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Direct, indirect and predator-mediated effects of humans on a terrestrial food web: implications for conservation.

机译：人类对陆地食物网的直接，间接和捕食者介导的影响：对保护的意义。

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摘要

Humans influence the density and distribution of other species through direct and indirect effects. Effects are indirect when a species influences another species via an intermediate species, whereas direct effects have no mediator. Humans have strong negative direct effects on wolves (Canis lupus) in areas where wolves kill livestock. Such effects could indirectly influence other species in food webs, particularly wolf prey (i.e., herbivores such as elk; Cervus elaphus) and vegetation species eaten by herbivores. In addition, humans simultaneously directly influence several species in food webs, triggering numerous indirect effects. For example, humans have direct effects on forage (e.g., through agriculture) that could indirectly influence herbivores (e.g. by providing food).;I documented strong direct and indirect effects of humans on an entire food web. To fully understand and where necessary mitigate the impact of humans on species in an ecosystem, managers must not limit their considerations to direct effects, but also consider the indirect effects on species at several trophic levels of food webs.;I studied direct and indirect effects of humans on several interacting species in a terrestrial food web. First, I found that despite the minor cost of livestock predation when evaluated in the broader context of the rural economy, it still constitutes an important issue that compensation programs will not easily eliminate. Livestock predation will likely continue to elicit strong direct effects of humans on wolves. Second, I found direct effects of wolves on prey. Elk selected forest cover and low-food-quality habitat in response to wolf presence. Cattle (Bos taurus) selected roads (likely to seek human protection) and low-food-quality habitat, but only after wolves left pastures, indicating poor anti-predator behaviour. Despite presence of the top-down effects described above, path analysis indicated that humans influenced species distribution from the bottom-up with direct effects on forage and positive indirect effects on herbivores (elk and cattle) and wolves. As a result, human presence influences multi-species assemblages. An overall assessment of mammalian species (humans included) relative density in the study area demonstrated that large herbivores were three times more abundant on high-use roads and trails whereas predators were less abundant.
机译：人类通过直接和间接影响来影响其他物种的密度和分布。当一个物种通过中间物种影响另一个物种时，效应是间接的，而直接效应则没有介体。在狼杀死牲畜的地区，人类对狼具有强烈的负面直接影响。这种影响可能间接影响食物网中的其他物种，特别是狼的猎物（即食草动物，如麋鹿；鹿），以及食草动物食用的植物物种。此外，人类同时直接影响食物网中的几种物种，从而引发许多间接影响。例如，人类对草料有直接影响（例如，通过农业），这可能间接影响草食动物（例如，通过提供食物）。；我记录了人类对整个食物网的直接和间接影响。为了充分理解并在必要时减轻人类对生态系统中物种的影响，管理人员不得将考虑的范围仅限于直接影响，而必须考虑在营养网的几个营养层面对物种的间接影响。在地面食物网中几个相互作用物种上的人类行为。首先，我发现，尽管在更广泛的农村经济背景下评估牲畜捕食的成本较低，但这仍然是一个重要的问题，即补偿计划不会轻易消除。牲畜捕食可能会继续引起人类对狼的强烈直接影响。其次，我发现了狼对猎物的直接影响。麋鹿为应对狼的存在而选择了森林覆盖率和低食物质量的栖息地。牛（Bos taurus）选择了道路（可能是为了寻求人类保护）和食物质量低下的栖息地，但是只有在狼离开牧场后，才表明反捕食行为不良。尽管存在上述自上而下的影响，但路径分析表明，人类从下至上影响了物种分布，对草料有直接影响，对草食动物（麋鹿和牛）和狼有积极的间接影响。结果，人类的存在影响着多种物种的聚集。在研究区域对哺乳动物物种（包括人类）的相对密度进行的总体评估表明，在高用途道路和小径上，大型食草动物的丰富度是其三倍，而掠食性动物的丰富度则较低。

著录项

  • 作者

    Muhly, Tyler Bryon.;

  • 作者单位

    University of Calgary (Canada).;

  • 授予单位 University of Calgary (Canada).;
  • 学科 Biology Ecology.;Biology Conservation.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 175 p.
  • 总页数 175
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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