Changes in carbon stocks and tree diversity in agro-ecosystems in south western Uganda: what role for carbon sequestration payments?

Abstract

Direct payments offered as compensation for adopting practices which increase carbon sequestration have implications for biodiversity conservation. This study analyzed changes in carbon stocks and tree diversity on carbon and non-carbon farmers’ plots in a pilot carbon offset project implemented by smallholder farmers in south western Uganda. On carbon farms, results indicate a respective decline and an increase in carbon density on farmlands and grasslands. On non-carbon farmers’ plots, there was an increase in both farmland and grassland carbon density. Carbon densities in farmland were significantly (t = −2.38; P = 0.023) higher than those in grasslands. There were no significant differences in tree diversity on farmlands but significant differences (species richness t = 2.18; P = 0.04; Shannon Index t = 2.92; P value = 0.0077) in grasslands. Tree diversity on carbon farmers’ plots decreased in farmlands, but increased in grasslands, while for non-carbon farmers there was a decline in tree diversity in both grasslands and farmlands. There were strong positive correlations between carbon density and tree diversity.