Measurement of aboveground biomass and belowground biomass
We measured aboveground biomass of plants from June to September 2020. In each month, we randomly selected three (1 m2) quadrats (108 quadrats in total) near the other sampling locations in each plot to record the community characteristics of plants. In each quadrat, we clipped all aboveground biomass and separated them to species. We then dried plants at 65 ℃ for 48 h and weighed them. We categorized species into four functional groups (perennial grass, shrub and semi-shrub, perennial forb, annual and biennial plants) based on their life type (Table S1).
We measured belowground biomass in August 2020. To do so, we selected six points near the other sampling locations and collected samples from the 0-10 cm layer with a root auger (7 cm diameter). We took two samples at each point and combined them for analyses. We picked roots from the soil, washed them and dried and weighed them as above.