Dominant plant identity determines soil extracellular enzyme activities of its entire community in a semi-arid grassland

Abstract

Dominant plants firmly affect community species composition, diversity, productivity, and belowground functions in terrestrial ecosystems. Soil extracellular enzyme activities (EEAs), as indicators for soil function, have linked the above- and belowground components and functions. However, in semi-arid grasslands, little is known about the effects of dominant plant and community type on soil EEAs, especially in the contribution of each dominant species to soil EEAs of its respective entire community. Given that, we established the comparison of the effects of three dominant herbal plants and their respective communities on soil EEAs and soil properties, determined the contribution of each dominant plant to its community-level soil EEAs, and examined key factors mediating these relationships in the Songnen grassland. Results showed that soil EEAs among the three dominant plants had more significant differences than among the three communities. This implied that dominant plant identities had significant effects on their rhizosphere soil EEAs and the difference of soil EEAs at the community level mainly depended on vegetation composition (including dominant species identity). The variations of soil EEAs at the dominant plant level and the community level were driven by different soil factors, the former being pH and electrical conductivity, and the latter being soil moisture and total carbon. Additionally, the distribution of soil EEAs was highly similar between each dominant plant and its respective community, which suggested dominant plants largely controlled soil EEAs in their respective communities. Overall, our findings expanded our understanding of the role of dominant species in soil function in semi-arid grassland ecosystems.