Svenja Kleinschmidt, Wolfgang Wanek, Felix Kreinecker, Daniel Hackl, Daniel Jenking, Anton Weissenhofer, Peter Hietz
Reforesting degraded tropical landscapes is important for biodiversity and can absorb large amounts of carbon from the atmosphere. But understanding as well as managing rainforests is challenging, given the huge diversity of tree species with little knowledge about their growth potential or the habitat where they grow best and naturally occur. This is often addressed by looking at features of leaves or stems that are easy to measure, have specific functions and have been found to be related to growth or habitat. For example, many rainforest trees have been classified either as pioneers that grow in open areas where the forest has been cut, or as species that grow best among other trees in the shade of a dense and old forest. For simplicity, trees with light wood are often considered pioneers and trees with heavy wood as old-growth types, but this classification is very rough and not correct for many species. We used a reforestation experiment in Costa Rica to describe 47 species based on where they prefer to grow, how fast they growth and how well this can be derived from wood and leaf characteristics. This showed that habitat is best explained by growth, and any relationship with wood density is indirect, because trees with light wood can grow faster and thus outgrow trees with heavy wood in an open field. A better understanding of how the many different rainforests trees can be usefully described can help to design the best reforestation strategies.