Evaluating the Utility of Object-Based Image Analysis for Ecological Monitoring of Pinon-Juniper Mortality

Forested ecosystems in the American Southwest are experiencing change at an unprecedented rate, largely due to mortality events triggered by increased temperatures, drought, and insect infestations. Large-scale changes in the distributions of these ecosystems can potentially alter regional-scale carbon, water and energy dynamics. One biome in particular that has experienced increased mortality and altered forest composition over the past 30 years are Piñon-Juniper woodlands (Pinus edulis, Juniperus spp.) in the American Southwest. New fields of study, in particular, Remote Sensing, are applying and adapting traditional methods for ecological monitoring of these woodlands. Remote sensing offers the potential to synoptically classify and quantify specific tree species within mixed communities such as Piñon-Juniper (PJ) woodlands. This thesis tests the utility and reliability of an Object-Based Image Analysis (OBIA) classification applied to Very-High Resolution (VHR) imagery fused with historical National Agricultural Imagery Program (NAIP) imagery for detecting and quantifying piñon-pine mortality trends on a plateau of PJ woodland in Central New Mexico. Specifically, the research seeks to determine: (1) the accuracy of OBIA applied to VHR imagery for quantifying live PJ and dead piñon; and (2) the potential of NAIP data for creating an ecological timeline of forest mortality from 2005-2014. The OBIA process generated an overall classification accuracy of over 70%, whereas the time-series analysis using NAIP resulted in an overestimation of piñon mortality when compared to two sample-plots at the region

Ecohydrologic Connections in Semiarid Rangeland Ecosystems in Oregon

An improved understanding of the ecohydrologic relationships in semiarid rangelands is imperative for the development of effective rehabilitation and land management practices. This thesis addresses the ecohydrologic relationships of two significant issues concerning semiarid rangeland ecosystems: western juniper encroachment and increasing stream temperatures. This thesis is divided into two chapters; each chapter is a manuscript reflecting a separate research site and project. The first chapter compares the use of ground and UAV-based measurements to assess vegetation and juniper characteristics in a juniper-dominated ecosystem. The second chapter describes the results of a preliminary investigation into stream temperature relationships of a semiarid riparian system in northcentral Oregon. Both manuscripts are currently being prepared for journal submission. Western juniper encroachment is a concern across many areas of the western United States and is associated with ecohydrological changes such as increased erosion and reduced intercanopy vegetation. The first research study took place at the Camp Creek Paired Watershed Study (CCPWS), as part of a long-term research project into the ecohydrological impacts of juniper encroachment and removal. The study sought to assess differences in vegetation cover between two watersheds with different densities of western juniper and to examine the accuracy of data collected using low-altitude Unmanned Aerial Vehicles (UAVs) to characterize canopy cover and vegetation cover. Based on ground-based measurements, some significant differences in vegetation cover were found between the two watersheds. Shrub cover was higher in the treated watershed than in the untreated watershed, although bare ground was similar. Herbage production in the treated watershed was also significantly greater in the treated watershed. Canopy cover estimates using UAV-based data were similar to ground estimates when multispectral vegetation indices were used. Additionally, supervised classification that utilized multispectral imagery and Normalized Difference Vegetation Index (NDVI) values yielded more accurate indications of overall vegetation cover than using multispectral imagery alone, but was only successful at differentiating between juniper from other vegetation when fall imagery was used. The second chapter of this thesis addresses stream temperature, a concern in many regions of the world because of its impact on cold-water species and biochemical processes. However, published research regarding stream temperature dynamics in arid or semiarid rangeland systems is limited. The research for the second manuscript took place in a semiarid rangeland system in northcentral Oregon along Fifteenmile Creek, which has been found to exceed suggested maximum stream temperatures. This study took place between 2014 and 2017, and examined stream temperature relationships associated with riparian shade, groundwater inflows, and ambient conditions. Stream temperatures generally followed the longitudinal gradient, with higher stream temperatures corresponding to lower elevations. During the summer, a difference of up to 5°C in the 7-day moving average stream temperature was observed between the highest and lowest elevation sites, while stream temperatures during the fall and winter seasons were more similar between sites. Air temperature was shown to be highly correlated to both shaded (r=0.960) and non-shaded (r=0.961) stream temperatures. In general, no significant difference was found between areas with riparian shading and non-shaded areas. Shallow groundwater temperatures showed less variability than stream temperatures. Groundwater was also generally cooler in the summer and warmer in the winter when compared to surface flow conditions. Differences between shallow groundwater temperatures and stream temperatures of up to 8°C in the summer and 10°C in the winter were observed, indicating that shallow groundwater inputs may have a moderating input on stream temperatures. Ecohydrologic connectivity, particularly concerning the relationship of vegetation and hydrologic characteristics, was an important consideration in both research studies. While additional research is necessary, this research provides insight into an improved understanding of how these connections can influence semiarid rangeland ecosystems

Remote Sensing Based Simple Models of GPP in Both Disturbed and Undisturbed Piñon-Juniper Woodlands in the Southwestern U.S.

Remote sensing is a key technology that enables us to scale up our empirical, in situ measurements of carbon uptake made at the site level. In low leaf area index ecosystems typical of semi-arid regions however, many assumptions of these remote sensing approaches fall short, given the complexities of the heterogeneous landscape and frequent disturbance. Here, we investigated the utility of remote sensing data for predicting gross primary production (GPP) in piñon-juniper woodlands in New Mexico (USA). We developed a simple model hierarchy using climate drivers and satellite vegetation indices (VIs) to predict GPP, which we validated against in situ estimates of GPP from eddy-covariance. We tested the influence of pixel size on model fit by comparing model performance when using VIs from RapidEye (5 m) and the VIs from Landsat ETM+ (30 m). We also tested the ability of the normalized difference wetness index (NDWI) and normalized difference red edge (NDRE) to improve model fits. The best predictor of GPP at the undisturbed PJ woodland was Landsat ETM+ derived NDVI (normalized difference vegetation index), whereas at the disturbed site, the red-edge VI performed best (R2adj of 0.92 and 0.90 respectively). The RapidEye data did improve model performance, but only after we controlled for the variability in sensor view angle, which had a significant impact on the apparent cover of vegetation in our low fractional cover experimental woodland. At both sites, model performance was best either during non-stressful growth conditions, where NDVI performed best, or during severe ecosystem stress conditions (e.g., during the girdling process), where NDRE and NDWI improved model fit, suggesting the inclusion of red-edge leveraging and moisture sensitive VI in simple, data driven models can constrain GPP estimate uncertainty during periods of high ecosystem stress or disturbance

Burning question: How much drought causes increased flammability in eastern redcedar?

Encroachment of eastern redcedar, Juniperus virginiana, due to fire suppression, is one of the greatest contributors to the degradation of North American grasslands. Mature trees are unlikely to burn during wet periods. However, during extended dry periods when live foliar moisture (LFM) approaches 80% they become more easily ignited and combustible. Currently, the amount of drought that is necessary to cause such reductions in LFM is unknown. To identify factors that contribute to wildfire risk I examined the relationship between leaf water potential and LFM in eastern redcedar. I used a dual greenhouse/field approach to link field conditions with changes in LFM and water potential. In the greenhouse, I designed a drought experiment to track LFM and leaf water potential in eastern redcedar. The field study was designed to relate greenhouse results to realistic field conditions. I chose 3 sites in Oklahoma with different levels of annual precipitation: Woodward (dry), Marena (moderate), and Cookson (wet). I measured LFM, water potential, and soil moisture in the field through a range of seasonal variation in climate. I used the Oklahoma Mesonet to identify other meteorological factors which contribute to changes in LFM. I found that leaf water potential can be used to predict LFM accurately and that relationship does not fluctuate based on site or previous drought conditions. Specifically, I observed a decline in LFM in two phases, a more rapid initial decline followed by a less rapid decline that is consistent with the onset of stomatal regulation in this species. Additionally, I identified a physiologically based model using metrics of soil water potential and vapor pressure data that I calculated from data available from the Oklahoma Mesonet to predict fire risk in eastern redcedar. Ultimately, my model can be used to predict LFM in populations of eastern redcedar across the state which can be used to improve fire risk predictions in Oklahoma

Evaluation of ecosystem integrity and services on regional level with the use of participatory approaches

TITLE: Evaluation of ecosystem integrity and services on regional level with the use of participatory approaches AUTHOR: Mgr. Jakub Zelený DEPARTMENT: Environmental studies SUPERVISOR: Mgr. Davina Elena Vačkářová, Ph.D. ABSTRACT: The presented work proposes and applies a set of methods designed to describe ecosystem integrity, services and landscape values, including their interaction, on the example of several studied regions. The included publications describes 4 types of methods for evaluating these phenomena: remote sensing of the Earth, regional statistics, expert matrices, and qualitative interviews and mapping. Applied methods can be divided into natural sciences and social sciences, and part of the work is to evaluate the benefits and compare the compatibility between these very different methods in evaluating selected elements of landscapes. The methods are applied in a variety of ranges, ranging from urban areas (10 km2) to the federal states. Natural ecosystems and forests have been assessed best in terms of ecosystem integrity, with the relationship between ecosystem integrity and crop production being negative. Qualitative mapping of landscape values revealed that pristine and inaccessible areas, as well as single- purpose sites, had low societal value in terms of intensity and / or diversity...NÁZEV: Hodnocení ekosystémové integrity sužeb na regionální úrovni s využitím participativních metod AUTOR: Mgr. Jakub Zelený KATEDRA (ÚSTAV) Environmentální studia ŠKOLITEL: Mgr. Davina Elena Vačkářová, Ph. D. ABSTRAKT: Předkládaná práce navrhuje a aplikuje sadu metod určených k popisu ekosystémové integrity, služeb a krajinných hodnot, včetně jejich interakce, na příkladu několika studovaných regionů. Zahrnuté publikace popisují 4 typy metod k hodnocení těchto fenoménů: analýzu dat z dálkového průzkumu Země, regionálních statistických údajů, expertních matic a kvalitativních rozhovorů a mapování. Aplikované metody lze rozdělit na přírodovědné a společenskovědní, přičemž součástí práce je ohodnocení přínosu a porovnání kompatibility mezi těmito značně odlišnými metodami při hodnocení vybraných prvků krajinných celků. Metody jsou aplikovány v různých škálách, sahajících od městských částí (10 km2 ) až po spolkové státy. Přírodní ekosystémy a lesy byly hodnoceny z hlediska ekosystémové integrity nejlépe, přičemž vztah mezi ekosystémovou integritou a produkcí zemědělských plodin byl záporný. Kvalitativní mapování krajinných hodnot odhalilo, že bezzásahové a nedostupné oblasti, stejně jako jednoúčelové hospodářské lokality, měly nízkou společenskou hodnotu z hlediska intenzity a/nebo pestrosti hodnot. Místa s...Doktorský program Environmentální studiaPhD Environmental StudiesFakulta humanitních studiíFaculty of Humanitie