中文摘要：

为了研究科尔沁沙地植物及叶片的C、N元素在沙丘固定过程中的化学计量差异及变化规律,在流动沙丘、半固定沙丘、固定沙丘、草地4种生境上分别采集整株植物样品和叶片样品,测定其C、N元素含量,并在群落水平和功能型水平上展开分析。结果表明：（1）随着沙丘的固定,植物群落及群落叶片的C含量逐渐上升而N含量逐渐下降,且C含量的变异系数较N含量小;（2）各生境植物及叶片C、N含量表现为灌木〉一年生植物、C3植物〉C4植物、豆科植物〉非豆科植物,各功能型植物的C、N含量正相关于其叶片的C、N含量;（3）沿沙丘固定梯度,一年生、C4与非豆科植物及其叶片C含量趋于上升,而一年生、多年生、C3、非豆科植物及其叶片N含量趋于下降。沙丘固定过程中群落C含量的变化主要源于一年生、C4、非豆科植物,而N含量的下降则受草本、C3、非豆科植物的共同影响。适当补植灌木、C3植物、豆科植物对于该地区的固C效率和生物固N以及改良土壤肥力会起到积极作用。

英文摘要：

In order to do the study on the stoichiometric difference and change rule of plant and leaf carbon（C）and nitrogen（N）in the process of sand dune fixation of Horqin Sandy Land,Inner Mongolia,China,mobile dune,semi-fixed dune,fixed dune and grassland——4 habitats were chosen to collect plant samples and leaf samples respectively. Then the carbon and nitrogen content were measured and analyzed on the level of community and functional type. The results showed as follows：（1）with the sand dune stabilization,plant community C and community leaf C increased gradually while their N content decreased,and the coefficient of variation of C was smaller than N;（2）in each habitat,C and N of plant and leaf were in order：shrubs〉annuals,C3 plants〉C4 plants,leguminous plants〉non-leguminous plants,and the C and N of each functional type of plants had positive relationship with their leaves’;（3）along the fixed gradient of sand dune,plants and leaves’ C in annuals,C4 plants and non-leguminous plants tended to rise while plants and leaves’ N in annuals,perennials,C3 plants and non-leguminous plants tended to decline. Variation of plant community C content in the sand dune stabilization resulted from changes of annuals,C4 plants and non-leguminous plants,while the drop of N content was caused by changes of perennials,C3 plants and non-leguminous plants. Replanting shrubs,C3 plants and leguminous plants appropriately would exert the positive effect on fixing carbon,nitrogen-fixing biologically,and improving soil fertility.