Mechanisms of Xylem Embolism in Tree Species

植物木质部的栓塞是空气的存在- 填充木质部导管（管胞和/或导管）， 导致水运能力大幅下降。 这 反过来会对植物的水分平衡产生不利影响 导致生长减少和枯死。 在初步研究中 北方糖枫（Acersaccharum）树的栓塞 佛蒙特、斯佩里和泰瑞发现，在冬季， 70%以上的树苗发生栓塞， 失去了所有的水传导能力而形成栓塞。 冬季栓塞的逐渐恢复发生在春季 与阳性木质部的发育有关 压力 在他们提出的研究中，斯佩里和泰瑞将 确定冬季栓塞现象有多普遍， 恢复是在共同发生的树种代表环和 散孔被子植物和针叶树。 这将在 在全年监测栓塞水平的背景下， 在融资期内， 通过现场和实验室 操纵他们打算确定因果关系之间的联系 环境条件和栓塞的诱导，以及 其逆转。 这些信息将指导他们评估如何 木质部栓塞是树木生态耐受性的重要组成部分 物种，并在解释物种枯死和 下降 这项研究可能会产生重要的影响， 造林做法，包括建立 现有林分的种植和管理，特别是在 冬季伤害流行的地区。 通过确定 栓塞诱导机制，本研究还将评估 栓塞在环境影响中的重要性 注重树木健康。

Embolism in the xylem of plants is the presence of air- filled xylem conduits (tracheids and/or vessels) and it can lead to a significant reduction in water transport capacity. This in turn can adversely influence the water balance of the plant causing reduction of growth and dieback. In a preliminary study of embolism in sugar maple (Acersaccharum) trees in northern Vermont, Sperry and Tyree found that during the winter the xylem of saplings became over 70% embolized, with many small twigs losing all of their water conducting capacity to embolism. Gradual recovery from winter embolism occurred during the spring and was associated with the development of positive xylem pressures. In their proposed research, Sperry and Tyree will determine how widespread the phenomenon of winter embolism and recovery is in co-occurring tree species representing ring-and diffuse-porous angiosperms, and conifers. This will be done in the context of year-round monitoring of embolism levels for each species over the period of funding. Through field and laboratory manipulations they intend to determine the causal link between environmental conditions and the induction of embolism, as well its reversal. This information will guide them in assessing how important xylem embolism is in the ecological tolerance of tree species, and in explaining episodes of species dieback and decline. This research may have important consequences for silvicultural practices, including the establishment of plantations and management of existing stands, especially in regions where winter injury is prevalent. By determining the mechanism of embolism induction, this research will also evaluate how important embolism is in the influence of environmental stress on tree health.