| Poyang lake is the biggest freshwater lake in China.As a typical lake wetland ecosystem,itplaysanirreplaceableroleinconservatingwater,regulating climate,protecting biodiversity and regulating the surface runoff.Besides,it can effectively control the area of water cycle and the biogeochemical cycle of C,Nand P elements.N and P is the essential nutrient element for plant growth.It reflects the dynamic balance between soil nutrient supply and plant nutrient demand.To clarify the characteristics of soil and plant nutrient stoichiometry in the typical distribution area of Poyang lake wetland and further explore the influence of soil nutrient changes on wetland plant leaves and root nitrogen and phosphorus content and their stoichiometric relationship in Poyang lake wetland ecosystem.In this study,four typical wetland areas of Poyang lake in Baishazhou,Wucheng,Nanji and Liaohua were selected.Through field sampling and indoor determination N and P content of plant leaves,roots and soil to analyzed the change characteristics and interaction mechanism of nutrient elements about plant-soil in Poyang lake wetland.And to explore the response mechanism of soil nutrient changes in wetland plant leaves and root nitrogen and phosphorus content.In order to reveal the nutrient adaptation mechanism of the large tongjiang lake wetland plant community to adapt the high dynamic water situation.The main results are as follows:?1?The variation range of N and P content in the root soil of poyang lake wetland was 0.15-4.59mg·g-1and 0.09-1.12mg·g-1,the mean value was 0.83mg·g-1and 0.48 mg·g-1.The correlation between total nitrogen and total phosphorus was not significant?P>0.05?.Soil N:P variation range was 0.27-12.45,with an average of 2.21.N:P value was significantly positively correlated with soil total nitrogen?P<0.001?,which was significantly negatively correlated with soil total phosphorus?P<0.001?.?2?The variation range of leaf N and P content of wetland plants in Poyang lake was 4.98-52.29 mg·g-11 and 0.49-3.69 mg·g-1,with an average value of 21.71mg·g-1and 1.38mg·g-1.There was a significant positive correlation between leaf N and P content?P<0.001?.N:P value variation range was 3.74-46.83,with an average value of17.19±8.23.However,Poyang lake wetland plant leaf nitrogen content and the correlation between soil total nitrogen content was not significant?P>0.05?,and the content of total phosphorus in the soil were extremely significant positive correlation?P<0.01?,Soil N,P values were significantly negative correlation?P<0.05?.There was no significant correlation between leaf phosphorus content and total nitrogen content in soil?P>0.05?,which was positively correlated with the total phosphorus content of soil?P<0.01?,which was significantly negatively correlated with N in soil?P<0.05?.Leaf N:P stoichiometric relationship was not significantly correlated with soil total nitrogen,total phosphorus content and N:P value?P>0.05?.?3?Under different soil nutrient gradient,leaf N content showed no significant difference in soil high N and low N nutrient environment,and leaf N content was21.76 mg·g-1and 21.72 mg·g-1respectively.Similarly,leaf P content was not significant in two soil N nutrient environments.This indicates that the N and P content of plant leaves in the study area are not sensitive to the change of soil N,and the changes of leaf N and P content are more sensitive to changes in soil P than N.At the same time,leaf N:P stoichiometric relationship has conservative characteristics,which does not vary significantly with soil N and P nutrient changes.Moreover,there was no strategic shift in the relationship between leaf N-P in different soil nutrients.?4?The root N content of the plant roots in Poyang lake was 13.27±7.28mg·g-1,with a range of 5.31-44.02 mg·g-1,and the root P content was 1.3±0.76 mg·g-1,and the range of variation was 0.16-3.74 mg·g-1,N:P was 13.39.There was no significant correlation between soil N,P content and root N and P,and root N:P stoichiometric relationship was less stable than that of leaves,and significant changes occurred in different soil N environments.Root system was also extremely significant linear relationship between N?P?P<0.01?,the linear relation exists in different soil nutrient conditions,but N-P the slope of the linear relationship under the environment of soil high N and low N significant difference. |
PDF Full Text Request