Sagebrush steppe vegetation monitoring in City of Rocks National Reserve: 2018 annual report

Nicolli, Melissa

As part of the Upper Columbia Basin Network sagebrush steppe vital signs monitoring program, a survey of sagebrush steppe ecological condition was conducted in June and July 2018 in City of Rocks National Reserve and adjacent Castle Rocks State Park (together referred to by acronym as CIRO) following methods outlined in the Upper Columbia Basin Network monitoring protocol (Yeo et al. 2009). The plots were surveyed on two separate weeks, approximately one month apart. The lower elevation plots were surveyed in June and the higher elevation plots in July. The plot-based surveys occurred within 10 sampling frames that are positioned to overlap grazing allotments (Figure 1). Canopy cover of exposed soil and of principal native and non- native plants or genera were estimated in six-hundred ninety-four 1 m2 quadrats randomly placed throughout the sampling frames. Quadrat locations were drawn using a spatially-balanced random sampling design, the Generalized Random Tessellation Stratified (GRTS) design, which ensures a good representative random sample with good dispersion and scope of inference within each sampling frame. Sagebrush steppe is one of the most threatened ecosystems in the intermountain west, and land use practices both within and adjacent to UCBN park steppe communities have resulted in fragmented and altered park ecosystems. Predicted climate change for the region may exacerbate these changes. This brief annual report summarizes some of the key findings from the 2018 field season. Big sagebrush was the most abundant shrub, occurring in all sampling frames, followed by green rabbitbrush, antelope bitterbrush, and snowberry. Sandberg’s bluegrass, a small stature and highly resilient native perennial grass, was the most widespread and abundant native perennial grass encountered. The percentage of plots with Sandberg’s bluegrass cover ranged among frames from 39% to 85%. Western wheatgrass, another important native perennial grass, ranged in frequency from 24-78.5%. Bluebunch wheatgrass, a hardy grass with drought resistant root systems, varied in frequency from 3% to 49%. Idaho fescue, indian ricegrass, needle and thread grass, sand dropseed and squirreltail were less abundant native perennial grasses encountered in many plots. Lupine, buckwheat, and phlox were the most abundant native perennial forbs. All frames in CIRO had some presence of cheatgrass with the proportion of plots containing cheatgrass cover ranging among frames from 18-92%. Yellow salsify was the most common non-native invasive weed, followed by common dandelion and tumble mustard. Noxious weeds were encountered that included dalmatian toadflax, white top, and Canada thistle. The frequencies of these noxious plants were relatively low, with only 2-3% cover being documented in frames where they occurred. We noted varying combinations among frames in the patterns of cheatgrass and native perennial grass abundance. As one might expect, frames with high cheatgrass abundance showed lower native grass abundance, and vice versa. Trail Canyon, Emery Canyon, and Circle Creek South had expected combinations of low cheatgrass and high diversity and abundance of native grasses and other native steppe species. Tracy Lane, which experienced a wildfire in 2000, as well as Circle Creek North, Kempton, and the Castle Rocks frames had much higher amounts of cheatgrass and lower amounts and diversity of native species. These kinds of patterns will vary over time in relation to winter precipitation and so should be interpreted cautiously. However, they provide preliminary insights into the relative health or ecological integrity of allotments. Similar patterns were noted in previous annual reports from 2012 and 2015 surveys, suggesting a of range natural resources management problems in those four frames. In general, upland vegetation management will benefit from increased understanding about the interactions between grazing, fire, and annual grass invasion, informed......

Sagebrush steppe vegetation monitoring in City of Rocks National Reserve: 2018 annual report

Series