@article{worm_saffer_takeuchi_walden-schreiner_jones_meentemeyer_2024, title={Border Interceptions Reveal Variable Bridgehead Use in the Global Dispersal of Insects}, volume={10}, ISSN={["1466-8238"]}, DOI={10.1111/geb.13924}, abstractNote={ABSTRACT Aim The global, human‐mediated dispersal of invasive insects is a major driver of ecosystem change, biodiversity loss, crop damage and other effects. Trade flows and invasive species propagule pressure are correlated, and their relationship is essential for predicting and managing future invasions. Invaders do not disperse exclusively from the species' native range. Instead, the bridgehead effect, where established, non‐native populations act as secondary sources of propagule, is recognised as a major driver of global invasion. The resulting pattern of global spread arises from a mixture of global interactions between invasive species, their vectors and, their invaded ranges, which has yet to be fully characterised. Location Global. Time Period 1997–2020. Major Taxa Studied Insects. Methods We analysed 319,283 border interception records of 514 insect species from a broad range of taxa from four national‐level phytosanitary organisations. We classified interceptions as coming from species native range or from bridgehead countries and examined taxonomic autocorrelation of global movement patterns between species. Results While 65% of interceptions originated from bridgehead countries, highlighting the importance of the bridgehead effect across taxa, patterns among individual species were highly variable and taxonomically correlated. Forty per cent of species originated almost exclusively from their native range, 28% almost exclusively from their non‐native range and 32% from a mix of source locations. These patterns of global dispersal were geographically widespread, temporally consistent, and taxonomically correlated. Conclusions Dispersal exclusively from bridgeheads represents an unrecognised pattern of global insect movement; these patterns emphasise the importance of the bridgehead effect and suggest that bridgeheads provide unique local conditions that allow invaders to proliferate differently than in their native range. We connect these patterns of global dispersal to the conditions during the human driven global dispersal of insects and provide recommendations for modellers and policymakers wishing to control the spread of future invasions.}, journal={GLOBAL ECOLOGY AND BIOGEOGRAPHY}, author={Worm, Thom and Saffer, Ariel and Takeuchi, Yu and Walden-Schreiner, Chelsey and Jones, Chris and Meentemeyer, Ross}, year={2024}, month={Oct} }
 @article{montgomery_walden-schreiner_saffer_jones_seliger_worm_tateosian_shukunobe_kumar_meentemeyer_2023, title={Forecasting global spread of invasive pests and pathogens through international trade}, volume={14}, ISSN={["2150-8925"]}, url={http://dx.doi.org/10.1002/ecs2.4740}, DOI={10.1002/ecs2.4740}, abstractNote={AbstractNon‐native plant pests and pathogens threaten biodiversity, ecosystem function, food security, and economic livelihoods. As new invasive populations establish, often as an unintended consequence of international trade, they can become additional sources of introductions, accelerating global spread through bridgehead effects. While the study of non‐native pest spread has used computational models to provide insights into drivers and dynamics of biological invasions and inform management, efforts have focused on local or regional scales and are challenged by complex transmission networks arising from bridgehead population establishment. This paper presents a flexible spatiotemporal stochastic network model called PoPS (Pest or Pathogen Spread) Global that couples international trade networks with core drivers of biological invasions—climate suitability, host availability, and propagule pressure—quantified through open, globally available databases to forecast the spread of non‐native plant pests. The modular design of the framework makes it adaptable for various pests capable of dispersing via human‐mediated pathways, supports proactive responses to emerging pests when limited data are available, and enables forecasts at different spatial and temporal resolutions. We demonstrate the framework using a case study of the invasive planthopper spotted lanternfly (Lycorma delicatula). The model was calibrated with historical, known spotted lanternfly introductions to identify potential bridgehead populations that may contribute to global spread. This global view of phytosanitary pandemics provides crucial information for anticipating biological invasions, quantifying transport pathways risk levels, and allocating resources to safeguard plant health, agriculture, and natural resources.}, number={12}, journal={ECOSPHERE}, author={Montgomery, Kellyn and Walden-Schreiner, Chelsey and Saffer, Ariel and Jones, Chris and Seliger, Benjamin J. and Worm, Thom and Tateosian, Laura and Shukunobe, Makiko and Kumar, Sunil and Meentemeyer, Ross K.}, year={2023}, month={Dec} }
 @article{tateosian_saffer_walden-schreiner_shukunobe_2023, title={Plant pest invasions, as seen through news and social media}, volume={100}, ISSN={["1873-7587"]}, DOI={10.1016/j.compenvurbsys.2022.101922}, abstractNote={Invasion by exotic pests into new geographic areas can cause major disturbances in forest and agricultural systems. Early response can greatly improve containment efforts, underscoring the importance of collecting up-to-date information about the locations where pest species are being observed. However, existing invasive species databases have limitations in both extent and rapidity. The spatial extent is limited by costs and there are delays between species establishment, official recording, and consolidation. Local online news outlets have the potential to provide supplemental spatial coverage worldwide and social media has the potential to provide direct observations and denser historical data for modeling. Gathering data from these online sources presents its own challenges and their potential contribution to historical tracking of pest invasions has not previously been tested. To this end, we examine the practical considerations for using three online aggregators, the Global Database of Events, Language and Tone (GDELT), Google News, and a commercial media listening platform, Brandwatch, to support pest biosurveillance. Using these tools, we investigate the presence and nature of cogent mentions of invasive species in these sources by conducting case studies of online news and Twitter excerpts regarding two invasive plant pests, Spotted Lanternfly and Tuta absoluta. Our results using past data demonstrate that online news and social media may provide valuable data streams to supplement official sources describing pest invasions.}, journal={COMPUTERS ENVIRONMENT AND URBAN SYSTEMS}, author={Tateosian, Laura G. and Saffer, Ariel and Walden-Schreiner, Chelsey and Shukunobe, Makiko}, year={2023}, month={Mar} }
 @article{pickering_walden-schreiner_barros_rossi_2020, title={Using social media images and text to examine how tourists view and value the highest mountain in Australia}, url={https://doi.org/10.1016/j.jort.2019.100252}, DOI={10.1016/j.jort.2019.100252}, abstractNote={Social media is an emerging source of data to address questions such as how do tourist view and value destinations? This research compared image content and text from Flickr posted by tourists visiting the alpine area around the highest mountain in Australia, in Kosciuszko National Park, to assess seasonal preferences for tourism (i.e., facilities and activities) and nature (i.e., landscapes, flora and fauna). In warmer months when access is easier and the alpine area receives more than 100,000 visitors, tourists' images focused on landscapes (54%) or biodiversity (50%), with fewer images including tourists (23%), mainly hiking (18%). Images were often labelled by the name of the mountain and Park. In contrast, during colder months when access is limited and approximately 400 people visit the alpine area, images still included landscapes (50%) though were also more likely to depict recreation activities (37%), including skiing (8.8%), nearly always showing snow (82%) and using tags such as 'snow', 'ski' and 'Snowy Mountains'. Images of plants tended to show flowering herbs (7.3%) when warm or snowgums when cold (11.4%), while lakes (6.8%), creeks (4.2%) and animals (2.4%) were uncommon in images. Seasonal differences in visitor views and preferences of an area have implications for tourism, conservation and management including better understanding what may attract visitors. Challenges with coding images and text and the benefits and limitations of this novel data source in comparison to onsite surveys are considered.}, journal={Journal of Outdoor Recreation and Tourism}, author={Pickering, Catherine and Walden-Schreiner, Chelsey and Barros, Agustina and Rossi, Sebastian Dario}, year={2020}, month={Mar} }
 @article{dario rossi_barros_walden-schreiner_pickering_2020, title={Using social media images to assess ecosystem services in a remote protected area in the Argentinean Andes}, volume={49}, ISSN={["1654-7209"]}, DOI={10.1007/s13280-019-01268-w}, abstractNote={Social media images are a novel source of data to assess how people view and value the environment. Access to these images is often free, the volume and spread of images is expanding rapidly and hence they are an increasingly valuable source of data complementing and expanding on other data. Recently, coding images has been used to assess sociocultural values relating to ecosystem services including those provided by national parks. To further explore the use of social media images, including for remote environments, we analysed the content of images posted to Flickr by people visiting a national park that contains the highest mountain in the southern hemisphere, Mt. Aconcagua, in Argentina, South America. The saliency of aesthetic landscapes, recreation, social relations and fresh-water provisioning was high across the 334 images posted to Flickr by 104 visitors to the Park, but location mattered. Images from visitors in easily accessible day-use areas were significantly more likely to include content that reflects biodiversity-existence, geology, culture and education services, while the content of images from remote areas was more likely to reflect social relations and fresh-water provision services. Comparisons of the content of images from Mt. Aconcagua with other studies in Europe, South America, Asia, Africa and Australia highlight similarities and differences in people's views of the diversity of locations, but also the benefits and limitations of user-generated social media content when assessing environmental and management issues.}, number={6}, journal={AMBIO}, publisher={Springer Science and Business Media LLC}, author={Dario Rossi, Sebastian and Barros, Agustina and Walden-Schreiner, Chelsey and Pickering, Catherine}, year={2020}, month={Jun}, pages={1146–1160} }
 @article{walden-schreiner_leung_kuhn_newburger_2018, title={Integrating direct observation and GPS tracking to monitor animal behavior for resource management}, volume={190}, ISSN={["1573-2959"]}, url={https://doi.org/10.1007/s10661-018-6463-3}, DOI={10.1007/s10661-018-6463-3}, abstractNote={Monitoring the behavior of pack animals in protected areas informs management about use patterns and the potential associated negative impacts. However, systematic assessments of behavior are uncommon due to methodological and logistical constraints. This study integrated behavior mapping with GPS tracking, and applied behavior change point analysis, as an approach to monitor the behaviors of pack animals during overnight periods. The integrated approach identified multiple grazing patterns (i.e., locally intense grazing, ambulatory grazing) not feasible through a single methodology alone. Monitoring behavior and corresponding environmental conditions aid managers in implementing strategies designed to mitigate impacts associated with pack animals in natural areas. Results also contrast the influence of temporal scale on behavior segmentation to inform decisions for further monitoring and management of domestic animal use and impacts in natural areas. This integrated approach reduced time and logistical constraints of each method individually to promote ongoing monitoring and highlight how multiple management tactics could reduce impacts to sensitive habitats.}, number={2}, journal={ENVIRONMENTAL MONITORING AND ASSESSMENT}, publisher={Springer Science and Business Media LLC}, author={Walden-Schreiner, Chelsey and Leung, Yu-Fai and Kuhn, Tim and Newburger, Todd}, year={2018}, month={Feb} }
 @article{walden-schreiner_dario rossi_barros_pickering_leung_2018, title={Using crowd-sourced photos to assess seasonal patterns of visitor use in mountain-protected areas}, volume={47}, ISSN={["1654-7209"]}, url={https://doi.org/10.1007/s13280-018-1020-4}, DOI={10.1007/s13280-018-1020-4}, abstractNote={Managing protected areas effectively requires information about patterns of visitor use, but these data are often limited. We explore how geotagged photos on Flickr, a popular photo-sharing social-media site, can generate hotspot maps and distribution models of temporal and spatial patterns of use in two mountain-protected areas of high conservation value. In Aconcagua Provincial Park (Argentina), two routes to the summit of Aconcagua were used in summer, but most visitors stayed close to the main road, using formal and informal walking trails and the Visitor Centre, while in winter, there was very limited visitation. In Kosciuszko National Park (Australia), alpine walking trails were popular in summer, but in winter, most visitors stayed in the lower altitude ski resorts and ski trails. Results demonstrate the usefulness of social-media data alone as well as a complement for visitor monitoring, providing spatial and temporal information for site-specific and park-level management of visitors and potential impacts in conservation areas.}, number={7}, journal={AMBIO}, publisher={Springer Nature}, author={Walden-Schreiner, Chelsey and Dario Rossi, Sebastian and Barros, Agustina and Pickering, Catherine and Leung, Yu-Fai}, year={2018}, month={Nov}, pages={781–793} }
 @article{walden-schreiner_leung_tateosian_2018, title={Digital footprints: Incorporating crowdsourced geographic information for protected area management}, volume={90}, ISSN={["1873-7730"]}, url={https://doi.org/10.1016/j.apgeog.2017.11.004}, DOI={10.1016/j.apgeog.2017.11.004}, abstractNote={Biodiversity loss driven by anthropogenic pressures highlights the importance of conservation efforts in protected areas globally. Protected areas are also locations providing myriad ecosystem services, including recreation and tourism. Advancements in mobile and web technologies have expanded the capabilities and accessibility of crowdsourced spatial content increasingly leveraged for research. This study explores the use of crowdsourced geographic information to model, at varying temporal scales, spatial patterns of visitor use and identify factors contributing to distribution patterns in a dynamic landscape, Hawaii Volcanoes National Park (Hawaii, USA). Specifically, this study integrated geotagged photo metadata publicly shared on Flickr with raster data about infrastructure and natural environmental using MaxEnt modelling. Infrastructure designated for visitor use (i.e., roads, trails) contributed most to models of visitor distribution for all years and seasons. During the spring months, elevation was also a top contributing variable to the model. Crowdsourced data provided empirical assessments of covariates associated with visitor distributions, highlighting how changes in infrastructure and environmental factors may influence visitor use, and therefore resource pressures, to help researchers, managers, and planners with efforts to mitigate negative impacts.}, journal={APPLIED GEOGRAPHY}, publisher={Elsevier BV}, author={Walden-Schreiner, Chelsey and Leung, Yu-Fai and Tateosian, Laura}, year={2018}, month={Jan}, pages={44–54} }
 @article{walden-schreiner_leung_kuhn_newburger_tsai_2017, title={Environmental and managerial factors associated with pack stock distribution in high elevation meadows: Case study from Yosemite National Park}, volume={193}, ISSN={["1095-8630"]}, url={https://doi.org/10.1016/j.jenvman.2017.01.076}, DOI={10.1016/j.jenvman.2017.01.076}, abstractNote={Parks and protected areas are integral strategies for biological diversity conservation, and their management often involves balancing visitor use with resource protection. Effectively balancing these objectives requires data about how use is distributed within areas of interest and how management strategies and environmental conditions interact to minimize negative impacts. This study examined which environmental and managerial factors most influenced the distribution of domestic pack stock animals, a common visitor use-related activity, when released to graze in high elevation meadows. Using a species distribution modelling approach, MaxEnt, managerial factors were found to be among the top contributors to models. Pack stock animals concentrated use near the locations where they were released as well as portable enclosure fencing confining the lead animal even though the remainder were allowed to roam freely. Elevation was the environmental factor contributing most, with animals remaining at similar elevations to the meadow even if moving into nearby understory. Results highlight the importance of release point and fence locations to overall pack stock animal distribution and rotational or strategic placement can be a tactic for mitigating impacts to sensitive habitats.}, journal={JOURNAL OF ENVIRONMENTAL MANAGEMENT}, publisher={Elsevier BV}, author={Walden-Schreiner, Chelsey and Leung, Yu-Fai and Kuhn, Tim and Newburger, Todd and Tsai, Wei-Lun}, year={2017}, month={May}, pages={52–63} }
 @article{leung_smith_seekamp_conlon_mayer_guo_walden-schreiner_adams_keane_2016, title={The Effects of 2D and 3D Imagery and an Educational Message on Perceptions of Trail Impacts}, volume={36}, ISSN={0885-8608}, url={http://dx.doi.org/10.3375/043.036.0115}, DOI={10.3375/043.036.0115}, abstractNote={ABSTRACT: The method of experiencing recreational resources, whether it be through on-site participation in an activity or viewing an image of the resource, might directly affect an individual's preference for, and evaluation of, those resources. In this research note, we explore the effect of three-dimensional (3D) displays, which are now widely available to consumer markets, on an individual's perceptions of degraded trail conditions. We also explore the hypothesis that viewing an educational message about responsible hiking behavior influences perceptions of trail conditions. The effects of imagery type and the educational message were tested through experimentally varying types of trail impacts (muddiness and erosion) and impact severity (minimal and severe) across 20 images presented to individuals in a controlled laboratory setting on a 60-inch, 3D capable LCD monitor. Results indicate neither the use of 3D imagery nor the presence of an educational message had a significant main effect on perceptions of trail degradation, but significant two-way interaction effects between image type and impact type on perceptions were identified. Perceptions of trail impacts were significantly different across impact type and severity level. These findings suggest the utility of 3D imagery in perception studies might be restricted to certain impact types (e.g., erosion); the findings also raise concerns over the efficacy of educational materials.}, number={1}, journal={Natural Areas Journal}, publisher={Natural Areas Journal}, author={Leung, Y.-F. and Smith, J.W. and Seekamp, E. and Conlon, K. and Mayer, J. and Guo, T. and Walden-Schreiner, C. and Adams, B. and Keane, R.}, year={2016}, month={Jan}, pages={88–92} }
 @article{leung_walden-schreiner_conlon_miller_2015, title={A simple method for monitoring dog leash compliance behavior in parks and natural areas}, volume={9}, ISSN={2213-0780}, url={http://dx.doi.org/10.1016/J.JORT.2015.03.001}, DOI={10.1016/j.jort.2015.03.001}, abstractNote={This article presents a monitoring protocol for dog leash compliance designed with public participation, mobile technology and flexible platforms in mind. We describe the protocol development and illustrate data utility by comparing results across three trail surface types. Implemented at an urban nature park in North Carolina, pilot tests indicated a high level of inter-observer reliability (>86%) for all variables. The consistency was improved further by refining the measures and the observation procedure. A total of 169 dogs were observed during the study period with an overall compliance rate of 87%. Significantly lower compliance was found on the woodchip and unpaved trail sections (71–74%) than the paved section (99%). Our results suggest this approach may serve as a reliable protocol for monitoring a common and important impact issue. Lessons learned are shared to stimulate further advancements and applications of technology in participatory monitoring of this and other indicators of sustainable recreation.}, journal={Journal of Outdoor Recreation and Tourism}, publisher={Elsevier BV}, author={Leung, Yu-Fai and Walden-Schreiner, Chelsey and Conlon, Katharine and Miller, Anna B.}, year={2015}, month={Apr}, pages={11–16} }
 @article{smith_leung_seekamp_walden-schreiner_miller_2015, title={Projected impacts to the production of outdoor recreation opportunities across US state park systems due to the adoption of a domestic climate change mitigation policy}, volume={48}, ISSN={1462-9011}, url={http://dx.doi.org/10.1016/j.envsci.2014.12.013}, DOI={10.1016/j.envsci.2014.12.013}, abstractNote={Numerous empirical and simulation-based studies have documented or estimated variable impacts to the economic growth of nation states due to the adoption of domestic climate change mitigation policies. However, few studies have been able to empirically link projected changes in economic growth to the provision of public goods and services. In this research, we couple projected changes in economic growth to US states brought about by the adoption of a domestic climate change mitigation policy with a longitudinal panel dataset detailing the production of outdoor recreation opportunities on lands managed in the public interest. Joining empirical data and simulation-based estimates allow us to better understand how the adoption of a domestic climate change mitigation policy would affect the provision of public goods in the future. We first employ a technical efficiency model and metrics to provide decision makers with evidence of specific areas where operational efficiencies within the nation's state park systems can be improved. We then augment the empirical analysis with simulation-based changes in gross state product (GSP) to estimate changes to the states' ability to provide outdoor recreation opportunities from 2014 to 2020; the results reveal substantial variability across states. Finally, we explore two potential solutions (increasing GSP or increasing technical efficiency) for addressing the negative impacts on the states' park systems operating budgets brought about by the adoption of a domestic climate change mitigation policy; the analyses suggest increasing technical efficiency would be the most viable solution if/when the US adopts a greenhouse gas reduction policy.}, journal={Environmental Science & Policy}, publisher={Elsevier BV}, author={Smith, Jordan W. and Leung, Yu-Fai and Seekamp, Erin and Walden-Schreiner, Chelsey and Miller, Anna B.}, year={2015}, month={Apr}, pages={77–88} }
 @article{walden-schreiner_leung_floyd_2014, title={Incorporating Physical Activity Measures Into Environmental Monitoring of National Parks: An Example From Yosemite}, volume={11}, ISSN={["1543-5474"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84920622592&partnerID=MN8TOARS}, DOI={10.1123/jpah.2012-0361}, abstractNote={Background:To address increasing prevalence of obesity and associated chronic disease, recent national initiatives have called upon federal agencies to promote healthy lifestyles and provide opportunities for physical activity. In response, the U.S. National Park Service has developed strategies promoting health through physical activity in addition to its well-established biodiversity and landscape conservation mission. Incorporating physical activity measures with routine environmental monitoring would help identify areas where parks can promote active pursuits with minimal environmental impact. This study provides one example of how protocols developed for visitor and environmental monitoring can generate data to evaluate physical activity.Methods:Researchers implemented an observational study in high-use meadows of Yosemite National Park during the summer of 2011. Variables measured include the spatial location of visitors and activity type. Metabolic equivalents (METs) were assigned to activity categories and analyzed for average energy expenditure.Results:Mean METs values indicated sedentary to light physical activity across the meadows, with greater means in areas with boardwalks or paved pathways.Conclusions:Data leveraged in this study provide park managers an example of adapting existing monitoring programs to incorporate indicators relevant to physical activity evaluation and how physical activity may impact resource conditions in national parks.}, number={7}, journal={JOURNAL OF PHYSICAL ACTIVITY & HEALTH}, publisher={Human Kinetics}, author={Walden-Schreiner, Chelsey and Leung, Yu-Fai and Floyd, Myron F.}, year={2014}, month={Sep}, pages={1284–1290} }
 @article{leung_walden-schreiner_matisoff_naber_robinson_2013, title={A two-pronged approach to evaluating environmental concerns of disc golf as emerging recreation in urban natural areas}, volume={18}, ISSN={1360-6719 1466-450X}, url={http://dx.doi.org/10.1080/13606719.2013.809181}, DOI={10.1080/13606719.2013.809181}, abstractNote={Urban natural areas offer a multitude of environmental and social benefits including recreation. As new forms of recreation quickly emerge, managers often make decisions with limited knowledge about the activities, participants, and environmental implications. We illustrate a two-pronged approach to evaluating environmental concerns of disc golf as an emerging recreational activity, which is conceptually similar to traditional golf, but clubs and balls are replaced with discs that go into baskets instead of holes. A media content analysis was conducted to assess public concerns about disc golf between 1995 and 2010, while a biophysical assessment measured disc-golf-related impacts at four courses in central North Carolina, USA. Results of the media analysis suggest growing environmental concerns associated with disc golf, while the biophysical assessment revealed evidence of tree and ground impacts. Managers could use such contextual public opinion and onsite physical data to inform decisions on permitting emerging activities and adopting sustainable practices, to gauge potential conflicts, and to frame communication to the public in ways so as to increase acceptance and compliance.}, number={4}, journal={Managing Leisure}, publisher={Informa UK Limited}, author={Leung, Yu-Fai and Walden-Schreiner, Chelsey and Matisoff, Craig and Naber, Michael and Robinson, Jessica}, year={2013}, month={Oct}, pages={273–285} }
 @article{walden-schreiner_leung_2013, title={Spatially Characterizing Visitor Use and Its Association with Informal Trails in Yosemite Valley Meadows}, volume={52}, ISSN={["1432-1009"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84879826402&partnerID=MN8TOARS}, DOI={10.1007/s00267-013-0066-0}, abstractNote={Ecological impacts associated with nature-based recreation and tourism can compromise park and protected area goals if left unrestricted. Protected area agencies are increasingly incorporating indicator-based management frameworks into their management plans to address visitor impacts. Development of indicators requires empirical evaluation of indicator measures and examining their ecological and social relevance. This study addresses the development of the informal trail indicator in Yosemite National Park by spatially characterizing visitor use in open landscapes and integrating use patterns with informal trail condition data to examine their spatial association. Informal trail and visitor use data were collected concurrently during July and August of 2011 in three, high-use meadows of Yosemite Valley. Visitor use was clustered at statistically significant levels in all three study meadows. Spatial data integration found no statistically significant differences between use patterns and trail condition class. However, statistically significant differences were found between the distance visitors were observed from informal trails and visitor activity type with active activities occurring closer to trail corridors. Gender was also found to be significant with male visitors observed further from trail corridors. Results highlight the utility of integrated spatial analysis in supporting indicator-based monitoring and informing management of open landscapes. Additional variables for future analysis and methodological improvements are discussed.}, number={1}, journal={ENVIRONMENTAL MANAGEMENT}, publisher={Springer Nature}, author={Walden-Schreiner, Chelsey and Leung, Yu-Fai}, year={2013}, month={Jul}, pages={163–178} }
 @article{walden-schreiner_leung_newburger_woiderski_2012, title={Developing an accessible methodology for monitoring visitor use patterns in open landscapes of Yosemite National Park}, volume={29}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84866421159&partnerID=MN8TOARS}, number={1}, journal={Park Science}, author={Walden-Schreiner, C. and Leung, Y.-F. and Newburger, T. and Woiderski, B.}, year={2012} }