The ecological effects of reducing pinon and juniper basal areas in northwestern New Mexico

Expansion, encroachment, and maturation of pinon-juniper woodlands has resulted in closing canopies and reductions in herbaceous undergrowth in northwestern New Mexico. With increasing oil and gas development in the region, an opportunity is provided to expand the disturbance area and restore the herbaceous undergrowth, improve the hydrological function, increase habitat for big game, and assess public values and acceptance. We evaluated the herbaceous undergrowth vegetative response of thinning pinon and juniper trees and scattering slash adjacent to the construction of a new gas pipeline. Analysis, four years after treatment, indicated that reducing the tree basal area to 5ft2 acre-1 (1.15 m2 ha -1) and 10ft2 acre-1 (2.30 m2 ha-1) and scattering slash increased total grass standing crop on the treated areas from 71.6 kg ha-1 (63.9 lb ac-1) to 310.4 kg ha -1 (277.1 lb ac-1), prevented the amount of bare ground from increasing, and increased vegetative cover from 4.3% to 9.6%.;Survey results indicate that the public recognized the improvement to the watershed function, increased herbaceous undergrowth, and improved wildlife habitat. Although the public perception of aesthetics changes were positive they were not rated high, which could be due to small area treated. The overall results of this research are likely synergistic and interactive, with indications that an approach which reduces tree basal area and scatters slash can increase herbaceous undergrowth vegetation, reduced bare ground, reduce runoff within intercanopy space, and increase the relative presence of wild ungulates.