Effects of land-use changes on woody species distribution and above-ground carbon storage of forest-coffee systems

Abstract

As deforestation and fragmentation continue in tropical regions with high human use and disturbance of natural habitats, production landscapes such as agroforests and plantations may provide some forest-based services depending on tree selection, agroforest management and intensification. This is typical to southwest Ethiopia with strong human-dependence on forest biodiversity and ecosystem services. We examined the effects of land-use changes and fragmentation on woody species distribution and the relative importance of forest fragments and coffee farms in wood use and carbon storage. We sampled heartwood from 71 woody species in three land use types: natural forest fragments, smallholder semi-forest coffee farms and state-owned coffee plantations. We calculated wood density as an oven-dry biomass per fresh volume of heartwood core samples, and above-ground carbon biomass using allometric methods. We found that average wood density values were not correlated with fragment size. Mean wood density of species in forests was greater than in state-owned plantations. The two coffee systems can store 50–62% of the above-ground carbon biomass found in forests, indicating the need to incorporate coffee farms and forest remnants in carbon incentive, or climate mitigation and adaptation programs. To correlate species wood density with local wood preferences, we interviewed focus groups and households about the use-values of 51 farmer-appreciated species. There was a strong correlation between wood density and local wood-values signifying the concordance of species functional traits and ecosystem service values. Our results indicate the need to integrate functional traits and local ecosystem service uses in climate adaptation and mitigation by incorporating coffee agroforests with the conservation of natural forest remnants.