桂西南岩溶区18种适生植物叶性状变异及经济谱

Leaf trait variations and leaf economic spectrum of 18 plant species suitable in a karst area of Southwest Guangxi

叶性状反映了植物的生活史对策。本研究以广西平果市岩溶山地18种适生植物为对象,分析其叶面积(LA)、叶厚度(LT)、比叶面积(SLA)、叶干物质含量(LDMC)和叶组织密度(LTD)等性状在种内和种间水平的变异特征,以了解岩溶植物对异质性生境的适应策略。结果表明:5个叶性状的变异程度差异较大,LA的种内和种间变异系数最大,分别达32.92%和228.44%,LDMC的种内和种间变异系数最小,分别为9.41%和20.33%;物种对各性状变异的解释度(85.3%~91.3%)最高,其次是科类群(28.4%~73.4%),再次是生活型(12.4%~59.1%),最次是生长型(3%~24.3%);生活型和生长型的交互作用对各性状变异的解释度(26.7%~61.2%)大于生活型和生长型的单独解释度;除LT与LA、SLA之间不存在显著相关关系外,叶性状间存在着广泛的相关性。这与全球尺度基本一致,验证了岩溶植物叶经济谱(LES)的存在。常绿植物具有较高LTD、LDMC和较低的SLA及LA,在LES中的位置更靠近"缓慢投资-收益"型物种的一端,而落叶植物则与之相反,位于LES"快速投资-收益"型物种一端,表明该区植物通过性状间的权衡采取了不同的适应策略。采取人工辅助措施促进植被恢复时,应结合植被不同演替阶段、立地条件以及经营目标等筛选适生物种,加速其自然恢复进程。

Leaf traits reflect the life history of plants.To determine leaf trait variability and plant adaptive strategies to heterogeneous habitats of karst,we measured leaf traits[leaf area(LA),leaf thickness(LT),specific leaf area(SLA),leaf dry matter content(LDMC),and leaf tissue density(LTD)]of 18 plant species in the karst region of Pingguo City,Guangxi,China.The results showed there were considerable variations in the five leaf traits.The intraspecific and interspecific variation coefficients were the highest for LA(32.92%and 228.44%,respectively)and lowest for LDMC(9.41%and 20.33%,respectively).Species-level variation in leaf traits was the highest(85.3%-91.3%),followed by plant family groups(28.4%-73.4%).Life form and growth form were the third(12.4%-59.1%)and fourth(3%-24.3%)most important factors in explaining leaf trait variations.The interaction between life form and growth form explained more variation than by single life form or single growth form(26.7%-61.2%).In general,the relationships between leaf traits were significant(P<0.05),except that between LT and LA(P>0.05)or SLA(P>0.05).These findings support those of previous studies and conform to leaf economic spectrum(LES)for karst plants.Evergreen karst species were located at the slow investment-return end of the LES,with high LTD and LDMC values but low SLA and LA values.In contrast,deciduous karst species were located at the quick investment-return end of the LES.The results demonstrated that all the examined species could adapt to different habitats with tradeoffs among leaf traits.These findings suggested that suitable plant species should be selected and combined with different succession stages,site conditions,and management objectives to accelerate vegetation restoration in karst areas.