The ephemerality of secondary forests in southern Costa Rica

Abstract

Secondary forests are increasingly recognized for conserving biodiversity and mitigating global climate change, but these and other desired outcomes can only be achieved after decades of regeneration, and secondary forests are frequently recleared before they recover to predisturbance conditions. We used a time series of aerial photographs (1947‐2014) to evaluate multidecadal persistence of secondary forests across a 320 km2 landscape in southern Costa Rica. Secondary forests had relatively short lifespans, with 50% recleared within 20 years and 85% recleared within 54 years of when they were first observed. Larger forest fragments and forests near rivers had a lower reclearance hazard, but forest persistence did not differ over time, indicating that regional forest regeneration may be generally ephemeral. Costa Rica has made an international commitment to restore 1 million ha of degraded land by 2020. Depending on how this is achieved, only half that target may remain forested by 2040.

Recovery of amphibian, reptile, bird and mammal diversity during secondary forest succession in the tropics

“…In conclusion, tropical secondary forests provide habitat for a diversity of vertebrates, but the slow recovery of species compositional similarity, forest specialists and some functional groups (e.g. insectivorous birds) highlighted the challenge of secondary forest persistence (Reid et al 2018), and strongly argues for the continued protection of old growth/mature forest (Gibson et al 2011) as habitat for forest specialists and as sources for secondary forest sites.…”

“…The lack of older secondary forest sites could be related with many socioeconomic factors (e.g. land tenure, fluctuation in commodity prices) and highlights the challenge of secondary forest persistence (Schwartz et al 2017, Reid et al 2018.…”

“…agriculture, pasture, slash and burn), the increase in natural regenerated secondary forest cover can provide habitat for many species and improve ecosystem services (Chazdon et al 2009, Poorter et al 2016, Rozendaal et al 2019. Although ecologists and conservationists have focused on deforestation, extensive areas of the tropics are naturally regenerated forest and their importance for biodiversity has not been fully explored (Achard et al 2002, Aide et al 2013, Chazdon et al 2016, Reid et al 2018. While most secondary forest studies have focused on vegetation, recent studies have analysed the recovery patterns of vertebrates during secondary forest succession (Andrade and Rubio-Torgler 1994, Medellin and Equihua 1998, Blake and Loiselle 2001, Crouzeilles et al 2017, or have evaluated the functional (Sayer et al 2017) and phylogenetic diversity (Edwards et al 2017) of vertebrates in tropical secondary forest.…”

Assessing the growth and climate sensitivity of secondary forests in highly deforested Amazonian landscapes

“…Initiatives such as the Bonn Challenge highlight two additional knowledge gaps linked to management. It seems likely that the increase in landscape‐scale restoration will also increase secondary forest permanence, moving beyond the current situation where secondary forests are often cleared again within 5–20 yr (Aguiar et al , Reid et al ). Although our current understanding of younger forests is good (Poorter et al , , , Martínez‐Ramos et al , Villa et al , Rozendaal et al ), and the nonlinear response of forest recovery over time is well established (Poorter et al , Ferreira et al , Lennox et al , Requena Suarez et al , Rozendaal et al ), there is far too much variation in the relationship to use young forests to predict recovery rates in older forests accurately.…”

The environmental impacts of palm oil and its alternatives

“…In some cases, the long-term environmental impacts of planting oil crops in areas of degraded versus old-growth ecosystems could therefore in theory be similar. However, given the current lack of effective policies that could practically ensure the long-term regeneration of degraded lands 33 , the uncertainty in predicting local recovery success 32 , and the importance of primary habitats as biodiversity sources 34 , we echo calls to prioritise future oil crop expansion on degraded areas, specifically those that are located 25 within optimal (i.e. dark blue) areas in Fig In our analysis we have not accounted for potential economic feedbacks related to shifts in the proportion of global oil demand supplied by individual crops.…”