Background:

Plant distribution depends, partially on dispersers that transport seeds to suitable habitats and the presence of other plants that facilitate or inhibit germination and establishment. It is important to determine how these factors influence plant distribution in vegetation and include such information in management plans.

Hypotheses:

Seeds and seedlings of the studied species will differ under tree species and position with respect to the vegetation edge. Higher seed and seedling density is expected under species of animal dispersed trees and in the edges of fragments.

Methods:

We carried out a direct count of seeds and seedlings of Zanthoxylum fagara (L.) Sarg. in North America and Zanthoxylum coco Gillies ex Hook.f. & Arn. in South America under the canopy of shrubs inside and at the edge of remnant vegetation.

Results:

For both species, seed density was similar at the edge and inside vegetation fragments. Z. fagara seedling density was higher at the edge than 40 m inside the scrub, also higher under trees dispersed by animals. For Z. coco no seedling density differences were found at edge or inside vegetation fragments.

Conclusions:

For both species, seed dispersers do not appear to be important, as seeds had similar seed density in edge and inside vegetation. However, they might have an effect on Z. fagara regeneration, as there was higher seedlings density at the edge than inside. Higher light at edge might promote regeneration of this species. For Z. coco there does not appear to be an effect of dispersers on regeneration.

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