Resource Type
Partner
Serial/Series Title
Degree Department
Degree Discipline
Degree Level
Country
States
Decade
12 Matching Results
Results open in a new window/tab. Unexpected Results? Search the Catalog Instead.
Results:
1 - 12 of
12
Structure, Composition, and Regeneration of Cross Timbers Forest Fragments in Different Land Use Contexts
Throughout its current range, the Cross Timbers forest ecosystem is vulnerable to land-use change. In this study, we examined the surrounding land use matrix on the vegetation structure, composition and regeneration of six Cross Timbers forest fragments in Denton County, Texas (north of the Dallas-Fort Worth metroplex). Two fragments adjacent to agricultural land, two to residential neighborhoods, and two formally protected forest sites were selected. In summer 2015, five 100 m2 plots were randomly established in each fragment at least 200 meters from the edge. In each plot, all live and dead trees ≥ 3 cm diameter were identified and their height and diameter at breast height (DBH at 1.3 m aboveground) measured. Evidence of dumping (presence of trash) was recorded as an index of human frequentation. Differences in vegetation structure among the forest fragments were found. Most notably, fragments adjacent to agriculture contained 25% to 50% fewer trees per hectare than all other sites (Kruskal-Wallis, p < 0.02), especially trees <10 cm DBH. However, residential fragments had fewer trees that were ≥15 cm DBH compared to the other fragments, indicating that these are the youngest of the forest patches surveyed. Trash was observed in 60% of plots surveyed at …
Date:
May 2015
Creator:
Dunn, Ingrid
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Developing a Forest Gap Model to Be Applied to a Watershed-scaled Landscape in the Cross Timbers Ecoregion Using a Topographic Wetness Index
A method was developed for extending a fine-scaled forest gap model to a watershed-scaled landscape, using the Eastern Cross Timbers ecoregion as a case study for the method. A topographic wetness index calculated from digital elevation data was used as a measure of hydrologic across the modeled landscape, and the gap model modified to have with a topographically-based hydrologic input parameter. The model was parameterized by terrain type units that were defined using combinations of USDA soil series and classes of the topographic wetness index. A number of issues regarding the sources, grid resolutions, and processing methods of the digital elevation data are addressed in this application of the topographic wetness index. Three different grid sizes, 5, 10, and 29 meter, from both LiDAR-derived and contour-derived elevation grids were used, and the grids were processed using both single-directional flow algorithm and bi-directional flow algorithm. The result of these different grids were compared and analyzed in context of their application in defining terrain types for the forest gap model. Refinements were made in the timescale of gap model’s weather model, converting it into a daily weather generator, in order to incorporate the effects of the new topographic/hydrologic input parameter. The precipitation …
Date:
August 2014
Creator:
Goetz, Heinrich (Heinrich Erwin)
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Assessing Rainfall Interception by Urban Tree Canopies in Denton, Texas
Rainfall interception is one mechanism by which tree canopies can reduce surface runoff in urban areas. The objectives of this research were to: 1) quantify rainfall interception by urban tree canopies, and 2) determine the influence of vegetation and microenvironmental factors on rainfall interception rates. In the city of Denton, Texas, 30 mature post oak (Quercus stellata) and blackjack oak (Quercus marilandica) trees were selected for study. Trees were assigned to one of three categories: clusters of trees on greenspace (CG), isolated trees on greenspace (IG), and isolated trees surrounded by pavement (IP). Throughfall (the volume of water that travels through the canopy and reaches the soil surface) collectors were placed beneath these trees and rainfall collectors were placed in nearby open areas. Throughfall and rainfall were collected daily from 19 March to 4 July. Interception was calculated as the difference between throughfall and gross rainfall. Over the study period, there were 27 days with measurable rainfall; daily rainfall ranged from 1-51 mm. Over the sampling period, rainfall interception for individual trees ranged from -10% to 49%, indicating high spatial variability in interception. Percent interception was highest for the CG treatment (22.7 ± 3.8 SE), intermediate for IG (27.4 ± …
Date:
May 2017
Creator:
Edington, Patrick
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Influence of Local Forage Variability on White-tailed Deer (Odocoileus virginianus) Body Size at Fort Hood, Texas
Nutritional quality and availability is thought to regulate geographic patterns of variability in animal body size due to phenotypic plasticity. The purpose of this study is to determine how vegetation quality, abundance and population density influence white-tailed deer (Odocoileus virginianus) body size on a subregional spatial scale at Fort Hood, Texas. Harvest and census records are used to test the hypothesis that white-tailed deer exhibit phenotypic plasticity (e.g. larger body size) in response to differences in vegetation quality and availability. Results from these analyses suggest that forage quality and abundance alone is not a main driver of white-tailed deer body size. Analysis of deer population density (generally) resulted in an inverse relationship with body size. Areas with high quality forage and low population density support larger deer while areas with low quality forage and high density support smaller than average deer. The few exceptions occur in areas exhibiting poor quality forage and low population density or high forage quality and high density. Results from this study suggest that continued overcrowding of deer within isolated areas may eventually lead to efficiency phenotypic conditions producing smaller sized deer. These results could prove useful in interpreting deer population responses to harvest management. For …
Date:
December 2015
Creator:
Eddins, Amy C.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Soil and Forest Variation by Topography and Succession Stages in the Greenbelt Corridor, Floodplain of the Elm Fork of the Trinity River, North Texas.
The Greenbelt Corridor (GBC), located in a floodplain of the Elm Fork of the Trinity River, contains patches of bottomland forest and serves as part of Lake Lewisville’s flood control backwaters. This study examines forest structure and composition in relation to topographic position and forest stage in the GBC. Thirty two plots were surveyed within various stage classes, topographic positions, and USDA soil types. Trees were identified and measured for height and DBH. Density, basal area, and importance value for each of species was calculated. Soil and vegetation were analyzed using ANOVA, Principal Component Analysis, Canonical Correlation, Canonical Correspondence Analysis and Cluster Analysis. Tests confirmed that calcium carbonate and pH show significant differences with topographic positions but not with forest stage. Potassium shows no significant difference with soil texture class. Sand shows a strong negative correlation with moisture, organic matter, organic carbon and negative correlation with calcium carbonate and potassium. Silt shows positive correlation with moisture, organic matter, organic carbon, and calcium carbonate. Clay shows strong positive correlation with moisture, organic matter and organic carbon but negative correlations with pH. Swamp privet is dominant tree types in wetland forest. Sugarberry cedar elm, green ash and American elm are widely distributed …
Date:
August 2011
Creator:
Rijal, Rajan
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Archeological Investigations at the Santa Maria Creek Site (41CW104) Caldwell County, Texas
Report on the excavations at the Santa Maria creek site in Caldwell County, Texas during 2006 and 2007. The report includes a discussion of research methods, analysis of the findings, and history of the area.
Date:
March 2013
Creator:
Rogers, Robert; Ellis, Linda W.; Harris, Brandy; Wallace, Candace; Rush, Haley; Shipp, Julie et al.
Object Type:
Report
System:
The Portal to Texas History
Ecology and Recolonization of Benthic Macroinvertebrates in a Groundwater-dependent Stream in North Central Texas During a Supra-seasonal Drought
Extreme climatic events such as droughts are known to eliminate aquatic biota and alter community structure and function. Perennial headwater springs provide important drought refugia to benthic macroinvertebrates and an important source of colonists via drift or aerial adults to intermittent streams post-drought. During a supra-seasonal drought in North-central Texas summer and fall 2006, benthic macroinvertebrates from persistent groundwater-dependent macrohabitats of varying hydrological connectivity and riparian shading were studied: perennial riffles, connected pools, shaded disconnected pools, and full sun disconnected pools. Riffles were a distinct habitat with significantly higher taxa richness, proportion of lotic taxa, diversity and evenness than other macrohabitats. Macrohabitats were found to be important refugia for 106 benthic macroinvertebrates and 4 microcrustacean taxa. Throughout the extreme drought, perennially flowing habitats were refugia to 19 taxa (17.9% total taxa) not collected in disconnected pools. Shaded disconnected pools contained lotic taxa not previously known to be able to complete their lifecycles in lentic habitats, emphasizing the importance of groundwater effluent and shading. With the resumption of flow at a downstream intermittent site of Ash Creek in mid-October 2006, an annual recolonization study was conducted comparing the perennial headwaters’ benthic macroinvertebrate taxa richness, densities and community ecology with the downstream …
Date:
May 2012
Creator:
Burk, Rosemary A.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Regional Water Plan: Region L (South Central Texas), 2016, Volume 1. Executive Summary and Regional Water Plan
Water plan for Region L (South Central Texas) describing water resources and suppliers in the area, usage statistics and forecasts, water needs, recommended water management strategies for the suppliers and counties, drought management, funding plans, and information on the creation of the plan.
Date:
December 2015
Creator:
South Central Texas Regional Water Planning Group
Object Type:
Report
System:
The Portal to Texas History
Regional Water Plan: Region G (Brazos), 2016, Volume II. Identification, Evaluation, and Selection of Water Management Strategies
Volume II of the Water plan for Region G (Brazos) including water management strategies, water conservation methods, wastewater reuse, new reservoirs, expansion of use of certain water sources, and water supply recommendations and projects.
Date:
December 2015
Creator:
Brazos G Water Planning Group
Object Type:
Report
System:
The Portal to Texas History
Regional Water Plan: Region K (Lower Colorado), 2016, Volume 1. Main Report
Water plan for Region K describing water resources and suppliers in the area, usage statistics and forecasts, water needs, recommendations for water management for different suppliers and areas, drought response measures, and plan creation activities.
Date:
November 2015
Creator:
Lower Colorado Regional Water Planning Group
Object Type:
Report
System:
The Portal to Texas History
Draft Environmental Impact Statement: Edwards Aquifer Recovery Implementation Program, Habitat Conservation Plan, Final Report, Volume 3
Final part of a report evaluating the environmental impacts of adopting a Habitat Conservation Plan (HCP) prepared by the Edwards Aquifer Recovery Implementation Program (EARIP) that would permit incidental take of endangered species during other lawful activities, while attempting to minimize or mitigate expected impacts. This volume contains memorandum of agreement for Edwards Aquifer Recovery Implementation Program with signature pages, as well as associated research reports referenced by the study.
Date:
June 2012
Creator:
U.S. Fish and Wildlife Service
Object Type:
Report
System:
The Portal to Texas History
Re-evaluation of DART Orange Line DFW Airport Extension Irving-3 Environmental Assessment: Final
This report represents a re-evaluation of the environmental impact of DART's Orange Line DFW Airport Extension following modifications made to the proposed project after both the FAA and FTA had issued a Finding of No Significant Impact (FONSI). The purpose of this report was to determine if the modifications might result in environmental impacts not previously not documented in the earlier environmental assessment, in which case the FONSIs would remain valid. Some modifications to the rail alignments were made to avoid the need to relocate FAA infrastructure, to eliminate bridge structers that could impact flight safety, and to provide enough space for future roadway expansions.
Date:
April 2012
Creator:
Dallas Area Rapid Transit
Object Type:
Report
System:
The Portal to Texas History