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in creator/contributor: "Ponette-González, Alexandra"  
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Automated Treetop Detection and Tree Crown Identification Using Discrete-return Lidar Data

Description: Accurate estimates of tree and forest biomass are essential for a wide range of applications. Automated treetop detection and tree crown discrimination using LiDAR data can greatly facilitate forest biomass estimation. Previous work has focused on homogenous or single-species forests, while few studies have focused on mixed forests. In this study, a new method for treetop detection is proposed in which the treetop is the cluster center of selected points rather than the highest point. Based on … more
Date: May 2013
Creator: Liu, Haijian
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Effects of Vegetation Structure and Canopy Exposure on Small-scale Variation in Atmospheric Deposition Inputs to a Mixed Conifer Forest in California

Description: Data on rates of atmospheric deposition is limited in many montane ecosystems, where high spatial variability in meteorological, topographic, and vegetation factors contributes to elevated atmospheric inputs and to the creation of deposition hotspots. Addressing the ecological consequences of increasing deposition in these areas will require a better understanding of surface controls influencing atmospheric deposition rates at both large and small-scales. The overarching objective of this thesi… more
Date: May 2014
Creator: Griffith, Kereen
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Informing Conservation Management Using Genetic Approaches: Greater Sage-Grouse and Galápagos Short-Eared Owls as Case Studies

Description: Small isolated populations are of particular conservation interest due to their increased extinction risk. This dissertation investigates two small wild bird populations using genetic approaches to inform their conservation. Specifically, one case study investigated a Greater Sage-grouse (Centrocercus urophasianus) population located in northwest Wyoming near Jackson Hole and Grand Teton National Park. Microsatellite data showed that the Jackson sage-grouse population possessed significantly re… more
Date: May 2016
Creator: Schulwitz, Sarah E.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Are Streams Protected? Outcomes of Environmental Regulation

Description: Urban areas experience the loss of natural stream channels through conversion to artificial conveyances. This process tends to target headwater and other low order streams. The purpose of this study is to determine the patterns of stream loss in Denton, Texas, and explore the regulatory structure that manages these streams. Historic and current maps and stream data are used to map Denton's streams and categorize them according to their vertical connectivity as: 1) "intact", streams that are … more
Date: August 2017
Creator: Rowen, Zachary
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Wildfire Influence on Rainfall Chemistry and Deposition in Texas during the 2011-2014 Drought

Description: From 2011 to 2014, one of the most severe and intense droughts in Texas recorded history led to widespread wildfires across the state, with unknown effects on atmospheric nutrient and pollutant deposition. The objectives of this research were to: (1) characterize the frequency, magnitude, and spatiotemporal distribution of Texas wildfires (2011-2014); (2) identify smoke occurrence and source regions at eight Texas National Atmospheric Deposition Program (NADP) National Trends Network (NTN) site… more
Date: August 2021
Creator: Williamson, Thomas
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

American Lawn Addictions: Effects of Environmental Education on Student Preferences for Xeriscaping as an Alternative in North Central Texas, USA

Description: Urban land use and land cover has changed in the USA, giving rise to the American lawn – manicured, resource-intensive, and non-native. Green infrastructure design has been suggested in the literature as a potential alternative to the American lawn when managed as native xeriscapes, which require little to no irrigation after establishment. Given the influence of public preference on landscaping decisions, what is the relationship between the perceived value and ecological benefits of the Ameri… more
Date: May 2019
Creator: Williams, Jared L.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Urban Trees as Sinks for Soot: Deposition of Atmospheric Elemental Carbon to Oak Canopies and Litterfall Flux to Soil

Description: Elemental carbon (EC), a product of incomplete combustion of fossil fuels and biomass, contributes to climate warming and poor air quality. In urban areas, diesel fuel trucks are the main source of EC emissions from mobile sources. After emission, EC is deposited to receptor surfaces via two main pathways: precipitation (wet deposition) and directly as particles (dry deposition). Urban trees may play an important role in removing EC from the atmosphere by intercepting and delivering it directly… more
Date: May 2018
Creator: Rindy, Jenna
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Structure, Composition, and Regeneration of Cross Timbers Forest Fragments in Different Land Use Contexts

Description: 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 rand… more
Date: May 2015
Creator: Dunn, Ingrid
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Pastoral Livelihoods and Household Water Management in the Central Argentine Andes

Description: Pastoralists tend to occupy highlands and drylands lands with uncertain climates and are experienced at coping with climatic variability and drought. Increasingly, however, the speed with which climate patterns are changing has become an issue of concern. This study examines household water management strategies of pastoralists in western Argentina. In this semi-arid region, pastoralists rely primarily on streams and springs fed by snow and glacier melt from the Andes, and have developed var… more
Date: May 2015
Creator: Parker, Julie
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Memory and Continuity Amidst Irreversible Decline in the Texas Big Empty

Description: This thesis interrogates sense of place and place attachment in the Big Empty on the north central Texas plains. The region stretches from the Red River on the north to the Colorado River basin on the south and from the Cross Timbers on the east to the Caprock escarpment on the west. Since 1930, the Big Empty has seen sustained and severe population decline such that some counties there now register less than a quarter the population they did at their peaks during the interwar years. Through in… more
Date: December 2016
Creator: Underwood, Robert Reed
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

A Quantitative Assessment of Site Formation at the Dmanisi Archaeological Site, Republic of Georgia

Description: The focus of this thesis was to gather and analyze micromorphological and petrographic data on soils at the archaeological site of Dmanisi in order to better understand the extent to which the deposition and alteration of the sediments has affected the preservation of artifacts and faunal remains. A major goal of this research was to test hypothesis related to why bone material is discovered in some strata and not in others. This research focuses on the application of micromorphology (supplemen… more
Date: August 2013
Creator: Crislip, Peter S.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Soil Carbon Accumulation in an Urban Ecosystem: Canopy Cover and Management Effects

Description: Black carbon (BC), a stable form of organic carbon (OC), is a byproduct of the incomplete combustion of biomass, biofuels, and fossil fuel. The main objectives of this research are to examine the spatial distribution of OC and BC in urban soil and determine the influence of tree canopy cover and landscape maintenance on soil carbon accumulation. Soil sampling was conducted at 29 sites throughout the City of Denton, Texas, in May 2019. Samples were collected from underneath post oak canopies and… more
Date: May 2020
Creator: Kang, Katherina A
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Importance and Spatial Distribution of Phytophthora Ramorum Host Species in a Coast Redwood Forest

Description: Phytophthora ramorum, an exotic forest pathogen known as ‘sudden oak death’ (SOD), has received considerable attention in recent years because of its effects on vegetation structure, composition, and fire disturbance regimes in western U.S. coastal forests. This research examines differences in the importance (e.g., density, dominance, and frequency) and distribution of five host species of P. ramorum–– Umbellularia californica (California bay laurel), Quercus agrifolia (coast live oak), Pseudo… more
Date: May 2014
Creator: Gray, Alicia E.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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