Assessing impacts of anthropogenic large woody debris and dynamic restoration on beach-dune morphodynamics and resilience in Pacific North America

沿海沙丘在全球范围内很少见，它提供关键的生态系统服务，如濒危物种的栖息地、具有高旅游价值的地点、地下水补给以及防止海岸侵蚀和海平面上升。在不列颠哥伦比亚省，这些系统非常罕见(占海岸面积的5%)，这是因为：1)极端的风、浪和水位状况；2)对气候变化信号(厄尔尼诺-拉尼娜；太平洋年代际振荡)的敏感性；以及3)缺乏冰盖效应(降雪、快速上岸的冰)。在北美太平洋，有两种常见的人为变化会影响未开发海岸的海滩沙丘的形态和功能--大型木质碎片(LWD，主要是历史上的伐木垃圾)和入侵植被(引入以稳定沙丘)。对这两方面的研究有限，影响重大，管理对策正在进行中，例如按照联邦立法(例如，加拿大濒危物种法、美国濒危物种法)恢复地貌过程和本地植物群落的“动态”恢复项目。 拟议方案的长期目标是改变人们对随地分配(焦点1)和动态恢复以移除入侵植物(焦点2)如何影响海滩沙丘地貌动力学、沉积物收支以及对海岸侵蚀、气候变异性影响和海平面上升的恢复能力的理解。反过来，这将为正在进行的沿海管理和生态系统恢复工作提供有用的信息。该计划建立在与3个研究地点的管理机构建立的合作伙伴关系的基础上：1)加拿大-太平洋沿岸国家公园，不列颠哥伦比亚省托菲诺；2)美国鱼类和野生动植物管理局-洪堡湾野生动物保护区，加利福尼亚州阿尔卡塔；3)不列颠哥伦比亚省公园和哈凯研究所，不列颠哥伦比亚省卡尔弗特岛。因此，该计划是协作性的，并提供了极好的HQP培训机会。 重点1将量化随日变化对海滩-沙丘沙运移、地貌动力学和景观演变(沙丘生长、沙丘迁移、侵蚀-恢复周期、海岸线进积/退缩)的影响。焦点2将评估移除入侵植被、刺激动态地貌过程和重建本地植物群落的各种恢复处理的有效性。这两个中心将使用前沿技术和方法进行基于事件的实验，并结合详细的陆地激光扫描(TLS)和无人驾驶飞行器(UAV)测量，以测量沙粒运移、侵蚀/沉积模式和泥沙体积变化。这些数据将补充高分辨率延时摄影测量和地理信息系统对研究地点历史航空照片的分析，以量化和解释这些变化对沙丘对自然(例如侵蚀性水位)和人为(例如植被移除)干扰事件的恢复能力的季节性和年际影响，这与土地管理和制定气候变化适应战略直接相关。

Coastal dunes are rare globally and provide key ecosystem services such as habitat for endangered species, sites of high tourism value, groundwater recharge and protection against coastal erosion and sea-level rise. In British Columbia, these systems are rare (<5% of the coast) and distinct due to: 1) extreme wind, wave and water level regimes; 2) sensitivity to climatic variability signals (El Niño-La Niña; Pacific Decadal Oscillation) and 3) lack of nival effects (snow, shore-fast ice). In Pacific North America, there are two common anthropogenic alterations that affect beach-dune form and function on undeveloped coasts - large woody debris (LWD, mostly historic logging refuse) and invasive vegetation (introduced to stabilize dunes). Research on both is limited, impacts are substantial and management responses are underway, such as 'dynamic' restoration projects that restore geomorphic processes and native plant communities in compliance with federal legislation (e.g. Canadian Species at Risk Act, US Endangered Species Act). The long-term goals of the proposed program are to transform understanding on how LWD (Focus 1) and dynamic restoration to remove invasive plants (Focus 2) affect beach-dune morphodynamics, sediment budgets, and resilience to coastal erosion, climatic variability impacts and sea-level rise. In turn, this will provide useful information for ongoing coastal management and ecosystem restoration efforts. The program builds on established partnerships with management agencies at 3 study sites: 1) Parks Canada-Pacific Rim National Park, Tofino BC; 2) US Fish & Wildlife Service-Humboldt Bay Wildlife Refuge, Arcata CA; and 3) BC Parks & the Hakai Institute, Calvert Island, BC. As such, the program is collaborative and presents excellent HQP training opportunities. Focus 1 will quantify the impacts of LWD on beach-dune sand transport, morphodynamics and landscape evolution (foredune growth, dune migration, erosion-recovery cycles, shoreline progradation/retrogradation). Focus 2 will assess the effectiveness of various restoration treatments that remove invasive vegetation, stimulate dynamic geomorphic processes and re-establish native plant communities. Both foci will use leading-edge technologies and methods to conduct event-based experiments coupled with detailed terrestrial laser scanning (TLS) and unmanned aerial vehicle (UAV) surveys to measure sand transport, erosion/deposition patterns and sediment volume changes. These data will complement high-res time-lapse photogrammetry (TLP) and GIS analyses of historic aerial photos of study sites to quantify and interpret seasonal to interannual impacts of these alterations on dune resilience to natural (e.g. erosive water levels) and artificial (e.g. vegetation removal) disturbance events with direct relevance for land management and development of climate change adaptation strategies.