Forest expansion in Cypress Hills Interprovincial Park

由于火灾、干旱、放牧和其他因素，半干旱地区的森林和草原的分布正在发生变化，无论是局部还是全球。在加拿大，这两种植被类型之间的变化在面积为400平方米的柏树山省际公园尤为显著。横跨阿尔伯塔省南部-萨斯喀彻温省边界的公里保护区。该公园坐落在草原内的一个高地上，包含了粗糙的羊茅草原和森林的混合景观，主要是樟子松、颤抖的杨树和白云杉。在过去的一个世纪里，树木和森林已经扩展到以前的草原地区，总体上减少了生物多样性和牛可获得的饲草量。该项目与艾伯塔省和萨斯喀彻温省的公园机构合作，将描述整个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速度是否在多个时期(20世纪70年代至90年代；90年代至2010年)发生了变化，哪些物理环境特征与森林扩张关系最密切，哪里土地覆盖进一步变化的风险最高，以及哪些因素预计将限制未来森林扩张速度。我们的调查结果将纳入新的管理计划，这些计划规定了与维护草原和森林复盖有关的具体目标。如果预计随着时间的推移，森林扩展将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，公园管理者可能会开出新的植被管理做法或改变放牧活动。这项研究将为柏树山的公园管理者、养牛者和游客提供具体的好处，以及与生物多样性保护和碳封存相关的更普遍的好处，让世界各地的加拿大人受益。

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.