Status and trends in upland vegetation and soils at Capitol Reef Nation-al Park, 2009–2018 (revised with cost estimate)

Witwicki, Dana

doi:10.36967/nrr-2279505

When Capitol Reef National Park (NP) was established in 1971, there were 19 active grazing allotments in the park. By the 1990s, all but two of these grazing permits were retired. Through long-term monitoring, resource managers at Capitol Reef NP are interested to identify impacts of recent livestock grazing on grasslands and track plant and soil recovery after grazing has ceased. The Northern Colorado Plateau Network (NCPN) has monitored the ecological health of vegetation and soils in grasslands in the northern part of Capitol Reef NP for more than 10 years. This report uses grassland data collected at the park from 2009 to 2018 to explore the following questions: 1. What is the current status of upland vegetation and soils (vegetation and surface cover, shrub density, exotic plant frequency, soil stability, and gaps) in Capitol Reef NP grasslands, and how has that status changed from 2009 to 2018? How do status and trends in grassland condition diﬀer by grassland type and livestock grazing history? 2. Which climate conditions are most inﬂuential in Capitol Reef NP grasslands? How did they aﬀect upland vegetation and soils from 2009 to 2018? Three livestock-grazing allotments in the northern part of the park, with diﬀerent grazing histories, were selected for long-term monitoring: Hartnet, grazed until May 2018, the last year of monitoring data included in this report; Cathedral, where ~80% of animal unit months (AUMs) were retired in 1989, and the rest retired in 1999; and Rock Springs, retired in 1989. Two groups of grassland ecological sites were monitored: deep grasslands and rocky grasslands. Each has diﬀerent soil and geomorphic properties, as well as some diﬀerences in the dominant perennial grass and shrub species present. We combined ecological-site groups and grazing history to obtain three sampling strata: 1. Deep grasslands in the combined retired Cathedral and Rock Springs allotments (Cathedral/Rock Springs deep grasslands), 2. Deep grasslands in the grazed Hartnet allotment (Hartnet deep grasslands), and 3. Rocky grasslands in the grazed Hartnet allotment (Hartnet rocky grasslands). Rocky grasslands were not sampled in the Cathedral and Rock Springs allotments because there was only a very small amount present. In the Cathedral and Rock Springs allotments, deep grasslands retired from livestock grazing were generally in good condition, with trends that were stable or improving. The allotments had low invasion by exotic annual plant species and good recovery from past grazing based on limited historical data. In actively grazed areas of the Hartnet allotment, conditions of cool-season grasses and soils were in relatively poor condition. The Hartnet deep grasslands had lower soil stability and some evidence of lower cool-season grass cover, lower biological soil crust cover, higher bare-soil cover, and larger gaps between plant canopies than the allotments retired from grazing, though the evidence was not particularly strong. Perennial grasses, especially cool-season grasses, showed declining trends (i.e., declining resource condition). Average to above-average precipitation in later years of monitoring (2013–2016) kept changes in grass cover less negative than would be predicted under long-term mean precipitation conditions from 2009 to 2018. Soil conditions showed some improvement over the 10 years of monitor-ing, but the current condition of these indicators suggests there is still a moderate-to-high potential for wind and water erosion. In the Hartnet rocky grasslands, vegetation cover declined from 2009 to 2018 for all analyzed indicators, and was lower during the drought conditions of 2018 than in any of the other years monitored. Soils in the rocky grasslands had low cover of biological soil crust and bare soil, but were still in relatively good condition because a high cover of rocks protects them from trampling and wind erosion. In areas with exposed soils, biological soil crust cover...

Status and trends in upland vegetation and soils at Capitol Reef Nation-al Park, 2009–2018 (revised with cost estimate)

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