Tree recovery following disturbance in the boreal forest

我们将研究影响加拿大西部北方森林颤抖白杨和白色云杉招聘的基质，播种和再生环境。 首先，我们将完善我们的理解如何演替阶段，包括林分组成和密度之前的干扰和干扰类型影响树木的再生环境。 我们将使用干扰前的遥感和干扰后的远程和地面采样相结合，以确定每个系统的演替轨迹。 进一步.我们将使用类似的技术来评估已经转变为纯针叶林，然后又受到火灾干扰的密集管理的北方森林的恢复情况。 由于这些森林的许多遗留因素已被除草剂的使用所消除，它们的自然演替发展模式将因缺乏发芽繁殖体和存在侵略性草而受到阻碍。 第三个研究领域将研究白杨从种子中再生--允许白杨随着气候变化迁移到更高海拔和纬度。 白杨种子的丝状绒毛使它能够随风移动很远的距离，即使在它着陆后，它也会继续在地面上移动，直到它停留在它的最后一个微型位置。 使用现场和实验室实验，我们将研究诉诸白杨种子到不同的水分和质地的微网站，种子土地后，为了更准确地评估种子停止在良好的微网站的概率。 第四，羽藓占主导地位的针叶树为主的北方森林的林下植物。 这些藓类植物既没有吸收水分的根，也没有控制水分流失的气孔，因此它们在降雨后会迅速干涸，但它们会影响氮循环、树木补充和生态系统过程。 使用现场观察和实验，我们将评估这些干湿循环羽藓活力，基板孔隙度，导水率和氮的可用性。 工作适用于苗木的建立和模拟火灾风险为这一重要的基质。 将培训4名学生。

We will study the substrate, seeding and regeneration environments affecting the recruitment of trembling aspen and white spruce of boreal forests of western Canada. First we will refine our understanding of how successional stage, including stand composition and density before disturbance and type of disturbance affects the regeneration environment for trees. We will use a combination of remote sensing prior to disturbance and remote and ground sampling after disturbance to determine successional trajectories in each system. Further. we will use similar techniques to assess the recovery of intensively managed boreal forests that have been converted to pure conifer forests and then redisturbed by fire. As many of the legacy elements of these forests have been removed by herbicide applications, their natural pattern of successional development will be impeded by lack of sprouting propagules and by the presence of aggressive grasses. A third area of study will examine regeneration of aspen from seed - allowing movement of aspen into higher elevations and latitudes with climate change. The silky hairs of aspen seed allows it to move great distances by wind and even after it lands it will continue to move over the ground surface until it is lodged on its final microsite. Using both field and lab experiments, we will examine the resorting of aspen seed onto microsites of different moisture and texture, after the seed lands, in order to more accurately assess probability of seeds stopping on good microsites. Fourth, feather mosses dominate the understory in conifer-dominated boreal forests. These mosses have neither roots for water uptake nor stomata to control water loss, therefore they undergo rapid dry-down after rainfall, but they influence nitrogen cycling, tree recruitment and ecosystem processes. Using both field observations and experiments, we will assess these wet-dry cycles in relation to feather moss vigor, substrate porosity, hydraulic conductivity and N availability. Work applies to seedling establishment and modelling risk of fire for this important substrate. Four students will be trained.