呼伦贝尔草原羊草(Leymus chinensis)光合速率的季节变化--以鄂温克旗牧业气象试验站为例  

Examining seasonal variations of Leymus chinensis photosynthetic rates in the Hulunbeier Grassland:a case study of a grassland meteorological experiment station in Ewenke

作　　者：陈效逑[1] 周萌[1] 郑婷[1] 张荣菊 

机构地区：[1]北京大学城市与环境学院,地表过程分析与模拟教育部重点实验室,北京100871 [2]内蒙古呼伦贝尔市鄂温克旗气象局,呼伦贝尔021100

出　　处：《生态学报》2008年第5期2003-2012,共10页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(40671028,40371042)~~

摘　　要：利用2005年和2006年5～9月对内蒙古呼伦贝尔草原鄂温克旗牧业气象试验站所在地羊草光合速率的系统观测数据,分析了羊草光合速率的季节变化和年际差异,及其与气象因子和土壤水分状况的关系。结果表明:(1)在整个生长季节内,羊草光合速率的变化大致呈三峰二谷的形式,峰值分别出现在返青期之后、夏季降水高峰期和秋季降水回升期。2005年光合速率的峰值明显大于2006年,前者夏季峰值的持续时间也明显长于后者,这与该年降水量较多、相对湿度和土壤含水率较高有关。(2)羊草的光合速率与测量当日前3～8d的累计降水量均呈显著正相关关系,2005年与测量当日前6d累计降水量的相关最显著,2006年与测量当日前3d累计降水量的相关最显著。与此相似,羊草光合速率与各层土壤含水率亦呈正相关关系,且2005年的相关程度一般明显优于2006年,其中,与0～20cm土壤含水率的相关系数最大,表明羊草光合速率主要受到20cm以上土壤水分的影响。(3)在水分条件较好、气温偏低的2005年,羊草光合速率与日平均气温之间呈微弱负相关关系,与相对湿度之间呈显著正相关关系,表明在水热组合满足羊草生长需要的情况下,相对湿度通过增加或降低气孔导度对光合速率产生显著的影响,而气温对光合速率的影响不大。在水分条件较差、气温偏高的2006年,羊草光合速率与日平均气温之间呈显著负相关关系,与相对湿度之间呈不显著正相关关系,这与水热组合失衡情况下气温升高加剧蒸发,使土壤水分亏缺有关。由此可见,土壤水分状况可能是羊草光合速率决定性的影响因素,而气温和相对湿度则是次生的影响因素。Grasslands are one of the most widespread vegetation types worldwide, covering nearly one-fifth of the Earth＇s land surface. They support myriad different species, and play a major but poorly defined role in the global carbon cycle. Studying seasonal variations in the photosynthesis of grasses is crucial for revealing ecophysiological mechanisms of grassland phenology and biomass development, as well as estimating annual carbon sequestration, primary production, and appropriate grazing and harvesting times. Grasslands of Leymus chinensis are an endemic and dominant formation in the eastern part of Eurasia. Many studies have focused on the photosynthesis of Leymus chinensis over short periods of time within the growing season and in the southern part （ typical steppe） of Inner Mongolia. The objectives of the current study were therefore to identify seasonal patterns and interannual variations of Leyraus chinensis photosynthetic rates over the entire growing season and in the northern part of typical steppe （ the Hulunbeier grassland） , and to analyze relationships among Leymus chinensis photosynthetic rates, meteorological factors, and soil moisture. The Leymus chinensis photosynthetic rate data and soil moisture data were observed at a grassland meteorological experiment station in Ewenke （49°04′N, 119°42′E, 626m） from May to September of 2005 and 2006. The climatic data were also acquired from the Ewenke weather station. Over the entire growing season, changes in the Leyraus chinensis photosynthetic rate were characterized by three peaks and two valleys. The peaks appeared directly after the green-up of Leymus chinensis, in the heavy summer rain period, and during the autumn rainy period, respectively. The three photosynthetic rate peaks were obviously higher in 2005 than in 2006, whereas the duration of the second peak （ in summer） was also much longer in 2005 （about 30 days） than in 2006 （about 10 days）. These could be caused by more precipitation and higher soil moisture in 20

关 键 词：羊草 光合速率 季节变化 水热因子 呼伦贝尔草原 

分 类 号：S543[农业科学—作物学]