Mechanically Shredding Utah Juniper and Soil Characteristics.

Juniper species are taking over thousands of hectares of sagebrush steppe. In absence of fire, juniper density increases thereby decreasing understory vegetation while increasing canopy fuel loads and the potential for catastrophic wildfire. To reduce canopy fuel loads, the Bureau of Land Management is mechanically shredding Utah juniper on hundreds of hectares annually in Utah. Juniper is shredded by a large rotating drum with hardened spikes that is mounted on a large articulating tractor. Trees were shredded at 3 locations in Utah. This treatment leaves patches of shredded fuels over preexisting canopy litter and interspace soil. Annual soil samples were collected from the top 2-cm of bare interspace soil, under juniper canopy litter, and under shredded juniper fuels. PRS probes, exchanged at four month intervals, were used to quantify soil nitrogen supply rate. Total soil carbon, nitrogen, and organic matter were measured each summer. Soil moisture and temperature were measured continuously using data loggers, thermocouples, and gypsum blocks. Preliminary results suggest that mechanically shredding juniper increased soil nitrogen availability and wet degree days. These preliminary results suggest that plant vigor will increase following mechanical shredding of juniper in comparison with untreated juniper dominated areas.