桂西南喀斯特地区优势木本经济植物叶功能性状变异及其适应策略

Leaf function traits variations and adaptive strategies of dominant woody economic plants in karst area of Southwest Guangxi

关键词:  叶功能性状, 叶经济谱, 木本经济植物, 喀斯特, 桂西南

Key words:  leaf functional traits, leaf economics spectrum, woody economic plants, karst, Southwest Guangxi

摘要:

植物叶功能性状可直接或间接地反映植物对环境变化的响应与适应策略。该文采用野外气体交换测量和实验室分析相结合的方法,以桂西南典型喀斯特灌丛常见种龙须藤和黄荆为对照,对该区域5种优势木本经济植物的叶功能性状指标及其关系进行研究。结果表明:(1)11个叶功能性状指标种内均存在不同程度的变异,除胞间CO₂浓度和水分利用效率外,其余指标均存在显著差异。(2)比叶面积与叶干物质含量、叶组织密度呈极显著负相关; 净光合速率与气孔导度、蒸腾速率呈极显著正相关; 叶绿素与净光合速率、胞间CO₂浓度和蒸腾速率呈显著或极显著负相关。(3)结合叶经济谱理论分析,毛葡萄、长穗桑和黄荆属快速投资-收益型物种,趋向于选择光合能力强、比叶面积大但寿命短的生存策略; 而柠檬、山黄皮、枇杷和龙须藤属缓慢投资-收益型物种,趋向于选择光合能力弱、比叶面积小和寿命长的生存策略; 其中,枇杷和龙须藤的功能性状又发生了趋异分化,枇杷具有较高的水分利用效率,而龙须藤具有较高的叶干物质含量。综上结果说明桂西南喀斯特地区5种优势木本植物通过叶功能性状间的权衡采取了不同的适应策略,对于喀斯特退化生态系统植被恢复与重建具有重要的理论指导意义。

Abstract:

Plant leaf functional traits can reflect the responses and adaptation strategies of plants to environmental changing directly or indirectly. Using field gas exchange measurement and laboratory analysis, the relationships of five dominant woody economic plants in karst area of Southwest Guangxi were studied, with Vitex negundo and Bauhinia championii, two common species in typical karst mountains of this area as control. The results were as follows:(1)There were considerable intraspecific variations for the eleven leaf function traits, and threr were significant differences in leaf function traits except for intercellular carbon dioxide concentration(C_i)and water use efficiency(WUE).(2)There was highly significant negative correlation between specific leaf area(SLA)and leaf dry matter content(LDMC), and leaf tissue density(LTD); However, net photosynthetic rate(P_n)was very significant positive related to stomatal conductance(G_s)and transpiration rate(T_r); Relative chlorophyll content significantly negatively correlated with P_n, and significantly negatively with C_i and T_r remarkably.(3)Vitis heyneana, Morus wittiorum, and Vitex negundo were quick investment-return species on the leaf economics spectrum, and they tend to choose a survival strategy of strong photosynthesis and large SLA, but short life span; However, Citrus limon, Clausena excavata, Eriobotrya japonica and Bauhinia championii were slow investment-return species on the leaf economics spectrum, and they tend to choose a survival strategy of weak photosynthesis, small SLA, and long life span; The leaf function traits occurred divergent differentiation between Eriobotrya japonica and Bauhinia championii, and the former had higher WUE, while the latter had higher LDMC. The results proved that the five dominant woody economic plants took different adaptation strategies to habitats by trade-off among leaf functional traits. The results had important theoretical significance to the vegetation restoration and reconstruction of karst degraded ecosystem.