Ecology of tree seed and seedlings: Implications for tropical forest conservation and restoration

Seed and seedling traits vary strongly across the tropical forest biome to cope with the variations in the distribution and amount of rainfall, light, temperature and soil nutrient regimes, and the intensity of predation and disturbance. Proportion of species producing dormant seeds increases along a gradient of dryness and unpredictability of rainfall. Seed longevity is generally higher for dry tropical than for wet tropical species. Environmental variables and the dispersal syndrome have led to the selection for and production of different seed sizes, with implications for germination and seedling establishment in different situations, and for the build up of persistent soil seed bank. Seeds have evolved mechanisms to recognize environmental cues which enable them to confine their germination in particular periods and locations to allow for a greater probability of seedling establishment and survival. While for a majority of wet tropical species gap dependency and shade tolerance are important, seedlings of many dry tropical species show shade dependence, Successional hierarchy is frequently reflected in ecological requirements for germination and seedling fitness. Field microsites represent multiple-variable cues for germination and establishment. Knowledge on the ecology of germination and seedling growth is vital, not only for understanding the community processes of plant recruitment and succession, but also for developing strategies for the conservation of biodiversity and restoration of tropical forests.