Physiological Plant Ecology: Some Contributions to the Understanding of Secondary Succession in Tropical Lowland Rainforest

Abstract

The current status of the field of physiological plant ecology of tropical secondary tree species is reviewed, focusing on seed germination, net CO2 exchange studies, water relations, and energy balances; its contributions to the understanding of recovery in disturbed areas are discussed. Suggestions of areas in need of future research and methodology are provided. IN RECENT YEARS, the topic of secondary succession in tropical rainforests has received increasing attention due to the accelerated rates of destruction of these areas (G6mez-Pompa et al. 1972, Richards 1973). Secondary succession involves changes of community species composition, structure, and microclimate at a specific site (Pickett 1976). An understanding of the physiological ecology of secondary plants can further our understanding of the nature of the process of secondary succession. Yet except for research on seed germination, relatively little work has been done on the physiological ecology of secondary species in the tropics. This paper presents a brief summary of progress in the field of physiological ecology of tropical secondary tree species, discusses some of the ways in which studies can contribute to our understanding of the process of secondary succession in these forests, and indicates areas in need of future research. It will focus on secondary succession starting from clearcut areas since this is the topic for which most information is available. Secondary succession in naturally occurring canopy gaps, although important in the general dynamics of the forest populations, has scarcely been studied (Whitmore 1966).