| Plant nutrient and stoichiometry is one of the hot field in ecology at present. In this paper, as to typical steppe, desert steppe, steppe desert, typical desert, and different stages of restoring succession community in typical steppe, I measured and analysised the seasonal dynamic and spatial pattern of soil nutrient, space-time dynamic of plants nutrient and stoichiometry, correlation of plant and soil nutrient, and so on. Aims to reveal the nutrient use traits, the formation mechanism of stoichiometry spatial pattern and the limited factor estimation of plant. Furthermore, trying to recongnizing the composition and structure of vegetation, characteristics and mechanism of grassland degradation and restoring succession. The results are as follows:1. The content of soil organic matter (SOC), total nitrogen (STN) and available phosphorus (available P) in the 0～30 cm soil under four types of vegetation decrease along the water decreasing gradient. While the contents of available nitrogen (available N) and total phosphorus (STP) in the soil show no significance trend.2. The content of SOC, STN, available N and available P in the 0～30 cm soil of seriously degraded community slightly less than restoring community for 24 years in typical steppe. The value of STN/STP and SOC/STN shows the restored community is lack of P more than seriously degraded community. While the seriously degraded community is lack of N more than restored community.3. In steppe region, the content of total organic carbon (TOC) shows a rising trend in whole growing season. Meanwhile, the content of total nitrogen (TN) and total phosphorus (TP) both show a double-peak curve. However, the TOC content shows a slightly decreasing trend, with no significant trend of TN and TP content in desert region.4. In the process of restoring succession, the TOC content of plants was positively correlated with the restoring succession time, the TN and TP content of plants was positively correlated with the degradation degree, and the change amplitude of TP higher than TN. In addition, the ratio of N:P and C:N of seriously degraded community are significantly lower than restored community. Degradation of vegetation has more effects on the ratio of N:P in the plants than C:N, which accords with the growth rate hypothesis of ecological stoichiometry.5. Compared with china and the world, leaf TOC is the highest in the Inner Mongolia steppe region, lowest in desert region. Leaf N of steppe region higher than china and the world lever, and desert region near them. Leaf P of steppe and desert regions is below the global level, but slightly higher than the china level.6. The change amplitude of the plant Stoichiometry of four types of vegetation is far lower than single element. The range of N:P is between 12.5 and 16.48, the range of C:N is between 20.79 and 28.56. This shows that the Stoichiometry has higher stability along the water decreasing gradient.7. Along the water decreasing gradient, TOC content of community was positively correlated with SOC, STN and available P. TN content has positive correlation with SOC and available P, but no significant correlation with STN, available N and STP. TP content was significantly correlated with available N.8. There is a significantly correlation between the TOC content of Artemisia frigida and the degradation degree in steppe region. The TOC content of Stipa grandis, Agropyron michnoi and Carex korshinskyi has higher sensitivity to the degradation degree, the TP content of Cleistogenes squarrosa has especially higher sensitivity to the degradation degree. N is the limited factor in the prosess of plants growth in the seriously degraded community, P or N and P is the limited factors in the restored community.
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