10 Years of Conservation Science on the Zumwalt Prairie

10 YEARS OF CONSERVATION SCIENCE ON THE ZUMWALT PRAIRIE What Have We Learned? Geographically isolated and comprised mostly of private lands, scant scientific information exists regarding the soils, vegetation, wildlife and ecology of the Zumwalt Prairie. Science is at the core of the Nature Conservancy’s conservation approach and soon after the Conservancy acquired the Zumwalt Prairie Preserve in 2000, the organization recognized the need to support scientific inquiry into the prairie’s ecology and how human actions such as livestock grazing, fire, and invasive species affect it. Beginning with a study of the prairie’s raptor populations in 2003, the Conservancy has collaborated with universities and agencies for over ten years in its quest to find answers to key conservation questions. Over 10 published papers, dozens of reports and presentations have resulted in these efforts, broadening our knowledge of the biodiversity and ecological processes of the Zumwalt and informing stewardship and other conservation actions. Conservancy staff also serve on technical advisory groups, review boards, and in other roles to promote scientific inquiry and communication of information to landowners and other stakeholders. Short summaries of findings resulting from Zumwalt Science efforts are summarized below. For more information contact Rob Taylor ([email protected]). Many of the reports, lists, and publications cited here can be found on the Conservation Gateway at: https://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/oregon/grasslands/zumwalt BIODIVERSITY While no formal “bio blitz” has ever been undertaken on the Zumwalt Prairie, various inventory, monitoring and research projects have contributed to our understanding of the biodiversity that inhabits this extraordinary grassland ecosystem. A total of 491 vascular plant species belonging to 69 families have been documented on the Zumwalt Prairie, the majority of these from the Zumwalt Prairie and Clear Lake Ridge Preserves. The aster family (Asteraceae) and grass family (Poaceae) are the most prolific, having 74 and 73 species, respectively. Other common families are the snapdragons (Scrophulariaceae), sedges (Cyperaceae), roses (Rosaceae), peas (Fabaceae), mustards (Brassicaceae), carnations (Caryophyllaceae), lilies (Liliaceae), rushes (Juncaceae), and buckwheats (Polygonaceae). Twenty-five families are represented by just a single species. Forbs (310 species) and grasses (72 species) are the most common growth forms. Over 40 species of sedges/rushes and shrubs are found. Trees species are few, with only 15 species documented to date. The majority of species (385) on the Zumwalt Prairie are native. Of these 144 range across much of North America while 192 are found throughout the west. Pacific northwest endemics constitute a total of 48 species of which just 1, Wallowa needlegrass (Achatherum wallowensis), occurs only in eastern Oregon. Of the 106 exotic species, 72 are forbs and 30 are grasses. The Zumwalt herbarium contains specimens of over half of the documented species (271). A diversity of non-vascular plants have also been documented on the Zumwalt Prairie with 50 lichen species documented to date, 15 of which are soil lichens (Anonymous 2010), including the newly described vagrant lichen Aspicilia rogeri (Sohrabi et al. 2011). Both research and monitoring efforts have revealed a rich diversity of insect and other invertebrate life on the Zumwalt Prairie. Visits to the Prairie by prominent lepidopterists such as Cliff Ferris and Dana Ross have elucidated many butterfly and moth species. To date, 54 species have been documented which includes 21 brush-footed butterflies (Nymhphalidae), 14 gossamer-winged butterflies (Lycaenidae), 8 skippers (Herperiidae), 6 whites (Pieridae), and 5 swallowtails (Papilionidae) (Jansen 2008). A research project investigating the role of cattle grazing on invertebrates has provided us with detailed information on the bee species which inhabit the prairie which (Kimoto 2011, Rao et al. 2011, Kimoto et al. 2012a, Kimoto et al. 2012b). At last count 94 species and 117 morphospecies have been documented (Kimoto et al. 2012a). Macro- invertebrate sampling on Camp Ck and Pine Ck has helped in understanding the diversity of aquatic insects, worms, crustaceans, and molloscs with 91 species documented to date (Wooster and DeBano 2011). 1 The Zumwalt Prairie and adjacent canyons provides habitat for many bird species having a variety of life histories. Initial surveys by Frank Conley provide a backbone of valuable knowledge of these species while additional inventory work (Taylor and VanCantfort 2003) and the efforts of many visitors and volunteers continue to add to our knowledge of Zumwalt bird life. To date 188 species have been documented (Anonymous 2008) of which songbirds (order: Passeriformes) comprise, by far the richest group (93 species). Raptors are another well-represented group with 7 hawks (3 accipiters, 4 buteos), both bald and golden eagles, northern harrier, osprey, and 4 falcons documented. Surprisingly, 20 duck species, have been documented attesting to the importance that artificial water sources now play in attracting waterfowl during the spring and fall migration seasons. Many of the birds of the Zumwalt Prairie migrate there in the summer to breed (79 species) while 66 species are resident. Five species of raptor (1 hawk, 3 falcons, and bald eagle) and 8 species of songbirds regularly use the Zumwalt primarily during the winter months, most migrating there from there more northern breeding grounds while some species, such as snowy owl, occasionally wander to the prairie sometimes remaining for the winter. Little work has been done to document the mammal diversity of the Zumwalt Prairie and what is known primarily comes from casual observation of mid-size and large mammals and inference from range maps and other accounts. Forty-seven species of mammals are thought to occur on the Zumwalt Prairie which include 16 rodents (Rodentia), 12 carnivores (Carnivora), 9 bats (Chiroptera), 5 species of hooved mammal (Artiodactlya), 3 rabbits/hares, and 2 shrews (Insectivora) (Trask and Taylor 2012). Investigations into small mammals would be helpful in corroborating existing information. The generally arid landscape of the Zumwalt Prairie is reflected in the paucity of reptiles and amphibians species found there. Of the 7 reptile species, 5 are snakes. Three frog and toad species and a single salamander (Ambystoma macrodactlyum) are known (Taylor 2008). Limited work has been done to date to document herptile biodiversity of the area and it is likely that additional efforts, especially if focused on canyon areas adjacent to the prairie, would reveal additional snake and lizard species. SOILS AND PLANTS Investigations by the Conservancy and others have expanded our knowledge of the soils and certain plant species of conservation concern on the Zumwalt Prairie. In some cases this information has allowed land managers to adjust management to accommodate the conservation of these species and for others it has raised questions which compel future research. Soils on the Zumwalt prairie are dominated by silt-loam soils and influenced greatly by windborne loess (Schmalz 2007). The fine grain heterogeneity of vegetation on the Zumwalt Prairie, evidenced by dramatic changes in plant communities from one location to another just a few meters distant, is a consequence of soil heterogeneity, slope, and aspect (Schmalz 2011). This diversity of soils drives patterns of plant diversity, contributing to the high richness of grass and forb species (Darambazar et al. 2007). Several years of mapping and monitoring efforts by Conservancy staff have documented the largest known population of the federally-listed wildflower Spalding’s catchfly (Silene spaldingii) (Taylor et al. 2008, Jansen and Taylor 2009b, 2010d, Schmalz and Taylor 2011c). This population is currently estimated at 50-60,000 individuals on the Zumwalt Prairie Preserve (Schmalz and Taylor 2011c) while Clear Lake Ridge is estimated to have a population of approximately 4,000 (Youtie 1990, Schmalz and Taylor 2011b). The health of the Spalding’s catchfly population, however, is not known and research by Conservancy staff suggest that this species may produce an insufficient amount of seed to maintain the population over time (Taylor et al. 2012b). One possible cause for the low reproductive rates is lack of pollination services by bumble bees, which have been shown to be the primary pollinator of this species (Tubbesing et al. in press) and which may be sensitive to cattle grazing (Kimoto et al. 2012b). Predation by moth larvae is another possible cause (Taylor and DeBano 2012). Cattle do not appear to forage extensively on Spalding’s catchfly, at least during the early summer when the plant is emerging (Cullen and Taylor 2010). Though it lacks federal or state protection, the Wallowa rice (Achnatherum wallowaensis) is a rare plant limited to approximately 30 populations in eastern Oregon and considered “imperiled” due to its limited occurrence and for the 2 threat that cattle grazing poses in those areas (Maze and Robson 1996, NatureServe 2012). Inventory efforts conducted by the Conservancy reveal that this species is common throughout the ridges of Clear Lake Ridge Preserve (249 point locations to date) and has been found in three areas of the Zumwalt Prairie Preserve (TNC, unpublished data). Little is known of the ecology of this species and how human actions

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