Determining forest disturbance thresholds for managing cumulative hydrological impacts

由于森林干扰和气候变化的加剧及其对供水和其他水生功能的影响，森林干扰对水文的影响日益受到重视。然而，这项研究的大部分是在小流域(500平方公里)上进行的，因为森林干扰经常在空间和时间上累积发生，其水文影响是累积的。在我的NSERC发现基金的支持下，我建立了一个名为“大流域的森林干扰和水文学”的研究计划，其中我们成功地开发了一种称为修正双质量曲线(MDMC)的方法，用于量化任何单个流域的森林干扰造成的累积水文影响。利用该方法和其他统计技术，我们研究了诸如累积水文效应、森林干扰与气候之间的相互作用以及跨嵌套流域的水文影响的空间尺度等关键研究问题。我们的研究成果已发表在影响力较大的期刊上(例如，《水资源研究》、《水文学杂志》、《全球变化生物学》、《自然通讯》)。我们的进展导致了一个重要的研究问题：什么是森林干扰的阈值，超过这个阈值就可以检测到重大的累积水文影响？令我们惊讶的是，鉴于其在可持续性方面的重要性，关于这一主题的研究非常有限，这主要是由于几个方法学上的挑战。回答这个问题可以极大地推动流域科学的发展，促进流域的可持续发展。在这项原创性和创新性的研究中，将选择来自不列颠哥伦比亚省(BC)内陆的50个流域，然后应用包括MDMC在内的几种统计技术来单独确定每个流域的森林干扰阈值。短期目标(2021-2026年)是：(1)定量确定年平均流量的森林干扰阈值；(2)确定高流量和低流量的森林干扰阈值；(3)评估气候和流域性质是否也是这些阈值的控制因素。我的长期目标是在考虑到更多的生态过程的更广泛的背景下，评估生态阈值或临界点和复原力，并扩大空间范围，在更大的空间尺度上检查森林干扰阈值。不列颠哥伦比亚省内陆是这项拟议研究的理想区域，因为那里有许多测量流域，可以获得关于水文、气候和森林干扰的长期历史数据。这项研究将为BC管理森林干扰、保护水生功能提供重要和及时的信息。它将允许制定森林干扰阈值，以有效管理累积的水文风险。最后，该项目将培养2名HQP和5名本科生。

The impacts of forest disturbance on hydrology have been receiving growing attention due to increasing forest disturbance and climate change, and their effects on water supply and other aquatic functions. However, the majority of this research has been conducted on small watersheds (500 km2), as forest disturbance often occurs cumulatively over space and time, its hydrological impacts are cumulative. With support from my NSERC Discovery Grants, I established a research program entitled "Forest Disturbance and Hydrology in Large Watersheds" where we have successfully developed a method referred to as modified double mass curve (MDMC) for quantifying the cumulative hydrological effects caused by forest disturbance in any individual watershed. Using this method and other statistical techniques, we have studied critical research questions such as cumulative hydrological effects, interactions between forest disturbance and climate, and spatial scaling of hydrological impacts across nested watersheds. Our results have been published in high-impact journals (e.g., Water Resources Research, Journal of Hydrology, Global Change Biology, Nature Communications). Our progress has led to an important research question: what are forest disturbance thresholds over which significantly cumulative hydrological impacts can be detected? To our surprise, there is very limited research on this topic given its significance in sustainability, mainly due to several methodological challenges. Answering this question can greatly advance watershed science and promote watershed sustainability. In this original and innovative study, 50 watersheds from the interior of British Columbia (BC) will be selected, whereby several statistical techniques including MDMC will then be applied to determine forest disturbance thresholds for each watershed individually. The short term objectives (2021-2026) are: (1) to quantitatively determine forest disturbance thresholds on annual mean flows; (2) to determine forest disturbance thresholds high and low flows; and (3) to above results from all 50 watersheds to assess whether climate and watershed property are also controls on these thresholds. My long-term objectives are to assess ecological thresholds or tipping points and resilience in a broader context considering more ecological processes, and to expand spatial scopes to examine forest disturbance thresholds at larger spatial scales. The BC interior is an ideal region for this proposed study because there are numerous gauged watersheds where long-term historic data on hydrology, climate and forest disturbance are available. The proposed research will provide important and timely information for BC to manage forest disturbance to protect aquatic functions. It will allow development of forest disturbance thresholds for effectively managing cumulative hydrological risks. Finally, this project will train 2 HQPs and 5 undergraduate students.