Effect of rangeland degradation on biomass allocation in alpine meadows on the Qinghai-Tibet Plateau, China

Rangeland degradation has serious impacts on grassland community structure and productivity in alpine meadows across the Qinghai-Tibet Plateau, China. In order to reveal the impact of rangeland degradation on the community structure and aboveground/underground biomass distribution in alpine meadows, we selected three blocks near the Haibei Alpine Meadow Ecosystem Research Station in Qinghai Province that were within the random block design. There were four types of degradation in each block, which were intact, slightly degraded, moderately degraded, and severely degraded. In August 2020, plant sampling and a community survey were carried out at the same time. Our results showed that as the degradation got worse: 1) the grassland coverage, height, and aboveground biomass significantly decreased; 2) there was a significant change in the proportion of aboveground biomass allocated to different functional groups and the dominance species gradually changed from grasses into forbs; and 3) the underground biomass significantly decreased, but the proportion of biomass in deep soil increased. These results indicated that as the degradation intensified, the community structure underwent subversive changes, and the aboveground and underground biomass severely declined. Therefore, restoration plans for degraded grassland in this area should consider the grassland species composition, and corresponding measures for restoring aboveground and underground biomass should occur simultaneously.