Recent studies have shown the positive effect of diversity on primary productivity. Here we investigated this diversity-productivity relationship between the established tree richness gradient in the main experiment and the naturally occurring tree and shrub layer. Moreover, we made use of the integrated BEFmod experiment arranged along a tree species richness gradient at site A and B, with subplot treatments of phosphorus addition, insecticides addition, fungicide addition, herb layer weeding and no weeding, to compare this relationship among three different manipulated environmental settings.

In all plots in BEF-China (including C, P, F and I treatment) the herb layer has been continuously weeded twice a year, (since 2009 and 2010, for site A and site B, respectively) and since 2014 once a year on both sites to increase the establishment of planted trees. In each VIP, subplots were subjected to a manipulation of resource supply and biotic interactions (BEFmod experiment), which started in 2014. On the northern edge of each VIP, 5 subplots were established, each measuring 5.16 x 5.16 m and containing 4 × 4 trees. Subplots were randomly assigned to five different treatments: “No weeding“ (NW, i.e., admitting all types of weeds, already established in 2011), “Phosphorus fertilization” (P, i.e., applying 40 g triple super phosphate (H2PO4)2 per tree, corresponding to 100 kg P/ha once in April 2014), "Fungicide application" (F), "Insecticide application" (I) and “Control” (C, i.e., weeding as on the total plot level together with monthly H2O application). We recorded the basic diameter, height and the numbers of individuals per species as a proxy for productivity.

VIP Plots of the main experiment on Site A