Abstract
Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields.
Highlights
Second-growth tropical forests provide a new source of hope for biodiversity conservation in an era of rapid destruction of oldgrowth tropical forests [1,2,3]
Local richness and diversity of the regenerating forest We found a total of 171 species in the surveyed quadrats representing 49 families, composed of 117 species representing 42 families in the 10 remnant tree plots (227 quadrats, each 25 m2, all stems $5 cm diameter at breast height (DBH)) and 131 species representing 42 families in the 20 control plots (461 quadrats, each 25 m2, all stems $5 cm DBH)
Extrapolated species richness for all stems $5 cm DBH was significantly greater in the remnant tree plots than in the control plots by an average of 7 species (Table 1, Figure 1)
Summary
Second-growth tropical forests provide a new source of hope for biodiversity conservation in an era of rapid destruction of oldgrowth tropical forests [1,2,3]. Remnant trees—old-growth forest trees left standing on anthropogenically modified land—can potentially accelerate forest regeneration following pasture abandonment by facilitating seed dispersal into the pasture. This facilitation by remnant trees can occur by attracting frugivorous birds and bats, serving as seed sources, and ameliorating abiotic conditions beneath their crowns Current theories about how remnant trees function as regeneration nuclei are largely based on studies conducted in active pasture or within a few years after pasture abandonment ([12], but see [13]) Most of these studies investigate effects of remnant trees on the structure and species richness of regenerating forest, but do not evaluate effects on composition of species Most of these studies investigate effects of remnant trees on the structure and species richness of regenerating forest, but do not evaluate effects on composition of species (i.e. [14,15], but see [13])
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
