林木幼苗对切根的生理生态响应及根-冠互作机制

Rapid establishment after transplanting is important for seedlings to compete efficiently for site resources both below and above ground. Ecology and vegetation restoration are concerned with the relationship between structure and function, but the excellent tree individiul and the perfect performance of seedling to the tasks would be the core of the restoration study of nature. Tree seedlings are normally root pruned in the nursery to facilitate transplanting and to induce branching of the root system and hence more growth apices. However, in many woody species the ideal root system size and architecture for transplanting are not known. Root prunning must be consided as a stress or damage to the seedling inherent characters, though the mechanisms of morphological, physiological and biochemical responses and the control to root –shoot interaction remain unclear. Understanding the morphological, physiological responses to root prunning stress is essential for a holistic opinion of vegetation restoration strategy. In this study, we use two species, a conifer Platy cladusorientalis and a deciduous species Quercus variabilis, and focus on the response of seedling morphological, physiological and biochemical characters and the interaction of root-shoot to different root-prunning ratio. We try to understand the process of signal transport and the mechnism of root-shoot signaling by exploring the concentrations of root secretion and xylem sap inclusions including hormone and protein. The seedling mortality and growth potential can be significantly affected by abiotic stresses such as drought or root damage. To address the tolerance to drought of seedlings with different root-prunning ratio, we study the response of two species potted seedlings subjected to different drought stress. Based on these results, we can achieve a comprehensive index to indicate the optimum root architecture for transplanting probably consists of some balanced combination of fine and coarse roots. The purpose of this study is to give a theoretical support to success vegetation restoration strategies of higher ecological benefits.

研究森林群落或生态系统的结构与功能，一直是生态学家和植被恢复领域研究的热点。但优良林木个体质量和造林后的表现，是影响植被恢复能否成功的最根本因素。切根是发生在植被恢复过程中的常见现象，但其作为伤害胁迫因子，是如何影响苗木生理生化过程及调节形态-生理和根-冠相互关系，仍是一个没有解决的科学问题。本研究以侧柏和栓皮栎为研究对象，探明不同切根比例对幼苗形态结构和生理特征的影响及形态-生理互作机理，探索不同树种苗木根系分泌物和木质部汁液内含物对不同切根伤害的应激反应特征，揭示切根伤害信号的传导及根-冠互作机制，判明不同比例切根苗木对环境胁迫的反应，把握根构型影响造林后苗木成活和生长的生理机制，建立客观全面科学描述侧柏和栓皮栎根系理想构型的综合指标体系以及根构型的生态评价体系。为今后建立科学有效的植被恢复技术措施打下良好的理论基础。