Tropical forests store 20-40% of terrestrial carbon (C) and contain 90% of all known tree species. Land use change in the tropics is one of the main causes of species loss and greenhouse gas (GHG) emissions. On the other hand, human-modified tropical landscapes can also mitigate climate change and conserve biological diversity. The importance of managed landscapes for biodiversity conservation and C-storage is increasingly acknowledged, especially in the case of agroforestry (the integration of trees with crops or livestock).
Since 2008, the SFS Center for Sustainable Development Studies has been monitoring tree diversity and C-storage in the vegetation and soils of shaded coffee plantations, silvo-pastoral systems and forest fragments in the Central Valley of Costa Rica. We found that shade-grown coffee farms and pastures with trees store about 60% of the amount of C and maintain nearly 20% of the tree diversity found in natural forests. Tree species composition and diversity determine the amount of C stored, which suggests that synergies exist between tree diversity conservation and GHG mitigation.
After eight years of research, we now want to know how tree diversity and land management affect C-sequestration in vegetation and soils in the long term. A successful crowd-funding campaign on the platform experiment.com helped us to secure a part of the funds needed to continue this research throughout the next years. We are planning to establish permanent plots that differ in tree species diversity and composition within coffee farms, pastures and forests. We will install dendrometer tapes, in order to precisely monitor the growth of selected, dominant tree species with different functional traits (e.g. fast vs. slower growth rates). In addition, trees will be tagged and re-measured annually over 5 years to estimate above-ground C-sequestration. During the next 5 years we are also planning to re-sample the soils at all our research sites, which will allow us to estimate soil C-sequestration over a period of several years. We hope that the results of this research will help us to understand the relationships between tree diversity and carbon sequestration. This project is relevant for tropical regions, where the management of altered landscapes will determine the future capacity of biological systems to remain functional in terms of providing critical ecosystem services and harboring high levels of biological diversity.