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University of Arizona (1973)

AN ANALYSIS OF A SONORAN DESERT SPECIES DIVERSITY GRADIENT

Yensen, Arthur Eric

Titre : AN ANALYSIS OF A SONORAN DESERT SPECIES DIVERSITY GRADIENT

Auteur : Yensen, Arthur Eric

Université de soutenance : University of Arizona

Grade : Doctor of Philosophy (PhD) 1973

Résumé
Ten species diversity indices were discussed and compared using hypothetical and actual species abundance distributions. Only two indices, H’ and D , consistently b increased with increases in richness and evenness. Since H’ has been widely used, it was adopted in order to facilitate comparisons to other studies. H1 values for birds, rodents, lizards, ants, foliage arthropods, perennial plants, spring annual plants, and summer annual plants were determined at five study sites on a complex environmental gradient in the Tucson Mountains, Arizona. The eight groups of organisms exhibited six different diversity patterns along the gradient, indicating that the diversity of one community relative to other communities cannot be judged from a single group of organisms. A reciprocal relationship, termed "consumer trade-off," was observed between lizards and rodents and between ants and foliage arthropods. When the diversity of one member of the pair increased, the other decreased. MacArthur’s foliage height diversity model failed to predict bird species diversity, whereas models based on the diversity of coverage of plant physiognomic growth forms were highly correlated with bird species diversity. The number of plant species was also highly correlated with the number of bird species and bird species diversity. Bird species diversity fluctuated less, seasonally, in more complex habitats.

Mots clés : Plant communities — Arizona — Pima County. ; Animal populations. ; Desert ecology — Arizona.

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