Plant Attributes that Drive Dispersal and Establishment Limitation in Tropical Agricultural Landscapes

Marinés Peña-Domene,Cristina Martínez-Garza,Luz Ayestarán-Hernández,Henry Howe

doi:10.3390/f9100620

Abstract

Factors that influence tropical-forest regeneration have been of interest across the tropics. We tested the degree of dispersal and establishment limitation of pioneer and non-pioneer tree species with different dispersal modes and seed sizes, using data on both seed fall and seedling establishment in primary forest, secondary forest, and pasture excluded from livestock. The study took place in a lowland tropical rain forest in southeastern Mexico. To calculate dispersal and establishment limitation, we used a density-weighted index that considers: (1) whether a seed or seedling of a given species has arrived in the sample area; and (2) the fraction of seeds or seedlings contributed by a given species relative to the total number of seeds or seedlings arriving at a sampling station. Dispersal limitation of non-pioneer species and animal-dispersed species decreased with succession. The secondary forest had less dispersal limitation for wind-dispersed pioneers than pasture, resulting in a dense aggregation of species with seeds dispersed by wind. Overall, establishment limitation differed between animal-dispersed and wind-dispersed species in the primary forest, and was negatively correlated with seed size. The low capacity of most species to arrive, germinate, and establish as seedlings in pastures slows succession back to forest. To overcome barriers to natural succession in pastures, transplanting seedlings of non-pioneer species is suggested because most of them show high dispersal and establishment limitation.

Highlights

Two of the critical barriers to plant recruitment are failure of seeds to reach a site, and failure of seedling germination, survival and growth.Dispersal limitation strongly limits regeneration of many plant species [1]
We calculated dispersal and establishment limitation indices for 33 species, of which 12 species arrived to the primary forest, 15 species to the secondary forest and 13 species to pasture
This indicates that trees that produce high numbers of wind-dispersed seeds that are not in open areas might work as seed sinks of those species, leading to an over-representation of these seeds in the seed rain of secondary forests more than open pastures

Summary

Introduction

Two of the critical barriers to plant recruitment are failure of seeds to reach a site (dispersal limitation), and failure of seedling germination, survival and growth (establishment limitation). Dispersal limitation strongly limits regeneration of many plant species [1]. Seed arrival is influenced by dispersal agents; for example, some seeds depend on the mobility of animals such as primates, large rodents and large birds that select specific foraging areas while avoiding open areas [2,3,4,5]. Dispersal by wind is often inefficient inside the forest because wind currents are blocked and seeds collide with standing vegetation [6]. Very few large seeds of wind-dispersed species travel more than 10 m from the forest edge [7]. In open or early successional areas, small wind-dispersed

Methods

Results

Discussion

Conclusion