Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, School of Ecology and Environment, Inner Mongolia University, Hohhot, China.
Otago Regional Council, Dunedin, New Zealand.
Elife. 2024 Mar 18;12:RP91193. doi: 10.7554/eLife.91193.
Habitat loss and fragmentation per se have been shown to be a major threat to global biodiversity and ecosystem function. However, little is known about how habitat loss and fragmentation per se alters the relationship between biodiversity and ecosystem function (BEF relationship) in the natural landscape context. Based on 130 landscapes identified by a stratified random sampling in the agro-pastoral ecotone of northern China, we investigated the effects of landscape context (habitat loss and fragmentation per se) on plant richness, above-ground biomass, and the relationship between them in grassland communities using a structural equation model. We found that habitat loss directly decreased plant richness and hence decreased above-ground biomass, while fragmentation per se directly increased plant richness and hence increased above-ground biomass. Fragmentation per se also directly decreased soil water content and hence decreased above-ground biomass. Meanwhile, habitat loss decreased the magnitude of the positive relationship between plant richness and above-ground biomass by reducing the percentage of grassland specialists in the community, while fragmentation per se had no significant modulating effect on this relationship. These results demonstrate that habitat loss and fragmentation per se have inconsistent effects on BEF, with the BEF relationship being modulated by landscape context. Our findings emphasise that habitat loss rather than fragmentation per se can weaken the positive BEF relationship by decreasing the degree of habitat specialisation of the community.
生境丧失和破碎化本身已被证明是全球生物多样性和生态系统功能的主要威胁。然而，人们对于生境丧失和破碎化本身如何改变自然景观背景下生物多样性与生态系统功能（BEF 关系）之间的关系知之甚少。本研究基于中国北方农牧交错带采用分层随机抽样方法识别的 130 个景观，利用结构方程模型，研究了景观背景（生境丧失和破碎化本身）对草地群落中植物丰富度、地上生物量及其关系的影响。结果表明，生境丧失直接降低了植物丰富度，进而降低了地上生物量，而破碎化本身直接增加了植物丰富度，进而增加了地上生物量。破碎化本身也直接降低了土壤含水量，进而降低了地上生物量。同时，生境丧失通过降低群落中草地专类物种的比例，降低了植物丰富度与地上生物量之间的正相关关系的幅度，而破碎化本身对这种关系没有显著的调节作用。这些结果表明，生境丧失和破碎化本身对 BEF 有不一致的影响，景观背景调节了 BEF 关系。本研究结果强调，生境丧失而非破碎化本身通过降低群落的生境特化程度，可能会削弱正的 BEF 关系。
