Woody plant expansions are altering ecosystem structure and function, as well as fire regimes, around the globe. Tree‐reduction treatments are widely implemented in expanding woodlands to reduce fuel loads, increase ecological resilience, and improve habitat, but few studies have measured treatment outcomes over long timescales or large geographic areas. The Sagebrush Treatment Evaluation Project (SageSTEP) evaluated the ecological effects of prescribed fire and cut‐and‐leave treatments in sagebrush communities experiencing tree expansion in North American cold desert shrublands. We used 10 yr of data from the SageSTEP network to test how treatments interacted with pre‐treatment tree dominance, soil climate, and time since treatment to affect plant functional groups and dominant species. Non‐sprouting shrub (Artemisia spp.), sprouting shrub, perennial graminoid, and annual grass responses depended on tree dominance and soil climate, and responses were related to the dominant species' life‐history traits. Sites with warm and dry soils showed increased perennial graminoid but reduced Artemisia shrub cover across the tree dominance gradient after prescribed burning, while sites with cool and moist soils showed favorable post‐burn responses for both functional types, particularly at low to moderate tree dominance. Cut‐and‐leave treatments sustained or increased native perennial plant functional groups and experienced smaller increases in exotic annual plants in both soil climates across the tree dominance gradient. Both treatments reduced biocrust cover. Selecting appropriate tree‐reduction treatments to achieve desired long‐term outcomes requires consideration of dominant species, site environmental conditions, and the degree of woodland expansion. Careful selection of management treatments will reduce the likelihood of undesirable consequences to the ecosystem.

中文翻译：

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林地扩展处理十年后，植物功能群和物种有助于生态恢复

木本植物的扩张正在改变全球的生态系统结构和功能以及火灾状况。减少树木的治疗方法广泛用于扩大林地以减少燃料负荷，提高生态适应力和改善栖息地，但是很少有研究在长期范围或较大的地理区域内评估治疗效果。鼠尾草治疗评估项目（SageSTEP）对北美寒冷沙漠灌木丛中经历树木扩张的鼠尾草群落中规定的除火和砍伐和砍伐处理的生态效应进行了评估。我们使用了来自SageSTEP网络的10年数据来测试处理如何与预处理树的优势，土壤气候以及处理后的时间相互作用，从而影响植物的功能群和优势种。不发芽的灌木（蒿spp。），萌芽灌木，多年生禾本科植物和一年生禾草的响应取决于树木的优势和土壤气候，并且响应与优势物种的生活史特征有关。土壤温暖干燥的地方显示多年生的类蠕虫增多但蒿蒿减少规定的燃烧后，灌木覆盖度遍及树木优势梯度，而凉爽湿润的土壤对两种功能类型均表现出良好的燃烧后响应，尤其是在低至中等树木优势下。在两种土壤气候下，砍伐和处理都可以维持或增加本地多年生植物的功能群，而异国一年生植物的增加幅度较小。两种处理都降低了生物结皮的覆盖率。选择适当的减树措施以实现所需的长期效果，需要考虑优势树种，现场环境条件以及林地扩展程度。精心选择管理措施将减少对生态系统造成不良后果的可能性。