Vegetation and Soil Trends, Black Canyon of the Gunnison National Park and Curecanti National Recreation Area, 2011–2022

Livensperger, Carolyn

doi:10.36967/2309325

In 2011, the Northern Colorado Plateau Network (NCPN) began long-term monitoring of vegetation and soils in upland communities at Black Canyon of the Gunnison National Park (BLCA) and Curecanti National Recreation Area (CURE). Managers wanted to understand conditions in sagebrush shrublands, aspen forests, pinyon-juniper woodlands, and Gambel oak shrublands. These four vegetation types are associated with a range of management concerns. These include suitable habitat conditions for the threatened Gunnison sage-grouse, planning for livestock grazing management, responses to disturbances (e.g., fire, plant diseases, and insect pests), wild ungulate usage and community responses to different climate conditions. The primary goals of monitoring are to track the status of these vegetation types and identify trends that describe changes over time. Status and trend of vegetation and soil indicators were analyzed for the 2011 – 2022 monitoring period. Key findings from this analysis are: 1) In both grazed and ungrazed sagebrush shrublands, total grass cover was stable. However, in grazed sagebrush, native perennial grasses decreased over time while non-native perennial grasses increased. 2) Most elements of Gunnison sage-grouse structural habitat guidelines were within recommended ranges in both grazed and ungrazed sagebrush shrublands; however, forb cover was lower than recommended. 3) Native perennial grass cover, primarily cool-season grasses, decreased in three of four vegetation types. Aspen forests were the only vegetation type with stable grass cover. 4) Pinyon-juniper woodlands maintained stable density and cover of overstory trees, saplings, and seedlings. Non-native plant cover was low and non-native plant frequency decreased. However, native perennial grass cover also decreased. 5) Aspen forests are in decline. Overstory trees and saplings experienced mortality and decreased canopy closure. Non-native plants, primarily perennial species, had high but stable cover. 6) Gambel oak shrublands show resistance to change. Gambel oak and other shrub cover and density remained stable over time but native perennial grasses decreased. 7) Actual evapotranspiration and water deficit predicted vegetation and soil response well. Water deficit or actual evapotranspiration in June, the month with lowest precipitation, was associated with declines in native perennial grasses in sagebrush shrublands, Gambel oak shrublands, and pinyon-juniper woodlands. Future changes in these water balance variables will influence conditions in all vegetation types.

Vegetation and Soil Trends, Black Canyon of the Gunnison National Park and Curecanti National Recreation Area, 2011–2022

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