De ruimte in getallen

Stel je voor dat je iets wilt weten over een gebied, een land, een regio of een terrein. Vroeger zou je een atlas pakken, een encyclopedie, of gaan praten met de mensen ter plaatse om zo een beeld te krijgen van wat je kunt verwachten. Tegenwoordig hebben we nieuwe mogelijkheden. Soms wat verfijnder, soms wat specifieker. In ieder geval hebben we nu meer mogelijkheden om kwantitatieve uitspraken te doen. Een belangrijk hulpmiddel hierbij is de ruimtelijke statistiek

An overview of spatial sampling procedures and experimental design of spatial studies for ecosystem comparisons

Comparison of ecosystems and land use studies often require the use of non-classical statistics. This paper describes modern ways of approaching optimal sampling for ecological and environmental purposes. The first part of the paper deals with a description of different sampling procedures. A distinction is made between sampling surveys, optimal grid spacing and adaptive sampling. The second part of the manuscript uses a simulated example to illustrate the different sampling procedures. The third part contains an actual field study where various constraints were met that had to be incorporated in the lay out of the sampling scheme. Optimal statistical sampling procedures can be implemented and utilized to collect maximum information from limited resources

Nested spatial biodiversity patterns of nematode genera in a New Zealand forest and pasture soil

Biodiversity has a spatial dimension, which we estimated by examining generic turnover (beta diversity) of nematodes in adjacent forest and pasture sites. Dissimilarity was estimated in small and intermediate scale transects, the distribution of sampling points being determined by spatial simulated annealing. On an average, the forest yielded fewer nematodes per 24 mm dia 0-10 cm deep core than did pasture (435 vs 2818) but more genera (23.7 vs 19.1). Dissimilarity analysis suggests generic turnover is higher in forest than pasture, at both scales. At the small scale both communities have comparable dissimilarities up to 0.6 m, but only in forest does increasing distance increase dissimilarity. At the intermediate scale no spatial structure was apparent in the pasture nematode community, but in forest dissimilarity increased with distance, with no plateau. Quantifying the difference in spatial patterns between ecosystems illustrates the utility of geostatistical methods for addressing soil biodiversity. (C) 2003 Elsevier Science Ltd. All rights reserved