Ferguson Phoebe L, Martyn Trace E, Downey Michelle C, Fischer James M, Burke Ingrid C, Lauenroth William K
School of the Environment, Yale University, New Haven, Connecticut, USA.
Eastern Oregon Agricultural Research Center - Union Experiment Station, Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, USA.
Ecol Appl. 2025 Jun;35(4):e70056. doi: 10.1002/eap.70056.
A major conservation challenge in the western United States is implementing management treatments that reduce fire risk, control for invasive species, and maintain herbaceous understories in big sagebrush ecosystems. Studies have found that mechanical treatment of big sagebrush can reduce fire risk and promote herbaceous understories, but a consensus on the long-term impacts of big sagebrush reduction remains unclear. We used a time series (20 years) of treated sites to understand the short- and long-term response of herbaceous plants and shrubs to mastication treatment in big sagebrush plant communities of south-central Colorado. We found that mastication to a height of 15 cm significantly reduced big sagebrush cover and increased perennial grass cover in the short term. The significant increase in perennial grass cover on recently treated (1-2 years) sites was largely attributed to C rather than C perennial bunchgrasses. Recently treated sites had greater annual plant cover and density than untreated sites. However, on sites treated more than 2 years ago, there was no significant difference between perennial grass and annual plant cover or density. Perennial forb cover and density was not affected by treatments. Initially reduced by nearly 80%, big sagebrush cover returned at a rapid and constant rate over time and returned to a statistically indistinguishable cover from the untreated sites within 8-10 years while height recovered slowly. Our results underscore the resilience of big sagebrush to partial canopy removal and emphasize the long-term dynamics following treatment.
美国西部面临的一项重大保护挑战是实施管理措施，以降低火灾风险、控制入侵物种，并在大艾草生态系统中维持草本植物下层植被。研究发现，对大艾草进行机械处理可以降低火灾风险并促进草本植物下层植被生长，但对于减少大艾草的长期影响仍未达成共识。我们利用一系列经过20年处理的地点，来了解科罗拉多州中南部大艾草植物群落中草本植物和灌木对粉碎处理的短期和长期反应。我们发现，将大艾草粉碎至15厘米的高度在短期内显著降低了大艾草的覆盖度，并增加了多年生草本植物的覆盖度。近期处理过（1 - 2年）的地点多年生草本植物覆盖度的显著增加主要归因于C而不是C多年生丛生禾本科植物。近期处理过的地点一年生植物的覆盖度和密度比未处理的地点更大。然而，在2年多以前处理过的地点，多年生草本植物和一年生植物的覆盖度或密度没有显著差异。多年生杂类草的覆盖度和密度不受处理影响。大艾草的覆盖度最初降低了近80%，但随着时间的推移以快速且稳定的速率恢复，在8 - 10年内恢复到与未处理地点在统计学上无显著差异的覆盖度，而高度恢复缓慢。我们的结果强调了大艾草对部分树冠去除的恢复力，并强调了处理后的长期动态变化。
