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，以减少对溪流和水生生态系统产生不利影响的风险。然而，河岸带并非不受自然干扰，其中一些可能对维持河流功能至关重要。例如，河岸地带原木的补充和保留改变了河流地貌和水文，从而成为无脊椎动物和鱼类的关键栖息地。这项研究是英属哥伦比亚大学（UBC）的树木年轮实验室、山麓模型森林（FMF）、辛顿木材产品（西弗雷泽）和ANC木材有限公司（阿尔伯塔新闻纸公司（ANC））的合作，将量化松树和云杉为主的河岸森林中大型木质碎片（LWD）的吸收、腐烂率和停留时间，这些森林围绕着阿尔伯塔西部上下山麓次区域的小一级溪流。三个相互关联的项目将使用多条证据线来量化LWD的动态，如下所示。(1)树木年轮分析可以确定不同衰变阶段和不同年龄森林中原木的死亡时间。这些结果将用于计算随钻回注速率，并开发随钻持续时间和衰减速率的预测模型。(2)山地森林永久样地的树木年轮分析将量化陆生粗木屑的腐烂过程。我们将利用这些信息来确定衰减速率和外环侵蚀速率，以提高随钻年龄估计的准确性。(3)我们将开发模型来测试陆地和河岸木屑在腐烂率和过程上的差异。这项研究的结果将对阿尔伯塔山麓和其他山地和北方森林的理论生态学和应用森林管理有价值。我们将与山麓示范森林合作开发工具，确保从这项研究中获得的新知识有效地融入森林管理实践和政策。

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.