A Comparison of Growth, Structure and Diversity of Mixed Species and Monoculture Reforestation Systems in the Philippines

Forests in the Philippines, and many other developing countries in the tropics, have been extensively cleared over recent decades. There have been increasing efforts to reforest these cleared lands to achieve both socio-economic and environmental objectives. To date, planted forests have been dominated by monocultures. There has however been increasing calls to use mixtures of species, although there is limited evidence to support mixed-species plantations being a better or win-win approach to reforestation. To address this, we compared the tree growth, forest structure, and tree species diversity performance of monoculture and mixed-species tree plantations across 168 sites (251 survey plots) on Leyte Island, the Philippines. Our results indicate that mixtures of fast-growing exotics species had better growth performance compared to monocultures of fast-growing exotics species, and also better tree species diversity performance at both the plot and landscape scale. Our results suggest that mixtures of exotic or native species can provide benefits over monoculture plantations. Mixtures of productive exotic species are most suited to situations where the production function of the forest is most important, while mixtures of native species are most suited to situations where the biodiversity function of the forest is most important.