State Key Laboratory of Soil Erosion and Dryland Farming On the Loess Plateau, College of Natural Resources and Environment, Northwest A & F University, Yangling, 712100, Shaanxi, China.
State Key Laboratory of Grassland Agro-Ecosystems, and College of Ecology, Lanzhou University, Lanzhou, 730000, China.
Oecologia. 2022 Dec;200(3-4):491-502. doi: 10.1007/s00442-022-05279-5. Epub 2022 Nov 4.
Spatial heterogeneity of climatic and edaphic gradients can substantially affect the grassland productivity function. However, few studies have tested the importance of species richness and evenness on regulating grassland productivity across spatial-scale climatic and edaphic changes. This study examines the complex mechanisms by which species richness and evenness regulate productivity in alpine meadow and steppe. We used field survey data to explore above-ground productivity formation and sensitivity to spatial-scale climatic and edaphic response of alpine grassland based on species richness and evenness. Results showed that the growing season solar radiation was the main driving factor of above-ground biomass and was strongly negatively correlated with above-ground biomass. Furthermore, compared with alpine steppe, above-ground biomass in alpine meadow was more responsive to climatic variables, but less responsive to soil variables. Unexpectedly, we found that the regulation patterns of species richness and evenness on above-ground biomass were different in both habitats by a structural equation model analysis. Our study demonstrated that species evenness and richness were both important in co-regulating above-ground biomass in alpine meadow, whereas species richness mattered more than species evenness in regulating above-ground biomass in alpine steppe. Our results offer further support for species richness and evenness co-regulating grassland productivity across spatial-scale climatic and edaphic gradients, which helps maintain the benefits of plant diversity and alpine grassland ecosystems.
空间异质性的气候和土壤梯度会显著影响草原生产力函数。然而，很少有研究测试物种丰富度和均匀度对调节跨越空间尺度气候和土壤变化的草原生产力的重要性。本研究检验了物种丰富度和均匀度调节高山草地和草原生产力的复杂机制。我们使用野外调查数据，根据物种丰富度和均匀度，探索了高山草地地上生产力形成及其对空间尺度气候和土壤响应的敏感性。结果表明，生长季太阳辐射是地上生物量的主要驱动因素，与地上生物量呈强烈负相关。此外，与高山草原相比，高山草地的地上生物量对气候变量的响应更为敏感，而对土壤变量的响应则较弱。出乎意料的是，通过结构方程模型分析，我们发现物种丰富度和均匀度对地上生物量的调节模式在两种生境中存在差异。我们的研究表明，物种均匀度和丰富度在共同调节高山草地地上生物量方面都很重要，而在调节高山草原地上生物量方面，物种丰富度比物种均匀度更为重要。我们的研究结果进一步支持了跨越空间尺度气候和土壤梯度的物种丰富度和均匀度共同调节草地生产力的观点，这有助于维持植物多样性和高山草地生态系统的效益。
