Jurasinski, G; Beierkuhnlein, C: Spatial Patterns of Biodiversity - Assessing Vegetation Using Hexagonal Grids, Biology and Environment - Proceedings of the Royal Irish Acadamy, 106B(3), 401-411 (2006) [Link]
Key words: beta-diversity, systematic sampling, equidistant grid, similarity measure, line-intercept method, Morocco
Abstract:
We still lack quantitative and comprehensive methods to assess spatio-temporal changes in biodiversity of landscapes. Even more, we need methods to determine the amounts of change especially in the light of the current acceleration in the loss of biodiversity. We have developed a widely applicable method to reveal spatio-temporal changes in vegetation patterns and relate them to ecosystem processes. We use a systematic grid of hexagonal plots in a spatially nested design (three spatial scales and levels) to examine these patterns. The hexagonal grid, as well as the hexagonal plot, provides several advantages compared to other methods. Most important in the context of evaluating patterns is the equidistant nature of the grid. This facilitates data analysis and circumvents statistical and logical problems (compared to squared or circular plots). Correlation is very strong (r=0.88**) between structural data assessed with the Line-Intercept-Method and that gathered from field sketches. This indicates that the lines used to mark out the plots provide an easy and feasible method to assess quantitative data on structure and disturbance. We show that frequency data does not perform better than presence-absence data regarding correlation with other variables. We conclude that the hexagonal grid provides an efficient method to assess patterns of biodiversity.
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