Browsing by Author "Dr. Gary Blank, Committee Member"

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    An Evaluation of Methods for Estimating Ground Cover and Soil Compaction as Visitor Impact Indicators
    (2004-06-14) Meyer, Kristin Jennifer; Dr. Gary Blank, Committee Member; Dr. Yu-Fai Leung, Committee Chair; Dr. Gene Brothers, Committee Member
    The purpose of this study was to perform an empirical comparison of several methods of data collection for two visitor impact indicators. This study is the result of a bigger carrying capacity research endeavor in which one of the goals was to come up with indicators to monitor visitor impacts at the Boston Harbor Islands National Park Area. Specifically, the two visitor impact indicators evaluated in this study were soil compaction and ground cover estimation. These indicators were measured on two high use and two low use plots on selected islands in the Boston Harbor Islands National Park Area in Boston, Massachusetts. Georges and Grape Islands had the accessibility to the public and the soil types found on the islands that are of interest. There were three data collection periods during the visitor use season: June (beginning of season), August (middle of season), and October (end of season). A sampling plot consisting of six radial transects and two quadrats was placed randomly on each transect. The first transect was placed randomly and then there was 60° between each transect. A penetrometer and a soil compaction tester were the two methods used to measure soil compaction. Four measurements from both methods were taken in each of the twelve quadrats. Eight control measurements were taken in nearby undisturbed areas. The pocket penetrometer measurements are more variable than those of the soil compaction tester, but the pocket penetrometer is easier to carry and easier for one person to take and record readings. To estimate ground cover, specifically vegetation and bare soil, the following three methods were used: overall, quadrat, and transect. For the overall and quadrat methods the ground cover types were ranked based on a Daubenmire cover scale. The quadrat method was used as the reference method to be compared to the other methods because the quadrat method was used regularly in low herbaceous (grassy) areas. For the transect method, changes in principal cover type along the transect were recorded. The high use areas were found to have a higher percentage of bare soil cover than the low use areas. The transect method produced higher mean than did the quadrat method. The overall and quadrat methods indicated vegetation recovery from the middle to the end of the visitor use season on both islands. The transect method indicated a decrease in vegetation ground cover from the middle to the end of the visitor use season for Grape Island but not Georges Island. Researchers and managers may use the findings of this study to aid them in their data collection choices. This study contributes to the future management of BOHA by evaluating monitoring techniques of two potential visitor impact indicators. It is hopeful that through efficient monitoring of use and resource indicators and effective management BOHA will achieve a balance recreation provision and resource protection.
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    Resin Flow Induction in Southern Pines: Implications for Defense Against Southern Pine Beetle
    (2005-10-04) Knebel, Larissa; Dr. Fred Hain, Committee Member; Dr. Gary Blank, Committee Member; Dr. Dan Robison, Committee Member; Dr. Tom Wentworth, Committee Chair
    The interactions between conifers, bark beetles and their common fungal associates have been widely studied, in part due to the severe economic and natural losses that occur annually. Host resistance, involving constitutive and induced defensive measures, and the factors associated with pest success are now widely understood and some losses can be avoided with proper management. Recent research with Norway spruce (Picea abies) has provided additional insight into the chemical pathways involved in host resistance, and has determined that trees exposed to mechanical wounding or fungal inoculation show acquired resistance to future pathogen attacks. This aspect of defense in loblolly pine (Pinus taeda) has not been adequately investigated. However, our recent studies indicate that fungal inoculation results in elevated resin flow levels that last up to one year after treatment. Further research in southern Appalachian pines showed that elevated resin flow occurs in response to low intensity fire, and that this response is still present at 18 months after burning. These studies indicate that acquired resistance through induced resin flow in southern pines is a possibility. Further research with beetle or fungal challenges could determine new possibilities for management of both natural and planted stands in order to maximize host defenses against southern pine beetle.