Browsing Journals and Magazines by Publisher "University of Arizona (Tucson, AZ)"
Now showing items 1-20 of 508
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The Acanthaceae of the Southwestern United StatesThe predominantly tropical family Acanthaceae are represented in the southwestern United States by 25 species in 11 genera. Within this region, species of Acanthaceae are found primarily in the Sonoran and Chihuahuan Desert regions. Name changes, changes in taxonomic status, and range extensions update the treatments of Acanthaceae in state floras which cover the region. In addition, six species not previously included in state floristic manuals are documented from the Southwest. Keys to and descriptions of each genus and species are provided. Information on synonymy, distribution, habitat preference, and phenology of each species is also given.
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AcknowledgementUniversity of Arizona (Tucson, AZ), 1982
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Agave Adaptation to AridityTo show features of Agave taxa adapting to arid habitats, comparative studies at three taxonomic levels in the genus are presented. There is a brief review of Agave physiology and some aspects of recent evolution are discussed. Comparisons among species groups within the genus show several traits differentiating desert species from related taxa. Related taxa in the Deserticolae group are examined over a transect in Baja California, revealing patterns linking leaf shape to climate. In a comparison of leaves of A. desert] Engelm. along an elevational gradient, high intrapopulation variation obscures differences between the sites. Results are summarized as hypotheses to be tested.
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Agave Research Progress in YucatanThe Center for Scientific Research of Yucatan carries out research aimed at solving some of the problems posed by the henequen industry in northern Yucatan. This paper briefly describes CICY's main research lines related to the hard fiber-producing agaves: a) taxonomic studies are being pursued to obtain a better understanding of the flora of the region; b) tissue culture techniques are used for the genetic improvement of agaves, and c) studies of composite materials and chemical substances derived from Henequen wastes are being carried out as possible alternatives to cordage production.
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Allometric Equations for Predicting Above-ground Biomass of Tamarix in the Lower Colorado River BasinAllometric equations are essential for quantitative study of aboveground biomass. The paper presents an effort in acquisition and validation of allometric equation for salt cedar (Tamarix spp.), a species that has been criticized for its invasion and negative impacts on the riparian ecosystem in the western United States. In the summers of 2009 and 2011, biomass destructive samplings were conducted to harvest and collect salt cedar samples at Cibola National Wildlife Refuge, Arizona. The allometric equations were developed by establishing the relationship between aboveground biomass with average basal diameter, tree height, and total basal area. The validity and the strength of the allometric models were examined with the adjusted coefficient of determination (r²), standard error of estimate (SSE), and Akaike Information Criterion (AIC). Total basal area was identified as the best predictor for salt cedar biomass, followed by tree height. Average basal diameter was a poor predictor. In linear equations, total basal area accounted for 78.4 percent of the total variation in aboveground biomass. In logarithmic equations, tree height and total basal area together explained 87.7 percent and yielded the small AIC and SSE. These equations will advance the quantitative estimation of salt cedar biomass and provide useful information for studying evapotranspiration, water consumption, and carbon storage.
