Responses Of Leaf C,N,P,?¹³C And ?¹⁵N Of 32 Plant Species To Nitrogen Deposition In Gushan Mountain In Fuzhou

In this study,32 kinds of common plants in Gushan of Fuzhou have been selected as the research objects,two groups of fresh leaves samples were collected in June 2006 and June 2016,C,P,C/N,C/P,N/P,?13C and ?15N of 32 plant leaves were determined to analyze the responses of plants to different levels of nitrogen deposition.In this study,the plant herbarium specimens were used to overcome the restriction of the time span on the nitrogen deposition experiment in the previous experiment,and to investigate the response of these plants to nitrogen deposition,which provided a theoretical basis for the nitrogen deposition under natural conditions.The results are as follows:(1)Comparing samples in 2016 with those in 2006,leaf C and N content increased 22.63 mg/g and 4.42 mg/g,respectively;and leaf P content decreased by 0.49 mg/g;leaf C/N decreased by 3.56;C/P,N/P respectively increased by 163.48 and 10.75;the different value of leaf ?13C and ?15N were:-3.14 and-2.93,respectively;there is significant difference between the two year sample leaves C,N,P,leaf C/N,C/P,N/P,?13C and ?15N(P<0.01).The results were different from those of most simulated nitrogen deposition experiments in which with the increase of nitrogen deposition level,the C and C/N of leaves increased firstly and then decreased,and the leaf N first descended and then increased;and in agreement with the results of the study on leaf C,N and P of three forest plants,such as taining of Huang Zhiquin by using herbarium specimens.It's show that the effects of nitrogen deposition and artificially simulated nitrogen deposition on plants are not exactly equal,so it is very important to carry out the response experiment of plant to nitrogen deposition under natural conditions.(2)Under the influence of different nitrogen deposition levels,there were significant differences in leaf N,P,C/N,C/P,N/P,?13C and ?15N in arbor plants(p<0.01),but no significant difference was found in the difference level of each element in shrubs and herbaceous plants.Further analysis of the response of plants to nitrogen deposition from the perspective of different life forms is more balanced and more representative than the previous studies on the response to nitrogen deposition of plants that only focus on a single tree species or a single life type plant.(3)Two sampling years or three species of plant leaves C,N,P,C/N,C/P,N/P,?13C were significantly different(P<0.01),and bet.ween different sampling years ?1SN marked a significant difference(P<0.01),and there were significant differences in the production of N/P in the plant leaves of different sampling years and life types(P<0.05).It is indicated that the sampling year and life type are the variation sources of plant physiological indexes,and the reason of leaf?15N change is different nitrogen deposition level in different sample years.(4)From 2006 to 2016,plant WUE decreased 29.52umoI/mol,and the difference was very significant(p<0.01).There were significant positive correlations between plant WUE and leaf P(p<0.05)in two years,and significant negative correlations between plant WUE and the leaves C(p<0.05),N and N/P.It showed that the plant WUE is reduced by the negative effect of nitrogen deposition,and denied the study of that plant WUE not affected by plant nutrient utilization efficiency.