The effect of simulated warming on root dynamics and soil microbial community in an alpine meadow of the Qinghai-Tibet Plateau

- Warming reduced top soil root production and promoted root mortality and turnover.
- Warming changed the distribution of root production toward deeper soil.
- Warming also changed the type and abundance of different microorganisms.
- Climate change will have direct and indirect impacts on both above and belowground.

Previous studies have explored the effects of global change on above-ground vegetation in grassland ecosystems. Few, however, have investigated the responses of root dynamics and soil microbes to simulated warming in alpine meadows of the Qinghai-Tibet Plateau. This research used field open top chamber experiment to examine warming's impacts. Root production, mortality, and turnover were observed in situ using minirhizotron tubes, while soil microbial community composition and diversity were assessed by using phospholipid-derived fatty acids (PLFA) and Biolog-Eco plates. The results showed that 1) warming shifted the root standing crop distribution to deeper soil while increasing the accumulated root mortality and root production at 0-10 cm soil depth; 2) warming increased the abundance of fungal PLFAs while decreasing the abundance of other functional groups; 3) warming decreased the soil microbial functional diversity at the different soil layers; 4) bacterial and fungal PLFA contents were positively correlated with root mortality and turnover but were negatively correlated with root standing crop; 5) root dynamics significantly affect carbon utilization of the soil microbial community; and warming induced changes in root dynamics are associated with soil microbial community structure and function. Overall, these findings indicate that warming alters root production, mortality, and turnover and the relative abundance of different microorganisms in different soil layers. As a result, warming tended to shift microbial communities from bacteria toward fungi, leading to changes in the microbial community structure in different soil layers.

Root production, mortality, and turnover were observed in situ using minirhizotron tubes for plants grown in open top chambers (OTCs) to simulated warming for 6 years. Phospholipid-derived fatty acids (PLFA) analysis was used to analyze the soil microbial composition. Overall, these findings indicate that warming alters root production, mortality, and turnover and the relative abundance of different microorganisms in different soil layers. As a result, fungi become the dominant population in the topsoil microbial community, leading to changes in the microbial community structure in different soil layers.77