Abstract:

Based on niche theory, recruitment limitation is to discuss population regeneration through the population demographic characteristics in different life stages, such as seed germination, seedling survival and growth, propagule dispersal, and varied environmental factors (soil moisture, nutrients, litter, etc.). The core of recruitment limitation consists of seed limitation and microsite limitation; however, there is no universal conclusion on which of them is more dominant. Seed limitation is related to insufficient propagules of seed production, soil seed bank and underground bud bank. Specifically speaking, inter-annual climate fluctuation, soil seed bank life time and animal predation can lead to seed limitation. Soil seed bank is often regarded as the vault of population recruitment, which promotes population recruitment together with the above ground seed rain. In contrast, if soil seeds have high death rate and dormancy rate, the role of seed bank will decline. The contribution of underground bud bank and its clonal ramets for population regeneration are more reflected on stronger resilience to disturbance. Dispersal limitation is a common phenomenon in population regeneration, which is related to many factors including seed production, dispersal ability, spreading media and seedling density. In terms of microsite limitation, embodying in how abiotic factors such as water, nutrients, litters, and biotic factors such as competition and predation effect on seed vigor, germination, seedling viability, and biomass allocation, its importance often varies with the stages of plant life history. In the future, it is necessary to conduct comprehensive and long-term experiments to focus on the underlying mechanisms involving evolution and ecology on seed limitation and its associated ecological processes, so as to obtain a more profound understanding of population recruitment, and establish a more comprehensive and systematic framework of population recruitment.

Key words: seed limitation, microsite limitation, seedling survival, belowground bud-bank, dispersal limitation