Spatial-Temporal Dynamic Of Plants Nutrlent And Its Ecological Stoichiometry In Huangfuchuan Watershed

Huangfuchuan is the first tributary of the middle reaches of the Yellow River, originated from the transitional zone between the Ordos Plateau and the Loess Plateau,inflowed the Yellow River in Shanxi Province.The total length of Huangfuchuan is 120 km and drainage area is 3240 km~2,the main part of Basin in the Zhungeer Region. Plant nutrient and stoichiometry is one of the hot field in ecology at present.This paper selected the doinant species in different region of Huangfuchuan watershed as study area,measures and analysised the seasonal dynamic and spatial pattern of space-time dynamic of plants nutrient and stoichiometry,correlation of nitrogen(N) and phosphrus(P) of plant in different organ,and so on. Aims to reveal the nutrient use traits,the different region affect to nutrient of plant and the limeted factor estimation of plant. The results are as follows:1 .The content of total nitrogen (TN) and total phosphorus (TP) both shows a double-peak curve. However,N/P because of the changes in species differences,the trends are varide.2.The TN,TP nutrient content of leaf in Huangfuchuan Watershed as follows: the nutrient content of plants in aeolian sand is the highest,and the nutrient content of plants in arsenic sandstone is the lowest. Compared with China and the global level, Leaf N of aeolian sand soil and sandy loess soil both higher than the TN content of Chinese and global level,and leaf N of arsenic rock zone lower than the TN content of Chinese and global level;Leaf P of aeolian sand soil and sandy loess soil higher than china level and lower than the global level,Leaf P of arsenic rock zone lower than the TP content of China and global level. N and P content of plants in different organs were positively correlated,but the proportion of different organs is not the same,and the correlation cofficient is in the order:leaf >stem > root.3. In three soil type of Huangfuchuan watershed,although the nutrient content of Plants in different organs is different,TN and TP is the same distribution:in various organs,the leaf were the highest,followed by stem and root. The change amplitude of the plant stoichiometric of three soil types is far lower than single element. The range of N:P is between 14.72 and 16.20,this shows that the Stoichiometry has higher stability in the large-scale ecosystems. The same species in different soil types N: P ratio is different,but the trend is the same.4. The most plants we studied in Huangfuchuan Watershed N:P ratiio ranged from between 14 and 16,N and P is the co-limited factor in it. P is the limited factor in Stipa grandis and Stipa bungeana,N is the limited factor in Thymus serpyllum.