Effects of nutrient and water content on leaf nitrogen recovery efficiency of dominant plants in sandy grasslands
Climate change and human activities will affect grassland resource use efficiency and internal nutrient cycling.In order to clarify the nutrient regulation strategies of plants in the semi-arid grassland region of China,this study took four dominant plants(Setaria viridis,Artemisia scoparia,Pennisetum centrasiaticum,Cleisto-genes squarrosa)in sandy grassland as the research objects,and based on the interactive simulation test platform of increase or decrease precipitation and nitrogen addition,the soil moisture content,soil total nitrogen content,dominant plants'aboveground biomass,leaf nitrogen concentration in mature leaves,leaf nitrogen concentration in senescent dead leaves,and nitrogen resorption efficiency(NRE)were analyzed.The results showed that nitro-gen addition promoted biological activity and increased soil water content(P＜0.05)under natural precipitation(CK)or drought treatment conditions.Precipitation changes and nitrogen addition and their coupling effects will cause changes in species structure and composition,which ultimately affect the productivity of dominant plants.Under drought treatment,nitrogen addition significantly increased the nitrogen content in mature leaves of Setar-ia viridis and reduced the NRE(P＜0.05).Under the treatment of increasing precipitation by 100％(+60 d)in the early growing season(May to June),nitrogen addition significantly increased the mature leaf nitrogen con-tent of Artemisia scoparia(P＜0.05).For the Pennisetum centrasiaticum,the nitrogen addition significantly in-creased the nitrogen content in mature leaves under decreasing precipitation by 100％(-60 d)in the early grow-ing season(May to June)(P＜0.05),and the nitrogen addition significantly increased the nitrogen content of se-nescent dead leaves(P＜0.05)under CK and+60 d treatment,and the nitrogen addition significantly reduced the NRE under+60 d treatment(P＜0.05).For Cleistogenes squarrosa,nitrogen addition significantly increased the nitrogen content in mature leaves under CK treatment(P＜0.05),and nitrogen addition significantly increased the nitrogen content of senescent dead leaves under+60 d treatment(P＜0.05).The structural equation model(SEM)showed that precipitation had a positive effect on soil moisture and a negative effect on nitrogen content in mature leaves,nitrogen addition had a positive effect on the nitrogen content in mature leaves,soil moisture and the nitrogen concentration in senescent dead leaves,and the nitrogen content in mature leaves had a positive effect on NRE,and the nitrogen content of senescent dead leaves had a negative effect on NRE.In the Korqin Sandy Land,soil moisture may be a more important influencing factor in regulating the NRE of plant leaves than soil nitrogen.
NETL
NSTL
万方数据
维普
