Reproductive traits and seed dynamics at two environmentally contrasting annual plant communities: From fieldwork to theoretical expectations

Current research has determined that traits involved in reproductive strategies and processes of seed dynamics should be studied together, and under varying environments, in order to clarify their roles in the ecology of plant communities. Here, we analyzed reproductive traits (allocation to reproduction, efficiency of seed production, and seed size) at the community level and their relationships to seed dynamics (seed production, dispersal, storage, loss, and germination) in a Mediterranean and a semiarid ecosystem in Israel. The results showed that aboveground biomass production was two-fold greater in the Mediterranean community compared to the semiarid. Conversely, relative reproductive allocation in the semiarid community almost doubled that of the Mediterranean. Seed size and seed output correlated negatively but, despite large differences in seed production between communities (73% higher in the semiarid site), average seed size was similar between sites. Seed losses in the semiarid community were significantly greater than those in the Mediterranean (80% vs. 13%), and contrasting seed-density patterns between the communities were noted. Despite small seed sizes, dispersal was of low importance and did not differ between communities. Our results show that whereas some plant traits are reflected at the community level according to theoretical functional predictions, others fail to follow the expected patterns due to variations in the relative importance of environmental constraints and the existence of alternative strategies for coping with them.