Linking plant traits to ecosystem service provision through a management gradient in a tropical dry forest

The exploitation of pristine forests decreases their functional diversity and ecosystem service provision. The forest management strategies of some rural societies, though, can increase the provision of specific ecosystem services useful to the community. This is tightly linked to shifts in forest functional traits, but few studies have investigated the changes to multiple provisioning, cultural and regulating ecosystem services across a traditional forest management gradient. This can give insights into the role of traditional management systems in the conservation of ecosystem services. Here we used a plot network of 60 tropical dry forest plots in Sri Lanka to test whether different forest management intensities are linked to differences in forest functional traits and ecosystem service provision through different tree size classes. Furthermore, we investigated the link between functional traits and ecosystem service provision with both redundancy analysis and linear mixed models. We found that the most intensely managed forest plots had some early successional traits such as light wood, small seeds and large leaves but, unexpectedly, taller trees than the least intensely managed plots. The intensely and moderately managed plots had a greater abundance of species delivering cultural and provisioning services than the least managed plots. We found significant links between the provision of construction services and mean tree height, and the delivery of cultural services and wood density. The links between functional traits and ecosystem services were clearest for individuals smaller than 10 cm DBH. Overall, the forest use and management by this rural community increased ecosystem provisioning services. For the first time we have characterised different links between species' functional traits and the ecosystem services they provide in a tropical dry forest. We highlight that the differences across forest management intensities were clearest for trees in the smaller cohorts, which are generally ignored by many researches. Similar studies will identify relevant functional traits that will help discover new species providing key ecosystem services. Understanding the interactions between rural societies and the forests they manage will foster the creation of guidelines for sustainably enhancing forest cultural and provisioning services.