Talk, 47th Annual Symposium of the International Association of Vegetation Science (IAVS): "Landscape Change and Ecosystem Disturbance: Islands and Continents", Kailua–Kona, Hawai'i, USA: 2004-07-18 - 2004-07-23
The documentation of biodiversity is lacking quantitative and comprehensible methods to detect and quantify changes at the level of ecosystems and landscapes (LOREAU et al. 2001). Major factors for the expected losses are changes in land-use (SALA et al. 2000). Thus, it is crucial to examine the influence of disturbances on spatial patterns of diversity. Our motivation is to develop applicable methods to reveal the impacts of land-use onto spatial patterns of floristic diversity. Ecological monitoring of biodiversity patterns has to be spatially and temporally explicit (Beierkuhnlein 2000). Our approach is based on a systematic grid of hexagonal plots. We apply a spatially nested design at several spatial scales and levels to examine these patterns. The hexagonal grid provides several advantages compared to other methods. Most important are equal distances and borders to neighbouring plots. This facilitates data analyses and circumvents geostatistical problems (compared to squared or circle plots). In the field, the plots are marked and subdivided into six sections, respectively. This provides an easy method to assess semi-quantitative data on structure and disturbance in a standardized way. The hexagonal plot approach also optimizes the relationship between workload for marking, area-perimeter-ratio, accuracy, consistency of statistical analyses and grid consistency. The identified biodiversity patterns can be explained by site conditions and disturbance effects. The method is widely applicable in ecological patterns analysis.