Abstract
Roots account for a major part of plant biomass in Tibetan alpine meadows. Understanding root decomposition with global change is key to predict carbon (C) and nutrient dynamics on the Qinghai-Tibet Plateau. Yet, few experiments have carefully examined root decomposition as influenced by global change. We conducted a field study to investigate the effects of nitrogen (N) addition, air warming, precipitation change, and the presence/absence of living roots on root decomposition in a Tibetan alpine meadow. Our results showed that N addition increased the mass and C remaining, and induced N accumulation in the litter. Increased precipitation significantly amplified the positive effect of N addition on litter mass remaining. The presence of alive roots in the litterbags decreased root litter C remaining but significantly increased N and phosphorus remaining of the litter. However, we did not find any significant effects of air warming on the litter decomposition. In the Qinghai-Tibet Plateau, N deposition is predicted to increase and precipitation regime is predicted to change. Our results suggest that the interaction between increased N and precipitation may reduce root decomposition in the Qinghai-Tibet Plateau in the future, and that the large stock of living roots exert a dominant impact on nutrient dynamics of root decomposition in the Tibetan alpine systems.
Highlights
Roots account for a major part of plant biomass in Tibetan alpine meadows
In order to better understand C and nutrient cycling in the belowground part of the Qinghai-Tibet Plateau, we investigated the effects of global change factors, including temperature, precipitation and N availability, and the presence/absence of living roots on early stage of root decomposition in an alpine meadow of the Qinghai-Tibet Plateau
Soil moisture was significantly higher in the increased precipitation treatment than in the reduced precipitation treatment (24.3 ± 0.9% vs 20.3 ± 1.0%; F2,11 = 4.1, p = 0.046; Fig. 1c); soil moisture was higher in the non-warming treatment than in the air warming treatment (21.2 ± 0.5% vs 24.1 ± 0.8%, F2,11 = 5.9, p = 0.033; Fig. 1c)
Summary
Roots account for a major part of plant biomass in Tibetan alpine meadows. Understanding root decomposition with global change is key to predict carbon (C) and nutrient dynamics on the QinghaiTibet Plateau. Alpine meadows of the Qinghai-Tibet Plateau have high root biomass[12,13] which constitutes the dominant source of soil organic carbon[14], making root decomposition critical in C flux and nutrient cycling in these ecosystems. The large proportion of roots in alpine meadows in the Qinghai-Tibet Plateau makes effects of living roots on the decomposition of dead roots critical in C flux and nutrient cycling in these ecosystems. In order to better understand C and nutrient cycling in the belowground part of the Qinghai-Tibet Plateau, we investigated the effects of global change factors, including temperature, precipitation and N availability, and the presence/absence of living roots on early stage of root decomposition in an alpine meadow of the Qinghai-Tibet Plateau
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