Grazing reduces bee abundance and diversity in saltmarshes by suppressing flowering of key plant species
Grazing reduces bee abundance and diversity in saltmarshes by suppressing flowering of key plant species
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DOI：
10.1016/j.agee.2019.106760
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发表时间：
2020-04
期刊：
影响因子：
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通讯作者：
K. Davidson;Mike S. Fowler;M. Skov;D. Forman;J. Alison;M. Botham;Nicola J. Beaumont;J. Griffin
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文献类型：
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作者：
K. Davidson;Mike S. Fowler;M. Skov;D. Forman;J. Alison;M. Botham;Nicola J. Beaumont;J. Griffin
全球传粉者数量和相关服务的下降使得识别和敏感地管理有价值的栖息地势在必行。沿海栖息地，如盐沼，可以支持广泛的开花草甸，但它们对传粉者的重要性，以及这如何随着土地利用强度的变化，知之甚少。我们假设盐沼提供了重要的蜜蜂觅食栖息地，牲畜放牧通过减少开花植物的丰度或增加其多样性来抑制或提高其价值。为了验证这些假设，我们调查了11个盐沼在威尔士（英国）不同的放牧管理（长期未放牧，广泛放牧，密集放牧）超过三个夏天，并调查因果关系的途径放牧强度与蜜蜂的丰度和多样性，使用一系列线性混合模型。我们还比较了观察到的蜜蜂丰度11个常见的陆地栖息地使用国家调查数据。放牧减少蜜蜂的丰度和丰富度通过在两个关键的食物植物：海紫菀Tripolium pannonicum和海熏衣草Limoniumspp。放牧也增加了开花植物的丰富度，但花朵丰富度的积极影响并不能弥补花朵覆盖减少对蜜蜂的负面影响。蜜蜂的丰度大约减半，在广泛放牧沼泽（相对于未放牧），并再次减半，在密集放牧沼泽。盐沼花主要由蜜蜂蜜蜂和熊蜂Bombusspp。在仲夏和夏末。相比其他广泛的栖息地类型在威尔士，未放牧盐沼排名很高的蜜蜂和熊蜂在7月至8月，但相对不重要的孤独的蜜蜂。在适当的放牧管理下，盐沼为蜜蜂提供了一个宝贵的、以前被忽视的觅食栖息地。这里确定的牲畜放牧的强烈影响可能会扩大地理上的牲畜放牧和关键放牧敏感的植物在欧洲盐沼广泛分布。我们建议保护长期未放牧的盐沼不放牧，并在放牧的沼泽地保持广泛的放牧水平。通过这种方式，盐沼可以为野生和管理的蜜蜂种群提供饲料，并支持生态系统服务。
Global declines in pollinator populations and associated services make it imperative to identify and sensitively manage valuable habitats. Coastal habitats such as saltmarshes can support extensive flowering meadows, but their importance for pollinators, and how this varies with land-use intensity, is poorly understood. We hypothesised that saltmarshes provide important bee foraging habitat, and that livestock grazing either suppresses or enhances its value by reducing the abundance - or increasing the diversity - of flowering plants. To test these hypotheses, we surveyed 11 saltmarshes in Wales (UK) under varying grazing management (long-term ungrazed, extensively grazed, intensively grazed) over three summers and investigated causal pathways linking grazing intensity with bee abundance and diversity using a series of linear mixed models. We also compared observed bee abundances to 11 common terrestrial habitats using national survey data.Grazing reduced bee abundance and richnessviareductions in the flower cover of the two key food plants: sea asterTripolium pannonicumand sea lavenderLimoniumspp. Grazing also increased flowering plant richness, but the positive effects of flower richness did not compensate for the negative effects of reduced flower cover on bees. Bee abundances were approximately halved in extensively grazed marshes (relative to ungrazed) and halved again in intensively grazed marshes. Saltmarsh flowers were primarily visited by honeybeesApis melliferaand bumblebeesBombusspp. in mid and late summer. Compared to other broad habitat types in Wales, ungrazed saltmarshes ranked highly for honeybees and bumblebees in July-August, but were relatively unimportant for solitary bees. Intensively grazed saltmarshes were amongst the least valuable habitats for all bee types.Under appropriate grazing management, saltmarshes provide a valuable and previously overlooked foraging habitat for bees. The strong effects of livestock grazing identified here are likely to extend geographically given that both livestock grazing and key grazing-sensitive plants are widespread in European saltmarshes. We recommend that long-term ungrazed saltmarshes are protected from grazing, and that grazing is maintained at extensive levels on grazed marshes. In this way, saltmarshes can provide forage for wild and managed bee populations and support ecosystem services.