中亚干旱区分布着世界80％以上的温带荒漠,受气候变化影响显著.论文首先收集实验观测数据验证了干旱区生态系统模型(AEM),然后运用AEM开展数值模拟实验量化研究了1980-2014年中亚净初级生产力(NPP)的时空格局,评估了不同环境因子(降水、温度、CO.)的相对贡献率及其交互效应.结果表明:过去35 a中亚干旱区年均NPP总量为l 125±129 TgC(1T=1012)或218±25 g C/m2.哈萨克斯坦北部地区年NPP值较高(349±39 g C/m2),而南疆地区年NPP值较低(123±45 g C/m2).1980-2014年间,中亚NPP总体呈减少趋势[-0.71 g C/(m2·a)],南疆极端干旱区的NPP降低最为显著[-2.05 g C/(m2·a)].相较于1980-1984年NPP均值,在1985-2014年中亚区域NPP总体降低了118 Tg(-10％).其中CO.施肥效应促进NPP增加了99.7 Tg(+8％),气温升高的正效应促进NPP增加了35.4 Tg(+2％),而降水减少导致NPP降低了221 Tg(-18％).研究区内9％的地区的NPP主要控制因子为温度,主要分布在天山和哈萨克斯坦北部等高纬高寒地区.降水主控区面积占整个研究区的69％,主要分布在荒漠平原特别是南疆等植被受水分限制的区域.CO2主控区占研究区面积的20％,主要分布在天山中山带森林区和低海拔地区等水热条件好的区域.研究表明新疆南部地区是中亚的关键生态脆弱区,其生态安全面临着气候变化的挑战,但21世纪的升温不大可能因刺激自养呼吸而对中亚区域NPP造成显著影响.
The Responses of the Net Primary Productivity of the Dryland Ecosystems in Central Asia to the CO2 and Climate Changes during the Past 35 Years
More than 80％ of world's temperate desert locates in Central Asia,dryland that experienced strong warming and significant changes in precipitation pattern in recent decades.The objectives of this study was to quantify spatio-temporal patterns of net primary productivity in Central Asia over the past 35 years,and investigate the relative contribution and interactive effect of climate controls including temperature,precipitation and CO2,using the Arid Ecosystem Model (AEM),which performed well in predicting the dryland ecosystems' responses to climate changes according to our evaluation.The results show the 35-year averaged annual NPP of Central Asia amounted to 1 125±129 Tg C/a (1 T=1012),or 218±24 g C /(m2· a),with an overall declining trend of 0.71 g C/(m2· a).The northem Kazakhstan had relatively high NPP of 349±39 g C/(m2· a),while the southern Xinjiang of China had relatively low NPP of 123±45 g C/(m2· a).During the last 35 years,the NPP of the southern Xinjiang subregion declined significantly with a trend of-2.05 g C/(m2· a).Comparing the NPP during 1985-2014 to the NPP during 1980-1984,we found the regional NPP decreased 118 Tg or 10％,with positive contribution of 35.4 Tg or + 2％ from temperature change,positive contribution of 99.7 Tg or +8％ from CO2 change,negative contribution of 221 Tg or 18％ from precipitation change.The temperature was the dominant factor on NPP in 9％ of the study area,mainly in the Tianshan Mountains and northern Kazakhstan,where the temperature increased by 0.03 ℃/a during 1980-2014.Precipitation was the dominant factor on NPP in 69％ of the study area,mainly in the desert subregion and the dryland of southern Xinjiang of China,where the vegetation was limited by water.CO2 was the dominant factor on NPP in 20％ of the study area,mainly in the lower altitude regions of Tianshan Mountains,where the hydrothermal condition was suitable for vegetation growth.This study shows that the southern Xinjiang of China is the fragile eco-environmental subregion in Central Asia,whose ecosystem security is facing the challenges of climate change.However,increasing temperature is unlikely to stimulate autotrophic respiration and cause a significant impact on regional NPP in Central Asia.
Central Asiaarid ecosystem modelNPPdrylandclimate change
NETL
NSTL
万方数据
