Broadcast Burning of Sagebrush in the Winter

Abstract

Sagebrush-grass vegetation occupies about 5.5 million hectares of Idaho rangelands. Rangeland productivity has decreased as presettlement sagebrush densities have increased. Prescribed burning of such rangeland has proven to be an efficient and economic tool to reclaim sagebrush- dominated areas, but firing techniques and weather prescriptions for fire use have not been developed. Feasibility of winter burning with snow or ice on the surface of the soil was tested with the following restrictions: (1) sagebrush was dense, with a canopy cover about 50%, and (2) distance between plants cannot exceed 50% of their average height. With these restrictions, fire carried through sagebrush canopies when effective wind speed was above 8 km/hr (5 mph) and winter ignition index was Y1 was greater than or equal to 29. Under the above prescription, only small areas burned. Winter burning might be impractical in most areas because of imposed stand limitations and the low number of days with proper burning conditions. However, winter broadcast burning is possible, inexpensive, and completely safe when snow or ice is present, and requires no fire control preparation or mop-up.