地下水埋深对灰胡杨叶性状与化学计量学特征的影响

Effects of Groundwater Depth on Leaf Traits and Stoichiometric Characteristics of Populus pruinosa Schrenk

以塔里木荒漠河岸林优势树种灰胡杨为研究对象,分析灰胡杨叶性状与化学计量学特征沿地下水埋深梯度(GWD)的变异格局及其相互关系,以揭示灰胡杨适应极端干旱环境的生态策略。结果表明:(1)不同地下水埋深条件下灰胡杨叶性状和化学计量学特征存在显著差异(P<0.05),叶面积(LA)、叶片含水量(LWC)、叶氮含量(LNC)和叶磷含量(LPC)随GWD增加呈下降趋势,叶干物质含量(LDMC)、叶组织密度(LTD)、叶碳含量(LCC)、碳氮比(C∶N)、碳磷比(C∶P)和氮磷比(N∶P)随GWD增加呈上升趋势;其中C∶P、N∶P、LPC和LA变异系数较大(39.90%、36.09%、30.63%和28.22%),对GWD变化较为敏感。(2)LA与LTD和LDMC, LWC与LTD和LDMC, LNC与C∶N, LPC与LCC、N∶P和C∶P分别呈极显著负相关关系(P<0.01),LA与N∶P和C∶P呈显著负相关(P<0.05);逐步回归分析表明LA、LDMC、LTD、C∶P可作为响应地下水埋深变化的重要指标。(3)C∶N、N∶P、C∶P随GWD增加均呈上升趋势,LCC、LNC和LPC的均值(438.617 mg/g、14.991 mg/g和0.728 mg/g)均低于全球陆生植物叶片的平均标准;灰胡杨叶片C∶N<30、N∶P>16,表明灰胡杨生长主要受P限制。(4)随GWD增加,灰胡杨以增加LCC、LTD、LDMC、C∶N、N∶P和C∶P,并降低LA、LWC、LPC和LNC的保守型策略来适应极端干旱环境。

We analyzed the variation pattern and their relationship of leaf traits and stoichiometry characteristics of Populus pruinosa Schrenk,the dominant tree species in Tarim desert riparian forest,along the groundwater depth gradient(GWD),in order to reveal the ecological strategy of P.pruinosa adapting to extreme drought environment.The results show that:(1)there are significant differences(P<0.05)in leaf traits and stoichiometry characteristics of P.pruinosa across the groundwater gradient.The leaf area(LA),leaf water content(LWC),leaf nitrogen content(LNC)and leaf phosphorus content(LPC)decreased with the increase of GWD.The leaf dry matter content(LDMC),leaf tissue density(LTD),leaf carbon content(LCC),carbon-nitrogen ratio(C∶N),carbon-phosphorus ratio(C∶P)and nitrogen-phosphorus ratio(N∶P)increased with the increase of GWD.The coefficients of variation of C∶P,N∶P,LPC and LA were larger(39.90%,36.09%,30.63%and 28.22%)and more sensitive to the changes in GWD.(2)LA was highly significantly negatively correlated with LTD and LDMC,LWC with LTD and LDMC,LNC with C∶N,LPC with LCC,N∶P and C∶P,respectively(P<0.01).There are significant negative correlation(P<0.05)between LA with N∶P and C∶P.The stepwise regression analysis shows that LA,LDMC,LTD and C∶P can be used as important indicators to respond to the change of groundwater depth.(3)C∶N,N∶P and C∶P all show an increasing trend with increase GWD.The mean values(438.617 mg/g,14.991 mg/g,0.728 mg/g)of LCC,LNC and LPC are lower than the mean values of global terrestrial plant leaves.The leaf C∶N<30,N∶P>16 of P.pruinose showed that the growth of P.pruinose was mainly limited by P.(4)As GWD increased,P.pruinose adopted a conservative strategy of increasing LCC,LTD,LDMC,C∶N,N∶P,C∶P and decreasing LA,LWC,LPC,LNC to adapt to the extreme drought environment.