典型石漠化生态系统演替过程优势植物种叶片功能性状特征及影响因素

Leaf Functional Traits Characteristics of Dominant Species and Influencing Factors in Succession of the Typical Rocky Desertification Ecosystems

为了明确喀斯特石漠化生态系统不同演替阶段优势种的叶片功能性状特征及其影响因素,探讨石漠化梯度上优势种的适应策略,在中国南方喀斯特2个典型石漠化地区(贵州关岭-贞丰花江、毕节撒拉溪),以不同等级石漠化地区植物优势种为研究对象,运用单因素方差分析、主成分分析、相关性分析和冗余分析,对优势种叶片功能性状以及与环境因子的关系进行分析。结果表明,随着石漠化的加剧,比叶面积(SLA)、叶干物质含量(LDMC)、净光合速率(Pn)、气孔导度(Gs)和水分利用效率(WUE)呈先增后降的趋势,变化范围分别为101.89-195.68cm^2·g^-1、0.40-0.32g·g^-1、6.44-12.82μmol·m^-2·s^-1、0.36-0.95mol·m^-2·s^-1和2.49-4.99μmol·mmol-1,而叶厚度(LT)、叶面积(LA)呈降低趋势,变化范围分别为0.35-0.18 mm和357.41-15.90 cm^2。环境因子中,pH(6.24-7.13)和岩石裸露率(PER)随着石漠化的加剧逐渐升高,而SWC(46.90%-29.10%)呈逐渐下降的趋势,TN、AN和AK呈现先升高后降低的趋势;TP、AP和光和有效辐射(PAR)呈先降低后升高的趋势。主成分分析显示无石漠化地区优势种具有较高的LT和LDMC,较低的SLA,而强度石漠化地区优势种具有较高的Pn、SLA,较低的LMDC。相关性分析显示SLA与Pn、Gs和WUE呈显著正相关,与LT呈显著负相关,WUE与Tr呈显著负相关;TN与AN和TP呈显著正相关,与AP呈显著负相关,PER与SWC呈极显著负相关(r=-0.62,P=0.001),与PAR呈极显著正相关。结合RDA分析,环境因子对优势种叶片功能性状和光合的影响大小为PER>SWC>pH>TK>TN,表明PER是最大影响因子,随着石漠化的演替,SWC、pH和土壤养分随之发生变化,SWC、pH、TK和TN是石漠化梯度上优势种功能性状变化的主导因素。综上,石漠化生态系统正向演替伴随着植物生境条件的改善,但优势种适应策略由演替早期的开拓型适应策略转变为演替后期的保守型适应策略。

In order to clarify the leaf functional traits characteristics of dominant species in different successional stages in the karst rocky desertification ecosystem and their influencing factors,and to explore the adaptation strategies of dominant species on the rocky desertification gradient,in the two typical rocky desertification areas of South China Karst(Guanling-Zhenfeng Huajiang and Bijie Salaxi in Guizhou),taking dominant species of different grades of rocky desertification as the research object,using one-way ANOVA,principal component analysis,correlation analysis and redundancy analysis(RDA),the dominant species leaf functional traits of their indicators and relationships with environmental factors were analyzed.The results showed that with the aggravation of rocky desertification,SLA,LDMC,Pn,Gs and WUE showed a trend of increasing first and then decreasing,the range of variation was 101.89-195.68 cm^2·g^-1,0.40-0.32 g·g^-1,6.44-12.82μmol·m^-2·s^-1,0.36-0.95 mol·m^-2·s^-1 and 2.49-4.99μmol·mmol-1 respectively,while LT and LA showed a decreasing trend,the range of variation was 0.35-0.18 mm and 357.41-15.90 cm^2 respectively;among the environmental factors,pH(6.24-7.13)and PER increased gradually with the aggravation of rocky desertification,while SWC(46.90%-29.10%)decreased gradually,and TN,AN and AK increased first and then decreased.TP,AP and PAR decreased first and then increased;Principal component analysis showed that the dominant species in no rocky desertification area had higher LT and LDMC and lower SLA,while the dominant species in intensive rocky desertification area had higher Pn,SLA and lower LMDC;Correlation analysis showed that SLA was significantly positively correlated with Pn,Gs and WUE,and negatively correlated with LT.WUE was significantly negatively correlated with Tr.TN was significantly positively correlated with AN and TP,and negatively correlated with AP,PER and SWC showed a significant negative correlation(r=-0.62,P=0.001)and was significantly positively correlated with PAR;Combined with RDA,the effect of environmental factors on leaf functional traits of dominant species was PER>SWC>pH>TK>TN,indicating that PER was the biggest influencing factor.With the succession of rocky desertification,SWC,pH and soil nutrients changed accordingly.SWC,pH,TK and TN were the dominant factors affecting the functional traits of dominant species on rocky desertification gradient.The results showed that the positive succession of rocky desertification ecosystem was accompanied by the improvement of plant habitat conditions,but the adaptive strategies of dominant species changed from pioneering adaptive strategies in early succession to conservative adaptive strategies in later succession.