The role of root grafting in competitive/cooperative relationships between trees

根嫁接在树木竞争/合作关系中的作用

• 批准号: RGPIN-2017-05532
• 负责人: Desrochers, Annie
• 金额: $ 2.33万
• 依托单位: Université du Québec en Abitibi-Témiscamingue
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684465
• 关键词: role; root; grafting; competitive; cooperative

***Natural root grafting (anastomosis) challenges the notion of plant individuality and the consideration of forests as groups of individual trees competing with each other for resources. The sharing of substances (e.g. water, sugars) between trees, allows for cooperative relationships to occur. The long term objective of this research program is to demonstrate the ecological significance of root grafting. In the short term, I want to answer the following question: are root-grafted trees better competitors? First, occurrence, timing and effect of spacing on root grafting will be assessed in monospecific plantations of hybrid poplar, white and Norway spruce. Root grafts will be collected and brought to the lab for dendrochronological analysis. Size and age of roots at grafting, and distance between grafted trees will be determined and linked to root grafting frequency and timing. Then, using densely planted plots, inter- vs intraspecific competition/facilitation relationships will be evaluated in mixed-species plots in relation to root grafting. Relationships between trees will be characterized using distance-dependent and independent competition indices. Using dendrochronology techniques, timing of root grafting will be determined and linked with chronological competition index values throughout the lifespan of the stands. This will enable us to determine if stand development exhibited a predictable time-sequence spatial pattern resulting from competition for resources or if root grafting stalled stand development by allowing trees to respond (and compete) as a group rather than as individual stems. The different spacings and mixed species plantations will also allow us to examine stand development sequence to see if competition forces act as a trigger for root grafts to form between neighboring trees.***Ecological significance of root grafting forces us to reconsider traditional forest stand dynamics concepts such as competition, dominance and succession, concepts on which modern forestry is based on. The proposed research will throw light on the role that root grafting plays in tree-to-tree interactions during stand evolution by looking at stand-level grafting in plantations and in balsam fir natural forests. So far, my research has shown a general positive impact of root grafting on growth of connected trees, and suggests that grafted groups of trees benefit from each other to confront stress. From an applied perspective, few practitioners have associated successful or unsuccessful silvicultural operations to root connections. For example, it is often said that some suppressed trees are unable to respond to thinning (reduced competition), while the answer lies in skewed root-shoot ratios created by reducing leaf area of stands sharing communal root systems. Our work in plantations thus has the potential to impact how intensively managed plantations are established. *****

*天然根部嫁接(吻合)挑战了植物个性的概念，并挑战了森林是一组相互竞争资源的个体树木的观点。树木之间物质(如水、糖)的共享，使合作关系得以发生。这项研究计划的长期目标是证明根嫁接的生态意义。短期内，我想回答以下问题：嫁接根的树是更好的竞争对手吗？首先，将在单种杂交杨树、白云杉和挪威云杉人工林中评估根接的发生、时间和间距的影响。根移植物将被收集并带到实验室进行树状年代学分析。嫁接时根的大小和年龄，以及嫁接树之间的距离将被确定，并与根嫁接频率和时机挂钩。然后，利用密植小区，将在与根嫁接相关的混合树种小区中评估种间和种内竞争/促进关系。树木之间的关系将使用依赖于距离和独立的竞争指数来表征。利用树状年代学技术，将确定嫁接的时间，并将其与林分整个生命周期中的年际竞争指标值联系起来。这将使我们能够确定林分发展是否表现出可预测的时间序列空间格局，这是由于资源竞争造成的，还是根嫁接通过允许树木作为群体而不是作为单独的茎来反应(和竞争)而阻碍了林分的发展。不同的间距和混合树种人工林也将使我们能够检查林分的发育顺序，看看竞争力量是否触发了相邻树木之间形成根部嫁接。*根部嫁接的生态意义迫使我们重新考虑传统的林分动态概念，如竞争、优势和演替，现代林业所基于的概念。这项拟议的研究将通过研究人工林和香脂冷杉天然林中的林分水平嫁接，阐明根接在林分进化过程中树与树的相互作用中所起的作用。到目前为止，我的研究表明，根部嫁接对相连树木的生长总体上是积极的，并表明嫁接的树木群体在应对压力时相互受益。从应用的角度来看，很少有从业者将成功或不成功的营林操作与根连接联系在一起。例如，人们经常说，一些受抑制的树木无法对间伐(减少竞争)做出反应，而答案在于通过减少共享公共根系的林分的叶面积而产生的扭曲的根冠比。因此，我们在种植园方面的工作有可能影响种植园的集约化管理。*****