Papers H-N

Papers A-G | Papers H-N | Papers O-Z | Posters

Title:	Bumblebees in montane meadows of the Sierra Nevada, California
Author:	Richard Hatfield, San Francisco State University Gretchen LeBuhn, San Francisco State University
Format:	paper
Presentation:	Concurrent Sessions II, Community Ecology and Biodiversity, 11:20 - 12:20 pm, 2060 VLSB
Abstract:	Montane meadows and wetlands, especially those with emergent vegetation are some of the most productive wildlife habitats in California. Insects are potentially powerful indicators of habitat richness, pollution and environmental perturbations. This is particularly true of bees because of the large number of species present in California. California contains approximately 1500 of the 4000 bee species known to the United States. Native bees are the most important animal pollinators of flowering plants in the Sierra Nevada ecosystem. I investigated the properties of eastern slope meadows that contribute to bumblebee diversity. I compared wet and dry meadows to determine if there were differences in Bumblebee (Bombus sp.) diversity. Among the other meadow characteristics compared were size, presence of grazing, grazing history, floral diversity and proximity to other meadows. Through my study, I hope to compare local vs. regional characteristics of Sierra Neva da Eastern slope meadows that contribute to native bee diversity. My findings show that wet meadow habitats are particularly important to bumblebees. Wet meadow habitats have higher bumblebee species richness and plant species richness than dry meadow habitats. My findings also show that grazing has a negative impact on bumblebee abundance in both wet and dry meadow habitats. This is particularly true of sheep grazing as bumblebee abundance dropped to zero in all meadows that were grazed by sheep. As the U.S. Forest Service, Bureau of Land Management, The Nature Conservancy and others are currently developing plans for Northern Sierra Meadow restoration; my study will provide critical information that will contribute to these agencies recommendations for management of these incredibly important and diverse habitats.

Title:	From silent spring to silent night: Modern-day pesticides and endocrine disruption in amphibians
Author:	Tyrone Hayes, University of California at Berkeley
Format:	paper
Presentation:	Keynote Address, 4:30 - 5:15 pm
Abstract:	In recent studies, we demonstrated that the herbicide, atrazine, had dramatic effects on amphibian development at low ecologically relevant doses. These effects included abnormal sex differentiation, such as hermaphroditism and testicular oogenesis. Further, we demonstrated that such effects were detectable in animals exposed in their natural environment. In reality, however, animals are exposed to mixtures of chemicals, not single compounds. So, we examined the effects of chemical mixtures on amphibian development. Laboratory experiments that mimicked ecologically relevant mixture produced complex effects on growth, development, immuno-capabilities and sex differentiation. Effects of chemical mixtures may far exceed the effects of any one chemical. These studies demonstrate the importance of amphibians as sentinel species as well as the importance of studying the combined effects of chemicals rather than single chemical exposures.

Title:	A ten-year study of the Argentine ant invasion at Jasper Ridge Biological Preserve
Author:	Nicole Heller, Stanford University Deborah Gordon, Stanford University
Format:	paper
Presentation:	Concurrent Sessions III, Invertebrates, 1:30 - 2:50 pm, 2063 VLSB
Abstract:	The Argentine ant, Linepithema humile, is a successful invader worldwide. Established in the San Francisco Bay Area since the early 1900s, it continues to invade new habitat, including biological preserves. Its invasion into Jasper Ridge Biological Preserve, San Mateo County, has been tracked for 10 years, from 1993-2002. Important components of the invasion, including rate of spread, preserve-wide distribution, and impact on native ant species and other arthropods, show interesting patterns of temporal and spatial variation. The total invaded area within the preserve has fluctuated over the years, with the most widespread distribution in 1998 and 1999. There is a strong inter-annual pattern in the invasion distribution as well, with more hectares invaded in the fall than the spring. Seasonal shifts in nesting behavior help explain the inter-annual pattern in distribution. Nests are large and spaced in tight aggregations over the winter. These aggregations slowly break apart over the spring, and by summer, nests are smaller and more dispersed in space. The impact of the Argentine ant on native ant fauna is severe, but varies by species, time of year, and habitat type. More native ants are found coexisting with the Argentine ant in the spring than the fall. The affect to other arthropods appears complicated, and also shows temporal variation. There are strong habitat interactions with the invasion distribution and rate of spread. Chaparral habitat is an effective barrier to spread, and there is a pattern of increased invasion resistance near ‘ecotones’ areas. Argentine ants appear highly dependent on shrubs and trees for nesting habitat and/or food availability. The ants use woody plants as stepping-stones for invasion. A developed understanding of this interaction may help predict where and how Argentine ants will spread in an area.

Title:	Living with urban wildlife: Urban sprawl and the wildland interface
Author:	Juliet Hoffman, California State University at Hayward
Format:	paper
Presentation:	Concurrent Sessions II, Human Wildlife Interface, 11:20 - 12:20 pm, 2050 VLSB
Abstract:	As in many other parts of the country, urban sprawl is encroaching upon wildlands in the Mount Diablo region of the San Francisco Bay Area. During the five-year period from 1990 to 1995, over 600 acres of new development occurred, resulting in the loss of 122 acres of open space. The growth of associated urban-wildland interface explains why residents in many areas have reported an increase in wild animal sightings in recent years. Resident and wildlife encounters will increase as development continues. Many residents of urban-wildland areas are accustomed to, and even enjoy the wildlife found there. Other residents are concerned about the wildlife that are present, and believe that wildlife should not be “allowed” in developed areas. A questionnaire was developed and distributed to residents living at the Mount Diablo wildland interface, to determine if interactions with wildlife are widely perceived as a problem. The main objective of this survey is to determine: What wildlife issues are the most important to residents living in wildland interface areas? What factors should be addressed to best meet the needs of wildlife and residents in the urban interface? How can better planning help mitigate negative wildlife interactions? Preliminary survey results indicate that residents appreciate the opportunity to live among the animals, and consider wildlife to be an asset to their quality of life. When people encounter wildlife, the majority of those sightings do not result in any negative outcome, unless some precipitating factor is present. When completed, the wildlife survey will benefit the community and its residents by accurately evaluating residents perceptions of wildlife, and the circumstances of human wildlife interactions. It will provide substantive data for any changes that may be warranted to help residents successfully coexist with any wildlife they encounter in urban areas.

Title:	MPAs needs assessment survey for effective management and coral reef conservation
Author:	Tegan Hoffmann, The Coral Reef Alliance
Format:	paper
Presentation:	Concurrent Sessions IV, Aquatic Conservation and Biology, 3:10 - 4:10 pm, 2060 VLSB
Abstract:	As a partner of the International Coral Reef Action Network (ICRAN), CORAL is assisting selected MPA sites with their coral reef management and outreach efforts through capacity building initiatives and by providing tools and resources. MPAs in East Asia, Wider Caribbean, East Africa, and South Pacific were surveyed to assess the management needs, threats facing the reef, and education and outreach needs of different stakeholders. Listed are examples of different types of survey questions: whether or not there is community support, who are the key stakeholders, what are the primary languages, what management materials and training are needed, if they have user-fee systems, what do park practitioners think are the primary threats to their reefs and more. We administered the first set of surveys August 2002 in East Asia with the help of the East Asia Seas UNEP/Regional Coordinating Unit (RCU). We received detailed responses to over 40 questions from 8 sites. Result s from the Wider Caribbean from 12 sites were received November 2002 from the UNEP/RCU. Results from East Africa and the South Pacific will follow. This talk will present results to date from the survey. East Asia results show that the biggest challenge sites face is enforcement of regulations. Another example of our findings show that the perceived most critical issues facing the sites are over-fishing and destructive fishing, followed by a tie between sewage/garbage and impacts from dive operators and divers.

Title:	Influence of invasive species and cumulative watershed effects on threatened California red-legged frog (Rana aurora draytonii) distribution in a suburban stream
Author:	Gordon Holtgrieve, Stanford University Scott Loarie, Stanford University Alan Launer, Stanford University
Format:	paper
Presentation:	Concurrent Sessions II, Vertebrates, 11:20 - 12:20 pm, 2063 VLSB
Abstract:	Suburban landscapes are conservation focal points in that native species are typically subjected to multiple pressures, such as modified or degraded habitat, invasive exotic species, and human encroachment, in a small, highly fragmented area. Few multi-year studies have monitored the populations of at-risk species within such settings. From 1997 to 2002, threatened California red-legged frogs (CRLF), Rana aurora draytonii, were monitored in San Francisquito Creek on the Stanford University campus, along with non-native bullfrogs (Rana catesbeiana), fishes, and crustaceans. This region of the creek is characterized by rapid change from preserved open space and low-density development in the upper reaches to moderate agriculture and suburban developments in downstream areas. Data on the abundance and distribution of fishes and frogs within the creek were compiled and analyzed in 250-meter segments and placed into a spatially explicit framework using a geographic information system (GIS). Cumulative effects of land-use change upon these stream segments was also quantified using GIS by calculating the cumulative land area developed in proportion to total watershed area for each segment. Results indicate that the year-to-year distribution of CRLF is consistent but suggest a trend of decreasing abundance. For all years, the CRLF population within San Francisquito Creek was concentrated in segments immediately downstream of high non-native fish abundance and immediately upstream from segments with higher proportions of developed watershed areas and high non-native crustacean abundance. These data suggest that CRLF are limited to areas within San Francisquito Creek with a minimum of multiple pressures typical of the suburban landscape, and as development within the watershed continues, their range may become more restricted. The relationship of CRLF distribution to areas free of non-native species and minimal suburban pressures has conservation implications for other riparian species and advocates the protection of riparian habitats within fragmented suburban landscapes.

Title:	The history and consequences of introduced wild turkey populations
Author:	Alan Krakauer, University of California at Berkeley
Format:	paper
Presentation:	Concurrent Sessions II, Vertebrates, 11:20 - 12:20 pm, 2063 VLSB
Abstract:	Wild Turkeys (Meleagris gallopavo) are not native to California. A century of intensive introduction and management programs by the Department of Fish and Game have established healthy populations throughout the state. Many hunters and wildlife enthusiasts appreciate the influx of this introduced species. However, biologists, agricultural interests, and homeowners are concerned about the impact of current populations as well as plans for future introductions. Currently state agencies may be at odds with local governments to determine the turkey’s fate. I will describe the history of California turkey introductions as well as highlight issues that have surrounded both recent introduction and control efforts. My goal is to present background information on this topic, specify areas where empirical data are lacking, and discuss the problems facing future game managers and policy makers.

Title:	Chinese mitten crabs in San Franciscquito Creek: Tracking the invasion
Author:	Scott Loarie, Stanford University Gordon Holtgrieve, Stanford University Alan Launer, Stanford University
Format:	paper
Presentation:	Concurrent Sessions III, Invertebrates, 1:30 - 2:50 pm, 2063 VLSB
Abstract:	The Chinese mitten crab (Eriocheir sinensis) is a burrowing crab native to costal rivers in Korea and China. During the last decade, it has invaded the San Francisquito Bay in California, one of the most invaded aquatic systems on the planet. Of the many invaders that arrive in the Bay each year it is difficult to predict which will become permanently established and what population densities they will eventually attain. The Chinese mitten crab invasion provides an interesting case study of an ongoing invasion in the San Francisco Bay. Eight years of biological surveys in San Francisquito Creek conducted by the Center for Conservation Biology at Stanford University have charted the development of the mitten crab invasion. Surveys were conducted along six kilometers of creek every summer from 1995, when mitten crabs were unreported in the creek, to 2002. San Francisqutio Creek is home to several federally threatened species, including steelhead (Oncorhynchus mykiss) and California red-legged frog (Rana aurora draytonii), and two other well established non-native crustacean species. The number of crabs surveyed has varied dramatically from year to year. Numbers climbed steadily from a single individual surveyed in 1996 to over 350 in 1999. Numbers declined in subsequent years and 2002 surveys yielded no individuals.

Title:	Human-black bear interactions in Yosemite National Park
Author:	Sean Matthews, Wildlife Conservation Society Brenda Lackey, University of Idaho
Format:	paper
Presentation:	Concurrent Sessions II, Human Wildlife Interface, 11:20 - 12:20 pm, 2050 VLSB
Abstract:	Black bears (Ursus americanus) in Yosemite National Park have obtained food provided intentionally and unintentionally by humans since the 1920’s. This feeding of black bears has led to conflicts between humans and bears. In 1975, the National Park Service (NPS), in an effort to eliminate human-provided food and garbage accessible to bears, initiated the Human-Bear Management Program in Yosemite National Park. Despite the initiation of these efforts, the annual number of bear incidents and property damage estimates have been documented as high as 1,590 and $659,000, respectively. Increases in the number of human-bear incidents has focused the need to examine and evaluate the system of human-bear interactions in the Park, with the goal of recommending ways to improve bear management and reduce the number of problem bear incidents. The Wildlife Conservation Society is using a systems approach to characterize and investigate components of both the bear and human elements of the bear management program. Human-bear incidents of the recent past are being categorized based on the cause of the incident, age class and sex of the bear involved, backcountry or front country location, season, and time of day. Radio telemetry is being used to quantify seasonal and daily activity patterns and movements of black bears in Yosemite Valley. The effectiveness of the content and methods of dissemination of bear-related information provided to the public are being assessed. Visitor’s salient beliefs about bears and food storage behavior are being evaluated using over 4,000 surveys administered to park visitors.

Title:	The role of fire and soil disturbances in the persistence of two endangered plants, central coastal California
Author:	Jodi McGraw, University of California at Berkeley
Format:	paper
Presentation:	Concurrent Sessions I, Plants, 10:00 - 11:00 am, 2063 VLSB
Abstract:	Natural disturbance can enhance diversity by creating spatial and temporal refugia that allow the persistence of fugitive native plant species. However, many exotic plants are also successful colonizers of disturbances, and may in turn compete with native populations. Thus, it is essential to understand the complex interactions between disturbance and invasion in order to successfully conserve rare, disturbance-dependent plant species in invaded plant communities. My research examines the direct and indirect effects (via exotic plant species) of natural disturbances on the demographic performance of two federally endangered plants, Chorizanthe pungens var. hartwegiana and Erysimum teretifolium. Endemic to the sandhills, a unique edaphic plant community in central coastal California, these species are threatened by habitat destruction and habitat degradation due to fire suppression and the invasion and spread of exotic plants. Using a series of small-scale manipulative experiments, I examined the effects of reintroducing fire and managing soil disturbances in the sandhills. I found that fire enhanced native plant cover and the population growth of the two endangered plants directly by removing accumulated litter that inhibits establishment and survivorship. Rather than facilitating exotic plants, however, fire disproportionately reduced exotic plant cover and, in doing so, indirectly facilitated endangered plant performance. In a separate experiment, I found that small-scale soil disturbances prevalent in the sandhills including slides, trails, and gopher mounds increased native plant cover and the demographic performance of the two endangered species by the same direct and indirect mechanisms. These results indicate the essential role of the natural disturbance regime in the persistence of these two endangered species and the maintenance of native biodiversity in the sandhills, as well as the importance of understanding the system-specific consequences of disturbance in California’s invaded plant communities.

Title:	Plant and abiotic diversity of montane meadows in the Sierra Nevada
Author:	Kathren Murrell Stevenson, University of California at Davis
Format:	paper
Presentation:	Concurrent Sessions II, Community Ecology and Biodiversity, 11:20 - 12:20 pm, 2060 VLSB
Abstract:	I completed three meadow studies in the Southern Sierra Nevada, the Golden Trout Wilderness Area, and the Lake Tahoe Basin. Each study had slightly different research questions aimed at solving practical conservation problems. The southern Sierra study addressed the impacts of grazing on channel morphology and incision, surface soil moisture and species composition by sampling ten pairs of grazed and ungrazed meadows in the southern Sierra Nevada. Meadows were selected randomly from a U.S. Forest Service (USFS) registry according to multiple criteria. Additionally, meadows were stratified by grazing regime and position in basin. In each meadow, I sampled five 50 meter (m) transects, from the center of the meadow to the meadow edge. I sampled 100 data points per transect and identified all species in a 1x50 m belt. At each data point, the species hit and soil moisture class were recorded. Channel width and depth at bankful were measured, and the number of channels w as recorded. Preliminary results show species richness varied significantly with the interaction of grazing and hydrologic position of meadow in the basin. However, patterns of richness can be misleading as both native and non-native species, and both meadow specialists and regional generalists are collapsed into one number. Therefore, analyses are being performed to assess which species were most impacted by grazing and what character traits these species had in common. Tall annual herbs with cauline foliage and determinate inflorescences were consistently absent from grazed meadows, and in the Golden Trout study we hypothesized that sod banks, willows, and stringers would be the only refuges for these species in grazed situations. Results from these studies indicate how physical meadow characteristics and abundance of habitat types affect plant biodiversity. Together, these studies should have important implications for conservation and restoration efforts in the Sierra Nevada.

Title:	Preliminary study of the chloroplast DNA phylogeography of the black mangrove, Avicennia germinans L. (Avicenniaceae)
Author:	Alejandro Nettel-Hernanz, University of California at Berkeley Richard S. Dodd, University of California at Berkeley
Format:	paper
Presentation:	Concurrent Sessions III, Phylogeography and Conservation, 1:30 - 2:50 pm, 2060 VLSB
Abstract:	Mangrove forests are focus of conservation efforts all over the Tropical and Subtropical areas in which they are present because of their ecological roles, direct or indirect economic value, and the threat of anthropogenic impacts. Avicennia germinans is one of the major components of mangrove communities on the Western Hemisphere; it is present on both coasts of the American Continent and on the West Coast of Africa. African populations are usually regarded as a different species, Avicennia africana. Among the questions that I pretend to answer are: How effective as isolation barriers have been the uplift of the Central American Isthmus around 3 Ma and the immensity of the Atlantic Ocean? Should African populations be considered as a different species? I present preliminary PCR-RFLP data of four chloroplast DNA non-coding regions in a sample of comprising 15 populations with the aim of having a better understanding on the species historical seed dispersal ability and its relationship to the questions about population differentiation.

Title:	The importance of economics and land use change for reserve site selection
Author:	David Newburn, University of California at Berkeley
Format:	paper
Presentation:	Concurrent Sessions I, Conservation Planning, 10:00 - 11:00 am, 2050 VLSB
Abstract:	The purpose of this research is to examine land conservation strategies for California’s coastal watersheds that are experiencing rapid urban and vineyard expansion. The optimal targeting framework developed here to prioritize the acquisition of conservation sites relies on: (1) estimating the site-specific purchasing costs for developable land; (2) developing a spatially-explicit land use change model for the study region, Sonoma County, CA; (3) valuing the multiple conservation objectives (i.e. critical habitat, open space and prime farmland). A necessary step has been to develop an economic land use change model which links parcel-level transactions to site and neighborhood characteristics within a geographic information system (GIS). The economic land use change model being proposed is based on a two-stage process: 1) hedonic models of land value for each use type (i.e. rural residential, vineyard, and “extensive use” land), and 2) a discrete choice model to predict land conversion probabilities. The model output is a probability map representing the likelihood of future residential and vineyard development scenarios for each developable land parcel. Hedonic models additionally provide the site-specific cost surface for all developable land parcels. Our targeting approach achieves the optimal allocation of conservation funds to minimize the expected loss in environmental benefits. In comparison, “benefit-cost” targeting obtains a suboptimal outcome, since it ignores the effect of future land use change on the reserve site selection problem. The main reason being that “benefit-cost” targeting purchases a higher percentage of low cost sites, which also are unlikely to face future land use conversion.

Title:	The impact of invasive spartina on avian communities in San Francisco bay salt marshes: Direct and indirect influences
Author:	J. Cully Nordby, University of California at Berkeley Andrew N. Cohen, San Francisco Estuary Institute Steve Beissinger, University of California at Berkeley
Format:	paper
Presentation:	Concurrent Sessions II, Vertebrates, 11:20 - 12:20 pm, 2063 VLSB
Abstract:	The invasion of an Atlantic cordgrass (Spartina alterniflora) into Pacific salt marshes provides an ideal model system in which to investigate ecosystem-wide ramifications of exotic invasions and how animals respond to these changes in their environment. The profound changes in habitat structure and composition that accompany the S. alterniflora invasion will likely have the greatest impact on species, such as birds, that are wholly dependent on the tidal salt marsh system. Alameda song sparrows (Melospiza melodia pusillula), a California Species of Special Concern, reside entirely within the salt marshes in the south portion of San Francisco Bay. These sparrows are affected not only by the S. alterniflora invasion directly, but also indirectly by new competitive interactions with marsh wrens (Cistothorus palustris) who are occupying the newly available habitat. In this study, we examined how the cordgrass invasion affected breeding territory distribution, nesting habitat preferences and reproductive success of song sparrows. We also examined the breeding territory distribution of marsh wrens, territory overlap between the two species, and depredation of sparrow eggs by wrens. These measures are compared within and between three separate sites that encompass varying degrees of invasion. Results from the first year of this study suggest that invasive Spartina may be negatively impacting song sparrow populations.

Papers A-G | Papers H-N | Papers O-Z | Posters

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