Effects of nitrogen and water addition on leaf nitrogen and phosphorus stoichiometry of the dominant species in an Artemisia ordosica community
Aims Water and nitrogen(N)availability are two of crucial factors affecting the growth of desert plants,and are sensitive to global climate change.With increasing N deposition and precipitation,the understanding of the responses of leaf N and phosphorus(P)stoichiometry of dominant species in sandy semi-shrub community could provide insights into the adaptive strategies of sand-fixing plants in the Mau Us Sandy Land.Methods An experiment of N and water addition was conducted in an Artemisia ordosica community in the southern edge of the Mau Us Sandy Land.Soil available N and P concentrations,soil available N:P,leaf N and P concentrations,leaf N:P,and the corresponding homeostasis index of dominant species A.ordosica and Leymus secalinus were measured.Important findings(1)Soil N and P availability and species identity jointly influenced the response of leaf N concentration,leaf P concentration,and leaf N:P in A.ordosica and L.secalinus to N and water addition,and the leaf N concentration of A.ordosica and L.secalinus showed different responses to treatments.(2)Both A.ordosica and L.secalinus showed higher stoichiometric homoeostasis indices for leaf P than for leaf N,which was closely related to the fact that the growth of A.ordosica and L.secalinus were both N-limited.(3)The stoichiometric homoeostasis indices of leaf N concentration,leaf P concentration,and N:P in A.ordosica were relatively higher than those of L.secalinus,and A.ordosica adopted more conservative nutrient utilization strategies,while L.secalinus adopted more flexible nutrient utilization strategies.Therefore,A.ordosica was more competitive than L.secalinus in growth in arid and infertile environments.Under the scenarios of increasing N deposition and precipitation,the species composition of the A.ordosica community may change due to the contrasting competitiveness and nutrient utilization strategies between A.ordosica and L.secalinus.
Mau Us Sandy Landnitrogen depositionprecipitation alterationecological stoichiometrynutrient limitationhomoeostasis
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