黄河干流河岸带C4植物群落特征及其对水库生态效应的指示

于2008年9月16日至10月31日对黄河干流河岸带植物群落开展了系统调查。共采集高等植物124种,分属于32科、97属,其中C4植物9科、24属、34种,占科、属、种总数的28%、25%和27%。对该区域的研究结果还表明：（1）C4植物主要分布于单子叶植物纲的禾本科和莎草科,两者共占C4植物总种数的61%。（2）从上游到下游C4植物种数递增,但中游C4/C3比、C4植物密度和生物量要明显高于上游和下游。（3）C4植物种数及C4/C3比与海拔、年均气温、年均降水量及年均流量均有相关关系,C4植物生物量仅和年均降水量显著相关。（4）水库位置的C4/C3比要明显高于其临近样区,说明C4植物对水库干扰下河岸带植被的动态变化具有一定的指示作用。

Riparian C4 Plants on the Mainstream of the Yellow River: Assemblage Characteristics and Their Indication on the Effects of Reservoirs

We conducted an investigation into the plant assemblage of the Yellow River＇s mainstream between September 16th and October 31st,2008.The total of 34 C4 plant species were recorded,belonging to 9 families and 24 genera,which corresponded to 27%,28% and 25% of the total species,families,and genera respectively.Further analyses indicated that：（1）Gramineae and Cyperaceae were the dominant taxa in the area,contributing 61% of the C4 plants in species number.（2）The number of C4 plant species increased from the upper to the lower reaches of the river,while the standing crops and the C4/C3 ratio in the middle reaches were higher than those in the upper and lower reaches.（3）The number of C4 plant species and C4/C3 ratio were correlated with altitude,annual air temperature,precipitation,and discharge,while the biomass of C4 plants only had a significant correlation with annual precipitation.（4）The C4/C3 ratio in the reservoir region was higher than that in adjacent regions,which suggests this ratio may be an indication of vegetation dynamics under the disturbance of reservoirs.