Plants, Habitats and Wildlife Interactions

Friday, October 21 at 1:00-2:40 pm, Donner Room

Session Description: The relationships of plants and wildlife will be explored through plant/habitat – wildlife resource monitoring, functional assessments, and wildlife – habitat analyses. The effects of management techniques, restoration, and environmental impacts on plant/wildlife relationships including of plant–pollinator, plant–frugivore (seed disperser), plant–herbivore, and other complex, interspecific ecological interactions will be discussed.

Session Chairs: Graciela Hinshaw (Pine Hill Preserve, BLM Mother Lode Field Office, El Dorado Hills, CA, USA), Debra Ayres (CNPS El Dorado Chapter, Shingle Springs, CA, USA)

*Session generously sponsored by Bureau of Land Management

21.1    Effects of a firebreak on plants and wildlife at Pine Hill, a biodiversity hotspot, El Dorado County, California

Virginia Meyer (CNPS El Dorado Chapter, Shingle Springs, CA, USA), J. Mario K. Klip (California Department of Fish and Wildlife, Rancho Cordova, CA, USA), Debra R. Ayres (CNPS El Dorado Chapter, Shingle Springs, CA, USA)

We examined the effects of hand clearing and pile burning of chaparral on plants and wildlife on the perimeter of Pine Hill 1-2 years after clearing. Pine Hill is home to four federally listed plant species, necessitating botanical surveys prior to clearing activities to prevent harming these species. We found over 65 new locations for the listed plants. We compared vegetation within burn scars, in cleared only plots, and in intact chaparral and the germination and survival of a listed species, Ceanothus roderickii (Pine Hill Ceanothus). The density of C. roderickii seedlings was far lower in the cleared, unburned treatment than in the burned treatments, while mature C. roderickii was only present in unburned treatments and mature chaparral. Intact chaparral had higher cover but lower species richness of both native and exotic species than disturbed treatments. The cleared only treatment had almost three times the cover by exotic grasses as did the burned treatments, and cover by palatable species was almost twice that of the burned treatments; mature chaparral contained few palatable plants. Increased availability of palatable plants in treated areas may have contributed to 3-4 times higher probabilities of detection by cameras of herbivores in treated versus intact chaparral; which may have attracted smaller predators (bobcats [Lynx rufus] and gray foxes [Urocyon cinereoargenteus]) that were positively associated with western gray squirrel (Sciurus griseus) detections. Large carnivore detections were higher in areas with higher mule deer (Odocoileus hemionus) detections. Larger animals (pumas [Puma concolor], black bears [Ursus americanus], and mule deer) were detected 2-4 times more in treated areas, likely due to the physical impediment of mature chaparral. Invasion of nonnative grasses and increased wildlife usage may have been accelerated through the creation of fuel breaks; continued monitoring will investigate long-term effects.

21.2    Native plant and pollinator interactions at the Pine Hill Preserve

Landon Eldredge (Pine Hill Preserve, BLM Mother Lode Field Office, El Dorado Hills, CA, USA), Graciela Hinshaw (Pine Hill Preserve, BLM Mother Lode Field Office, El Dorado Hills, CA, USA)

The Pine Hill Preserve (PHP) was established in April 2001 to ensure that habitat for eight rare plant species growing on gabbro soils in western El Dorado County, California, would be protected from factors threatening their survival and recovery. The soil, rolling topography, and Mediterranean climate in the PHP area support about 10 percent of the total vascular plant species in California, and include several species that are protected under federal and state laws and are considered narrow endemics. Ten federal, state, and local agencies and organizations work together under a Cooperative Management Agreement to protect rare plant habitat at PHP.  As of 2022, 4,940 acres have been designated, purchased and/or donated to form the PHP system of managed lands. Since 2014 a particular interest has been placed on the native plant-native bee relationships to obtain foundational knowledge on which native pollinators are present at the PHP and how our management practices might affect these relationships. The pollinator studies have yielded a species lists of about 150 native bees. Because fire is a natural component of the PHP habitats, the use of prescribed burns and mechanical treatments to reduce shrub competition with the rare plants has been implemented over 8 percent of rare plant occupied habitat. The reduction of shrub competition increases diversity of native plant species, which is likely to also benefit the diversity of pollinators present on PHP managed lands. The collection of native seeds for germplasm banking and restoration purposes is another important aspect of habitat management for rare plants and wildlife species. As of 2022 more than 240 collections of native seeds have been completed following the BLM’s Seeds of Success protocols.

21.3    Reproductive and mortality rates of the native solitary bee Osmia lignaria in the Sierra Nevada foothills of California

Steve Peterson (Foothill Bee Ranch, Foresthill, CA, USA)

From 2017 to 2019 nesting substrates consisting of paper tubes were placed in oak woodland habitats of the Sierra Nevada foothills to monitor blue orchard bee, Osmia lignaria, population reproductive rates and mortality factors. Osmia lignaria is a native, solitary bee that nests in the spring (March-April), with a single generation each year. Favored plants for pollen collection include Quercus, Cercis, Ceanothus, Arctostaphylos, Nemophila, Collinsia, and Phacelia. Three sites on Bureau of Land Management property were sampled with permission: two in El Dorado County and one in Tulare County. Two of the three sites had abundant populations which increased up to 4.8-fold annually. The largest categories of mortality factors found in the nests were the cleptoparasites Tricrania stansburyi (a blister beetle) and Sapyga sp. (a Sapygid wasp), and pollen balls, which is a failed provision with unknown causes.

21.4    Keeping Mission blue butterflies in the loop…inus

Christopher Schwind (Creekside Science, Los Gatos, CA, USA), James Quenelle (Creekside Science, Los Gatos, CA, USA), Marissa Kent (Creekside Science, Los Gatos, CA, USA), Kirra Swinnerton (Root Wisdom, Oakland, CA, USA), Stu Weiss (Creekside Science, Los Gatos, CA, USA)Native plants provide food for innumerable native insects. The Mission blue butterfly is federally endangered and resides only in the fog belt around the Golden Gate. Adults lay eggs and larvae feed exclusively on three species of perennial lupines: Lupinus albifrons, L. formosus, and L. variicolor. Their decline has been driven by the loss of suitable grassland habitat from urban development. The largest population is on San Bruno Mountain. Even there, on protected habitat, grasslands have been lost to native scrub encroachment, and lupines are often outcompeted by nonnative grasses. In 2017, Creekside Science, in collaboration with the University of Florida and with funding from the Disney Conservation Fund, set out to bolster and diversify populations of perennial lupines on San Bruno. The Creekside Science Conservation Nursery has produced hundreds of thousands of lupine seeds, planted thousands of these, and provided tens of thousands to other partners for planting on San Bruno Mountain and nearby Mission blue habitats. We have honed our ability to produce seeds, found optimum strategies to maximize germination and survival in the field, and even documented Mission blues laying eggs on our seeded plants. Scarification increases first year germination rates, but unscarified seed often germinates after one or two years. Planting a mix of scarified and unscarified seeds hedges bets in today’s uncertain climate. Carefully placing seeds into appropriately rocky habitat increases survival rates substantially. Diversifying local lupine stands provides resilience against a fungal disease that differentially affects the three species. Creekside Science is currently working to engage volunteers in seeding, since our careful planting method is time-consuming, and a bottleneck to planting more lupines. We are also working with Stephanie Porter of the University of WA, to experiment with rhizobium inoculation of seedlings to increase survival and growth rates.