Exploring relationships between abundance of non-timber forest product species and tropical forest plant diversity

Despite the importance of non-timber forest products (NTFPs) for local livelihoods in tropical countries and the increasing attention for biodiversity-ecosystem services relationships, it remained unclear how the ecosystem service of NTFP provisioning is related to plant diversity. Although it is generally assumed that plant diversity is positively related to ecosystem services, this had not been assessed for NTFP provisioning. We applied bivariate and multiple regression models to explore the relationships between the abundance of 58 commercially relevant NTFP species and woody plant diversity across 287 plots of tropical forests in Northern Suriname. We found that NTFP abundance showed both positive and negative relationships to plant diversity indicators. In contrast to expectations, NTFP abundance was negatively related to woody species richness. In addition, across the plots disproportionately few (2-6) NTFP species determined >50% of NTFP abundance. The occurrence and the identity of these 'NTFP oligarchs' was associated to specific floristic compositions. Overall, more than half, i.e. 55.9%, of the observed variation in NTFP abundance could be explained by a combination of taxonomic and structural plant diversity indicators. Our case study findings are relevant for conservation policies in general. In most countries NTFPs are not on the agenda of governments and current tropical conservation policies often focus on forests with high species richness and/or carbon stocks. Our findings indicate that current policies may not cover valuable forests in terms of high NTFP abundance. To support sustainable NTFP provisioning, additional conservation efforts would need to include those vegetation types with high NTFP abundance.