关键词: 净生态系统CO₂交换, 温度敏感系数, 光响应, 温度响应, 生物因子, 环境因子

Abstract: Alpine meadow is widely distributed on the Tibetan Plateau. The studies on the greenhouse gases (GHGs) flux in the alpine meadow are mostly carried out during growing season, but scarcely quantified during nongrowing season. By using static chamber technique and gas chromatography, this paper studied the characteristics of CO₂, CH₄, and N₂O fluxes in this alpine meadow during nongrowing season. The mean fluxes of CO₂, CH₄, and N₂O were 89.33 mg·m^-2·h^-1, -11.35 μg·m^-2·h^-1, and 8.02 μg·m^-2·h^-1, and the cumulative fluxes were 280.01 g·m^-2, -124.74 mg·m^-2, and 39.51 mg·m^-2, respectively. Therefore, this alpine meadow was performed as the sources of CO₂ and N₂O and the sink of CH₄ during nongrowing season. The cumulative CH₄, CO₂ and N₂O fluxes during nongrowing season contributed 13.33%, 53.47% and 62.67% of the total in a whole year. During freezethawing period (April, 2012), cumulative CH₄ flux was smaller, only contributing 4.5% of the total during non-growing season, whereas the cumulative CO₂ and N₂O fluxes were larger, contributing 25.8% and 20.8%, respectively. The CO₂ flux during nongrowing season had significant positive correlations with air temperature, soil temperature at the depths of 5 cm and 10 cm, and soil moisture at depth 5 cm. Our results showed that though the cumulative CH₄ flux during freezethawing period only occupied a smaller part of that during nongrowing season, the cumulative CH₄ and N₂O fluxes during nongrowing season contributed more than 50% of the total in a whole year, which should not be neglected in the estimation of the GHGs fluxes and their global warming potential in the alpine meadow on the Tibetan Plateau.

Key words: temperature sensibility coefficient (Q₁₀), light response, temperature response, environmental factors., net CO₂ ecosystem exchange (NEE), biotic factors