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Kurt Mantel 《Forstwissenschaftliches Centralblatt》1935,57(13):432-438
Ohne Zusammenfassung 相似文献
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The perceived realism of simulated maps with contagion (spatial autocorrelation) has led to their use for comparing landscape
pattern metrics and as habitat maps for modeling organism movement across landscapes. The objective of this study was to conduct
a neutral model analysis of pattern metrics defined by morphological spatial pattern analysis (MSPA) on maps with contagion,
with comparisons to phase transitions (abrupt changes) of patterns on simple random maps. Using MSPA, each focal class pixel
on a neutral map was assigned to one of six pattern classes—core, edge, perforated, connector, branch, or islet—depending
on MSPA rules for connectivity and edge width. As the density of the focal class (P) was increased on simple random maps, the proportions of pixels in different pattern classes exhibited two types of phase
transitions at threshold densities (0.41 ≤ P ≤ 0.99) that were predicted by percolation theory after taking into account the MSPA rules for connectivity and edge width.
While there was no evidence of phase transitions on maps with contagion, the general trends of pattern metrics in relation
to P were similar to simple random maps. Using an index P for comparisons, the effect of increasing contagion was opposite that of increasing edge width. 相似文献
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European Journal of Forest Research - 相似文献
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James F White Kathryn L Kingsley Qiuwei Zhang Rajan Verma Nkolika Obi Sofia Dvinskikh Matthew T Elmore Satish K Verma Surendra K Gond Kurt P Kowalski 《Pest management science》2019,75(10):2558-2565
Endophytes are microbes (mostly bacteria and fungi) present asymptomatically in plants. Endophytic microbes are often functional in that they may carry nutrients from the soil into plants, modulate plant development, increase stress tolerance of plants, suppress virulence in pathogens, increase disease resistance in plants, and suppress development of competitor plant species. Endophytic microbes have been shown to: (i) obtain nutrients in soils and transfer nutrients to plants in the rhizophagy cycle and other nutrient‐transfer symbioses; (ii) increase plant growth and development; (iii) reduce oxidative stress of hosts; (iv) protect plants from disease; (v) deter feeding by herbivores; and (vi) suppress growth of competitor plant species. Because of the effective functions of endophytic microbes, we suggest that endophytic microbes may significantly reduce use of agrochemicals (fertilizers, fungicides, insecticides, and herbicides) in the cultivation of crop plants. The loss of endophytic microbes from crop plants during domestication and long‐term cultivation could be remedied by transfer of endophytes from wild relatives of crops to crop species. Increasing atmospheric carbon dioxide levels could reduce the efficiency of the rhizophagy cycle due to repression of reactive oxygen used to extract nutrients from microbes in roots. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献
559.
Kurt C. Heim Thomas E. McMahon Leonardo Calle Mark S. Wipfli Jeffrey A. Falke 《Fish and Fisheries》2019,20(4):802-816
Temporary aquatic habitats are not widely appreciated fish habitat. However, fish navigate the transient waters of intertidal zones, floodplains, intermittent and ephemeral streams, lake margins, seasonally frozen lakes and streams, and anthropogenic aquatic habitats across the globe to access important resources. The selective pressures imposed by water impermanence (i.e., freezing, drying, tidal fluctuations), however, operate similarly across taxa and ecosystems. These similarities are formalized into a conceptual model relating habitat use to surface water phenology. Whereas all necessary life history functions (spawning, foraging, refuge, and dispersal) can be accomplished in temporary habitats, the timing, duration, and predictability of water act as a “life history filter” to which habitats can be used and for what purpose. Habitats wet from minutes to months may all be important—albeit in different ways, for different species. If life history needs co‐occur with accessibility, temporary habitats can contribute substantially to individual fitness, overall production and important metapopulation processes. This heuristic is intended to promote research, recognition and conservation of these frequently overlooked habitats that can be disproportionately important relative to their size or brevity of existence. There is a pressing need to quantify how use of temporary aquatic habitats translates to individual fitness benefits, population size and temporal stability, and ecosystem‐level consequences. Temporary aquatic habitats are being impacted at an alarming rate by anthropogenic activities altering their existence, phenology, and connectivity. It is timely that scientists, managers and policymakers consider the role these habitats play in global fish production. 相似文献
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