1901-1995年气候变化导致陆地生态系统净吸收碳(英文)

The Climatic-induced Net Carbon Sink by Terrestrial Biosphere over 1901-1995

利用所建立的直接计算上壤呼吸速率的简单模型，对近一百年来陆地生态系统碳通量的变化进行了模拟。结果显示，１９０１—１９９５年间整个陆地生态系统表现为一个碳汇。这期间总碳吸收量的低估计值为４４Ｐｇ（０．５Ｐｇ碳／年）。而高高估计值为８９Ｐｇ（０．９Ｐｇ碳／年）。其中大部分碳的吸收发生在３０年代以后，１９３１—１９９５年间共吸收碳的低估计值为２５Ｐｇ，高估计值为５６Ｐｇ。另外模拟出的净碳通量与利用其他方法估计出的“丢失汇”十分接近。在空间分布上，三个主要碳汇分别在热带（１０°Ｓ—１０°Ｎ）、北半球的中高纬度（３０°－６０°Ｎ）以及南半球（１０°－４０°Ｓ）。４０年代至７０年代的气候状况（温度下降而降水增加）十分接近。在空间分布上，三个主要碳汇分别在热带（１０°Ｓ—１０°Ｎ）北半球的中高纬度（３０°Ｎ－６０°）以及南半球（１０°Ｓ－４０°）。４０年代至７０年代的气候状况（温度下降而降水增加）十分有利于陆地生态系统对碳的吸收；但７０年代期后的气候条件（即温度上升而降水下降）则不利于陆地生态系统对碳的吸收，甚至导致净释放碳。模式结果显示：净碳通量受温度影响很大，而湿度和降水对它的的影响也不能忽视。除了二氧化碳和氮素的“?

The spatial and temporal variability of land carbon flux over the past one hundred years was investi- gated based on an empirical model directry calculating soil respiration rate. Our model shows that during 1901-1995, about 44-89 PgC (equals to 0.5, 0.9 PgC/ yr respectively) were absorbed by terrestrial biosphere. The simulated net ecosystem productivity (NEP) after the 1930s was close to the estimated value of u missing C sink' from deconvolution analysis. Most of the total carbon sink happened during 1951 -1985 with the estimated value of 33-50 PgC Three major sinks were located in the tropics (10°S-10°N), North- ern mid-latitudes (30°-60°N) and Southern subtropics (10°-40°S). During 1940s-mid-1970s, carbon sinks by terrestrial ecosystem increased with time, and decreased after the mid-1970s. These may be due to the ch anging of climate condition, as during the 1940s-1970s, temPerature decreased and precipitation increased, while after the mid-1970s, an opposite climate situation occurred with evident increasing in temperature and decreasing in precipitation. Usually, warmer and dryer climate condition is not favor for carbon absorption by biosphere and even induces net carbon release from soil, while cooler and wetter condition may induce more carbon sink. Our model results show that the net carbon flux is particularly dependent on moisture / precipitation effect despite of temperature effect, The changing of climate in the past century may be a possible factor inducing increases in carbon sink in addition to CO2 and N fertilizer.