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Springs geomorphology influences on physical and vegetation ecosystem characteristics, Grand Canyon Ecoregion, USA

Sinclair, David A. (2018) Springs geomorphology influences on physical and vegetation ecosystem characteristics, Grand Canyon Ecoregion, USA. Masters thesis, Northern Arizona University.

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The Grand Canyon Ecoregion (GCE) represents the entire landscape that drains into Grand Canyon. This region encompasses a wide array of environments and corresponding plant communities of biological interest. Springs are numerous in the GCE and play a multitude of roles in this generally arid land. Springs serve as critical sources of water and support many endangered and endemic species, many of which are springs-dependent species including Flaveria mcdougalii, Epipactis gigantea, and Eleocharis palustris. I conducted a statistical community analysis of 352 springs in the Grand Canyon Ecoregion across four spring types – helocrene wet meadows; hanging gardens; rheocrene flowing springs; and hillslope springs – and examined their physical traits and floral assemblages. Mann-Whitney tests were used to detect differences between spheres of discharge and correlation and multiple regression were used to determine relations of physical and geomorphic traits with plant species diversity. An astounding species packing was demonstrated with nearly 1000 species recorded across all springs, representing over 45% of the region’s entire flora in less than one square kilometer of springs habitat area. Geomorphic microhabitat diversity was positively related to springs diversity (p<0.00001; multiple linear regression). All springs types were distinguished by differences in physical site characters which in turn were associated with plant community structure and specific species. Geomorphic features including microhabitat features and substrate composition were important in distinguishing springs types. There were also different physical characteristics distinguishing springs types including elevation and water chemistry. These features were correlated strongly with plant assemblages at springs and sets of indicator species were associated with each spring type. Multivariate regression analysis identified suites of variables related to springs biodiversity metrics explaining nearly half of the variation in species richness between springs. Microhabitat richness, area, and elevation were most important in explaining species richness. Grazing intensity did not have any discernable impact on species richness but did have a negative relation to the percentage of native species found at springs. In this study, I identified key differences between spring types; however, springs are highly individualistic and each spring needs to be understood in an individual context. Stewardship efforts should aim to protect geomorphic microhabitats and restore them to natural conditions. Their concentrations of biodiversity warrant further conservation and additional inventory and study will prove useful in furthering understanding of springs of the GCE.

Item Type: Thesis (Masters)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: community analysis; geomorphology; Grand Canyon; groundwater-dependent ecosystems; plant diversity; springs
Subjects: ?? QE ??
NAU Depositing Author Academic Status: Student
Department/Unit: ?? ETD ??
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Date Deposited: 08 Aug 2019 17:49
URI: http://openknowledge.nau.edu/id/eprint/5479

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