Eco-Stoichiometry On Plants In Salt Marsh Zone Of Salt Lakes In Qaidam Basin

There are many salt lakes in the Qaidam Basin.A large number of halophytes which have high ecological and economic value are growing in the salt marsh zone around the salt lakes.The stoichiometric characteristics and changes of dominant halophytes,such as Tamarix laxa Willd,Nitraria sibirica and Phragmites australis in the inland salt marsh zone at different soil salinity and growth stages,as well as their relationship with soil nutrients,pH value,water content and the composition of salt segregators were studied.The main conclusions were as follows:(1)The total stoichiometric characteristics of the leaves of the three Halophytes in Tuanjiehu lake research area are low C,N and high P contents,high C:N values and low C:P and N:P values.The mean values were 377.31 mg/g,16.68 mg/g,2.23 mg/g,26.19 mg/g,180.24 mg/g and 7.74 mg/g,respectively.(2)The soil in salt marsh zone is characterized by high humidity,high salinity and low nutrition.The average values of soil water content,salt content,pH,Total carbon,Total nitrogen and Total phosphorus in Tuanjiehu Lake study area were 12.03%,14.29%,8.79,11.83 mg/g,0.17 mg/g and 0.08 mg/g.(3)There was no significant correlation between C,N,C:N and soil salinity in the study area of Tuanjiehu Lake,but there was a very significant positive correlation between soil salinity and P content in leaves(P<0.01).Soil salinity was negatively correlated with leaf C:P ratio(P<0.01).Soil salinity was negatively correlated with leaf N:P,but did not reach the significant level(P=0.068).(4)Redundancy analysis(RDA)sequencing results showed that the most significant soil factor which affecting the stoichiometric characteristics of C,N and P in the leaves of Halophytes in Tuanjiehu Lake research area was Mg2+content.There was a significant positive correlation between Mg2+content in soil and P content in leaves(P<0.01),and a significant negative correlation between Mg2+content and C:P and N:P ratio in leaves(P<0.01,P<0.05).(5)The stoichiometric characteristics of three halophytes at different growth stages(May-October)showed that the C and N contents in leaves decreased gradually from May and June,which was the beginning of the growing seasons,at the end of the growing season,while the C/N values increased gradually.Leaf P value decreased at first.then increased and reaching the lowest value in September.The whole process showed like a inverted arch.(6)The N:P ratio of halophyte leaves in Tuanjiehu Lake research area was significantly less than 14,indicating that plant growth was mainly limited by N.