期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 762, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2020.143091
关键词
Alpine ecosystem; Climate change; Cushion species; Environmental gradient; Insect diversity; Microclimatic refugia
资金
- Second Tibetan Plateau Scientific Expedition and Research (STEP) program [2019QZKK0502]
- Strategic Priority Research Programof Chinese Academy of Sciences [XDA20050203]
- National Natural Science Foundation of China [U1802232]
- National Natural Science Foundation of China (NSFC) [31500185]
Cushion plants such as Arenaria polytrichoides play a significant role in promoting insect diversity in alpine ecosystems. The presence of hermaphroditic cushions is associated with higher insect diversity due to the provision of more resources like nectar and pollen. Additionally, the positive effects of cushions on insect dynamics are stronger under higher environmental stress, potentially leading to expanded distribution ranges of insects in the face of climate change.
Cushion plants' significant role for alpine biodiversity has been demonstrated in particular through their positive effects on plant diversity. However, their effects on higher trophic levels (e.g. insects) remain largely unclear. In this study, by field sampling in the Hengduan Mountains (HDM) in southwestern China, we evaluated the effects of an alpine gynodioecious cushion species, Arenaria polytrichoides (Carophyllaceae), on insect richness, abundance and population dynamics at two different elevations (4427 m vs. 4732 m) separately at two time periods (day vs. night) and in two growing seasons (early vs. late). The results showed that the total insect diversity decreases from low to high elevation sites. Some insect species were exclusively detected within A. polytrichoides cushions, leading to an increase in local insect richness from 7% to 35%. The positive effects of cushions on insect diversity could be attributed to unique biotic properties provided by cushions. Firstly, the effects were determined by the sexual dimorphism of the cushion with hermaphroditic cushions supporting higher insect diversity than female cushions. This could be because hermaphroditic cushions provide more resources, such as nectar and pollen grains, for insects than female cushions. Secondly, the cushions' associated beneficiary plants can also provide extra resources for attracting more insects, but this effect was mediated by the micro-environmental conditions. Finally, the magnitude of cushions' positive effects on insect dynamics were stronger under higher than under lower environmental stress. This study confirmed that facilitation by A. polytrichoides cushions in HDM plays an important role in constructing the alpine insect community and further regulating its dynamics. Moreover, the positive effects of cushions on insect dynamics increase with increasing environmental stress. Therefore, the distribution range of insects would quite possibly be expanded into higher elevation under future climate changes, which will induce new challenges for the local alpine ecosystems. (C) 2020 Elsevier B.V. All rights reserved.
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