Yosemite
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Recent papers in Yosemite
Yosemite Valley has experienced over 600 rock falls since 1850, but determining the exact source areas, volumes, and failure mechanisms for these rock falls has previously been difficult because of a lack of comprehensive imagery of the... more
Yosemite Valley has experienced over 600 rock falls since 1850, but determining the exact source areas, volumes, and failure mechanisms for these rock falls has previously been difficult because of a lack of comprehensive imagery of the cliff faces. We obtained high-resolution imagery, acquired before and after large rock falls in Yosemite Valley, California, by combining of gigapixel panoramic photography and terrestrial laser scanning (LiDAR). Following comprehensive baseline image acquisition of Glacier Point in eastern Yosemite Valley, two large rock falls occurred from within the imaged area in October of 2008. We used repeat gigapixel photography acquired with GigaPans to characterize the rock-fall detachment surface and adjacent cliff area in high resolution. Coupled with LiDAR analyses, these photos reveal that the rock falls consisted of a near planar, vertically oriented rock slab with a detachment surface area of 2,409 m2 and a volume of 5,663 m3. These data inform hazard...
Fens and wet meadows are important mountain wetland types, but influences onassemblage structure of associated invertebrates are poorly understood compared with other aspects of eScholarship provides open access, scholarly publishing... more
Fens and wet meadows are important mountain wetland types, but influences onassemblage structure of associated invertebrates are poorly understood compared with other aspects of eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. the ecology of these habitats. We sought to determine the relative contributions of terrestrial and aquatic invertebrates to diversity and abundance in these wetlands, the extent to which terrestrial and aquatic invertebrate assemblages differ with wetland type, and to what degree the aquatic assemblages vary as a function of slow sheet flow. We compared assemblages in fens and wet meadows, with and without flow, at 80 backcountry sites dispersed across the 6200 km2 landscape of Yosemite, Sequoia,and Kings Canyon National Parks in the Sierra Nevada mountains of California,U.S.A., using standard aquatic and terrestrial sweep netting. Cicadellid leafhoppers, aphids, and thomisid crab spiders were the most abundant terrestrial taxa. Cicadellids,Lepidoptera, anthomyiid, muscid, chloropid, and ephydrid flies, and thomisids were more abundant in fens than in wet meadows. Only mirid leaf bugs were significantly more abundant in wet meadows than fens. Sphaeriid clams and chironomid midges dominated aquatic assemblages both with and without flow. Chloroperlid stoneflies, mites, clams, and flatworms were all more abundant in flow, and Hemiptera and mosquitos were significantly more abundant in quiescent water. Mosquitos were more abundant in wet meadows, but there were few other population differences as a functionof wetland type. Terrestrial diversity was 1.1 to 2.0 times that of aquatic diversity,depending on metric and habitat. Fens had greater terrestrial abundance, richness,evenness, and diversity than wet meadows; there were fewer differences as a function of wetland type for aquatic fauna. Presence or absence of slow sheet flow had more effect on these aquatic assemblages than did wetland type. Cluster analyses, ordination, and multi-response permutation procedures were generally consistent with the univariate results. Vegetation-based wetland classifications should be extrapolated to faunal assemblages with caution, particularly for aquatic invertebrates.