Latitudinal variation in southern Rocky Mountain forests /

Source: OAI

ABSTRACT Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 1988. Includes bibliographical references (leaves 212-223).

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    ABSTRACT: This community is dominated by a mixture of tall (1-2 m) and mid (0.5 - 1 m) grasses with an understory of shortgrasses (
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    ABSTRACT: A novel method, surfactants or sodium phosphate as auxiliary agent of template 18-crown-6 for synthesis of zeolite EMT, was presented, by which the pure EMT with high crystallinity could be synthesized at low ratio of 18-crown-6 to Al2O3 (0.4–0.33) and in short crystallization time (5–6days). The EMT synthesized from the new method was characterized by the alkylation of isobutane with butenes.
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    ABSTRACT: Species distribution and abundance patterns in the southern Cascades are influenced by both environmental gradients and fire regimes. Little is known about fire regimes and variation in fire regimes may not be independent of environmental gradients or vegetation patterns. In this study, we analyze variation in fire regime parameters (i.e., return interval, season, size, severity, and rotation period) with respect to forest composition, elevation, and potential soil moisture in a 2042 ha area of montane forest in the southern Cascades in the Thousand Lakes Wilderness (TLW). Fire regime parameters varied with forest composition, elevation, and potential soil moisture. Median composite and point fire return intervals were shorter (4-9 yr, 14-24 yr) in low elevation and more xeric white fir (Abies concolor)-sugar pine (Pinus lambertiana) and white fir-Jeffrey pine (P. jeffreyi) and longest (20-37 yr, 20-47 yr) in mesic high elevation lodgepole pine (Pinus contorta) and red fir (Abies magnifica)-mountain hemlock (Tsuga mertensiana) forests. Values for mid-elevation red fir-white fir forests were intermediate. The pattern for fire rotation lengths across gradients was the same as for fire return intervals. The percentage of fires that occurred during the growing season was inversely related to elevation and potential soil moisture. Mean fire sizes were larger in lodgepole pine forests (405 ha) than in other forest groups (103-151 ha). In contrast to other parameters, fire severity did not vary across environmental and compositional gradients and >50% of all forests burned at high severity with most of the remainder burning at moderate severity. Since 1905, fire regimes have become similar at all gradient positions because of a policy of suppressing fire and fire regime modification will lead to shifts in landscape scale vegetation patterns.
    Plant Ecology 01/2001; 155(1). DOI:10.1023/A:1013263212092 · 1.64 Impact Factor