Reproductive phenology, seed removal and early regeneration in relation to distance from parental plants of a native palm in small Atlantic forest fragments

Vanessa Mariano,Alexander V Christianini

doi:10.1590/0102-33062015abb0302

Vanessa Mariano, Alexander V Christianini

Open Access

https://doi.org/10.1590/0102-33062015abb0302

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Abstract

The Brazilian Atlantic Forest is a global biodiversity hotspot, but most of what remains are small fragments. Small fragments are often harsh environments for forest plant recruitment due to edge effects and the loss of frugivorous animals that provide seed dispersal. We recorded the one-year reproductive phenology of the keystone palm Syagrus romanzoffiana in small (<2.5ha) Atlantic Forest fragments in southeastern Brazil. We tested the Janzen-Connell hypothesis with seed-removal experiments and followed the five-year survival of recruits in relation to the distance from parental plants. Palms produced many fruits throughout the year (mean 2,600/plant). More seedlings were found away from parental plants than near them, thereby supporting the Janzen-Connell hypothesis. Almost 45% of seedlings alive in 2010 were dead five years later, but recruitment of new seedlings compensated for this mortality. Distance-dependent factors influenced the density of early ontogenetic stages, but had limited effects on juveniles or on seed removal. High seed production, seed dispersal provided by disturbance-tolerant frugivores and the relatively long-term survival of adults, seedlings and juveniles seem to allow the persistence of S. romanzoffiana in the forest fragments, but possibly at the cost of an increased clumped distribution and reduced gene flow at the landscape scale.

Highlights

The Brazilian Atlantic Forest is considered a hotspot of biodiversity with high levels of endemism (Myers et al 2000)
We recorded the one-year reproductive phenology of the keystone palm Syagrus romanzoffiana in small (
High seed production, seed dispersal provided by disturbance-tolerant frugivores and the relatively long-term survival of adults, seedlings and juveniles seem to allow the persistence of S. romanzoffiana in the forest fragments, but possibly at the cost of an increased clumped distribution and reduced gene flow at the landscape scale

Summary

Introduction

The Brazilian Atlantic Forest is considered a hotspot of biodiversity with high levels of endemism (Myers et al 2000). This biome originally covered an area of 1.5 million km along eastern Brazil, but an extensive habitat loss and fragmentation reduced forest cover to about 11%-16%, with 80% of the remnants smaller than 50 ha (Ribeiro et al 2009). Fragmentation and hunting interact synergistically contributing to decrease the abundance of many vertebrate frugivores and seed dispersers, with large animals being more susceptible to local extinctions (Peres & Palacios 2007). Plants with large seeds (>15 mm) are more susceptible to the loss of dispersers because their regeneration is strongly seed-limited

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