Vegetation characteristics and biomass dynamics in desert grasslands-effects of controlled precipitation variation
Abstract
Climate change-induced alterations to the hydrological cycle affect the structure and functionality of grassland ecosystems. However, a significant gap in our understanding of the trade-offs associated with how shifts in precipitation influence the biomass of plant communities in desert grasslands remains. We conducted a precipitation manipulation experiment, which featured five precipitation levels set at 33%, 66%, 100%, 133%, and 166% of the average natural precipitation (designated P33, P66, PCK, P133, and P166, respectively), with each level maintaining the same precipitation duration and frequency throughout the experiment. The study aimed to assess the responses of vegetation characteristics, including aboveground biomass (AGB) and belowground biomass (BGB), to various precipitation levels. Our findings indicate significant interannual variations in the height, richness, and density of the vegetation community from 2019 to 2021, mirroring the patterns observed in annual precipitation. However, no significant differences were observed in the community coverage. Although the diversity indices showed no significant differences in the first year of treatment, they exhibited notable changes in the second and third years. Furthermore, the AGB and BGB demonstrated a positive non-linear relationship with the precipitation gradient. Among the different functional groups, the biomass of grasses and forbs increased with changes in precipitation, whereas that of legumes decreased. Grasses were more sensitive to precipitation changes than legumes or forbs across the years studied. These results highlight that functional group classification is crucial for understanding biomass distribution and ecological responses to climate change, and long-term experiments are needed.