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A Geometric Method for Evaluating the Null Hypothesis of Random Habitat Utilization
Author(s) -
Kincaid W. Bradley,
Bryant Edwin H.
Publication year - 1983
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1937501
Subject(s) - habitat , differential (mechanical device) , ecology , productivity , resource (disambiguation) , mathematics , statistics , computer science , biology , economics , computer network , engineering , macroeconomics , aerospace engineering
A geometric method is proposed for direct evaluation of habitat utilization by comparing the vector of utilized resources with the vector of available resources. The observed habitat differential, the Euclidean distance between the mean utilization and mean availability vectors, is tested against a distribution of such distances from vectors drawn at random from the available resource spectru. The direction cosines for the observed habitat differential are corrected for intercorrelations among the resources, giving the contributions of the individual resources to the overall differential. Deviations from availability are influenced both by differences in the lengths of the utilization and availability vectors (preference for areas with high or low productivity but with same resource composition as available) and by the angular deviation between them (preference for areas of different composition than randomly available, but with the same overall productivity or cover). The methodology separates these contributions to the overall habitat differential by making direct analogy to the size and shape components of morphometric variation. The methodology is extended to comparisons between species in their utilization of a common resource space.