Sagebrush, Greater Sage-Grouse, and the Occurrence and Importance of Forbs

Abstract

Big sagebrush (Artemisia tridentata Nutt.) ecosystems provide habitat for sagebrush-obligate wildlife species such as the Greater Sage-Grouse (Centrocercus urophasianus). The understory of big sagebrush plant communities is composed of grasses and forbs that are important sources of cover and food for wildlife. The grass component is well described in the literature, but the composition, abundance, and habitat role of forbs in these communities is largely unknown. Our objective was to synthesize information about forbs and their importance to Greater Sage-Grouse diets and habitats, how rangeland management practices affect forbs, and how forbs respond to changes in temperature and precipitation. We also sought to identify research gaps and needs concerning forbs in big sagebrush plant communities. We searched for relevant literature including journal articles and state and federal agency reports. Our results indicated that in the spring and summer, Greater Sage-Grouse diets consist of forbs (particularly species in the Asteraceae family), arthropods, and lesser amounts of sagebrush. The diets transition to sagebrush in fall and winter. Forbs provide cover for Greater Sage-Grouse individuals at their lekking, nesting, and brood-rearing sites, and the species has a positive relationship with arthropod presence. The effect of grazing on native forbs may be compounded by invasion of nonnative species and differs depending on grazing intensity. The effect of fire on forbs varies greatly and may depend on time elapsed since burning. In addition, chemical and mechanical treatments affect annual and perennial forbs differently. Temperature and precipitation influence forb phenology, biomass, and abundance differently among species. Our review identified several uncertainties and research needs about forbs in big sagebrush ecosystems. First, in many cases the literature about forbs is reported only at the genus or functional type level. Second, information about forb composition and abundance near lekking sites is limited, despite the fact that lekking sites are an important center of Greater Sage-Grouse activity. Third, there is little published literature on the relationship between forbs and precipitation and between forbs and temperature, thereby limiting our ability to understand potential responses of forbs to climate change. While there is wide agreement among Greater Sage-Grouse biologists that forbs are an important habitat component, our knowledge about the distribution and environmental responses of forb species in big sagebrush plant communities is limited. Our work for the first time synthesizes the current knowledge regarding forbs in sagebrush ecosystems and their importance for Greater Sage-Grouse and identifies additional research needs for effective conservation and management.

Seed germination and dormancy traits of forbs and shrubs important for restoration of North American dryland ecosystems

“…, ; Pennington et al . ) and invigorated efforts for their reestablishment through direct seeding. To date, research into seed dormancy has targeted a narrow range of forb and shrub species restricted to a few genera (Allen & Meyer ; Meyer & Kitchen ; Scholten et al .…”

Plant community responses to historical wildfire in a shrubland–grassland ecotone reveal hybrid disturbance response

“…Although burned areas lack A. tridentata, they provide forage resources (perennial grasses and forbs) that are less abundant elsewhere on the landscape. These could be important for both livestock and sage-grouse (Centrocercus urophasianus) chicks (Pennington et al 2016, Scasta et al 2016. Shrub-free patches also provide grassland bird habitat for lark buntings (Calamospiza melanocorys), western meadowlarks (Sturnella neglecta), and grasshopper sparrows (Ammodramus savannarum) found in mixed-grass prairie with taller vegetation (Augustine and Derner 2015).…”

Oregon greater sage-grouse : draft resource management plan amendment and environmental impact statement /

“…Many studies have demonstrated the importance of forbs to Greater Sage-Grouse, providing food both directly and indirectly by supporting insects and providing cover (e.g., Connelly et al 2011;Dumroese et al 2015;Pennington et al 2016). Oregon BLM wildlife biologists have a list of high and moderate value species important to Greater Sage-Grouse that has been refined since the 2015 Final EIS (BLM Sage Grouse Forb List August 2017).…”

“…Forb richness and abundance are controlled by site characteristics and climate, with drought a particularly important driver (Blomberg et al 2014;Pennington et al 2016;Blomberg et al 2017;Gibson et al 2017;Pennington et al 2017). Only a few studies have examined forb response to disturbance, such as fire, and even fewer have attempted to correlate forb response to drought status, changes in temperature and precipitation regimes, and soil water availability whether in the absence or presence of grazing (Davies et al 2012a;Davis and Crawford 2015;Ellsworth et al 2016;Pennington et al 2016). A global literature review of the impacts of grazing on grouse species found too few studies that had enough detail concerning animal type, animal distribution, stocking rates, grazing timing, duration, and frequency, and similar factors to develop BMPs for grazing in Greater Sage-Grouse habitat (Dettenmaier et al 2017).…”

“…Mesic habitats are particularly important for pre-laying hens and chicks (Donnelly et al 2016;Freese et al 2016;Pennington et al 2016;Pennington et al 2017) with late brood-rearing habitat. This is a shortage category in eastern Oregon due to the lack of surface water.…”