Leaf Characteristics And Nutrient Recovery Characteristics Of Typical Desert Plants Around Jilantai Salt Lake

Leaf nutrient recovery is an important nutrient conservation strategy for perennial plants in an oligotrophic environment.The study of nutrient recovery characteristics of desert plants is of great significance to understand the nutrient utilization strategy of plants under stress and the nutrient cycle of the desert ecosystem.In this thesis,desert plants growing in four different site types around Jilantai Salt Lake in Alxa League were selected as the research objects.Through field investigation and indoor experiments,seven indexes of leaf water content(LWC),specific leaf area(SLA),leaf dry matter content(LDMC),and seven nutrient elements recovery characteristics of desert plants were determined,The relationship between leaf functional traits and nutrient recovery characteristics of desert plants was analyzed,and the adaptation strategies of nutrient recovery characteristics of plants to drought environment were explored based on soil base conditions.The main results are as follows:(1)In the arid ecosystem,18 species of plants all had different degrees of water deficit.The specific leaf area of Reaumuria soongarica growing in gravel desert is as low as 0.410 m²·kg^-1,and the leaf dry matter content of Calligonum mongolicum growing in semi–fixed longitudinal dune is as high as 0.350 g·g^-1.Higher leaf dry matter content and lower specific leaf area,leaf water content,and leaf succulence degree can adapt to a poor environment and maintain nutrients.In practice,these indicators can be used as the main characteristics of desert plant screening.(2)The average contents of N,K,Ca,Mg and Na in 18 species of plants were18.840 g·kg^-1,12.236 g·kg^-1,15.367 g·kg^-1,10.588 g·kg^-1,and 48.599 g·kg^-1,respectively,which were higher than the average level of terrestrial plants in the world.(3)The average recovery efficiency of N and P in leaves of desert plants was15.704%and 20.746%respectively,and the recovery potential was lower than the global level.K,Ca,Mg,and Na accumulated in senescent leaves,mainly due to environmental constraints such as drought and high salt,which inhibited nutrient recovery in varying degrees.Plants regulated nutrient balance in plants through recovery or accumulation to reduce ion toxicity.(4)The plants with high SLA have a high growth rate and high N,P,and K recovery efficiency,which is easy to gain a competitive advantage;the plants with high leaf thickness and leaf water content have high Ca and Mg recovery efficiency,which can regulate the water balance of plant cells.The contents of P,K,and Mg in senescent leaves of desert plants increased faster than those in mature leaves,and the recovery efficiency decreased with the increase of mature leaves.With the increase of OC,N,P,K,and Mg contents in senescent leaves,the recovery efficiency decreased.(5)The recovery efficiency of nutrients decreased with the increase of available phosphorus content in surface soil(0-20cm),while N,K and P recovery efficiency increased when the available nitrogen content in 20-40 cm soil layer was high.The recovery efficiency of leaf nutrients is easily affected by available nutrients content,and Ca recovery efficiency is significantly affected by soil physical and chemical properties.