Abstract
Plant biodiversity in Dutch heathlands and species-rich grasslands have declined severely during the last decades. Since 1900 huge areas have been converted into arable fields but serious losses in biodiversity occurred also in the remnants that have been preserved. Recent attempts to convert arable fields back into heathlands often showed no immediate success. It became clear that the spatial relations between restoration sites and their surroundings are essential. Seed rain in a site is directly related to its position relative to local sources. Tools to assess the restoration opportunities of heathland and species-rich acidic grassland in relation to the distance to the nearest seed sources are not available at present. It is the aim of the present project to develop such tools also for seed dispersal by wind and by animals. The aerodynamic properties of a large number (c. 200) of characteristic species of sand areas will be taken from literature or experimentally screened. These parameters will be used to set up two wind dispersal models, a statistical model of the so called 'Gaussian plume' type and a mechanistic particle model. Data on external seed transport by animals will be taken from literature while internal transport will be measured experimentally. Both will be related to daily animal movement and used to set up a spatially explicit model to simulate the likelihood of dispersal of characteristic species by animals. Once developed, the tools mentioned will give more insight in the potential dispersal of endangered species and the sustainability of the restored sites.
Netherlands