Conserving tropical tree diversity and forest structure: the value of small rainforest patches in moderately-managed landscapes.

Manuel A Hernández-Ruedas,Gilberto Jamangapé,Guillermo Ibarra-Manríquez,Miguel Martínez-Ramos,Bráulio A Santos,Esteban Martínez,Felipe P L Melo,Jorge A Meave,Víctor Arroyo-Rodríguez,Norman Wh Mason

doi:10.1371/journal.pone.0098931

Manuel A Hernández-Ruedas, Gilberto Jamangapé + Show 8 more

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https://doi.org/10.1371/journal.pone.0098931

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Abstract

Rainforests are undergoing severe deforestation and fragmentation worldwide. A huge amount of small forest patches are being created, but their value in conserving biodiversity and forest structure is still controversial. Here, we demonstrate that in a species-rich and moderately-managed Mexican tropical landscape small rainforest patches (<100 ha) can be highly valuable for the conservation of tree diversity and forest structure. These patches showed diverse communities of native plants, including endangered species, and a new record for the country. Although the number of logged trees increased in smaller patches, patch size was a poor indicator of basal area, stem density, number of species, genera and families, and community evenness. Cumulative species-area curves indicated that all patches had a similar contribution to the regional species diversity. This idea also was supported by the fact that patches strongly differed in floristic composition (high β-diversity), independently of patch size. Thus, in agreement with the land-sharing approach, our findings support that small forest patches in moderately-managed landscapes should be included in conservation initiatives to maintain landscape heterogeneity, species diversity, and ecosystem services.

Highlights

83% of earth’s land surface has been altered by human action [1], leading to the rapid destruction and fragmentation of terrestrial ecosystems
Whereas some studies argue that highly fragmented tropical landscapes can maintain high levels of the original diversity [7,8], others demonstrate that species diversity in forest patches declines rapidly after forest fragmentation [9,10]
Indicated that the resulting species-area curves were indistinguishable, regardless of whether small or large patches were added first. This pattern was almost identical to that observed in the landscape with lower deforestation level (24% of forest cover) at Los Tuxtlas, Mexico; in this region, the landscape with highest deforestation level (4% of forest cover) showed that collections of small patches contained a lower number of species than fewer larger patches (SI = 20.14; Figure 4), indicating that the relative contribution of small forest patches to regional diversity declines in landscapes with lower forest cover

Summary

Introduction

83% of earth’s land surface has been altered by human action [1], leading to the rapid destruction and fragmentation of terrestrial ecosystems. Increasing tree mortality rates have been reported near forest edges [9], among emergent species [11,12]. This process may lead to declines in tree species richness in smaller forest patches [10,13], near forest edges [11,12]. Approximately 40% of old-growth forest cover remains as remnant patches of variable sizes embedded in a heterogeneous matrix of secondary forests, human settlements, cattle pastures, and crop fields

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