6 results on '"Magness, Dawn R."'
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2. Satellite-Based Assessment of Grassland Conversion and Related Fire Disturbance in the Kenai Peninsula, Alaska
- Author
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Hess, Katherine A, Cullen, Cheila, Cobian-Iñiguez, Jeanette, Lenske, Victor, Ramthun, Jacob S, Magness, Dawn R, Bolten, John D, Foster, Adrianna C, and Spruce, John
- Subjects
Earth Resources And Remote Sensing - Abstract
Spruce beetle-induced (Dendroctonus rufipennis (Kirby)) mortality on the Kenai Peninsula has heightened local wildfire risk as canopy loss facilitates the conversion from bare to fire-prone grassland. We collected images from NASA satellite-based Earth observations to visualize land cover succession at roughly five-year intervals following a severe, mid-1990's beetle infestation to the present. We classified these data by vegetation cover type to quantify grassland encroachment patterns over time. Raster band math provided a change detection analysis on the land cover classifications. Results indicate the highest wildfire risk is linked to herbaceous and black spruce land cover types, The resulting land cover change image will give the Kenai National Wildlife Refuge (KENWR) ecologists a better understanding of where forests have converted to grassland since the 1990s. These classifications provided a foundation for us to integrate digital elevation models (DEMs), temperature, and historical fire data into a model using Python for assessing and mapping changes in wildfire risk. Spatial representations of this risk will contribute to a better understanding of ecological trajectories of beetle-affected landscapes, thereby informing management decisions at KENWR.
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- 2019
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3. EVALUATION OF SMALL UNMANNED AERIAL SYSTEMS AS A CENSUS TOOL FOR ALEUTIAN TERN ONYCHOPRION ALEUTICUS COLONIES.
- Author
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MAGNESS, DAWN R., ESKELIN, TODD, LAKER, MARK, and RENNER, HEATHER M.
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SEA birds , *TERNS , *DRONE aircraft , *COLONIAL birds , *BIRD population measurement - Abstract
Aleutian Tern Onychoprion aleuticus numbers in Alaska appear to be in decline; however, colonies are difficult to count for the purposes of monitoring due to their co-occurrence with Arctic Terns Sterna paradisaea, low nesting densities, high variability in attendance, sensitivity to human disturbance, and remote terrain. We paired visual observations with unmanned aerial systems (UASs) to test the feasibility of using this technology to survey a small colony of nesting Arctic and Aleutian terns in southcentral Alaska. We used counts of terns in the air and nest attendance to test for disturbance from UAS flights. We conducted 11 UAS flights over seven days at altitudes ranging from 15-30 m and located 23 nests in the 4.1 ha (0.041 km²) colony site (5.6 nests ha-1) by systematically searching the orthomosaics. We were most likely to distinguish tern species in the 18-m and 15-m altitude photos; the white forehead was most visible in side angle rather than top-down. Nest attendance and the number of aerial birds were not influenced by the UAS in this colony, which experiences high Larus gull activity. Aleutian Terns arrived on 19 May and were attending nests by 02 June; nest attendance declined throughout June. We believe the best approximation of total nesting pairs will be achieved by counting nests 7-10 d after first initiation. In mixed species colonies, we recommend that UASs fly in a 'lawn mower' pattern with overlap to maximize side angle images and aim for an image resolution of < 4 mm (which was achieved by 15-m altitude flights with our camera setup). In single species colonies, 30 m is sufficient and can be achieved more efficiently. [ABSTRACT FROM AUTHOR]
- Published
- 2019
4. A Climate-change Adaptation Framework to Reduce Continental-scale Vulnerability across Conservation Reserves
- Author
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Magness, Dawn R., Morton, John, Huettmann, Falk, Chapin, F. Stuart, and McGuire, A. David
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climate change ,vulnerability ,conservation ,General & Multiple Resources ,adaptation ,resilience - Abstract
"Rapid climate change, in conjunction with other anthropogenic drivers, has the potential to cause mass species extinction. To minimize this risk, conservation reserves need to be coordinated at multiple spatial scales because the climate envelopes of many species may shift rapidly across large geographic areas. In addition, novel species assemblages and ecological reorganization make future conditions uncertain. We used a GIS analysis to assess the vulnerability of 501 reserve units in the National Wildlife Refuge System as a basis for a nationally coordinated response to climate change adaptation. We used measures of climate change exposure (historic rate of temperature change), sensitivity (biome edge and critical habitat for threatened and endangered species), and adaptive capacity (elevation range, latitude range, watershed road density, and watershed protection) to evaluate refuge vulnerability. The vulnerability of individual refuges varied spatially within and among biomes. We suggest that the spatial variability in vulnerability be used to define suites of management approaches that capitalize on local conditions to facilitate adaptation and spread risk across the reserve network. We conceptually define four divergent management strategies to facilitate adaption: refugia, ecosystem maintenance, 'natural' adaptation, and facilitated transitions. Furthermore, we recognize that adaptation approaches can use historic (i.e., retrospective) and future (prospective) condition as temporal reference points to define management goals."
- Published
- 2011
5. Arthropod and oligochaete assemblages from grasslands of the southern Kenai Peninsula, Alaska.
- Author
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Bowser, Matthew L., Morton, John M., Hanson, John Delton, Magness, Dawn R., and Okuly, Mallory
- Subjects
TAIGAS ,ARTHROPODA ,CLIMATE change ,GRASSLANDS - Abstract
Background By the end of this century, the potential climate-biome of the southern Kenai Peninsula is forecasted to change from transitional boreal forest to prairie and grasslands, a scenario that may already be playing out in the Caribou Hills region. Here, spruce (Picea × lutzii Little [glauca × sitchensis]) forests were heavily thinned by an outbreak of the spruce bark beetle (Dendroctonus rufipennis (Kirby, 1837)) and replaced by the native but invasive grass species, Calamagrostis canadensis (Michx.) P. Beauv. As part of a project designed to delimit and characterize potentially expanding grasslands in this region, we sought to characterize the arthropod and earthworm communities of these grasslands. We also used this sampling effort as a trial of applying high-throughput sequencing metabarcoding methods to a real-world inventory of terrestrial arthropods. New information We documented 131 occurrences of 67 native arthropod species at ten sites, characterizing the arthropod fauna of these grasslands as being dominated by Hemiptera (60% of total reads) and Diptera (38% of total reads). We found a single exotic earthworm species, Dendrobaena octaedra (Savigny, 1826), at 30% of sites and one unidentified enchytraeid at a single site. The utility of high-throughput sequencing metabarcoding as a tool for bioassessment of terrestrial arthropod assemblages was confirmed. [ABSTRACT FROM AUTHOR]
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- 2017
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6. Factors influencing individual management preferences for facilitating adaptation to climate change within the National Wildlife Refuge System.
- Author
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Magness, Dawn R., Lovecraft, Amy Lauren, and Morton, John M.
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CLIMATE change research , *WILDLIFE refuges , *WILDLIFE management , *BIOLOGISTS , *INTRODUCED species - Abstract
National Wildlife Refuge System policies reference both historical condition and naturalness, but these concepts may not be valid management goals in a world with rapid climate change. Currently, within the refuge system, managers and biologists can individually decide whether management actions to maintain historical condition (retrospective) or actions to promote and enhance future condition (prospective) are appropriate. In February 2008, we surveyed 203 refuge system managers and biologists (via email) about climate change and management strategies to facilitate adaptation to climate change. Our goal was to explore factors that influence preference for retrospective or prospective strategies. Most managers and biologists (76%) believe that climate change has already influenced their refuge, but land-use change and invasive species were considered more important landscape drivers. We did not find evidence that refuge purpose or inclusion of climate change in planning documents influenced individual preferences about strategies to facilitate adaptation. However, managers and biologists who conceptualize climate change as anthropogenic in origin were more likely to prefer retrospective strategies. Written responses indicate that managers and biologists prefer historical condition, but believe that retrospective strategies will be costly or impossible. Written comments also indicate that managers and biologists prefer strategies that allow species to adapt naturally and without intervention. We conclude that land management agencies need to provide the rationale for how climate change should be conceptualized in the short and long terms. Explicitly addressing conservation values may help to refine agency priorities in a rapidly changing world and to build the consensus necessary to strategically coordinate management across individual units in conservation reserves. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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