Wattkast

To address how the spatial configuration of the landscape affects tree-herbivore interactions we have mapped every individual of our target plant, the on the island. Despite its small size (about 5 km²), Wattkast provides a diverse environment for our studies. The island consists of a patchwork of forests, fields and pastures. Most of the oak trees are situated in an area of high tree density, but individual trees are scattered over the rest of the island, enabling us to identify a range of tree densities and spatial settings for our studies.

Within Wattkast, the location of all oak trees more than 50 cm in height have been accurately measured with a GPS navigator. A number of tree characteristics such as growth form, diameter of the trunk and previous herbivore damage have also been estimated, and the type of the surrounding vegetation has been classified for each oak individual. The information from the oak inventory now forms a database with information about the more than 1800 oak individuals on the island.

Since 2003, we have visited a selection of small-sized oaks on Wattkast to score the presence or absence and abundance of leaf-mining and galling insect species. In the future our spatially referenced oak data will serve many other purposes, including studies of host-pathogen and multitrophic interactions.