IngentaConnect Dispersal of fleshy-fruited species: a matter of spatial scale?

Abstract:

The processes associated with the dispersal of fleshy-fruited species have been an important focus of ecological research during the last two decades. These processes include fruit removal, seed rain, seed predation, seed bank dynamics, germination and establishment. Some of them interfere with the mutualistic interaction of frugivorous birds and fleshy-fruited plants. We might expect such interference to be most pronounced where the intensity of the different processes has a spatial distribution similar to that of the original seed shadow. The central theme of this review is that the main processes associated with dispersal and recruitment act at different spatial scales. To investigate this idea, about 140 publications on dispersal of fleshy-fruited species from 1980 to 2000 were screened for the spatial scaling of these processes. Microhabitat, habitat, landscape, region and biome were the five spatial scales most commonly used. However, the representation of the different scales was not fully balanced; large-scale studies were scarce and most publications considered only one scale.

The review reveals some trends in scaling of the main processes of plant dispersal and recruitment. Seed dispersal by birds and seed predation by rodents are strongly determined at the habitat level, and several studies report negative results for contrasts between microhabitats. Germination and seedling establishment, on the other hand, appear to be mainly influenced by differences between microhabitats, though information on larger scales is scarce. Genetic differentiation and phenology of fruiting have mostly been investigated at the habitat, landscape and regional scale, whereas information on the abundance of frugivorous birds and patterns in plant distribution results are available across the full range of scales from the level of the microhabitat to the region and biome. Future research should be directed to the major gaps in our knowledge, i.e. regional and zonal comparisons of the processes associated with dispersal. They should also be more sensitive to scale issues and ideally should have a multi-scaled design.

Document Type: Research article

DOI: 10.1078/1433-8319-00003

Affiliations: 1: Geobotanisches Institut, ETH, Zürichbergstrasse 38, 8044 Zürich, Switzerland; present address: Department of Ecology, Royal Veterinary and Agricultural University, Rolighedsvej 21, 1958 Frederiksberg C., Denmark;, Email: jok@kvl.dk

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