Simulating spatial patterns of counts in agriculture and ecology

Two algorithms, useful in agriculture and ecology, are presented to simulate permutations of a given set of counts of individuals, with a specified spatial pattern. The first algorithm finds a permutation with a specified level of aggregation, measured in this case by the index of aggregation, I-a, from the methodology termed Spatial Analysis by Distance IndicEs (SADIE). The second algorithm finds a permutation of a given set of counts of one population over predefined locations at which there are known counts of a second population, with a specified level of association between the two. Examples of the use of both algorithms are given, based on real data, including the quantification of rates of detection for various proposed sampling plans for cyst-nematodes.