Effects of multi-resource addition on grassland plant productivity and biodiversity along a resource gradient

Light grazing increased but heavy grazing decreased the abundance and family richness of soil arthropods community in an alpine grassland in the Qinghai Lake Basin

Soil arthropods are important biological components of the soil food web, which are highly sensitive to environmental disturbances and can rapidly respond to changes in the external environment, then reflect the stability and health of the soil ecosystem. We investigated the community structure of soil arthropod and their responses to grazing intensity along soil depth (from topsoil to subsoil) through a manipulated grazing treatment with four intensity levels (no grazing, light grazing, moderate grazing and heavy grazing) in an alpine grassland in the Qinghai Lake basin. The results showed that: (1) Collembola was the dominant group in the experimental site. (2) Nearly two-thirds of the individuals were distributed in the topsoil (0-10 cm), and grazing did not cause soil arthropods to migrate from the topsoil to deeper soil layers. (3) Light grazing had a positive effect on increasing the individual number, family richness and diversity of soil arthropods, while heavy grazing had the opposite effect, exerting a negative impact on the soil arthropod community. (4) When the grazing intensity did not exceed moderate grazing (i.e. stocking rate of 3.86 Tibetan sheep·hm-2), grazing would have a positive effect on the soil arthropod community. In summary, light grazing is the intensity of disturbance that has a positive effect on the soil arthropod community in this region. This study not only revealed the impact of grazing on the community structure of soil arthropods but also aided in assessing the potential effects of grazing activities on the stability of soil ecosystems, providing scientific evidence for the sustainable management of alpine grasslands.

Precipitation-induced biomass enhancement and differential allocation in Inner Mongolia's herbaceous and shrub communities

Changes in precipitation patterns induced by global climate change have profound implications for the structure and function of grassland ecosystems. However, the relationship between plant diversity and ecosystem function across different grassland types, particularly those with varying plant compositions and dominant species, remains inadequately understood. To address this knowledge gap, a five-year experimental manipulation of precipitation was conducted within herbaceous and shrub communities in the desert grasslands of Inner Mongolia. We found that increased precipitation significantly enhances aboveground biomass (AGB), belowground biomass (BGB), and community total biomass (CTB) in both herbaceous and shrub communities. In herbaceous communities, increased precipitation led to a disproportionate increase in both aboveground and belowground biomass, supporting the optimal allocation hypothesis. Structural equation modeling (SEM) further elucidated that precipitation regulates AGB and CTB through species richness and functional traits in herbaceous communities. In shrub communities, precipitation influences AGB, BGB, and CTB by affecting species richness and soil water content. This study highlights the critical role of precipitation in shaping biomass dynamics and allocation strategies within herbaceous and shrub communities in desert steppe of Inner Mongolia. These findings provide essential insights into the potential responses of desert grassland ecosystems to ongoing climate change.

Functional Groups Dominate Aboveground Net Primary Production under Long-Term Nutrient Additions in a Tibetan Alpine Meadow

Anthropogenic nutrient additions are influencing the structure and function of alpine grassland ecosystems. However, the underlying mechanisms of the direct and indirect effects of nutrient additions on aboveground net primary productivity (ANPP) are not well understood. In this study, we conducted an eight-year field experiment to explore the ecological consequences of nitrogen (N) and/or phosphorous (P) additions on the northern Tibetan Plateau. ANPP, species diversity, functional diversity, and functional groups were used to assess species' responses to increasing nutrients. Our results showed that nutrient additions significantly increased ANPP due to the release in nutrient limitations. Although N addition had a significant effect on species richness and functional richness, and P and N + P additions altered functional diversity, it was functional groups rather than biodiversity that drove changes in ANPP in the indirect pathways. We identified the important roles of N and P additions in begetting the dominance of grasses and forbs, respectively. The study highlights that the shift of functional groups should be taken into consideration to better predict the structure, function, and biodiversity-ANPP relationship in grasslands, particularly under future multifaceted global change.