降水与CO_2浓度协同作用对短花针茅光合特性的影响  

Interactive effects of changing precipitation and elevated CO_2 concentration on photosynthetic parameters of Stipa breviflora

作　　者：王慧[1,2] 周广胜[1,3] 蒋延玲[1] 石耀辉[1,2] 许振柱[1] 

机构地区：[1]中国科学院植物研究所植被与环境变化国家重点实验室,北京100093 [2]中国科学院研究生院,北京100049 [3]中国气象科学研究院,北京100081

出　　处：《植物生态学报》2012年第7期597-606,共10页Chinese Journal of Plant Ecology

基　　金：国家重点基础研究发展计划(973计划(2010CB951300);中国科学院战略性先导科技专项(XDA05050400)资助

摘　　要：降水变化与CO_2浓度升高将严重影响陆地生态系统尤其是草地生态系统,阐明干旱半干旱区草原优势植物对降水与CO_2浓度变化的联合响应有助于理解和准确评估未来气候变化对草地生态系统的影响。基于开顶式生长箱(OTC),模拟研究了降水变化(-30%、-15%、0、+15%、+30%(以1978-2007年月降水平均值为基准))、CO_2浓度变化(对照、450μmol·mol^(-1)、550μmol·mol^(-1))及其协同作用对荒漠草原优势物种短花针茅(Stipa breviflora)光合特性的影响。结果表明:降水变化和CO2浓度升高对短花针茅光合参数影响显著,表现出显著的交互作用。随着CO2浓度升高,短花针茅叶片净光合速率(P_n)呈增加趋势,但随着时间延长(8月份)显示出光合适应现象;气孔导度(G_s)和蒸腾速率(T_r)则呈下降趋势,水分利用效率(WUE)显著增加。随着降水增加,短花针茅的P_n、G_s和T_r均呈增加趋势,P_n增加速率小于T_r,使得WUE降低。高浓度CO2和降水增加15%的协同作用可以显著提高短花针茅的P_n、G_s和T_r,但Pn增加速率接近于T_r,导致WUE变化不显著。这表明,在干旱半干旱地区,CO_2浓度升高可在一定程度上提高短花针茅的抗旱能力,增强短花针茅对暖干化气候情景的适应性。Aims Stipa breviflora, which is a dominant species of desert steppe in the arid region of China, would be seriously affected by changes of precipitation and atmospheric CO2 concentration. Our objective is to determine the interactive effects of changing precipitation and elevated CO2 concentration on photosynthetic parameters of S. breviflora, in order to evaluate the effects of future climate change on the desert steppe. Methods Open top chambers （OTCs） were used to simulate the elevated CO2 concentration （control, 450, and 550 gmol.mol 1） and changing precipitation （30%, 15%, 0, ＋15% and ＋30%, based on the average monthly precipitation during 19782007）. The photosynthetic parameters of S. breviflora were measured by a LI6400 portable photosynthesis system. Important findings The responses of photosynthetic parameters ofS. breviflora to changes of CO2 concentration and precipitation were significant, and interactive effects were observed. With increased CO2, leaf net photosyn thetic rate （Pn） of S. breviflora increased, and photosynthetic acclimation occurred during August. Stomatal con ductance （Gs） and transpiration rate （Tr） decreased, and the increase of Pn was more than Tr. As a result, its water use efficiency （WUE） increased. With increased precipitation, Pn, Gs and Tr increased, and the increase of P, was less than Tr, resulting in a decrease in WUE. Under higher CO2 and 15% increase in precipitation, Pn, Gs and Tr of S. breviflora increased greatly, the increase of Pn was close to Tr, and consequently WUE did not change signifi cantly.

关 键 词：降水变化 气候变化 荒漠草原 CO2浓度升高 光合参数 短花针茅 

分 类 号：Q945[生物学—植物学]