Lluvia de semillas bajo especies de árboles nativos y no-nativos en el Refugio de Vida Silvestre de Cabo Rojo, Puerto Rico

J. Danilo Chinea,Andrea Arias-García

doi:10.15517/rbt.v62i3.12942

Abstract

Seed dispersal is a fundamental process in plant ecology and is of critical importance for the restoration of tropical communities. The lands of the Cabo Rojo National Wildlife Refuge (CRNWR), formerly under agriculture, were abandoned in the 1970s and colonized mainly by non-native tree species of degraded pastures. Here we described the seed rain under the most common native and non-native trees in the refuge in an attempt to determine if focal tree geographic origin (native versus non-native) influences seed dispersal. For this, seed rain was sampled for one year under the canopies of four native and four non-native tree species common in this refuge using 40 seed traps. No significant differences were found for the abundance of seeds, or their diversity, dispersing under native versus non-native focal tree species, nor under the different tree species. A significantly different seed species composition was observed reaching native versus non-native focal species. However, this last result could be more easily explained as a function of distance of the closest adults of the two most abundantly dispersed plant species to the seed traps than as a function of the geographic origin of the focal species. We suggest to continue the practice of planting native tree species, not only as a way to restore the community to a condition similar to the original one, but also to reduce the distances needed for effective dispersal.

Highlights

Seed dispersal is usually the premier demographic process allowing plants to find adequate sites for their recruitment and eventual reproduction (Nathan & Muller-Landau, 2000, Wenny, 2001) and for avoiding the usually damaging effects of landing in the neighborhood of their parental plants (Howe & Smallwood, 1982)
Seed dispersal has been extensively studied in tropical moist and wet ecosystems (Holl, Loik, Lin, & Samuels, 2000), but relatively little is known about this process in tropical and subtropical dry forests (Bullock & Solis-Magallanes, 1990, Campbell, Lynam, & Hatto, 1990, Ceccon & Hernandez, 2009, Vieira & Scariot, 2006) even though these ecosystem types occupy approximately 40% of the tropics and subtropics (Murphy & Lugo, 1986)
Several studies have documented that native species regenerate under the canopy of non-native species we have not found any studies testing the relative influence of native and non-native focal species on seed dispersal

Summary

Introduction

Seed dispersal is usually the premier demographic process allowing plants to find adequate sites for their recruitment and eventual reproduction (Nathan & Muller-Landau, 2000, Wenny, 2001) and for avoiding the usually damaging effects of landing in the neighborhood of their parental plants (Howe & Smallwood, 1982). The Cabo Rojo National Wildlife Refuge (CRNWR), located within the Subtropical Dry Forest, was established in an area with a long history of agricultural disturbance (mostly for grazing) but later abandoned in the 1970’s. Since its abandonment a mixture of native and non-native plant species have colonized the area (Zuill, 1985). Non-native plant species have been long considered a threat to native biota (Heywood, 1989). Some of these species have been implicated in modifying their newly colonized habitats in respect to ecosystem properties like hydrology, nutrient dynamics, and disturbance regimes, or by directly competing with the native species. This study addressed the following questions: (1) does seed rain abundance, diversity and composition differ under native and non-native trees?, and (2) do the different focal tree species differentially influence the seed rain?

Methods

Results

Conclusion