Habitat integrity and population monitoring of Lepidium papilliferum (slickspot peppergrass): 2012

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Research premise: Lepidium papilliferum (slickspot peppergrass, Brassicaceae) is a small annual or biennial forb that flowers in late May and June across southwestern Idaho. It inhabits slickspots—slight depressions among shrubs where clay and salts have accumulated. Lepidium papilliferum has been the subject of conservation concern for many years. Our study is a continuation of intensive annual monitoring, termed ‘Habitat Integrity and Population (HIP) Monitoring’, begun in 2004 by biologists from the Idaho Natural Heritage Program (IDNHP). Less intensive monitoring, termed ‘Habitat Integrity Index’, had been conducted by IDNHP biologists from 1998 to 2002. Every year since 2004, the IDNHP has monitored L. papilliferum across its range, although in 2008, the portion of the monitoring on the Orchard Combat Training Center was conducted by the Idaho Army National Guard. Our 2012 work was conducted in cooperation with Idaho Army National Guard, Bureau of Land Management, Fish and Wildlife Service, and others. Each year, monitoring objectives have been to assess L. papilliferum abundance, habitat, and disturbance, as well as to evaluate performance metrics described in the Candidate Conservation Agreement for Slickspot Peppergrass (Caswell et al. 2006). <br> Methods: From 29 May to 19 July 2012, we collected data at 77 established transects, each of which included 10 permanently marked slickspots. Four types of data were collected at each transect: 1) slickspot attributes, including L. papilliferum counts, ground cover, non-native plant canopy cover, wildlife and livestock sign, and evidence of vehicles, restoration, firefighting, or fire; 2) counts of mounds of Owyhee harvester ants (Pogonomyrmex salinus, a native predator of L. papilliferum seeds); 3) attributes of the landscape—an area of ~500 m (0.31 mi) surrounding the transect; and 4) photos at the transect start, each slickspot, and each vegetation transect. We did not collect a fifth type of data that had been collected in the past—plant canopy cover on vegetation transects at three of the ten slickspots. The vegetation transect data collection is now on a 5-year assessment cycle and was last assessed in 2009. For each type of data, we calculated descriptive statistics, with comparisons among three geographic areas and ten management areas. <br> Results: In 2012, mean density of L. papilliferum plants within transects ranged from 0 to 145.2 plants/slickspot, with a mean across all transects of 12.2 plants/slickspot. Lepidium papilliferum had a frequency of 71.4% (i.e., it was present in 55 of the 77 transects). The total count—9245 plants—was lowest in the range of counts from 2005 to 2012. Ground cover within slickspots was largely bare or biotic crust, though proportions of each varied widely by management area. Mean non-native plant canopy cover ranged from 0.1 to 62.0%, with a mean across all transects of 14.2% and frequency of 100.0%. Highest cover means by geographic areas were for Bromus tectorum (cheatgrass), Vulpia spp. (fescue), Lepidium perfoliatum (clasping leaf pepperweed), Agropyron cristatum (crested wheatgrass), and Sisymbrium altissimum (tall tumblemustard). Mean active harvester ant mound density within transects ranged from 0 to 47.7 mounds/ha, with a mean across all transects of 10.4 mounds/ha and a frequency of 67.5%. Wildlife signs were predominantly ant mounds, badger burrows, and divots (any unclear diggings or tracks, including livestock tracks), with mean cover per slickspot of 0.3, 0.8, and 1.2%, respectively. Livestock sign was predominantly tracks, with low values for feces and trails. Among transects, mean track cover per slickspot ranged from 0.0 to 18.5%, with an overall mean of 1.7% and frequency of 61.0%. Mean track number ranged from 0.0 to 134.4 tracks per slickspot, with an overall mean of 14.2 tracks per slickspot and a frequency of 61.0%. Cattle feces cover had a low range (0.0 to 2.7%) and overall mean (0.5%), but a high frequency (72.7%). Vehicle tracks were found in slickspots at five transects, and in the vicinity of thirteen transects. Firefighting activity was observed within slickspots on two transects and within the vicinity of ten transects. No sign of restoration within the previous year was observed on transects. While not technically a restoration activity, the first two slickspots at transect 060 were destroyed from agriculture plowing on private land adjacent to BLM. Evidence of fire in slickspots within the previous year was recorded at four transects. After our field season ended, the BLM fire layer showed that six transects were burned. Additionally, fire came within 400 m (0.25 mi) of two transects. At the landscape scale, Chondrilla juncea was the noxious weed most frequently encountered—present at seven transects. Comparison of our results to performance metrics described in the Candidate Conservation Agreement for Slickspot Peppergrass (Caswell et al. 2006) showed that management actions were triggered for a fire >200 ac in Management Area (MA) 2, a fire >20 ac in MA 5, fires >100 ac in MA 6, 8, 9, and 10; fires in 13 L. papilliferum occurrences; firefighting activity within slickspots at two transects; motorized vehicle tracks within a slickspot at five transects; >1% cover of non-native seeded species in slickspots at twelve transects; ≥5% increase in total non-native plant species cover within slickspots at fifty-one transects; and ≥10% penetrating livestock trampling within slickspots at one transect. <br>

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Reference Code: U13KIN02IDUS <br>

Full Citation: Kinter, C.L., J.R. Fulkerson, J.J. Miller, and D.L. Clay. 2013. Habitat Integrity and Population Monitoring of Lepidium papilliferum (Slickspot Peppergrass): 2012. Prepared for Bureau of Land Management, Jarbidge & Four Rivers Field Offices and Idaho Army National Guard. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise. 53 pp. plus appendices. <br>

Location: ELECTRONIC FILE - BOTANY: PLANT SPECIES: {Lepidium papilliferum} <br>

Keywords: Lepidium papilliferum, slickspot peppergrass, monitoring, habitat, rare plant conservation, sagebrush steppe, Idaho, Snake River Plain, Owyhee Plateau <br>