Browsing by Author "Zedaker, Shepard"

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    Methods for Rapid Screening in Woody Plant Herbicide Development
    Stanley, William; Zedaker, Shepard; Seiler, John R.; Burch, Patrick (MDPI, 2014-07-04)
    Methods for woody plant herbicide screening were assayed with the goal of reducing resources and time required to conduct preliminary screenings for new products. Rapid screening methods tested included greenhouse seedling screening, germinal screening, and seed screening. Triclopyr and eight experimental herbicides from Dow AgroSciences (DAS 313, 402, 534, 548, 602, 729, 779, and 896) were tested on black locust, loblolly pine, red maple, sweetgum, and water oak. Screening results detected differences in herbicide and species in all experiments in much less time (days to weeks) than traditional field screenings and consumed significantly less resources (<500 mg acid equivalent per herbicide per screening). Using regression analysis, various rapid screening methods were linked into a system capable of rapidly and inexpensively assessing herbicide efficacy and spectrum of activity. Implementation of such a system could streamline early-stage herbicide development leading to field trials, potentially freeing resources for use in development of beneficial new herbicide products.
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    Recovery status of a cypress (Taxodium distichum)-water tupelo (Nyssa aquatica) wetland seven years after harvest disturbance
    Zaebst, Thomas Winter (Virginia Tech, 1997)
    Research documenting the functional changes of wetlands in response to harvest disturbance has often been limited to initial-response time frames of one or two years. A cypress (Taxodium distichum L. Rich.)-water tupelo ~ aQuatica L.) swamp located in the Mobile-T ensaw River Delta of Southwestern Alabama was harvested in the fall of 1986. Harvest treatments included: c1earcutting the entire study area with helicopter log removal, or with an added simulated rubber-tired skidder transport, or with herbicide control of all regenerating vegetation. An adjacent nondisturbed stand served as a reference area. Remeasurement of the area was initiated seven years after harvest. The helicopter logged and skidder simulation treatments have produced stands of comparable diameter, height, density, and basal area. ~ aqyatica was dominant in the skidder simulation treatment~ ~ tica, ~ nigra, and Fraxinus caroliniana dominated the helicopter treatment. Overstory biomass was less in the helicopter logged areas (20,981 kg/ha) than in the skidder simulation treatment (30,533 kglha). Lowerstory trees in both treatments were of comparable diameter and height, however, the helicopter treatment contained a greater density, basal area, and biomass ofFraxinus caroliniana. The rutting and mounding associated with the skidder simulation treatment favored a greater diversity of both diversity of both lowerstory and herbaceous species. Groundflora biomass was greatest in the herbicide controlled treatment (13,127 kg/ha), comparable in both the helicopter logged and skidder simulation treatments (5128 kg/ha; 5648 kglha, respectively), and least in the reference area (1495 kglha). Sediment accumulation reflected these differences in groundflora biomass; 104 mm in the herbicide controlled treatment, 79 mm and 63 mm in the helicopter logged and skidder simulation treatments, respectively, and 37 mm in the reference area. Three gradients were identified in the study areas via the tests of Latin squares, rows, and columns which actually corresponded to gradients of hydrology and! or sediment deposition. Square two was wetter than squares one or three because square two had fewer residual pullboat runs, which facilitate greater water movement. The rows are indicative of the distance from the main river channel; rows nearer the river are slightly higher in elevation, less inundated, and favor the less flood tolerant species. The columns reflect the sediment trapping patterns of the vegetation and the subsequent effects of site hydrology and nutritional status.