Technical Abstract: Conservation grasslands reduce soil loss, improve water quality, are important wildlife habitat, and have the potential to be a source of biomass for biofuel production. Although the importance of biodiversity to maximize biomass yield on degraded land has been described in experimental grasslands, our survey of conservation grasslands in the northeastern USA found biomass yield decreased with plant diversity, but increased as specific C4 grasses increased, providing support for the importance of specific species and functional groups. Harvest management, such as seasonal harvest time and frequency can affect the services these grasslands support, from wildlife habitat value to biomass yield.