Recruitment dynamics of a fleshy‐fruited plant (Olea europaea): connecting patterns of seed dispersal to seedling establishment

Abstract

Summary 1 Little is known about the consequences of seed‐disperser activity for plant demography. We compared the spatial patterns of seed dispersal generated by frugivorous birds with those of seedling survival for the shrub Olea europaea. We examined the relative importance of dispersal in determining plant recruitment and tested whether the initial dispersal pattern persisted throughout recruitment. 2 We quantified the processes affecting each stage of regeneration (seed within a ripe fruit, dispersed seed, seedling and sapling) in different microhabitats, and evaluated transition probabilities between stages. We could then determine the overall probability of a seed in a ripe fruit becoming a sapling, and compare the probability of such an event occurring in different microhabitats. 3 Only 9.3% of the emerged seedlings reached the sapling stage, whereas 35.3% of the seeds were dispersed; 27.0% of dispersed seeds produced seedlings and 62.9% of saplings survived for 2 years. Seedling survival was therefore the critical link in regeneration. Water stress was responsible for more than 70% of seedling losses, which suggests that abiotic factors (mainly rainfall) may account for most of the fluctuation in recruitment in this species. 4 Neither post‐dispersal seed predation nor germination caused changes in the initial spatial distribution of seeds, but differences in the requirements of seeds and seedlings then caused spatial uncoupling. The most favourable places for seeds were the worst for seedlings, and consequently frugivore‐generated dispersal patterns differed from the final spatial pattern of recruitment. 5 Recruitment under conspecifics was nearly zero and dispersers are therefore crucial if recruitment is to occur. Their effect on the amount of recruitment was, however, overwhelmed by processes acting on the seedling stage. 6 For Olea europaea, the pattern generated by short‐term recruitment dynamics persists in the long‐term spatial distribution of saplings.