Both Social and Ecological Factors are Linked to Recovery of Biodiversity During Natural Regeneration of Tropical Forests
Latawiec, A. E., R. Crouzeilles, P. H. S. Brancalion, R. R. Rodrigues, J. B. B. Sansevero, J. S. dos Santos, M. Mills, A. G. Nave, and B. B. N. Strassburg. 2016. Natural regeneration and biodiversity: a global meta-analysis and implications for spatial planning. Biotropica 48:844-855.
What socio-ecological factors are correlated with the effectiveness of natural regeneration for the recovery of biodiversity? This study addressed major knowledge gaps on natural regeneration as a cost-effective approach to ecological restoration of forests in tropical regions. Based on an extensive database of studies on the recovery of biodiversity a subset of natural regeneration studies in tropical regions provided data for both naturally regenerating and reference forest ecosystems. Data on socioeconomic, biogeographic, and ecological factors were gathered for each selected study were examined together with results from a meta-analysis of 123 studies including 1389 quantitative comparisons of biodiversity between naturally regenerating and reference sites across 117 study landscapes.
A novel finding of this analysis was that greater biodiversity benefits followed from natural regeneration within countries with low and high or very high levels of development as measured by the Human Development Index (HDI), which includes indicators of life expectancy, education and per capita income. This finding may reflect patterns of deforestation, recovery, and economic development as predicted by the environmental Kuznets curve. Countries with low levels of Human Development Index tend to have more highly forested landscapes, less intensive previous land use, and more recent deforestation, all of which facilitate natural regeneration. Countries with high levels of Human Development Index are characterized by increasing urbanization and economic development, which can promote natural regeneration in abandoned agricultural lands. These factors could explain why countries with intermediate levels of Human Development show lower recovery of biodiversity during forest regeneration, as these areas have higher intensity of previous land-use, decreases in forest cover, and higher environmental impacts due to hunting or pollution that can influence the recovery of biodiversity.
The results further showed that recovery of biodiversity in naturally regenerating forests was higher in Australasia and Afrotropics and in areas of less intensive past disturbance. Areas with agroforestry and shaded-plantation actually showed higher biodiversity responses in natural regenerated forests compared to reference forests.
The PARTNERS connection
Our results were initially presented in the symposium on “Low-cost restoration via natural regeneration”, organized by PARTNERS in Rio de Janeiro, Brazil, in 2014, and published in the Special Issue of Biotropica “The Role of Natural Regeneration in Large-scale Forest and Landscape Restoration: Challenge and Opportunity” organized by PARTNERS in 2016.