Data from: To burn or not to burn: comparing re-introducing fire with cutting an encroaching conifer for conservation of an imperiled shrub-steppe

Woody vegetation has increased on rangelands worldwide for the past 100-200 years, often because of reduced fire frequency. However, there is a general aversion to re-introducing fire and therefore, fire-surrogates are often used in its place to reverse woody plant encroachment. Determining the conservation effectiveness of re-introducing fire compared to fire-surrogates over different time scales is needed to improve conservation efforts. We evaluated the conservation effectiveness of re-introducing fire with a fire-surrogate (cutting) applied over the last ~30 years to control juniper (Juniperus occidentalis Hook.) encroachment on 77 sagebrush-steppe sites. Critical to conservation of this imperiled ecosystem is to limit juniper, not encourage exotic annual grasses, and promote sagebrush dominance of the overstory. Re-introducing fire was more effective than cutting at reducing juniper abundance and extending the period of time that juniper was not dominating the plant community. Sagebrush was reduced more with burning than cutting. Sagebrush, however, was predicted to be a substantial component of the overstory longer in burned than cut areas because of more effective juniper control. Variation in exotic annual grass cover was explained by environmental variables and perennial grass abundance, but not treatment, with annual grasses being problematic on hotter and drier sites with less perennial grass. This suggests that ecological memory varies along an environmental gradient. Re-introducing fire was more effective than cutting at conserving sagebrush-steppe encroached by juniper over extended time-frames; however, cutting was more effective for short-term conservation. This suggests fire and fire-surrogates both have critical roles in conservation of imperiled ecosystems