Browsing by Author "Joyce, Michael"

Now showing 1 - 8 of 8
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    Accuracy of a Modular GPS/GLONASS Receiver
    (University of Minnesota Duluth, 2018) Joyce, Michael; Moen, Ronald
    One of the main factors that affect GPS location accuracy is the type of GPS receiver being used. In general, more expensive receivers (e.g., mapping-grade or survey-grade receivers) provide better accuracy, and GPS users must balance GPS receiver cost with location accuracy when determining which receiver to use. Applications of GPS often require use of GPS receivers in less than ideal conditions while GPS manufacturers often report accuracy specifications that can be expected under ideal conditions. Forest canopies reduce GPS accuracy by interfering with signal transmission between GPS satellites and the GPS receiver and causing multipath errors. When GPS receivers are to be used in forest conditions and accuracy thresholds must be met, it is important to conduct accuracy testing in forest conditions rather than relying on accuracy specifications provided by the manufacturer. We tested the accuracy of the SXBlue II + GNSS, a modular, mapping-grade GPS receiver, under forest canopies in northeastern Minnesota. We estimated cumulative accuracy to evaluate the relationship between collection period and accuracy. GPS test sites covered a range of canopy conditions. We compared accuracy among sites to determine how canopy closure influenced location accuracy. Finally, we compared post-hoc methods to evaluate accuracy based on characteristics of the sites and acquired GPS fixes. The SXBlue II + GNSS receiver typically provided meter or sub-meter accuracy, even under forest canopy. Maximum accuracy was achieved after 10-30 minutes. Accuracy was lower at sites with higher canopy closure values. In sites with canopy closure >65%, maximum accuracy was reduced to 1.5 m. Post-hoc filtering to remove outliers did not improve accuracy. There was a strong, positive relationship between 50% CEP, a measure of location precision, and accuracy, suggesting that 50% CEP can be used for post-hoc accuracy assessment. Our results suggest that the SXBlue II + GNSS provides sufficient accuracy for a wide range of applications, including those that require GPS location measurement in forest conditions.
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    Accuracy of a Modular GPS/GLONASS Receiver
    (University of Minnesota Duluth, 2018) Joyce, Michael; Moen, Ronald
    One of the main factors that affect GPS location accuracy is the type of GPS receiver being used. In general, more expensive receivers (e.g., mapping-grade or survey-grade receivers) provide better accuracy, and GPS users must balance GPS receiver cost with location accuracy when determining which receiver to use. Applications of GPS often require use of GPS receivers in less than ideal conditions while GPS manufacturers often report accuracy specifications that can be expected under ideal conditions. Forest canopies reduce GPS accuracy by interfering with signal transmission between GPS satellites and the GPS receiver and causing multipath errors. When GPS receivers are to be used in forest conditions and accuracy thresholds must be met, it is important to conduct accuracy testing in forest conditions rather than relying on accuracy specifications provided by the manufacturer. We tested the accuracy of the SXBlue II + GNSS, a modular, mapping-grade GPS receiver, under forest canopies in northeastern Minnesota. We estimated cumulative accuracy to evaluate the relationship between collection period and accuracy. GPS test sites covered a range of canopy conditions. We compared accuracy among sites to determine how canopy closure influenced location accuracy. Finally, we compared post-hoc methods to evaluate accuracy based on characteristics of the sites and acquired GPS fixes. The SXBlue II + GNSS receiver typically provided meter or sub-meter accuracy, even under forest canopy. Maximum accuracy was achieved after 10-30 minutes. Accuracy was lower at sites with higher canopy closure values. In sites with canopy closure >65%, maximum accuracy was reduced to 1.5 m. Post-hoc filtering to remove outliers did not improve accuracy. There was a strong, positive relationship between 50% CEP, a measure of location precision, and accuracy, suggesting that 50% CEP can be used for post-hoc accuracy assessment. Our results suggest that the SXBlue II + GNSS provides sufficient accuracy for a wide range of applications, including those that require GPS location measurement in forest conditions.
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    Effect of Temperature on Habitat Use by Moose in Voyageurs National Park in the Summer
    (University of Minnesota Duluth, 2015) Moen, Ronald; Joyce, Michael; Windels, Steven K
    Moose (Alces alces) are an integral part of biological processes and a favorite sight of visitors to Voyageurs National Park (VNP). In the face of global climate change moose may also become a bellwether species for the persistence of northern species in VNP and the surrounding area. Climate change will affect national parks like VNP in many ways, ranging from changes in vegetation and possible loss of wildlife species to altered visitation rates by people. Minnesota is at the southern edge of moose distribution. Climate change predictions are for a 3o to 4o C increase in average summer temperatures by 2100, which would result in an increased number of summer days during which moose would be heat stressed. We deployed GPS collars on moose in VNP to evaluate changes in habitat use and activity as related to fine-scale changes in ambient temperature. We captured and radiocollared 21 moose by aerial darting or net-gunning. We measured black globe temperatures in habitats across VNP. The annual Minimum Convex Polygon home range area was about 15 km2, while seasonal home ranges were about 10 km2. Home range size was slightly less than in adjoining areas of northeast Minnesota. There was no difference in proportional cover type in the home range among annual, winter, and summer home ranges, and cover type use was similar to cover type use by moose in northeast Minnesota. Wet bog and wet marsh/fen cover types were preferred in hot summer temperatures, while open water was not used very much, with less than 1% of locations in water when temperatures were above 30 C. Use of almost all cover types was similar whether temperature, dew point, or heat index were used as the metric. For future analysis of cover type use ambient or black globe temperature should be an adequate metric. Habitats that are of most use to moose in hot temperatures have a wet substrate and some canopy cover during the day. At night moose seemed to be less limited by heat dissipation because of colder temperatures and the lack of solar radiation. Monitoring the population status of moose at Voyageurs National Park is of critical importance in order to make contrasts with the declining moose populations in other regions of Minnesota.
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    Evaluating American marten habitat quality using airborne light detection and ranging (LiDAR) data
    (2018-09) Joyce, Michael
    Understanding the factors that influence animal distribution and density is a central theme in animal ecology. For imperiled species, understanding the resources and conditions that allow animals to occupy the landscape is critical for development of effective conservation strategies. Not surprisingly, habitat selection is a common focus of wildlife research. This dissertation project focused on addressing two main challenges that limit the application of a fitness-based approach to understanding habitat selection: 1) data on fine-scale habitat resources and conditions required for the development and testing of resource- and fitness-based definitions of habitat are generally not available across entire study areas, and 2) indirect measurements of fitness (e.g., survival or reproductive success) are often not considered when assessing habitat selection patterns, in part, because of the difficulty of measuring fitness correlates for free-ranging animals with long life-spans and large home ranges. My first two chapters address the first challenge by using airborne light detection and ranging (LiDAR) data to measure fine-scale characteristics known to be selected by my focal species, American martens (Martes americana). In Chapter 1, I demonstrate that LiDAR data can be used to detect individual pieces of coarse woody debris, an important habitat component that provides martens with foraging habitat and access to the subnivean layer. In Chapter 2, I created statistical models to estimate 5 response variables relating to tree size and density and evaluated how well models will perform when imputed across the entire study area. I found that the models I created performed well when applied to new data, but that performance depended on the response variable being modeled. My last two chapters address the second challenge by evaluating how landscape and forest structure influence mortality risk for martens. In Chapter 3, I evaluated factors influencing harvest mortality risk. I found that martens living close to roads have higher harvest risk because trappers use roads to set and check traps efficiently. Consequently, distribution of roads can have a profound impact on habitat quality, which has important implications for gene flow and population structure. In Chapter 4, I used LiDAR data and classified satellite imagery to examine the role of forest structure in mediating interactions between martens and predators. I found that sites where martens were killed by predators were associated with non-forested areas including wetlands, shrublands, and young and regenerating forests. Although martens generally avoid non-forested areas that are associated with higher predation risk, martens must move near or through risky areas while moving across heterogeneous, managed landscapes.
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    Fisher Den Box Building Plans
    (University of Minnesota Duluth, 2022-08) Joyce, Michael; Moen, Ronald
    The design for this fisher den box is based on a design that has been used for fishers in British Columbia (Davis 2016). We made minor design modifications as described in this manual, for example we used screws instead of nails in all construction. Almost 100 of these boxes were deployed in northern Minnesota, with several boxes used by fishers (M. Joyce, 2022, Final Report, Environment and Natural Resources Trust Fund project M.L. 2019, First Special Session, Chp. 4, Art. 2, Sec. 2, Subd. 03i).
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    Mammal Mediated Dispersal of Mycorrhizal Fungi: Using Microscopy as a Method for Quantifying Diet and Fungal Richness
    (2024-04-30) Weiss, Teagan; Joyce, Michael; Stephens, Ryan; Moen, Ron
    Small mammals help initiate mycorrhizal fungal networks by consuming fungi and dispersing spores through their scat. Quantifying small mammal diets can help define the role these species play in mediating the colonization of mycorrhizal fungal networks that play important roles in ecosystem health such as soil aggregation, carbon sequestration, and tree establishment. In this study, fecal material was collected from the gastrointestinal tracts of small mammal specimens to be analyzed for diet quantification. Preliminary results found red-backed voles to have the greatest fungal abundance on average, with fungi making up 83% of their diet. Short-tailed shrew diets were composed primarily of insects, while White-footed mice and Deer-mice diets were composed primarily of plants and insects.
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    Measuring what matters: Assessing the full suite of benefits of OHF investments
    (2021-01-08) Noe, Ryan; Locke, Christina; Host, George; Gorzo, Jessica; Johnson, Lucinda; Lonsdorf, Eric; Grinde, Alexis; Joyce, Michael; Bednar, Josh; Dumke, Josh; Keeler, Bonnie