摘要
It is well known that plants have functional equilibrium between their above-ground parts (shoots) and below-ground parts (roots), but whether the above-ground parts of plants have functional equilibrium between their photosynthetic structures (leaves) and non-photosynthetic structures (branches and stem) is unknown. The purpose of this study is to test the hypotheses that: (1) the above-ground parts of plants have functional equilibriums between their photosynthetic structures and non-photosynthetic structures; (2) the maintenance of the equilibriums is guaranteed by the alteration of biomass partitioning to photosynthetic and non-photosynthetic structures. To test these hypotheses, a pruning experiment with four pruning intensities (0%, 20%, 50%, and 70%) were carried out with three subtropical Chinese tree species ( Ficus microcarpa, Ficus virens, Cinnamomum camphora). Pruning treatments were conducted in two successive years. The results were in conformity with the hypothesis, i.e. above-ground parts of trees had functional equilibriums between photosynthetic and non-photosynthetic structures. Pruning decreased instantaneously the mass ratios of photosynthetic structures to non-photosynthetic structures (P/NP) of all three tree species, the reduction in P/NP was strengthened with pruning intensity. However, one year after pruning, the P/NP of all pruned trees increased and were not smaller than those of unpruned trees. In agreement with the expectation, the biomass partitioning of pruned trees was altered, more newly produced above-ground biomass was partitioned to leaf growth and less to branch and stem growth, thus enabled the damaged trees to restore their functional equilibrium between photosynthetic and non-photosynthetic structures. It is clear that the maintenance of functional equilibrium between photosynthetic and non-photosynthetic structures guaranteed by the alteration of biomass partitioning provides plants a good strategy to resist external disturbance and damage.
植物的地上部分和地下部分存在功能性平衡现已十分清楚 ,但植物的地上部分是否在其光合结构 (叶组织 )和非光合结构 (枝和茎 )之间也存在功能性平衡尚不明晰。本文提出两个研究假设并检验之 :1)植物地上部分在其光合与非光合结构之间存在功能性平衡 ;2 )此功能性平衡的维持依赖于对光合和非光合结构生物量分配的调节。为验证此假设 ,采用枝叶修剪的方式 (连续两年修剪 ,四个修剪强度 :0 ,2 0 % ,5 0 % ,70 % )对 3种亚热带乔木树种榕 (Ficusmicrocarpa)、黄桷树 (Ficusvirens)和樟 (Cinnamomumcamphora)进行了研究。结果表明 ,修剪使所有树种地上部分的光合与非光合结构生物量比率 (P/NP)立即下降 ,下降程度随修剪强度的升高而增大。但不论是首次修剪还是第二次修剪 ,修剪处理一年后 ,修剪株地上部分的光合与非光合结构生物量比率升高 ,且此生物量比率不低于非修剪株的光合与非光合结构生物量比率。此研究结果证实了植物地上部分光合与非光合结构间存在功能性平衡的假设。与假设一致 ,植株的生物量分配在修剪后发生了改变 :修剪株加大了对光合结构 (叶组织 )的生物量分配 (大量的新生产地上部分生物量被分配到光合结构 ) ,同时却减少了对非光合结构 (枝和茎 )的分配。此分配格局的改变保证了光合与非光?
基金
荷兰热带研究进展基金 (WOTRO
WB84_411)
重庆市基金项目 (99_5 776)~~
