Physiological responses of Kobresia pygmaea to warming in Qinghai-Tibetan Plateau permafrost region

Kobresia pygmaea (C. B. Clarke) C. B. Clarke is one dominant herbaceous species in the alpine meadows of the Qinghai-Tibetan Plateau. From 2006 to 2009, a warming experiment was conducted in this permafrost region. Two 2-year warming treatments with an annual average warming of 2.1 °C and 4.4 °C, and one 4-year warming treatment with an annual average warming of 2.3 °C were established to examine physiological responses of K. pygmaea to warming. Our results indicated that 2-years of warming increased malondialdehyde and non-structural carbohydrates in the plants. There was no effect of 2-year warming on electrolyte leakage and free proline content. In the 2-year warming treatment, superoxide dismutase activity and peroxidase activity increased, ascorbate peroxidase activity and ascorbic acid only increased in 2-year high warming treatment, whereas in the 4-year warming treatment, active oxygen species, electrolyte leakage, UV-absorbing compounds and anthocyanins decreased. The 4-year warming treatment also significantly increased non-structural carbonhydrate and free proline accumulation for osmotic adjustment. The results of this study suggest that K. pygmaea could adapt to a warmer environment in the future.