Wetland decline under post-European settlement and land use change across western Canada has led to mitigation strategies, including wetland creation. Created wetlands can trigger environmental change, including woody species encroachment, in turn altering vegetation and soil. We quantify changes in shrub abundance from prior to wetland creation (1949) until 60 years later (2012) within a Mixedgrass ecosystem of the Verger watershed in Alberta, Canada. In addition, we compare remaining grassland with areas colonized by shrubland on similar ecosites for differences in (1) plant composition, including native and introduced flora, (2) herbage yield and forage accessibility for livestock, and (3) soil properties (surface organic depth, bulk density, mineral nitrogen (N), and carbon (C) concentration). Repeat photos show Shepherdia argentea shrublands increased from 0 to 88 ha (to 1.15% of study area) following wetland creation, with the greatest increase in the last 20 years. Relative to grasslands, shrublands had lower total plant diversity but greater presence of introduced plant species. Shrub patches were 94% lower in herbaceous production, with 77% of shrublands non-utilized by cattle, collectively leading to reduced grazing capacity. Relative to grasslands, shrublands had a thicker soil surface mulch layer, and where cattle were present, had increased mineral soil N and C. Overall, shrub encroachment following wetland creation has markedly altered vegetation and soils in this once grassland landscape, with negative impacts on native plant diversity, herbage production and forage accessibility, and has implications for the management of shrub encroachment.

中文翻译：

---

杂草草原湿地形成后的灌木侵占改变了草地植被和土壤

后欧洲定居和加拿大西部土地利用变化导致的湿地减少导致了缓解策略，包括湿地创建。人工湿地会引发环境变化，包括木本物种的侵占，进而改变植被和土壤。我们量化了从湿地创建之前（1949 年）到 60 年后（2012 年）在加拿大艾伯塔省 Verger 流域的混合草生态系统中灌木丰度的变化。此外，我们将剩余的草地与类似生态位点上灌木丛定植的地区进行比较，以了解 (1) 植物组成的差异，包括本地和引进的植物群，(2) 牧草产量和牲畜的草料可及性，以及 (3) 土壤特性（表面有机深度、堆积密度、矿物氮 (N) 和碳 (C) 浓度）。重复照片显示，在创建湿地后，牧羊人灌木丛从 0 公顷增加到 88 公顷（占研究面积的 1.15%），在过去 20 年中增幅最大。相对于草原，灌木丛的总植物多样性较低，但引入的植物物种较多。灌木丛的草本产量降低了 94%，其中 77% 的灌木地未被牛利用，共同导致放牧能力下降。相对于草原，灌木地具有更厚的土壤表层覆盖层，在有牛的地方，矿质土壤 N 和 C 增加。 总体而言，湿地形成后的灌木侵占显着改变了这片曾经的草原景观中的植被和土壤，对本地植物多样性、牧草生产和草料可及性，