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Dive into the research topics where Yu-Fai Leung is active.

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Featured researches published by Yu-Fai Leung.


Journal of Environmental Management | 2010

Comparing hiking, mountain biking and horse riding impacts on vegetation and soils in Australia and the United States of America

Catherine Marina Pickering; Wendy May Hill; D. Newsome; Yu-Fai Leung

Hiking, horse riding and mountain biking are popular in protected areas in Australia and the United States of America. To help inform the often contentious deliberations about use of protected areas for these three types of activities, we review recreation ecology research in both countries. Many impacts on vegetation, soils and trails are similar for the three activities, although there can be differences in severity. Impacts include damage to existing trails, soil erosion, compaction and nutrification, changes in hydrology, trail widening, exposure of roots, rocks and bedrock. There can be damage to plants including reduction in vegetation height and biomass, changes in species composition, creation of informal trails and the spread of weeds and plant pathogens. Due to differences in evolutionary history, impacts on soil and vegetation can be greater in Australia than in the USA. There are specific social and biophysical impacts of horses such as those associated with manure and urine, grazing and the construction and use of tethering yards and fences. Mountain bike specific impacts include soil and vegetation damage from skidding and the construction of unauthorised trails, jumps, bridges and other trail technical features. There are gaps in the current research that should be filled by additional research: (1) on horse and mountain bike impacts to complement those on hiking. The methods used need to reflect patterns of actual usage and be suitable for robust statistical analysis; (2) that directly compares types and severity of impacts among activities; and (3) on the potential for each activity to contribute to the spread of weeds and plant pathogens. Additional research will assist managers and users of protected areas in understanding the relative impacts of these activities, and better ways to manage them. It may not quell the debates among users, managers and conservationists, but it will help put it on a more scientific footing.


Environmental Conservation | 1999

Assessing trail conditions in protected areas: application of a problem-assessment method in Great Smoky Mountains National Park, USA

Yu-Fai Leung; Jeffrey L. Marion

The degradation of trail resources associated with expanding recreation and tourism visitation is a growing management problem in protected areas worldwide. In order to make judicious trail and visitor management decisions, protected area managers need objective and timely information on trail resource conditions. This paper introduces a trail survey method that efficiently characterizes the location and lineal extent of common trail problems. The method was applied to a large sample of trails within Great Smoky Mountains National Park, a high-use protected area in the USA. The Trail Problem-Assessment Method (TPAM) employs a continuous search for multiple indicators of pre-defined tread problems, yielding census data documenting the location, occurrence and extent of each problem. The present application employed 23 different indicators in three categories to gather inventory, resource condition, and design and maintenance data of each surveyed trail. Seventy-two backcountry hiking trails (528 km), or 35% of the Parks total trail length, were surveyed. Soil erosion and wet soil were found to be the two most common impacts on a lineal extent basis. Trails with serious tread problems were well distributed throughout the Park, although trails with wet muddy treads tended to be concentrated in areas where horse use was high. The effectiveness of maintenance features installed to divert water from trail treads was also evaluated. Water bars were found to be more effective than drainage dips. The TPAM was able to provide Park managers with objective and quantitative information for use in trail planning, management and maintenance decisions, and is applicable to other protected areas elsewhere with different environmental and impact characteristics.


Landscape and Urban Planning | 1999

The influence of sampling interval on the accuracy of trail impact assessment

Yu-Fai Leung; Jeffrey L. Marion

Trail impact assessment and monitoring (IA&M) programs have been growing in importance and application in recreation resource management at protected areas. This paper addresses a fundamental issue in designing trail IA&M surveys: the choice of sampling interval. Specifically, the influence of sampling interval on the accuracy of estimates for selected trail impact problems was examined using a resampling simulation method. A complete census of four impact-types on 70 backcountry trails in the Great Smoky Mountains National Park was utilized as the base dataset for the analyses. The census data were resampled at increasing intervals to create a series of simulated point datasets. At each sampling interval level, the accuracy of simulated datasets was evaluated by comparing the estimates of frequency of occurrence and lineal extent for each impact-type with actual census values. Simulation results indicate that increasing sampling intervals are associated with an overall increase in accuracy loss for all four impact-types. The direction of accuracy loss for lineal extent estimates is mixed, while frequency of occurrence estimates are consistently and substantially lower than the actual values. Responses of accuracy loss to increasing sampling intervals vary across impact-types on extent estimates, but are consistent on the frequency estimates. These findings suggest that systematic point sampling can be an appropriate method for estimating lineal extent but not the frequency of trail impacts. Sample intervals of less than 100 m appear to yield an excellent level of estimate accuracy for the four impact-types evaluated. The census-based trail survey and the resampling simulation method developed in this study can be a valuable first step in establishing long-term trail IA&M programs, in which an optimal sampling interval range with acceptable accuracy is determined before investing efforts in data collection.


Environmental Management | 2011

Developing a Monitoring Protocol for Visitor-Created Informal Trails in Yosemite National Park, USA

Yu-Fai Leung; Todd Newburger; Marci Jones; Bill Kuhn; Brittany Woiderski

Informal trails created or perpetuated by visitors is a management challenge in many protected natural areas such as Yosemite National Park. This is a significant issue as informal trail networks penetrate and proliferate into protected landscapes and habitats, threatening ecological integrity, aesthetics, and visitor experiences. In order to develop effective strategies for addressing this problem under an adaptive management framework, indicators must be developed and monitoring protocol must be established to gather timely and relevant data about the condition, extent, and distribution of these undesired trail segments. This article illustrates a process of developing and evaluating informal trail indicators for meadows in Yosemite Valley. Indicator measures developed in past research were reviewed to identify their appropriateness for the current application. Information gaps in existing indicator measures were addressed by creating two new indices to quantify the degree of informal trailing based on its land fragmentation effects. The selected indicator measures were applied to monitoring data collected between 2006 and 2008. The selected measures and indices were evaluated for their ability to characterize informal trail impacts at site and landscape scales. Results demonstrate the utility of indicator measures in capturing different characteristics of the informal trail problem, though several metrics are strongly related to each other. The two fragmentation indices were able to depict fragmentation without being too sensitive to changes in one constituent parameter. This study points to the need for a multiparameter approach to informal trail monitoring and integration with other monitoring data. Implications for monitoring programs and research are discussed.


Northeastern Naturalist | 2005

Research to support management of visitor carrying capacity of Boston Harbor Islands.

Robert Manning; Yu-Fai Leung; Megha Budruk

Abstract Visitor carrying capacity has been a long-standing issue in management of parks and protected areas. Contemporary carrying capacity frameworks rely on formulation of indicators and standards of quality to define and manage carrying capacity. This paper describes a program of research to support management of carrying capacity of the Boston Harbor Islands national park area, a recent addition to the national park system. Research included: (1) an inventory and analysis of recreation-related resource impacts on selected islands, and (2) surveys of visitors to islands open to public use. Study findings are being incorporated into a visitor carrying capacity management plan through formulation of indicators and standards of quality for the parks natural resources and visitor experience.


Journal of Tourism and Leisure Studies | 2011

Indicators and Protocols for Monitoring Impacts of Formal and Informal Trails in Protected Areas

Jeffrey L. Marion; Yu-Fai Leung

Trails are a common recreation infrastructure in protected areas and their conditions affect the quality of natural resources and visitor experiences. Various trail impact indicators and assessment protocols have been developed in support of monitoring programs, which are often used for management decision-making or as part of visitor capacity management frameworks. This paper reviews common indicators and assessment protocols for three types of trails, surfaced formal trails, unsurfaced formal trails, and informal (visitor-created) trails. Monitoring methods and selected data from three U.S. National Park Service units are presented to illustrate some common trail impact indicators and assessment options.


Journal of Sustainable Tourism | 2012

Understanding environmentally significant behavior among whitewater rafting and trekking guides in the Garhwal Himalaya, India

Christopher Serenari; Yu-Fai Leung; Aram Attarian; Christopher T. Franck

Garhwal, Uttarakhand, India, is planning for large-scale sustainable mountain tourism. However, current tourism practices have resulted in waste accumulation and vegetation loss. This paper explores the possibility of increasing the role of whitewater rafting and adventure tour guides to reduce tourists’ environmental impacts. Earlier studies on guides acquiescent with this role have found it to be effective in altering client behavior and minimizing environmentally destructive behavior. However, only limited research focuses on guides from developing countries outside an ecotourism context. This exploratory research in Garhwal, India, helps explain adventure guide intentions to perform pro-environmental behavior. The theory of planned behavior was applied to identify factors leading to a sample of 68 whitewater and trekking guides to perform three environmentally significant behaviors – packing out rubbish, burying their human waste and cutting living trees for firewood. Results suggest that the theoretical antecedents of the theory of planned behavior can predict intentions to perform pro-environmental behavior among non-western guides. Possible impediments to consistent performance of pro-environmental behavior among guides were noted, including lack of social pressure to change, abhorrence of contact with excreta, caste issues, effort expended to dig burial holes, etc. Managerial possibilities to encourage change are discussed.


Catena | 1997

Nutrient fluxes in the Shenchong Basin, Deqing County, South China

Kin-Che Lam; Yu-Fai Leung; Qingyin Yao

Abstract In the severely eroded granitic areas of south China, the hillslopes are the source areas of, and the valleys are the sinks for, nutrients, water and sediments. Overall, the amount of nutrient loss is limited, since the nutrient pool in the upland soils is small. Nutrient losses are generally higher on cultivated fields than on barren or wooded slopes. A substantial proportion of the nutrients is transported in the solid phase. Because of the selective process of deposition with regard to particle size, nutrients are relatively more enriched in the soils and around the wetlands than on the alluvial fans. Soils developed on the alluvial fans are highly acidic and deficient in available nitrogen and phosphorus. The hydrochemical environment in the wetlands favours the dissolution of iron-bearing clay minerals in the subsurface water. High levels of iron and acidity may complex nutrients present in the soil and inhibit plant growth. Agricultural activities in the area thus require revegetation of the hillslopes and soil amelioration in the lowlands through fertilizer application and soil structure improvement.


American Journal of Preventive Medicine | 2016

Urban Vegetative Cover Fragmentation in the U.S. Associations With Physical Activity and BMI

Wei-Lun Tsai; Myron F. Floyd; Yu-Fai Leung; Melissa R. McHale; Brian J. Reich

INTRODUCTION Urban vegetative cover provides a range of ecosystem services including contributions to human health and well-being. Urbanization exerts tremendous pressure on this natural resource, causing fragmentation and loss of urban greenspace. This study aimed to examine associations between vegetative cover fragmentation and physical activity and BMI at the county scale in the U.S. metropolitan statistical areas greater than 1 million in population. METHODS National Land Cover Database 2006 and Behavioral Risk Factor Surveillance System 2008 provided land cover and human health data, respectively. Analyses were performed in 2013 at the county scale where the health data were reported. Spearman rank correlation and stepwise and hierarchical regression models were applied to estimate relationships between land cover and health variables. RESULTS After controlling for median household income and race, greater forest edge density (β=0.272, p<0.05) and larger size of herbaceous patches (β=0.261, p<0.01) were associated with a higher percentage of participation in physical activity within counties. More connections between forest and developed area (β=0.37, p<0.01) and greater edge density of shrubland (β=0.646, p<0.001) were positively associated with a higher percentage of normal BMI (<25) within counties. CONCLUSIONS Forest land cover and some degree of fragmentation are associated with population physical activity. Future studies should examine how built environments and varying land cover configurations influence physical activity and weight status.


Ecology and Society | 2015

Private development-based forest conservation in Patagonia: comparing mental models and revealing cultural truths

Christopher Serenari; M. Peterson; Yu-Fai Leung; Paulina Stowhas; Tim Wallace; Erin O. Sills

Private protected area (PPA) conservation agents (CA) engaging in development-based conservation in southern Chile have generated conflict with locals. Poor fit of dominant development-based conservation ideology in rural areas is commonly to blame. We developed and administered a cultural consensus survey near the Valdivian Coastal Reserve (RCV) and Huilo Huilo Reserve (HH) to examine fit of CA cultural truths with local residents. Cultural consensus analysis (CCA) of 23 propositions reflecting CA cultural truths confirmed: (1) a single CA culture exists, and (2) RCV communities were more aligned with this culture than HH communities. Inadequate communication, inequitable decision making, divergent opinions about livelihood impacts and trajectories, and PPA purpose may explain differences between CAs and communities. Meanwhile, variability in response between and within communities may reflect differing environmental histories. Private protected area administrations might use CCA to confront cultural differences and thereby improve their community interactions.

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Jeffrey L. Marion

United States Geological Survey

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Chelsey Walden-Schreiner

North Carolina State University

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Jordan W. Smith

North Carolina State University

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Roger L. Moore

North Carolina State University

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Catherine E. Dorwart

North Carolina Central University

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Carla Barbieri

North Carolina State University

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Erin Seekamp

North Carolina State University

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Myron F. Floyd

North Carolina State University

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