Connectivity with primary forest determines the value of secondary tropical forests for bird conservation

Abstract

Species extinctions caused by the destruction and degradation of tropical primary forest may be at least partially mitigated by the expansion of regenerating secondary forest. However, the conservation value of secondary forest remains controversial, and potentially underestimated, since most previous studies have focused on young, single-aged, or isolated stands. Here, we use point-count surveys to compare tropical forest bird communities in 20-120-year-old secondary forest with primary forest stands in central Panama, with varying connectivity between secondary forest sites and extensive primary forest. We found that species richness and other metrics of ecological diversity, as well as the combined population density of all birds, reached a peak in younger (20-year-old) secondary forests and appeared to decline in older secondary forest stands. This counter-intuitive result can be explained by the greater connectivity between younger secondary forests and extensive primary forests at our study site, compared with older secondary forests that are either (a) more isolated or (b) connected to primary forests that are themselves small and isolated. Our results suggest that connectivity with extensive primary forest is a more important determinant of avian species richness and community structure than forest age, and highlight the vital contribution secondary forests can make in conserving tropical bird diversity, so long as extensive primary habitats are adjacent and spatially connected.Abstract in Spanish is available with online material. K E Y W O R D S bird communities, community structure, conservation, landscape management, land-use change, Panama, secondary forest, tropical extinction crisis S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Mayhew RJ, Tobias JA, Bunnefeld L, Dent DH. Connectivity with primary forest determines the value of secondary tropical forests for bird conservation.

Mediation of area and edge effects in forest fragments by adjacent land use

“…These results reinforce previous findings highlighting the value of extensive forest patches in providing source populations of forest‐dependent bird species (Mayhew et al. ), thereby enriching the surrounding matrix via a spillover of ecosystem services, such as pollination, pest control, and seed dispersal. Spillover of services has been widely documented for a range of taxa (Tscharntke et al.…”

“…populations of forest-dependent bird species (Mayhew et al 2019), thereby enriching the surrounding matrix via a spillover of ecosystem services, such as pollination, pest control, and seed dispersal. Spillover of services has been widely documented for a range of taxa (Tscharntke et al 2012), including insect and bird pollinators (Renjifo 2001;Ricketts et al 2008), and bird spillover has been shown to be particularly important in coffee plantations (Boesing et al 2018a), where birds control populations of pests (Johnson et al 2010).…”

Water availability drives aboveground biomass and bird richness in forest restoration plantings to achieve carbon and biodiversity cobenefits

“…It can take many decades for a forest to mature, and colonization by specialist bird species is likely to take much more than 20 years (Catterall et al, ; Freeman et al, ). Recent results from a chronosequence (20–120 years) of secondary tropical forests in Panana suggest that connectivity with extensive primary forest is a more important determinant of bird species richness than forest age (Mayhew, Tobias, Bunnefeld, & Dent, ), therefore the effect of landscape context in our study warrants further investigation.…”

“…Recent results from a chronosequence (20-120 years) of secondary tropical forests in Panana suggest that connectivity with extensive primary forest is a more important determinant of bird species richness than forest age (Mayhew, Tobias, Bunnefeld, & Dent, 2019), therefore the effect of landscape context in our study warrants further investigation.…”

Fire and distance from unburned forest influence bird assemblages in Southern Andean Yungas of Northwest Argentina: a case study

“…The understanding of fire ecology in this ecosystem is very important, since predictions for climatic change in the region foresee increases in mean temperatures that could, in turn, increase fire occurrence and effects (Scholze et al 2006;Flannigan et al 2009). Under this scenario, remnant undisturbed forests could be key to helping preserve biodiversity in the region and to designing appropriate conservation strategies (Mayhew et al 2019). These strategies will help assure a continuous provision of ecosystem services in a changing climate.…”