Phytochemistry of Scot's pine as a driver of spatial heterogeneity in insect herbivore and broader diversity in a native woodland landscape

We hypothesised that variation in the chemical characteristics of Scots pine trees will affect the distribution and abundance of insect herbivores in a native forest landscape. Because insects play a key role in nutrient cycling this could have consequences for forest soil processes and be a driver of heterogeneity in microbial, mycorrhizal, soil invertebrate and plant species diversity with cascading effects through the food chain. Interception funnels were constructed under Scots pine trees of contrasting phytochemistry to assess the composition of material falling from pine crowns. Material was continuously collected for two years and sorted into plant and insect categories. Significant spatial associations were detected during early summer. The distribution of insect herbivores in early summer was related to the concentrations of β-pinene and two other monoterpenes. However, the overall average distribution of herbivores each year was related to landform, especially altitude, and illustrates the complex terrain of the study site and potential interactions within the community.