青藏高原高寒草地群落叶片功能性状对降水的非线性响应

Non-linear response of leaf functional traits to precipitation in alpine grassland, Qinghai-Tibet Plateau

群落叶片功能性状受到外界环境和自身发育的共同影响,其响应特征和过程的研究有助于了解环境胁迫下植物的适应策略,以应对全球变化下的生物多样性和生态系统功能丧失。通过对青藏高原高寒草地115个样点的调查取样,测定群落叶片碳、氮和磷含量(LC、LN和LP)及干物质量(LDMC)4种能够反映植物生存策略的叶片功能性状,以物种相对多度为基础计算群落加权平均值(CWM)。结合降水量、气温和土壤因子,探索高寒草地群落叶片功能性状响应机制。结果表明:(1)降水量对群落叶片功能性状影响显著(P<0.01),而温度对群落叶片功能性状影响不显著(P>0.05);(2)土壤全氮和有机碳对CWM_LC、CWM_LN、CWM_LP和CWM_LDMC影响显著(P<0.01),且除CWM_LDMC外,其余性状均表现为非线性响应,呈先下降后上升趋势;(3)土壤含水量和容重对CWM_LC、CWM_LN、CWM_LP和CWM_LDMC影响显著(P<0.05),且土壤含水量对各性状的影响为非线性,呈先下降后上升趋势。该研究说明水分是青藏高原高寒草地群落叶片功能性状的主要影响因子,高寒草地对恶劣环境的适应是通过叶片功能性状来调节实现的。

Leaf functional traits are influenced by both the external environment and their own evolution,thus,study on response of leaf functional traits and processes to environmental stress can address biodiversity and ecosystem functions loss under global change.In this study,the community weighted mean(CWM)values of leaf carbon,nitrogen and phosphorus content(LC,LN and LP)and dry matter mass(LDMC)were collected from 115 observed sites across alpine grasslands on the Qinghai-Tibet Plateau.Furthermore,precipitation,temperature,and soil factors were used to explore the response mechanisms of the leaf functional trait to habitat.The results showed that:(1)precipitation affected(P<0.01)on community leaf functional traits significantly,while temperature had non-significant effects(P>0.05)on them;(2)soil total nitrogen and soil organic carbon presented significant non-linear correlations with CWM_LC,CWM_LN,and CWM_LP(P<0.01),and linear correlations with CWM_LDMC;(3)soil water content had significant non-linear effects on CWM_LC,CWM_LN,CWM_LP and CWM_LDMC(P<0.05),and soil bulk density showed significant linear effects on these four functional traits(P<0.05).Our results highlighted that water was the major factor which governed the leaf functional traits of alpine grassland communities across the Qinghai-Tibet Plateau.Besides,alpine plants adapted to harsh environments via regulating leaf functional traits.