Temporal dynamics of large woody debris in the Foothills of Alberta

在艾伯塔省，目前的管理战略保护河岸森林免受干扰，以减少对河流和水生生态系统造成不利影响的风险。然而，河岸地带也不能幸免于自然干扰，其中一些对维持河流功能可能是至关重要的。例如，河岸地带原木的补充和保留改变了溪流地貌和水文，导致无脊椎动物和鱼类的关键栖息地。这项研究由不列颠哥伦比亚大学(UBC)树轮实验室、山麓模式森林(FMF)、Hinton Wood Products(West Fraser)和ANC木材有限公司(艾伯塔省新闻纸公司(ANC))合作进行，将量化大型木质碎片(LWD)在以松树和云杉为主的河岸森林中的招募、衰减率和停留时间，这些森林环绕着艾伯塔省西部上下山麓亚区的小一级溪流。三个相互关联的项目将使用多种证据来量化LWD的动态，如下所示。(1)树木年轮分析将确定不同腐烂阶段和不同年龄的森林中原木死亡的时间。这些结果将被用来计算LWD招募的比率，并开发LWD持久性和衰减率的预测模型。(2)对山地森林永久样地中的陷阱和原木进行树轮分析将量化陆地粗木质碎屑的腐烂过程。我们将利用这些信息来确定衰变率和外环剥蚀率，以提高LWD年龄估计的准确性。(3)我们将开发模型来测试高地和河岸木质垃圾之间的腐烂速度和过程的差异。研究结果对阿尔伯塔省山麓及其他山地和北方森林的理论生态学和应用森林管理具有一定的参考价值。我们将与山麓模式林合作开发工具，以确保将从这项研究中获得的新知识有效地纳入森林管理做法和政策。

In Alberta, the current management strategy protects riparian forests from disturbance to reduce risk of adversely affecting streams and aquatic ecosystems. However, riparian zones are not immune to natural disturbance, some of which may be vitally important to maintain stream function. For example, the recruitment and retention of logs in riparian zones alters stream geomorphology and hydrology resulting in critical habitat for invertebrates and fish. This study, a collaboration of the Tree-Ring Lab at the University of British Columbia (UBC), Foothills Model Forest (FMF), Hinton Wood Products (West Fraser) and ANC Timber Ltd. (Alberta Newsprint Company (ANC)), will quantify recruitment and decay rates and residence times of large woody debris (LWD) in pine- and spruce-dominated riparian forests, surrounding small first order streams in the upper and lower foothills sub-regions of western Alberta. Three interconnected projects will use multiple lines of evidence to quantify the dynamics of LWD, as follows. (1) Tree-ring analyses will determine the time since death of logs in various stage of decay and in forests of different ages. These results will be used to calculate rates LWD recruitment and develop predictive models of LWD persistence and rates of decay. (2) Tree-ring analysis of snags and logs in permanent sample plots in upland forests will quantify decay processes for terrestrial coarse woody debris. We will use this information to determine the rate of decay and rate of outer ring erosion in order to improve the accuracy of age estimates of LWD. (3) We will develop models to test for differences in decay rates and processes between upland and riparian woody debris. The outcome of this research will have value to both theoretical ecology and applied forest management in the foothills of Alberta and other montane and boreal forests. We will work with the Foothills Model Forest to develop tools for ensure that new knowledge gained from this research is effectively integrated into forest management practices and policy.