崇明滩涂湿地不同盐度梯度下芦苇种群及土壤的生态化学计量学特征

为了研究不同盐度梯度下芦苇(Phragmites australis)的生态适应性及其生长的限制因子,对崇明盐度梯度下的3个滩涂湿地生长的芦苇及土壤生态化学计量学指标进行测定;分析不同盐度下芦苇种群的生态化学计量学之间的差异,及土壤与芦苇元素、元素比之间的相关性。结果表明:(1)崇明滩涂湿地土壤C、N、P含量和C/N、C/P、N/P平均值分别是15.01、0.69、0.86g/kg,22.09、21.87、0.96。芦苇的C、N、P含量及C/N、C/P、N/P平均值分别为413.17、10.75、2.53g/kg,41.49、293.58、7.29。(2)随着崇明滩涂湿地土壤盐度增加,土壤的C、N含量及芦苇的C含量、C/N先降低后增加;土壤的C/N、C/P、N/P及植物的C/P、N/P增加;土壤的P含量及植物N、P含量降低。(3)盐度梯度下滩涂湿地土壤与芦苇生态化学计量学中的C、P、C/P、N/P之间均正相关关系,土壤N含量与植物的C/P正相关,与N/P负相关;而C/N与植物P含量之间有负相关性。(4)该研究区土壤的C、N元素较为匮乏,P含量较高;植物的N/P值小于14,说明崇明芦苇生长主要受到N的限制。

ECOLOGICAL STOICHIOMETRY OF CARBON,NITROGEN AND PHOSPHORUS OF PHRAGMITES AUSTRALIS POPULATION UNDER SOIL SALINITY GRADIENTS IN CHONGMING WETLANDS

Chongming Island is a typical estuary alluvial island, seawater is upstream to the island, resulting that the soil salinity and moisture are different. It is unknown whether Phragmites australis population that are widely distributed in the Chongming Island is different across habitats, as affected by soil salinity. This research is to answer this question and to study the ecological Stoichiometry of P. australis and soil under the soil salinity gradient. We assume that the ecological stoichiometry of P. australis and soil will change under the soil salinity gradient. The object are P. australis and soil in the Chongming Island. The concentrations of carbon, nitrogen, phosphorus and the stoichiometry of them for P. australis and soil in three wetlands with different soil salinities were measured, to clarify the ecological adaptability of P. australis and its limiting factors in the Chongming Island. The results showed: 1) the average concentrations of soil carbon, nitrogen, phosphorus and ratio are 15.01, 0.69, 0.86 g/kg; 22.09, 21.87, 0.96. The average concentrations of P. australis carbon, nitrogen, phosphorus and ratios are 413.17, 10.75, 2.53 g/kg; 41.49, 293.58, 7.29. 2) With increasing soil salinity, the concentrations of soil carbon, nitrogen increased after the first reduced, they were maximum under the highest soil salinities, but the concentrations of soil phosphorus are minimum under the lowest soil salinities. The stoichiometry ratio of soil showed a steady increase. The concentrations of plant carbon and phosphorus were maximum under the lowest soil salinities, suggesting that plants nutrient absorption were effected by soil salinities. The C/P, N/P of plants were increasing with increasing soil salinity, which indicated P. australis would adapt the higher soil salinities and increase the nutrition use efficiency when it grow under higher soil salinities. The concentrations of plant nitrogen were continuously reduced with increasing soil salinity. 3) The concentrations of soil carbon, phosphorus had positive correlations with thoseof plants phosphorus, C/P, N/P ratios, while the concentration of soil nitrogen had positive correlations with C/P, negative correlations with N/P ratios of plants; the C/N in the soil only had negative correlations with phosphorus concentrations of plants. 4) The soil carbon, nitrogen elements was poor, but the phosphorus were abundant; the average N/P ratio were lower than 14, which indicate the P. australis growth were limited primarily by nitrogen.