Forest expansion in Cypress Hills Interprovincial Park

由于火灾、干旱、牲畜放牧和其他因素，半干旱地区的森林和草地分布在当地和全球都在发生变化。在加拿大，这两种植被类型之间的变化在柏树山省际公园特别明显，一个400平方米的公园。保护区横跨南部艾伯塔省萨斯喀彻温省边界。该公园位于大草原内的高原上，包含粗糙的羊茅草原和森林的混合景观，主要是黑松，颤抖的白杨和白色云杉。在过去的世纪里，树木和森林已经扩展到以前的草原地区，减少了整体生物多样性和牛的饲料量。与阿尔伯塔和萨斯喀彻温省的公园机构合作，该项目将描述柏树山森林扩张的方式和地点。利用实地数据和历史航空照片，我们将确定森林扩张的速度是否在多个时间段发生了变化（1970 - 1990年代; 1990年代至2010年代），哪些物理环境特征与森林扩张有着最密切的联系，在森林扩张中，土地覆被进一步变化的风险最高，以及哪些因素预计会限制未来森林扩张的速度。我们的研究结果将被纳入新的管理计划，制定与维护草原和森林覆盖有关的具体目标。如果森林扩张预计会随着时间的推移对生态系统功能和服务产生不利影响，包括生态系统多样性、碳固存和饲料供应，公园管理者可以规定新的植被管理做法或改变放牧活动。这项研究将为公园管理者、养牛者和柏树山的游客提供具体的好处，并为加拿大各地的生物多样性保护和碳封存提供更普遍的好处。

The distributions of forests and grasslands in semi-arid regions are changing, both locally and globally, as a result of fire, drought, livestock grazing, and other factors. In Canada, shifts between these two vegetation types are particularly notable in Cypress Hills Interprovincial Park, a 400 sq. km protected area straddling the southern Alberta-Saskatchewan border. The park is situated on an elevated plateau within the Prairies, and contains a mixed landscape of rough fescue grassland and forests dominated by lodgepole pine, trembling aspen, and white spruce. Over the past century trees and forests have expanded into former grassland areas, reducing overall biodiversity and the amount of forage available to cattle. Working in partnership with park agencies in both Alberta and Saskatchewan, this project will characterize how and where forest expansion is occurring across Cypress Hills. Using field data and historical aerial photographs, we will determine whether the rate of forest expansion has changed across multiple time periods (1970s-1990s; 1990s-2010s), which characteristics of the physical environment are most strongly associated with forest expansion, where the risk of further land cover change is highest, and what factors are expected to limit the rate of forest expansion in the future. Our findings will be incorporated into new management plans that set out specific objectives related to the maintenance of grassland and forest cover. Park managers may prescribe new vegetation management practices or changes to grazing activity if forest expansion is expected to adversely impact ecosystem functions and services over time, including ecosystem diversity, carbon sequestration, and the provision of forage. The research will provide specific benefits to park managers, cattle producers, and visitors in Cypress Hills, as well as more general benefits related to biodiversity conservation and carbon sequestration for Canadians everywhere.