Agroforestry for ecosystem restoration: SAVA-Biodiversity Enrichment Experiment testing tree diversity and tree spacing

SAVA-Biodiversity Enrichment Experiment (SAVA-BEE) is an agroforestry-based ecosystem restoration experiment established in a former pasture in north-eastern Madagascar. SAVA-BEE combines two factors in an orthogonal design: tree diversity and tree spacing. SAVA-BEE consists of 45 plots 40 m x 40 m each. The plots are of different land-use types. Agroforestry - our target land-use type - occupies 27 plots. Other plots are controls. Six plots are designed as forest where we planted only trees, no crops. Six plots are designed as agriculture where we planted only crops, no trees. Six more control plots are fallow land where we did not plant anything. The trees in the agroforestry and forest plots are native Malagasy species: Calophyllum inophyllum, Canarium madagascariense, Intsia bijuga, Ocotea racemosa, Syzygium emirnense and Viguieranthus pervillei. The tree diversity gradient in the agroforestry plots has three levels: monocultures, two randomly combined three-species mixtures and the mixture of all six tree species. Each tree monoculture and tree mixture is replicated in three tree spacing levels: 2 m x 2 m, 4 m x 4 m and 8 m x 8 m. The crops planted in the agroforestry and agriculture plots are an identical mixture of Ananas comosus, Citrullus lanatus, Coffea sp., Musa sp., Pipper sp., Theobroma cacao, Vanilla planifolia. In the first year after the establishment of SAVA-BEE, we observed the survival and growth of the planted trees. We also collected data on the soil properties and measured several functional traits of the planted tree species.