茂兰喀斯特区典型灌木枝系构型特征

Branch system configuration of typical shrubs in Maolan Karst areas

地形是导致植物构型异质性的重要因素,了解喀斯特区典型灌木枝系构型在不同地形部位的适应特征,对揭示喀斯特植物的维持机制具有重要意义。运用Harper构件理论,对喀斯特区不同地形部位5种典型灌木的枝系构型特征进行了调查分析。结果显示:(1)不同地形,槽谷灌木种分枝数、分枝长度显著大于坡面,逐步分枝率、分枝角度小于坡面,分枝间距大于坡面,槽谷较坡面灌木生长旺盛。同一地形不同灌木种间,分枝数、分枝角度间存在显著差异(P<0.05)。(2)灌木种各级分枝长度有明显变化,随分枝级数的增加枝条伸展能力呈现出相对减弱的趋势。逐步分枝率趋势为SBR_(1∶2)<SBR_(2∶3)<SBR_(3∶4),通过低分枝率来增加有效光合作用面积。灌木种枝径比随着分枝级数的增加而逐渐增大,说明高级枝之间水分和养分的运输状况对灌木的生长发育影响大。喀斯特灌木对空间资源的利用率高,在不同地形部位不同灌木树种枝系构型表现出一定的可塑性,反映了喀斯特灌木种对喀斯特环境的适应。

Topography is one of the most important factors for the heterogeneity of plant configurations.It is of great significance to reveal the adaptive characteristics of typical shrub branch configurations in different topographic parts of Karst areas.This study aims to explore the characteristic architecture of typical shrub species in different terrain locations in the Karst areas.The component theory was also used to clarify the maintenance mechanism of Karst plants.The results showed that:(1)The number and length of branches of shrub species in the valley terrain were significantly greater than those in the slope terrain.The gradual branching rate and branching angle were smaller in different terrain,whereas,the branch spacing was larger,compared with the slope.There were significant differences in the number and angle of branches among different shrub species in the same terrain(P<0.05).(2)The outstanding variation was found in the branch length at all levels of shrub species.The branch extension decreased with the increase of branch order.The trend of stepwise branching rate was ranked in the order of SBR_(1:2)<SBR_(2:3)<SBR_(3:4).The effective photosynthetic area also increased by the low branching rate.The branch diameter ratio increased with the increase of branching order.The transport of water and nutrients between the higher branches presented the great influence on the growth and development of shrubs.It infers that the high utilization rate was achieved in the space resources of Karst shrubs.The better resilience was found in the branch configurations of various shrub species in the different terrain parts,indicating the better adaptability of shrub species to the Karst environment.