life-history traits. We present a conceptual model for the study of plant demography within heterogeneous environments, and illustrate its use by reviewing how natural disturbance influences the demography of several lowland tropical tree species at Los Tuxtlas, Mexico. Our model assumes that habitat patches such as treefall gaps in tropical forests can affect a plant at all stages of its life-cycle, and reveals many potential life history patterns in relation to forest dynamics. We propose that only detailed demographic studies of whole life histories and genetics of tree populations, as well as forest disturbance regimes, will allow us to elucidate convergent life histories and the existence of discrete ecological groups among tropical forest trees.