Influence of ponderosa pine overstory on forage quality in the Black Hills, South Dakota

Forage quality was assessed in pole and sapling ponderosa pine (Pinus ponderosa) stands growing at five stocking levels—0, 5, 14, 23, and unthinned (which approximated 40 m2/ha basal area)—in the Black Hills of South Dakota. Crude protein, acid detergent fiber, acid detergent lignin, ash, calcium, and phosphorus were evaluated for cream peavine (Lathyrus ochroleucus), bearberry (Arctostaphylos uva-ursi), and timber oatgrass (Danthonia intermedia). Acid detergent fiber, acid detergent lignin, and ash showed some significant differences among growing stock levels for cream peavine growing in sapling stands. Crude protein content of timber oatgrass was different among growing stock levels in pole stands. In all cases, however, no trends or patterns relative to stocking levels were evident. When understory forage quality was compared within pole and sapling stands, only 4 of 18 possible comparisons were significant. In general, modifying the overstory of ponderosa pine in the Black Hills by clearcutting or thinning did not result in predictable changes in nutritional values of selected understory species.