桂西南喀斯特山地蚬木叶片性状对微地形变化的响应

Responses of Excentrodendron hsienmu Leaf Traits to Micro-topographical Changes in Karst Moutains of Southwest Guangxi,China

【目的】探究桂西南石灰岩季节性雨林优势树种蚬木叶片性状随微地形变化而变化的规律,为桂西南喀斯特山地植被恢复和生态重建提供理论依据。【方法】通过地形因子调查、样品采集和性状测定,采用相关分析、Kruskal-Wallis检验和灰色关联度分析等方法,研究蚬木叶片功能性状对微地形变化的响应。【结果】蚬木叶面积、鲜重和干重等性状间呈显著(P<0.05,下同)或极显著(P<0.01,下同)相关;叶干物质含量随着海拔的升高显著下降,叶片厚度随着海拔的升高极显著上升,叶磷浓度随着坡度的增加显著下降。坡位对叶鲜重和叶片厚度产生显著影响,上坡位蚬木的叶鲜重和叶片厚度显著高于下坡位。坡向对叶干重、比叶面积、相对叶绿素含量和叶氮浓度产生显著影响,对叶干物质含量产生极显著影响;位于西坡的蚬木叶干重、叶干物质含量和相对叶绿素含量最高,比叶面积和叶氮浓度最低。灰色关联度分析结果显示,除叶氮浓度外,影响其余叶片性状的首要地形因子均为海拔。【结论】不同地形条件下蚬木叶功能性状的差异,是蚬木适应喀斯特高度异质性微生境的策略。

【Objective】Variations of leaf traits of Excentrodendron hsienmu,distributed in the limestone seasonal rainforest of southwestern Guangxi,with changes in micro-topography were studied.The results would help to understand the adaptive strategy of E.hsienmu,and provide a reliable theoretical guidance to the vegetation restoration and ecological reconstruction of karst mountains in Southwest Guangxi.【Method】Topographical factors were investigated and leaf samples and traits were collected,Pearson correlation analysis,test of Kruskal-Wallis,and grey relativity grade analysis were used to test the adaptive responses of the leaf functional traits to micro-topographical changes.【Result】The results showed that there were significant correlations among leaf area,leaf fresh weight,and leaf dry weight(P<0.05,the same as below).Leaf dry matter content significantly declined,while leaf thickness very significantly increased with elevation increasing(P<0.01,the same as below).Meanwhile,leaf phosphorus concentration significantly declined with slope degree increasing.Slope position had significant impact on the leaf fresh weight and leaf thickness.The leaf fresh weight and leaf thickness at uphill were significantly higher than those at downhill.Slope aspect had significant effects on leaf dry weight,specific leaf area,relative chlorophyll content,and leaf nitrogen content,and it also had highly significant effect on leaf dry matter content.On the west slope,the leaf dry weight,leaf dry matter content and relative chlorophyll content of E.hsienmu were the highest,but the leaf area and leaf nitrogen content were the lowest.Result of grey relativity grade analysis showed that leaf traits,except for leaf nitrogen concentration,were primarily affected by altitude.【Conclusion】Differences in leaf traits under different topographic conditions was the strategy of E.hsienmu to adapt to the highly heterogeneous karst microhabitat.