中文摘要：

对内蒙古典型草原不同恢复演替阶段群落土壤养分动态及空间格局、植物养分及其化学计量比时空动态、植物与土壤养分相关性等进行了分析，以揭示放牧干扰对植物的养分及其化学计量比影响。结果表明：土壤各养分含量表现为恢复群落略高于严重退化群落，土壤全氮（STN）／土壤全磷（STP）恢复群落高于严重退化群落，土壤有机质（SOC）／STN恢复群落低于严重退化群落：大多数植物叶片C含量在恢复群落最高，严重退化群落最低，与恢复演替时间呈正相关，而植物的全氮（TN）和全磷（TP）含量则是严重退化群落最高，恢复群落最低，与退化程度呈正相关，且TP含量的变幅明显高于TN含量；植物叶的N：P和C：N表现为严重退化群落最低，与退化程度呈负相关；严重退化群落植物相对于P而言，总体上表现为缺N；而恢复群落相对于N而言，更为缺P，或同时缺N和P；群落优势种化学计量学特征对群落演替方向有一定的指示作用。

英文摘要：

Aims Much research is being done on plant nutrients and stoichiometry. Our purpose was to reveal the effects of grazing on plant nutrients and stoichiometry in a typical steppe of Inner Mongolia of China. Methods We studied nutrient content of C, N and P and their ratio in soil and leaves of dominant plants in three adjacent sites： fenced since 1983 and 1996 and unfenced. We employed the stoichiometric approach and assessed the effects of grazing on spatio-temporal patterns of nutrient cycling between plants and soil in restoration succession of degenerate steppes. Important findings Both total soil nutrient content and the ratio of the soil total nitrogen and soil total phosphorus （STN：STP） were lower in overgrazed plant communities compared to fenced plant communities at different levels of restoration. Conversely, the ratio of soil organic carbon and STN （SOC：STN） was higher in overgrazed plant communities. The total organic carbon content （TOC） of most plants was higher in fenced communities and lower in grazed communities and was positively correlated with time since community restoration began. However, the content of total nitrogen （TN） and total phosphorus （TP） in plants was higher in fenced communities than that in grazed communities. Both TN and TP correlated negatively with time since restoration began and positively with the degree of degradation due to overgrazing. TP had a larger range in values compared to TN. The stoichiometry ratios of nitrogen and phosphorus （N：P） and carbon and nitrogen （C：N） in leaves were the lowest in grazed communities and correlated negatively with the degree of degradation. These communities had less total N than total P; however, this pattern was reversed in fenced communities, where sometimes both N and P were limiting. We propose that stoichiometry ratios in dominant plant species can serve as indicators of direction of plant succession in this typical steppe.