ALBERT

Beschreibung: Questions Species co-existence may be achieved by limited dispersal due to the reduced chance of inter-specific competition. But the timing of seed release also provides clues for species co-existence because asynchronous reproduction can alleviate inter-specific competition for dispersal agents, while synchronous reproduction can facilitate overall seed dispersal. How strong is seed dispersal limitation, do co-existing species release seeds synchronously or asynchronously, and what is the relationship between seed production and main meteorological measures? Location A 25-ha plot in a temperate forest, Changbai Mountain, Northeast China. Methods We calculated Jaccard coefficients between seed rain composition and neighbouring adult tree composition, analysed long-term seed rain dynamics for both the whole community and different species, and regressed seed rain density with meteorological measures using autoregressive models. Results The Jaccard coefficient dropped sharply as neighbourhood radius increased to about 10 m, indicating severe dispersal limitation. Both synchrony and asynchrony in seed release were observed: most species released mature seeds synchronously from August to November, with small segregations in time; one species released seeds in Jun. Bimodal and unimodal seasonal dynamics of seed rain were observed and some species released seeds beyond the main fruiting seasons. The seasonal dynamics of seed release might be driven by different strategies of seed dispersal. Seed rain density is significantly positively related to temperature and precipitation, with a 2-mo time lag. Conclusions Both dispersal limitation and timing of seed release by co-existing species may contribute to maintenance of diversity of this forest, but variations in temperature and precipitation considerably alter seed rain density. It has long been recognized that species coexistence may be achieved by limited dispersal due to the reducing chance of interspecific competition. In this study, we find both dispersal limitation and the timing of releasing seeds by the coexisting species may contribute to the maintenance of diversity of this forest and variations in temperature and precipitation alter the seed rain density considerably.