Endozoochory decreases environmental filtering imposed to seedlings.

CAVALLERO, LAURA; AIZEN, MARCELO A.; RAFFAELE, ESTELA

JOURNAL OF VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. .23 p. 677 - 689

1100-9233

Questions: Recruitmentmicrosites are imposed on plants, first by seed dispersaland then by the environment. Different seed dispersal vectors could decrease orincrease the environmental filtering imposed on seedlings, depending on theirspecificity to deliver seeds to suitable microsites for germination and establishment.We addressed the hypothesis that endozoochory reduces the environmentalfiltering imposed to seedlings to a larger extent than does anemochory.We predicted that seedlings from animal-dispersed species should show a higherdegree of environmental coupling.Location: Northern Patagonian Andean region of Argentina, 40–42° S.Methods: We characterized the relationship of seedlings, saplings and reproductiveindividuals to total radiation, air temperature and relative humidity for16 woody species growing in 25 plant communities of different post-fire ages intemperate forests of southern South America.Results: Seedlings and saplings of endozoochorous species occurred undermoresimilar environmental conditions than seedlings and saplings of anemochorousspecies. Basically, the mean difference in plant–environment correlation coefficientsbetween saplings and seedlings was 0.2 for all anemochorous species for all environmental variables. Comparisonsbetween dispersal modes were also statistically significant before and aftercontrolling for phylogenetic relationships among species. Even though saplingsand seedlings of endozochorous species tended to occur under similar environmentalconditions, we did not find evidence that saplings and seedlings co-occurin the same physical microsites. Finally, we did not find evidence either thatseedlings of endozoochorous species tended to occur differentially underneathreproductive individuals of the same species (i.e. more seeds falling by gravitybeneathmaternal plants).Conclusions: The tighter coupling between seedlings of endozoochorous speciesand environmental factors persisting to the sapling stage suggests that relyingon animals for seed dispersal reduces mortality costs during the early stagesof recruitment by reducing the environmental filtering imposed on seedlings.