Crown function and dimensions in boreal conifers

北方针叶树的树冠功能和尺寸

• 批准号: 37582-2008
• 负责人: Lieffers, Victor
• 金额: $ 3.42万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=474782
• 关键词: Crown; function; dimensions; boreal; conifers

The size of tree crowns is linked to the productivity, water use and health of forests. In this proposal my students and I will explore the factors that control the development of crowns in trees. Put simply, crown size is controlled by the vertical and lateral extension of shoot and branches and the self-pruning of branches at the bottom of the crown. In terms of self-pruning, we plan studies that will test the hypothesis that as the lower branches of shade intolerant species enter zones of low light, these branches develop xylem with lower hydraulic conductivity and therefore they tend to restrict the water supply to the leaves of these lower branches. Shade tolerant species are proposed to have less change in hydraulic conductivity in branches and therefore slower self-pruning. Secondly, I propose that shade intolerant species will tend to allocate more of the sugars that they produce to upper branches and tend to remove mobile nutrients such as N from lower branches once they begin to experience shading. In terms of lateral extension of branches, I want to explore the linkage of branch extension with nutrient supply and changes in hydraulic conductivity of branches. Trees from field fertilization trials will be used to examine crown width and stem hydraulics. Crown friction from the collision of trees during their sway in wind is also thought to cause breakage of twigs and buds, thereby limiting lateral expansion of crowns. This will be explored by a regional study of crown width of trees from fully-stocked conifer forests in zones of different wind speeds. We will also study the effects of wind on stem shape and crown development in trees growing in zones of different wind speed. This work will provide new insights into the way that crowns develop and help managers control this important feature of tree growth under management or climate change.

树冠的大小与森林的生产力，用水和健康有关。 在此提案中，我和我的学生将探索控制树木冠状的因素。 简而言之，冠状大小由射击和分支的垂直和横向延伸以及冠底部的分支的自我修复控制。 在自我修复方面，我们计划研究将检验以下假设，即当阴影不耐受物种的下部分支进入低光区，这些分支以较低的水力传导率发展木质部，因此它们倾向于将供水限制为叶子这些下部分支。 提议耐阳性物种在分支中的水力传导率变化较小，因此自我修复较慢。 其次，我建议阴影不耐受的物种倾向于分配更多它们生产的糖，并倾向于去除诸如下部分支的移动营养素，一旦它们开始体验阴影。 在分支的横向延伸方面，我想探索分支扩展与营养供应和分支的液压电导率变化的联系。 现场施肥试验的树木将用于检查冠宽度和茎液压药。 人们认为，树木在摇摆过程中碰撞的牙冠摩擦也被认为会导致树枝和芽的破裂，从而限制了冠的横向膨胀。 这将通过对不同风速区域中储存的针叶树森林的冠状树木宽度进行区域研究来探讨这一点。 我们还将研究风在不同风速区域生长的树木中茎形和牙冠发育的影响。这项工作将提供有关冠冕发展方式的新见解，并帮助管理人员控制在管理或气候变化下树木生长的这一重要特征。