Recovery Across a Gradient of Disturbance Novelties: Patterns and Drivers of Understory Plant Community Dynamics in Northern Lodgepole Pine Forests

加拿大北部数百万公顷的森林每年都受到自然和人为干扰因素的影响。新的干扰正在将北方森林推向其历史上自然变化的范围；这些森林正在经历前所未有的干扰类型和严重程度。干扰机制的变化反过来又导致森林结构、功能和长期演替轨迹的变化，造成未知的生态后果。这些干扰对森林冠层、林下植物群落和地下属性的相对影响将在决定这些森林的演替、生物多样性和保护方面发挥重要作用。考虑到林下植物群落是森林生态功能和生物多样性的组成部分，了解干扰对这些植物群落的影响及其与其他生态系统特性和过程的联系将有助于我们更好地理解森林对不断变化的干扰机制可能做出的复杂反应。樟子松(Pinus Trorta)森林为评估各种新奇干扰对林下植物群落的影响提供了天然实验室。在加拿大西部，气候变化导致了前所未有的山松甲虫(MPB)暴发，而MPB范围不断扩大到新的栖息地对林下植物群落的影响尚不清楚。MPB选择性地杀死较大和较老的树木，使林下植被完好无损，而抢救被攻击的树木对林下植被有直接影响。直接影响在伐木地区更加显著，这些地区随后被用于石油和天然气开采，然后开垦成新的森林。当松树被引种到世界其他地区时，它们本身可能被认为是主要的干扰物。我的研究计划侧重于了解这些干扰中林下植物群落的反应与历史干扰物(林替代火)相比如何以及为什么不同。我提出的研究考察了单一森林生态系统类型--樟子松的植物群落结构和功能响应，跨越了干扰类型的新颖性梯度。我的研究活动将为开发一个框架奠定基础，使我们能够更好地预测：i)各种干扰对植物生物多样性和功能的长期影响，以及ii)松林在不断变化的干扰制度下的演替轨迹。此外，它将为北方森林的保护和恢复实践提供经验基础，包括推动制定省级长期监测计划，以评估艾伯塔省开垦森林的生态恢复情况。它同时为11名下一代UG、MSC、PHD和PDF科学家提供变革性的研究体验和培训，在一个包容的勇敢空间。

Millions of hectares of Canada's northern forests are impacted each year by both natural and anthropogenic disturbance agents. Novel disturbances are pushing northern forests beyond their historical natural ranges of variability; these forests are experiencing unprecedented types and severities of disturbance. The changes in disturbance regimes are in turn are leading to changes in forest structure, function, and long-term successional trajectories, with unknown ecological consequences. The relative impacts of these disturbances on the forest canopy, understory plant community, and below-ground properties will play an important role in determining succession, biodiversity and conservation of these forests. Given that understory plant communities are integral to the ecological functioning and biodiversity of forests, gaining an understanding of impacts of disturbance on these plant communities and their linkages with other ecosystem properties and processes will help us to better understand the complex responses that forests may have to shifting disturbance regimes. Lodgepole pine (Pinus contorta) forests provide natural laboratories for assessing the effects of varying novelties of disturbance on understory plant communities. In western Canada, climate change has contributed to an unprecedented mountain pine beetle (MPB) outbreak, and the impacts of ongoing range expansion of MPB into new habitats on understory plant communities remain unknown. MPB selectively kills larger and older trees, leaving the understory intact, whereas salvage harvest of attacked trees has immediate direct effects on the understory. Direct effects are even more dramatic in logged areas that are subsequently used for oil and gas extraction, and then reclaimed to new forest. When pine trees are introduced to other regions of the world, they may themselves be considered as the primary disturbance agent. My research program focuses on understanding both how and why understory plant community responses differ among these disturbances compared with historical disturbance agents (stand-replacing fire). My proposed research examines plant community structural and functional responses of a single forest ecosystem type, lodgepole pine, across a gradient of novelties of disturbance types. My research activities will set the stage for development of a framework that will allow us to better predict: i) long-term impacts of varied disturbances on plant biodiversity and function, and ii) the successional trajectories of pine forests under changing disturbance regimes. Further, it will provide the empirical basis to inform conservation and restoration practices in northern forests, including advancing development of a provincial long-term monitoring program to assess ecological recovery of reclaimed forests in Alberta. It simultaneously provides transformative research experience and training for 11 next generation UG, MSc, PhD and PDF scientists in an inclusive brave space.