Analysis On The Strategies Of Utilization Of Nitrogen And Phosphorus In Phragmites Australis And Spartina Alterniflora In Chongming Dongtan Wetland Based On Ecological Stoichiometry

In this paper, the concentration of N and P in Phragmites australis and Spartina alterniflora and habitat soil in the typical plant community were measured in the wetland of Chongming Dongtan. The relationship between plant nutrient and soil nutrient were also measured, the strategy of N and P utilization of the two species were analyzed using the theory of ecological stoichiometry. The findings are as follows:1. The concentration of N and P in different species and the different organs of the same species differed in the course of plant growth. The allocation of N and P in different organs of P. australis and S. alterniflora was in the order of leaf>stem> root. N and P contents in the different organs of the two species, showed that the concentration of the nutrient was high in the early growth stage, then decreased in the fast growth stage, at the last growth stage the contents of nutrient was increased again. The N:P<14of the two species at every month, suggesting the growth of Phragmites australis and Spartina alterniflora were N-limited.2. The concentration of N and P in Phragmites australis and Spartina alterniflora and habitat soil increased with the increase of the tidal gradient.3. The accumulation of N and P elements in the two communities was a growing trend changes with the seasons. The leaf of Phragmites australis had the highest concentration of N,P, but the stem is the largest nutrient accumulation organs. While the leaf of Spartina alterniflora had the highest concentration of N,P was also the largest accumulation of nutrient organs. The concentration of N were significantly higher than the concentration of P in both species, the accumulation of N was much higher than the accumulation of P.4. The concentration of N and P in the habitat soil decreased with the increase of the soil depth. The seasonal dynamic of the concentration of N and P in the habitat soil was similar with those of the two plants.5. The concentration of P in leaves of Phragmites australis and Spartina alterniflora were not significantly correlated with those in its habitat soil, while the concentration of N in leaves of Phragmites australis and Spartina alterniflora were significantly correlated with those in its habitat soil.6. The contents of N and P in the newborn rhizomes of Phragmites australis was higher than those in the old rhizomes.The contents of N and P decreased gradually with the increase of the duration of growth and development of the rhizomes.