Conifer expansion [Chapter M.]

Coniferous trees, principally juniper (Juniperus spp.) and pinyon pine (Pinus spp.), have increased considerably in cover and density in the western United States since European settlement with wide ranging consequences for sagebrush (Artemisia spp.) ecosystems. A continuum of vegetation types exists across the region, from conifer-encroached shrublands to persistent pinyon-juniper woodlands and savannas. This chapter focuses on the issue of conifer expansion into sagebrush shrublands and ensuing woodland succession, not the infill of persistent woodlands and savannas. Detrimental effects of conifer expansion on sagebrush ecosystem vegetation composition and productivity, wildlife, water and nutrient cycles, carbon storage, resilience to fire, and resistance to cheatgrass (Bromus tectorum) invasion are well-documented. Unprecedented partnerships have formed in recent years to address conifer expansion impacts across ownerships in the sagebrush biome. While significant conifer reduction has occurred in some strategic priority areas, the overall proportion of conifer being reduced through management and wildfire across the region remains relatively small. View entire document here.