荒漠草原4种优势植物叶片化学计量内稳性特征

Nitrogen and phosphorus stoichiometric homoeostasis characteristics of four dominant plants in a desert steppe

探讨植物生态化学计量内稳性特征对了解草原植物的生长适应策略具有重要意义。以内蒙古鄂克托前旗荒漠草原牛枝子(Lespedeza potaninii)、苦豆子(Sophora alopecuroides)、短花针茅(Stipa breviflora)和猪毛蒿(Artemisia scoparia)4种优势植物为研究对象,研究植物叶片氮、磷内稳性特征及其影响因素。结果表明:苦豆子叶片N、N꞉P含量显著高于其他3种优势植物(P<0.05),猪毛蒿叶片P含量显著高于其他3种优势植物;N元素内稳性指数(HN)以牛枝子最高,属于稳态型;P元素内稳性指数(H_(P))以猪毛蒿最高,属于稳态型;N꞉P内稳性指数(H_(N꞉P))以牛枝子最高,属于弱稳态型。冗余分析结果显示,土壤全碳和全氮含量对化学计量内稳性变异解释率分别为56.9%和9.9%,均达到显著水平(P<0.05),但其他土壤理化因子对其无显著影响(P>0.05)。综上所述,在氮含量较低的荒漠草原,多年生植物N内稳性和N꞉P内稳性较高,采用保守养分策略,其中N内稳性较高的灌木牛枝子适应性更强;一年生植物P内稳性较高,N꞉P内稳性比较低,采用奢侈分配策略;影响化学计量内稳性主要因子为土壤全碳和全氮含量。

Exploring the characteristics of plant stoichiometric homoeostasis is important to further understand the growth adaptation strategies of grassland plants.This study selected four dominant plants(Lespedeza potaninii,Sophora alopecuroides,Stipa breviflora,and Artemisia scoparia)in the desert steppe of Etuokeqianqi in Inner Mongolia as the research objects.The results indicated that:The contents of N and N꞉P in leaves of A.scoparia were significantly different from those of the other three dominant plants.The content of P in leaves of A.Artemisia was also significantly different from those of the other three dominant plants(P<0.05).The N homeostasis index(HN)of L.potaninii was the highest among the four dominant plants,belonging to homeostasis.The P homeostasis index(H_(P))of A.scoparia was the highest among the four dominant plants,implying homeostasis.The N꞉P homeostasis index(H_(N꞉P))of L.potaninii was also the highest among the four dominant plants,belonging to weak homeostasis.The results of RDA analysis showed that the explanation rates of soil total carbon and total nitrogen contents to the stoichiometric homoeostasis were 56.9% and 9.9%,respectively,reaching significant levels(P<0.05);the effects of the other soil physical and chemical factors were relatively weak.In conclusion,the endogenous stability of N and N꞉P of perennial plants were higher in the desert steppe with low nitrogen content,and perennial plants adopted conservative nutrient strategies.The shrub L.potaninii showed higher endogenous stability of N and better adaptation.The P internal stability of annual plants was higher but the N꞉P internal stability was lower,and adopted the luxury allocation strategy.The main factors of stoichiometric homoeostasis were soil total carbon and total nitrogen contents.