Overstory-Understory Relations in Pinyon-Juniper Woodlands in New Mexico

Abstract

Herbage biomass for blue grama (Bouteloua gracilis [H.B.K. Lag]), pinyon ricegrass (Piptochaetium fimbriatum [H.B.K.] Hitche.), New Mexico muhly (Muhlenbergia pauciflora Buckl.), other grasses and forbs was estimated on 25 pinyon-juniper stands of varying overstory cover on the Fort Stanton Experimental Ranch in south-central New Mexico. Negative 2nd degree polynomial curves best expressed the relationships between total understory and blue grama biomass and overstory canopy cover. Positive polynomial relationships were shown for cool-season graazs, New Mexico muhly, and pinyon ricegrass. Reducing pinyon-juniper canopy cover would likely increase blue grama production and reduce production of New Mexico muhly and pinyon ricegrass.