1. The conversion of tropical forests to farmland is a key driver of the current extinction crisis. With the present rate of deforestation unlikely to subside, secondary forests that regenerate on abandoned agricultural land may provide an option for safeguarding biodiversity. While species richness (SR) may recover as secondary forests get older, the extent to which phylogenetic diversity (PD)—the total amount of evolutionary history present in a community—is conserved is less clear. Maximising PD has been argued to be important to conserve both evolutionary heritage and ecosystem function.

2. Here, we investigate the effects of secondary forest regeneration on PD in birds. The regeneration of secondary forests could lead to a community of closely related species, despite maintaining comparable SR to primary forests, and thus have diminished biodiversity value with reduced evolutionary heritage.

3. We use a meta-dataset of paired primary and secondary forest sites to show that, over time, forest specialist species returned across all sites as secondary forest age increased. Forest specialists colonise secondary tropical forests in both the Old World and the New World, but recovery of PD and community composition with time is only evident in the Old World.

4. Synthesis and applications. Whilst preserving primary tropical forests remains a core conservation goal, our results emphasize the important role of secondary forest in maintaining tropical forest biodiversity. Biodiversity recovery differs between Old and New World secondary forests and with proximity to primary forest, highlighting the need to consider local or regional differences in landscape composition and species characteristics, especially resilience to forest degradation and dispersal capability. While farmland abandonment is increasing across marginal areas in the tropics, there remains a critical need to provide long-term management and protection from reconversion to maximize conservation benefits of secondary forests. Our study suggests such investments should be focused on land in close proximity to primary forests. 30-Mar-2020

This dataset is derived from 20 published pan-tropical studies containing 35 paired secondary and primary forest sites. C. Banks-Leite (Banks-Leite et al. 2012), D. Becker (Becker and Ágreda 2005, Becker et al. 2008), S.H. Borges (Borges 2007) and B. Maas (Maas et al. 2009), provided access and permission to use additional data for this study. All studies are outlined in the Data Sources section below. 

Data Sources:

Andrade, G.I., Rubio-Torgler, H., 1994. Sustainable use of the tropical rain forest: evidence from the avifauna in a shifting‐cultivation habitat mosaic in the Colombian Amazon. Conservation Biology 8, 545–554.

Banks-Leite, C., Ewers, R.M., Metzger, J.P., 2012. Unraveling the drivers of community dissimilarity and species extinction in fragmented landscapes. Ecology 93, 2560–2569.

Barlow, J., Mestre, L.A., Gardner, T.A., Peres, C.A., 2007. The value of primary, secondary and plantation forests for Amazonian birds. Biological Conservation 136, 212–231.

Becker, C.D., Ágreda, A., 2005. Bird community differences in mature and second growth garúa forest in Machalilla National Park, Ecuador. Ornitologia Neotropical 16, 297–319.

Becker, C.D., Loughin, T.M., Santander, T., 2008. Identifying forest‐obligate birds in tropical moist cloud forest of Andean Ecuador. Journal of Field Ornithology 79, 229–244.

Blake, J.G., Loiselle, B.A., 2001. Bird assemblages in second-growth and old-growth forests, Costa Rica: perspectives from mist nets and point counts. The Auk 118, 304–326.

Borges, S.H., 2007. Bird assemblages in secondary forests developing after slash-and-burn agriculture in the Brazilian Amazon. Journal of Tropical Ecology 23, 469–477.

Dawson, J., Turner, C., Pileng, O., Farmer, A., McGary, C., Walsh, C., ..., Yosi, C., 2011. Bird communities of the lower Waria Valley, Morobe Province, Papua New Guinea: a comparison between habitat types. Tropical Conservation Science 4, 317–348.

Gilroy, J.J., Woodcock, P., Edwards, F.A., Wheeler, C., Baptiste, B.L., Uribe, C.A.M., ..., Edwards, D.P., 2014. Cheap carbon and biodiversity co-benefits from forest regeneration in a hotspot of endemism. Nature Climate Change 4, 503.

Johns, A.D., 1991. Responses of Amazonian rain forest birds to habitat modification. Journal of Tropical Ecology 7, 417–437.

Maas, B., Putra, D.D., Waltert, M., Clough, Y., Tscharntke, T., Schulze, C.H., 2009. Six years of habitat modification in a tropical rainforest margin of Indonesia do not affect bird diversity but endemic forest species. Biological Conservation 142, 2665–2671.

Mulwa, R.K., Böhning‐Gaese, K., Schleuning, M., 2012. High bird species diversity in structurally heterogeneous farmland in western Kenya. Biotropica 44, 801–809.

Naidoo, R., 2004. Species richness and community composition of songbirds in a tropical forest-agricultural landscape, in: Animal Conservation Forum. Cambridge University Press, pp. 93–105.

O’Dea, N., Whittaker, R.J., 2007. How resilient are Andean montane forest bird communities to habitat degradation? Biodiversity and Conservation 16, 1131–1159.

Raman, T.R., Rawat, G.S., Johnsingh, A.J.T., 1998. Recovery of tropical rainforest avifauna in relation to vegetation succession following shifting cultivation in Mizoram, north‐east India. Journal of Applied Ecology 35, 214–231.

Reid, J.L., Harris, J.B.C., Zahawi, R.A., 2012. Avian habitat preference in tropical forest restoration in southern Costa Rica. Biotropica 44, 350–359.

Renner, S.C., Waltert, M., Mühlenberg, M., 2006. Comparison of bird communities in primary vs. young secondary tropical montane cloud forest in Guatemala, in: Forest Diversity and Management. Springer, pp. 485–515.

Sodhi, N.S., Koh, L.P., Prawiradilaga, D.M., Tinulele, I., Putra, D.D., Tan, T.H.T., 2005. Land use and conservation value for forest birds in Central Sulawesi (Indonesia). Biological Conservation 122, 547–558.

Tvardíková, K., 2010. Bird abundances in primary and secondary growths in Papua New Guinea: a preliminary assessment. Tropical Conservation Science 3, 373–388.

Wijesinghe, M.R., Brooke, M. de L., 2005. Impact of habitat disturbance on the distribution of endemic species of small mammals and birds in a tropical rain forest in Sri Lanka. Journal of Tropical Ecology 21, 661–668.