抄録
Tropical secondary forests own enormous potential and ecological function due to their vast area, and are an increasingly important component of the forest resources in the tropics. This paper reviews main research outcomes of secondary forests during their succession process. Soil-stored seeds significantly contribute to the development of secondary forests, increased levels of incident light temperature stimulate seed germination, whereas remnant vegetation and seed predator have strongly negative influence on the rate of initial colonization. Species and number of secondary forests generally increase with succession process. Early successional species are generally shade-intolerant while late successional species are shade-tolerant. The time frame that plant species richness in secondary forests approach old-growth forests varies considerably depending on forest type, type and intensity of past land use, and environmental conditions. Plantation can accelerate germination and growth of seeds by improving the light, temperature and the degree of humidity of soil surface layer, so that they greatly accelerate the processes of plant succession. Most herbivores feed in secondary forests because pioneer species in secondary forests do have little or no mechanical or chemical protection against herbivores and many early and late serial tree species in secondary forests produce edible fruits in large quantities. Environment and fire have some effects on secondary forest succession. In early succession, relatively more biomass is allocated to resource acquiring tissues (leaves and fine roots) and in later stages more is allocated towards structural materials (woody stems and coarse roots). The nutrient cycling of secondary forests is quick during approximately the first 15 years of succession and it decreases as forests age. The losses of soil organic matter and N due to deforestation and burning decreases soil fertility of secondary forests.
