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Management strategies were compared, including thinning and the production of fuelwood versus larger size-class volume, to develop a management plan for the mesquite woodland of the southern Arizona study site. Pre-commercial thinning of mesquite stands is not economic and the production and separate marketing of the larger size class at current stumpage rates gives only marginally higher returns than fuelwood alone, $9.57/ha/yr compared to $9.13/ha/yr. Equations were developed for prediction of fuelwood volume and for estimating volume in stem pieces 20 cm or greater in diameter. Estimated growth rates were 0.43 m3/ha/yr for the upland areas and 0.84 m3/ha/yr for the riparian areas. The culmination of mean annual increment suggests a rotation age of 40 years.

The density, diversity, and nest-site selection of riparian breeding birds were studied from 1982 to 1985 in mesquite (Prosopis glandulosa) and tamarisk (Tamarix chinensis) communites along the Colorado River in northern Arizona. Avian density in tamarisk communities was significantly greater (P=0.052 and 0.024 in 1984 and 1985, respectively) than avian density in native mesquite communities with similar vegetative cover and height attributes. Avian diversity was similar in both communities. Breeding bird densities in tamarisk were higher than those reported from other geographic areas. Vegetation structure and shrub species composition were measured at nest sites of eleven species of riparian birds in a tamarisk community to examine avian habitat relationships. Riparian birds exhibited differences in their choice of nesting habitat. Discriminant analysis indicated that Bell's Vireo (Vireo bellii), Yellow Warbler (Dendroica petechia) and Yellow-breasted Chat (Icteria virens) were relative generalists in nest site selection, while Common Yellowthroat (Geothlypis trichas) and Northern Oriole (Icterus galbula) were relative habitat specialists. Bell's Vireo and American Coot (Fulica americana) nested in habitats that were the most different. Willow Flycatcher (Empidonax traillii) and Yellow Warbler nested in habitats that were the most similar. Willow Flycatcher and Yellow Warbler consistently used habitat most similar to that used by all other species. Nest placement preferences of six riparian passerines were examined in the tamarisk community to test the null hypothesis that nest placement in any given species of shrub was random. Ninety-five of 105 nests sampled were located in tamarisk. Five of the six species of passerines exhibited a significant preference for tamarisk for nest placement. A highly significant preference for tamarisk was shown by the four species with the smallest median frequency of tamarisk in their nesting habitat. The usefulness of tamarisk for nest placement was higher than that reported from other areas.