LEE- Yer Sistem Bilimi Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/19499

Gözat

Analysis of global climate change on the hydrography of the Black Sea using CMIP6 climate models

(Graduate School, 2023-01-06) Çetin, Derin Ülger ; Ilıcak, Mehmet ; 601191004 ; Earth System Science

Climate change has numerous impacts on Earth from past to today. Specially after industrial revolution, the impact of climate change on Earth has been increasing and therefore has been focus of interest by scientists. The study of climate change has become important in terms of examining the negative effects such as drought, floods, the increase in the frequency and impact of severe hurricanes, as well as the increase of ocean and sea water levels, pH changes, salinity and temperature changes, and the melting of glaciers. The models used in this paper created using the close relationship between the ocean and the atmosphere and the use of past climate parameters, with an aim of modeling the ocean parameters for the next century. In this study, the behavior of the Black Sea water in different climate models for the next century was tried to be understood by considering the sea surface water temperature, salinity and heat exchange with the atmosphere, and comparisons between the models were included. In this study, we have analyzed the spatial and temporal variations of sea surface temperature (SST) and sea surface salinity (SSS) in the Black Sea using nine different climate models from the CMIP6 database. We have also examined the net heat flux (Qnet) and the heat transport through the Bosporus Strait, as well as the frequency and duration of marine heatwaves (MHWs) in the Black Sea. Our results show that the Black Sea is expected to experience significant warming and changes in salinity in the 21st century, with SST increasing by an average of 4.5 °C and SSS increasing by an average of 2.25 psu. These changes are expected to have significant impacts on the Black Sea ecosystem, as well as on human populations and industries in the region. Our analysis of SST and SSS using the nine CMIP6 models reveals a spatially asymmetrical pattern, with the western part of the Black Sea expected to experience greater warming than the eastern part. The multi-model mean also shows that the warming trend in the Black Sea is expected to continue in a nearly monotonic, corresponding to the increase phase of global climate change due to anthropogenic activities. Our analysis of Qnet and heat transport through the Bosporus Strait reveals that the asymmetrical warming pattern in the Black Sea is not due to heat transport from the Bosporus, but rather to net heat flux. We also found that the Rim Current system may play a role in this asymmetrical warming pattern. Our analysis of MHWs in the Black Sea shows that there is expected to be a regime shift in SST, with the frequency and duration of MHWs increasing significantly in the 21st century. In some models, the total number of days considered MHWs is projected to reach over 300 days per year by the end of the century. In conclusion, our study provides new insights into the expected impacts of global climate change on the Black Sea, highlighting the need for further research and efforts to mitigate and adapt to these changes. The asymmetrical warming pattern and the expected increase in MHWs have significant implications for the Black Sea ecosystem, as well as for human populations and industries in the region. Further research is needed to better understand the mechanisms driving these changes and to develop strategies for addressing their impacts.
Assessing the Bosphorus as a migratory corridor for Pipistrellus nathusii using acoustic monitoring methods

(Graduate School, 2024-07-02) İlbaş, Tuğçe Nur ; Çoraman, Emrah ; 601211009 ; Earth System Science

Türkiye has one of the richest bat diversity in the Mediterranean region. However, essential ecological information about bat species, such as population sizes, distributions and their migration behaviour is lacking. This information gap is primarily due to the elusive behavior of bats. Most of the bat research in Türkiye is about cave-dwelling species, which are relatively easier to study. Studies on other species, on the other hand, are generally based on opportunistic and non-systematic surveys. In this context, acoustic ecology methods offer an effective approach to investigating bats. This study aims to conduct a systematic acoustic ecology investigation in İstanbul, Türkiye, with a specific focus on the role of Bosphorus as a migratory corridor for bats. In particular, the migration patterns of Pipistrellus nathusii, a long-distance migratory bat species, were investigated. Additionally, the relationship between bat activity and meteorological parameters, as well as moon phases were explored to assess their impact on migration. Ultrasonic sound recordings were collected from four different locations along the Bosphorus, spanning from north to south, between April and November 2022. Recordings were preliminary analysed with Kaleidoscope Pro software and then processed manually. Analysis revealed that bat activity was positively related to temperature. Wind speed and direction affect bat activity in different ways depending on the season. In particular, light winds are positively associated with bat activity. When the effect of moon phases on bat activity was examined, it was found that the P. nathusii activity level in Yıldız City Park and ITU Campus was more affected by the moon phases, and especially the Nathusius Pipistrelle acoustic group activity decreased during the full moon phase. Pipistrellus nathusii activity in Yıldız City Park increased from mid-August and decreased towards the end of October. Activity on the ITU Campus started to increase in mid-August, peaked towards the end of September, and decreased at the end of October. Activity in the Atatürk City Forest started to increase in mid-August, peaked in September, and continued to decrease slightly in the autumn. In the Sarıyer Forest, there was an increase in August, the highest activity was seen in September and decreased with the end of the autumn. These findings show that the Bosphorus is a migratory corridor for P. nathusii. The insights gained from this study will contribute to the conservation of migratory bat routes between Europe and Asia.
Distribution of radionuclides in Arıklı region (Çanakkale/Ayvacık) and possible causes

(Graduate School, 2022-06-28) Top, Gülcan ; Tutay Örgün, Yüksel ; Karahan, Gürsel ; 601112002 ; Earth System Science

The aim of this thesis is to determine the indoor and outdoor gamma dose rates in Arıklı (Çanakkale/Ayvacık/Turkey) uranium mineralization region, to determine the activity concentrations of 226Ra, 232Th, 40K in selected samples (building materials, rocks, surface soils, beach sands and soil samples collected from excavation ditches), to map the outdoor gamma dose rates and the activity concentrations of the radionuclides specified in the surface soils using geographic information systems, to identify the geological sources that cause high doses and to evaluate the possible health risks for the region based on all these measurement results. The measurement of mass concentrations for U, Th on some selected samples is also included into the study. This study is the first comprehensive study for the region. For this thesis, the Arıklı region was considered as a research area due to the presence of a uranium mineralization zone and the prevalence of felsic volcanic rocks containing above-average uranium, thorium and potassium concentrations. In order to determine the level of radioactivity in the Arıklı uranium mineralization region, preliminary field studies were started in 2015 measuring the outdoor gamma dose taking into account the geological formations. It has been determined that anomalies are especially concentrated in and around the drilling points determined by the General Directorate of Mineral Researches (MTA) to search for uranium.
Ecological niche modeling of Myotis davidii

(Graduate School, 2022-06-09) Aksakal, Emre Can ; Çoraman, Emrah ; 601181012 ; Earth System Science

Myotis davidii is a whiskered bat species distributed in large areas of the Western Palaearctic. It has a cryptic sister species, Myotis mystacinus, which also has a similar distribution range in Europe and western Asia. The distribution of M. davidii extends from the Balkans to the Far East Asia, whereas M. mystacinus is found in Europe, Anatolia, and the Caucasus. They have a sympatric range in an area extending from the Balkans to the Transcaucasia via Anatolia. In this sympatric area, the populations of M. davidii had discordant patterns of mitochondrial and nuclear DNA, indicating that there were gene exchange between these species in the past. In this study, it was aimed to investigate the effects of the past climatic conditions on the evolutionary history of M. davidii and its cryptic sister species, M. mystacinus. The particular aims of this thesis are: 1) to construct the bioclimatic niches of M. davidii and M. mystacinus; 2) to identify their putative refugial areas during the last glacial period; and 3) to assess their responses to current climate change. In order to investigate these aims, ecological niche models were utilized. Ecological niche models aims to predict the distribution range of species by matching the environmental factors with species occurence points. Ecological niche modeling approach has become a common and practical application in conservation and biogeography study, especially with the advent of computer sciences and essential databases. In this study, ecological niche models are constructed by using the R programming language, as implemented in the BIOMOD2 package. A maximum entrophy appoach was used, which is a machine learning method developed for ecological niche modelling applications. The constructed models captured the current range of M. davidii but failed for M. mystacinus. For Myotis mystacinus, the lack of data from the Balkans and Anatolia was the likely reason for the unsuccessful model projections. The models for M. davidii suggest that inaccordance with the genetic lineages there might be to separate ecological units. Past projections suggest that Anatolia and the Balkans might have acted as refugial areas for both of the species during the Last Glacial Maximum. For M. davidii, the coastal regions of the Black Sea and the Mediterranean regions of Anatolia were likely refugial areas. These findings highlights the importance of Anatolia as a glacial refugium. Finally, the future projections suggested that there will major range shifts in the distribution of these species, especially for M. mystacinus moving towards norther Europe.
Effects of climate change on potential range shifts and composition of Türkiye's terrestrial ecosystems

(Graduate School, 2024-03-18) Ekberzade, Bikem ; Şen, Ömer Lütfi ; Yetemen, Ömer ; 601192001 ; Earth System Science

At the current critical juncture with climate change, centennial projections of potential species distributions in biodiversity hotspots, using dynamic vegetation models with integrated ecological notions such as competition, may provide vital insight into conservation efforts. The central aim of this thesis research is to estimate the current and future potential distribution of Türkiye's forests and their composition in the absence of anthropogenic landcover change, to calibrate the bioclimatic thresholds of certain key taxa to reflect their regional distribution in simulations using a process-based dynamic regional-to-global vegetation model (DGVM) to introduce new taxa to the simulations where necessary and in this manner to contribute to past studies on the distribution of European forest taxa by filling an important spatial gap. For this purpose, potential distribution of 25 forest taxa, and a C3-grass type are simulated by means of LPJ-GUESS v. 4.1 for the Anatolian Peninsula, keeping a spatial window large enough to track temporal changes in the vegetation range and composition in its surrounding areas. The model was forced with ERA5-Land reanalysis data for the historical period (1961-2014), and five different global climate model (GCM) contributions to the 6th phase of the Coupled Model Intercomparison Project (CMIP6) for the scenario period (2015-2100). The GCM datasets were interpolated to ERA5-Land's resolution and bias corrected with the climatology of the reference period 1995-2014 from the ERA5-Land dataset. The reference period for bias correction was selected in accordance with the 6th assessment report of Intergovernmental Panel on Climate Change (IPCC 2021), and in part, to reflect the current state of global warming. Shared Socioeconomic Pathways (SSP) 5-8.5, the high emissions scenario, was selected for all simulations. The bioclimatic tolerance levels of all plant functional types were calibrated using the temperature components of 1 km CHELSA dataset, and 9 km ERA5-Land datasets, calculating climatologies where necessary using Climate data operators (CDO) and R computing language; species distribution maps from European forest genetic resources programme (EUFORGEN); and the forest inventory data from General Directorate of Forestry (GDF) of Türkiye. In situ site visits were also undertaken to critical regions within the study area to further finetune the bioclimatic tolerance levels of certain key taxa, and further analysis of both observation data and the simulation results were made using R and ArcGIS. The simulation results from multiple model runs highlighted a consistent increase in woody species biomass for the entire study region, by the end of the century. The increase in biomass, mainly in the grasslands ecosystems was an important outcome of these series of simulations, which highlighted a consistent encroachment of woody taxa into terrain that is otherwise dominated by grasslands in simulations, in part reigniting the discussion over the past anthropogenic influence on the current vegetation composition of the Peninsula. The mountain systems also came out as important potential refugia for many cold-favoring woody taxa. Throughout the centennial simulations, the tree species prioritized an altitudinal move rather than a latitudinal one, consolidating their ranges around high elevation massifs, occasionally giving up their density dominance but gaining biomass. The composition of forest and woodland ecosystems shifted in large part in favor of the temperate taxa, as these species expanded their distribution ranges throughout the study area, without any particular prioritization for altitude or latitude. Temperate taxa with higher tolerance for drought increased their overall biomass and density, while the drought sensitive species gave up their dominance but continued to exist in smaller groups in areas where resource limitation became a determinant for the outcome of competition. All simulated taxa survived the 140-year simulation period at some capacity (there were no potential regional extinctions), finding some form of a footing along this ancient land bridge – some giving up their largely monotypic/homogeneous forest ranges for mixed forest compositions; others either leaving their dominant presence and becoming a "member of the team"; or exerting their dominance over a larger area. Overall, the results from these series of simulations, sans human presence, suggest a high potential for future forest cover throughout the study region by the end of the century under a high emissions scenario, and important changes in vegetation composition including encroachment of grasslands ecosystems by woody taxa. Our findings also corroborate recent paleo studies that highlight the early forest capacity of Asia Minor, and with the right environmental policies in place to ensure a fair human-nature co-existence, the region may continue to play its role as a cradle.
Effects on the transportation of pollen grains and inorganic particles in sedimentological processes

(Graduate School, 2024-06-12) Acar, Dursun ; Biltekin, Demet ; Kalenderli, Özcan ; 601191017 ; Earth System Science

Sedimentary particles can be inorganic or organic origin. While these materials are the size of clay or sand, the environments they are transported in are solid, liquid, gases or their mixtures. These sedimentary particles, no larger than grains of sand or clay, come from both inorganic and organic sources. Remarkably, they travel with forces that propel them through a surprising variety of environments, not just water or air, but also solids, and even mixtures of these states. Their transportation takes place in the form of creep movement under tectonics or gravity in solids, laminar flow, density flow, or discrete partial bulk or fully discrete granular, depending on the types of physical forces in gases and liquids. These forces, originating from inorganic or biological sources as same as particles, act on the particles with or without significantly altering the surrounding environment. For example, while the interactions of pollen grains with each other during their movements in the air and the interactions coming from the atmosphere are in question, today it has been understood that the bees flying in the air have gained a positive charge and accordingly, they collect and carry the pollen with a negative charge in the plant by static electricity attraction. Secondly atmospheric electric and other carrier environments such as wind, water, density currents understanding these interactions between themselves is essential for various fields at natural sciences.
Endless tug-of-war: impact of social media on science communication of climate change

(Graduate School, 2023-06-21) Altan, Derin ; Yetemen, Ömer ; 601201006 ; Earth System Science

The pervasiveness of social media in contemporary society necessitates a comprehensive, particularly by climate scientists, an understanding of social media's undeniable impact on the mass communication and perception of climate change by the "commons". This thesis provides an in-depth exploration into the multifaceted role that social media plays in the dissemination of, and – of course, most importantly – the public understanding of the incredibly complex issue of climate change. The study also further delves into the trajectory of science communication and climate change communication, providing a historical backdrop against which the emerging role of social media is investigated thoroughly. The undeniable capability of modern social media platforms to either augment public comprehension of climate change or contribute to misinformation and misunderstanding is critically evaluated, with a particular emphasis on the phenomenon of online polarization – an agonizing development that can dangerously shackle even the most careful climate communicator. An analysis of various polarized climate change topics on social media uncovers key actors and narratives that significantly shape the public discourse surrounding this critical issue. Parallel to this, the research contrasts the strategies adopted by mainstream media with the logic of effective climate change communication. The examination uncovers inherent contradictions between the two, largely driven by differing business models and journalistic practices that had lead mainstream media platforms for decades, which can ultimately impact public perception and action towards climate change. Moreover, the study sheds light on current trends in climate change communication across different social media platforms. It scrutinizes their potential and the challenges they pose in fostering widespread climate change awareness and inspiring public action. The findings underscore the complexity and multi-dimensionality of climate change communication in the digital age. A nuanced understanding of these dynamics offers scientists, communicators, and policymakers vital insights to develop more effective strategies for engaging the public in climate change discussions and inciting action. In summation, this thesis emphasizes the pressing need to navigate the challenges and seize the opportunities presented by social media. On one hand, the social media platforms provide an incredible opportunity: the ability to reach millions of people with the click of a button. On the other hand, the deep polarization probability of such communication rings the alarm bells, constantly. Regardless, an effective use of the social media platforms by climate change communicators (mostly climate scientists), is expected to enhance the public's general understanding of climate change science, reduce polarization that diminishes public discourse, and stimulate informed action towards developing effective mitigation, adaptation and resilience strategies, all of which are crucial steps in confronting the climate crisis.
Estimation of PM10 variations in the Southeastern and Eastern Anatolia regions of Türkiye using remote sensing and statistical models

(Graduate School, 2024-07-25) Murzaeva, Sultanay ; Ünal, Alper ; 601211016 ; Earth System Science

The significance of air quality extends to both indoor and outdoor settings, with poor air quality directly impacting the quality of life. Particulate Matters smaller than 10 μm in diameter (PM10) are of particular concern. Penetration to the airways is easier with these types of particles. Particulate Matters (PMs) can contribute to both respiratory and cardiovascular diseases (i.e. asthma, emphysema, and lung cancer). Air quality in Türkiye is affected by dust coming from Sahara Desert and Arabian Peninsula. Our study aims to research PM10 variations in the Southeastern and Eastern Anatolia regions of Türkiye from 2014 to 2016 using remote sensing and statistical models. The Moderate Resolution Imaging Spectroradiometer (MODIS) derived Level-3 Aerosol Optical Depth (AOD) data, air quality data and meteorological variables of 15 ground-observed stations present in the Southeastern and Eastern Anatolia regions of Türkiye were used in this study to assess PM10 estimations in the study area. The PM10 ground observations used in the study for the years 2014, 2015 and 2016 were received from the Republic of Türkiye Ministry of Environment and Urbanization and Climate Change. Hourly PM10 and meteorological data were converted to daily data and days having more than 30% missing values were not included into the study in order to find out PM10 variations. Moreover, statistical methods such as Multiple Linear Regression (MLR) model, Linear Mixed Effect (LME) model and Machine Learning (ML) techniques were used to anticipate the Particulate Matter (PM) concentration in the region using satellite-based AOD and meteorological variables such as temperature, wind speed, relative humidity, precipitation and atmospheric pressure. Since some cities are located on the same grid in the AOD study area map obtained from MODIS in the PM10 estimation studies, 12 out of 15 stations were included in the statistical analysis to avoid extra PM10 calculations. The results indicated that aerosol pollution in the region as a result of transported dust from the Arabian Peninsula in spring time was high enough and the PM10 concentration in the cities close to the borders of Iraq and Suria such as Hakkari and Mardin was observed more than 200 µg/m3 in spring of 2015. Both local heating emissions and long-range dust transport could have significantly impact on PM10 levels in Southeastern Anatolia in study period. In addition, stubble burning in those years may also be effective in the high PM10 levels in the region in the fall. Significant amounts of dust, pollution, or biomass combustion make contribution to higher atmospheric aerosol concentrations. MODIS data from the AOD maps of 2014, 2015 and 2016 show that the Southeastern and Eastern Anatolia regions were exposed to aerosol pollution. The results of statistical models for prediction of PM10 indicated that PM10 was very dependent on AOD and temperature. The statistical parameters such as Correlation Coefficient (R), R-Squared (R2) and Root Mean Square Error (RMSE) were calculated to understand performances of models applied in the study. In the MLR method, PM10 was estimated by including only one meteorological factor other than AOD. Each meteorological factor was used with AOD in the equation respectively in the MLR method. When PM10 was predicted by using all meteorological factors respectively, it showed that among these parameters, temperature affected PM10 values more. Based on the outcomes, performance of all statistical models was improved when AOD values with all meteorological parameters were used in estimating PM10. For example, the R, R2 and RMSE values of MLR for averaged data for summer season were calculated about 0.69, 0.47 and 8.21 with best performance in the study period, while winter accounted to the lower performance with R, R2 and RMSE values of 0.40, 0.16 and 25.10, respectively. MLR for all 12-station data gave its best result in autumn season with an R, R2 and RMSE values of 0.57, 0.33 and 42.46 respectively. For the LME model, the random effect parameter selected AOD enabled the model to have R, R2 and RMSE values of 0.51, 0.26 and 36.60, respectively for all study period. Atmospheric pressure also had a random effect in the LME model, with R, R2 and RMSE values of 0.86, 0.73 and 28.26, respectively for all studied years. AOD and atmospheric pressure had a significant impact on improving the LME model results. For whole study period Extreme Gradient Boosting (XGBoost) having 0.73, 0.54 and 17.88 values as R, R2 and RMSE, respectively for averaged data and having 0.69, 0.44 and 32.13 values as R, R2 and RMSE, respectively for non-averaged data making a moderate performance in estimating PM10 levels. Among all statistical methods, Random Forest performed the best in terms of fitting the regression line, with R, R2 and RMSE values of 0.97, 0.93 and 17.90, respectively, when averaged variables are included in the model, and R, R2 and RMSE values of 0.97, 0.93 and 29.26, respectively, when all variables are included in the model. While MLR depended on factors like quantity of meteorological variables included, its performance also was affected by which meteorological variable is chosen with AOD in PM10 estimation. In this study, the LME model also showed variability in performance depending on which meteorological variable was selected as a random effect for PM10 estimation. XGBoost's performance was moderate and it also had better results than MLR method for overall. In conclusion, satellite data with meteorological variables gives us the best performance when it is introduced to the Random Forest Model in order to forecast PM10 in study area. The correlation between PM10 and AOD is influenced by weather conditions, local pollutant emissions and the chemical composition of aerosols. Ground-based monitoring data is commonly used in health effect research. Because satellite data is readily available and inexpensive, AOD images can be used to estimate PM10 via using Machine Learning methods which processes factors that affect abundance of PM10.
Fire history and climate change: Black pine forests in Western Anatolia

(Graduate School, 2022-06-15) Şahan, Evrim Ayşe ; Dalfes, Hasan Nüzhet ; Köse, Nesibe ; 601172003 ; Earth System Science

Wildfire is a part of the ecological processes that is highly important for the sustainability of forest ecosystems in the Mediterranean Basin. Species adapted to crown fires, such as Turkish pine, are capable of regeneration after a fire and establishing new forests. On the contrary, tree species such as black pine adapted to surface fires have regeneration problems after severe crown fires, and mass extinctions in some regions can be observed. Many studies have revealed that the fire frequency of forests in the Mediterranean Basin is expected to increase due to climate change and the fire regime of black pine forests will shift from surface fires to crown fires. In order to understand the fire regime changes in the black pine forests in the Mediterranean Basin, including Turkey, centuries-long fire records are needed. Thus, dendrochronology is one of the most reliable and effective methods commonly used in fire history studies. In this doctoral thesis, the aims are to develop a high-resolution fire reconstruction of black pine forests in Turkey, determine the seasonality of historical fires, understand the association between climate variability and fire occurrence, understand the variability of spatiotemporal patterns of fires throughout the main distribution areas of black pine forests in Turkey using tree-ring analysis, and monitor the cambium activity in black pine forest. Several spatial and temporal studies are conducted in order to understand the effects of fire management strategies, climate types or geographical gradients on regional fire regimes in the world. A large number of dendrochronology-based studies were conducted, especially in North America, to understand the spatiotemporal patterns in different geographical gradients and different climate types and also corroboration of empirical data. However, in the Mediterranean basin, a few fire history studies based on dendrochronological methods was conducted in Greece, France and Spain to understand the regional fire regime and the relationship between fire and climate. To my knowledge, there is no any conducted fire history study for any species based on tree-ring analysis in Turkey. A total of 211 samples were collected from ten sites throughout western Anatolia. The collected samples were dated by standard dendrochronological methods and the seasonality of each sample was determined. The site-level composite and regional fire chronologies were created for Kütahya, Isparta, Bolu, and western Anatolia. The major fire years were calculated with the criteria that greater than or equal to 25% of recording samples have fire scars on that year in at least two of the samples, while the regular fire years were determined by recording samples have fire scars on that year in at least two of the samples. The relationship between the major fire years and climate was analysed using Superposed Epoch Analsis. Understanding the seasonality of historical forest fires facilitates the development of concepts related to fire as an ecological and evolutionary process. In order to understand the fire regime of a region, determination of the seasonality is a must. In dendrochronology-based fire history studies, the seasonality of fire scars is mostly classified according to the intra-ring position of the fire scars as a classical method. However, studies of cambial phenology are needed to accurately correlate the position of a fire scar with the months in a year. Because the timing of the earlywood and latewood production (cambial cell production) varies according to the species, location and climate. In this context, the aim of this part of this thesis is to determine in which months the cambium activity of black pine forests starts and in which month the early/latewood cells form. In order to monitor cambium activity, a total of 144 microcores were sampled from three sites near the fire history reconstruction sites during a vegetation period (April-November 2021). Monitoring the cambial activity helped to obtain information about which month(s) are risky for forest fires. The first tree-ring based 553-year long fire history reconstruction and cambial activity of black pine forests were presented to improve our understanding of the regional fire regime components with the effect of climate in Turkey. The fire return interval of black pine forests in Anatolia was calculated from a minimum of one year and a maximum of 105-year intervals over the study period. The seasonality of most of the fire scars in western Anatolia occurred in the latewood period. As conducted in a cambial activity study of black pine forests in western Anatolia, latewood tracheid cells are formed from (August in Isparta) from September to November. Since most of the fires in western Anatolia occur in latewood, the risky months for fires in the study area are from (July in Isparta) August to November (the late summer and autumn) based on xylogenesis studies. The relationship between climate and fire years calculated with regional fire chronologies showed that the major fires in Kütahya and Bolu are associated with dry years, while the wet conditions two years prior to major fire events in Isparta. The decrease in fire frequency was observed in the late 19th and early 20th centuries due to human-induced fire suppression activities. That can cause the accumulation of combustible material and pose a risk for more intense fires. Based on future climate projections, as a result of increased drought frequency, we will face extended fire seasons that may shift the fire regime from the surface to crown fires and even cause mega fires. A large number of simultaneous fires were recorded in the period between the mid-1800s and the early 1900s. The decrease in fire frequency after the early 1900s coincides with the first forest protection law in 1937. As a result of the comparison of fire years in western Anatolia, Spain, and Greece, more common fire years were found in studies of Greece than in Spain. The differences in climate conditions of the eastern and western Mediterranean due to frontogenesis or depressional activity might explain these different common fire years. The year 1879 was the most extensive fire year in Greece in the 19th century and it was recorded as one of the most common fire years in western Anatolia. The year 1945 was the only common fire year in the Mediterranean region sites. Results in this study showed that the fires in 1945, observed simultaneously in Anatolia, Greece, and Spain, occurred in the most severe and widespread drought among the spatially visualized common fire years. In this study, long-term fire history data were developed by using dendrochronological methods to understand the fire regime of black pine forests for the first time in Turkey. These fires were analyzed with a new approach with the determination of the seasonality by taking samples with microcores. Unlike studies only current fires are analyzed or fire history reconstructions, the results were obtained by integrating both ecological and statistical methods.
The impact of climate change on future extreme precipitation in Turkey

(Graduate School, 2021-08-06) Albayrak, Derya ; Şen, Ömer Lütfi ; 601191005 ; Earth System Science ; Yer Sistem Bilimi

This study investigates the impact of climate change on extreme precipitation in Turkey with the aid of both historical and model-based future projection data. Firstly, we have applied the equidistant quantile matching method and generated bias-adjusted extreme precipitation daily and sub-daily time series of 73 stations in Turkey from a 14 member CMIP6 ensemble. The resulting data are utilized for deriving the Intensity-Duration-Frequency curves for two future periods (2020-2050 and 2070-2100) and results are spatially presented. Thus, annual extreme precipitation with 1-hr, 2-hr, 6-hr, 12-hr, and 24-hr durations over Turkey are examined for 10-yr, 25-yr, 50-yr, and 100-yr return periods in two future periods through a CMIP6 ensemble-based analysis. The impacts of climate change on annual extreme precipitation in the regions of Turkey are estimated. Our CMIP6-ensemble analyses reveal that for the reference period 1970-2000 the highest impacts over Turkey are estimated for shorter duration (≤ 6-hr) generally higher-frequent annual extreme precipitation which may be attributed to the thermal enhancement due to the mean temperature increase in Turkey. Moreover, for all durations and frequencies covered here, till the mid-century, change in regional medians varies between 4.6-10.4% in the Marmara region, 4.9-8.4% in south-eastern Anatolia, 7.4-10.4% in the Aegean region, -1.8-0.8% in central Anatolia, 6.8-12.1% in eastern Anatolia, 5.2-7.2% in Black Sea region, 4-14.2% in Mediterranean region. Due to the high spatial variability of the extreme precipitation, both decreasing and increasing relative changes occur in the regions. However, by the end-century, the impact of annual extreme precipitation in the regions noticeably intensifies, relative regional medians raise to 18.5-21.7% in Marmara region, 14.8-18.7% in south-eastern Anatolia, 10.2-13.9% in Aegean region, 13.4-16.6% in central Anatolia, 19.3-23.3% in eastern Anatolia, 16.2-20.7% in Black Sea region, 15.1-21.1% in Mediterranean region. Coastal regimes in Turkey receive a higher amount of annual extreme precipitation than the continental parts, especially local extremes that are noticeable on the coastal line, which is projected for all future periods and extreme precipitation durations presented in this study. Moreover, according to the median of the relative changes among the regions, the south and north coasts of Turkey are subject to the impact of different annual extreme precipitation durations. Northern coastal regimes are projected to have the highest impact by the intensification of the short-duration annual extremes (≤ 2-hr annual extreme precipitation). Southern coastal regimes are estimated to have the highest impact by the longer duration (≥ 6-hr) annual extreme precipitation events. Central Anatolia, the only region with persistent decreasing median changes till the mid-century, experiences a substantial increase in the impact of the 1-hr and 2-hr high-frequent convective precipitation extremes at the end-century. Crucial for adaptation and mitigation strategies, our current practice of deriving and implementing Intensity-Duration-Frequency curves rely on the historical data, which may be insufficient for capturing the variable impacts of climate change. Consequently, underestimating the impact of climate change on extreme precipitation may result in a decrease in the capacity of the numerous hydrological systems to deliver the required services at their optimum. Thus, decision and policymakers should evaluate and consider the intensification of different extreme precipitation durations among both the regions and the future periods to eliminate the exacerbated vulnerability of the hydrological systems to climate change-related extreme precipitation events and manage adverse socio-economic consequences.
Invasive species distribution modeling under climate change

(Graduate School, 2023-08-08) Kanmaz, Oğuzhan ; Dalfes, Hasan Nüzhet ; 601152001 ; Earth System Science

Biological invasions are one of the most significant components of global environmental change. The biological consequences of invasions such as biodiversity loss, biotic homogenization, alterations in the structure and function of ecosystems are difficult to reverse and even impossible in many cases. The damages and loss caused by biological invasions are estimated to reach billion dollars each year. Post introduction control of an invasive species is often futile alongside being expensive and labor intensive. In this sense, prevention is considered to be the most effective strategy against invasions. Determination of the areas under risk of invasion and evaluation of the potential invasion scenarios are extremely important. To that end computational models constitute crucial tools. In recent decades increased availability of powerful hardwares, alongside with the accessibility of environmental and biogeographic data, due to the developments in information technologies, lead to the utilization of computational models in various fields of ecology. Species Distribution Models (SDMs), which are an example of such applications, especially the data-driven correlative methods, were utilized widely to investigate the impacts of global environmental change on the current and future distribution of species. Application of SDMs on invasive species to determine the areas under invasion via the projected suitability/presence probabilities, despite the criticism on the violation of the equilibrium assumption, has become a widely used method with various successful and promising examples. However, another problematic aspect of such applications is that the projected suitability cannot always be interpreted as an actual invasion since the dispersal is a crucial process of biological invasions. Agent-Based Modeling (ABM) is a population modeling method with wide applications in ecology to simulate various complex processes via the functional units called agents which can interact with each other and the environment. In this respect agent-based models constitute a remarkable alternative to simulate biological invasions with various examples in the literature. While agents-based models are especially useful to investigate the theoretical problems and considered as in silico laboratories for paradigmatic models, their application on spatially explicit, real world cases to construct pragmatic models is mostly difficult due to the lack of a priori knowledge on the majority of the species to calibrate such models. Hybrid modeling is a promising approach which can utilize more than one modeling method in tandem, by taking advantageous aspects of these methods which can complement each other to obtain more reliable results. Within the scope of this thesis, a hybrid modeling framework, which consists of a correlative and an agent- based component was constructed. Accordingly, while the framework proceeds in yearly time steps, correlative component produces bioclimatic suitability projections to be used by the agent-based component and the agent-based component generates simulated occurrence records to be utilized by the correlative component for making projections. Beyond the basic structure of the framework, the modular structure enables the inclusion of species specific processes which are constructed based on the a priori knowledge to obtain more realistic projections. For the implementation of the modeling framework, Impatiens glandulifera, a highly aggressive invasive plant native to Himalayas, was selected. Since its introduction to Europe and North America in the late 19th century as an ornamental plant, it has primarily invaded riparian habitats. The current invasive range of I. glandulifera spreads across the northern hemisphere. In the last two decades, it was observed to invade forests and mountainous areas. The spatial context of the model was determined as North America where the invasive range is far from reaching its bioclimatic potential and the simulations were conducted for 2020-2050 period under RCP 4.5 climate change scenario. In accordance with the a priori knowledge on I. glandulifera, the agent-based component of the framework which consists of three procedures (Climatic Window Procedure, Landscape Suitability Procedure and Propagule Procedure) to process three types of agents (productive, post-production and pre-productive agents) was constructed. The Climatic Window Procedure which consists of Chilling Period, Bioclimatic Suitability, and Productive Agent Sampling sub-procedures, performs the transformation of pre-productive agents to productive agents based on the chilling requirement and bioclimatic suitability projections that are generated by the correlative component alongside the sampling of the generated agents. The Propagule Procedure performs the generation and dispersal of post-generation agents. The Landscape Suitability procedure evaluates the transformation of post- generation agents to pre-productive agents based on the pH, elevation, slope, and land use properties. As the result of the conducted simulations, it was observed that the initial invasive range in North America, which is on the west and the east shores initially, has expanded through the 2020-2050 period. While in the eastern part of the invasion range, Great Lakes region and New England shores were observed to be saturated, progression on the western part was primarily determined by the mountain ranges. The severity of the projected invasion range on the Alberta-Saskatchewan region is especially remarkable, considering the limited presence of I. glandulifera in this area in the initial conditions. Another important result is the potential formation of a continuous range crossing the continent in the long term, due to the aggressive expansion to the interior regions. The projected latitudinal progression of the invasion is compatible with the large- scale pattern of the northward progression of the species due to climate change. While the northern boundary of the projected invasion range was roughly following the boreal biome, the southern boundary was formed on latitudes similar to the southern boundary of the invasion range in Europe. Another striking similarity was the southern progression on the west shores being limited by the Mediterranean climate observed in the region, which is also the determinant of the limited southward progression in Europe. The potential impacts of the I. glandulifera on the boreal forests, which are expected to be more fragile in the future due to climate change, must be carefully evaluated since I. glandulifera is known to spread in such disturbed forests. The long distance dispersal is mostly a result of anthropogenic activity, and unlike many of the natural processes, can lead to unpredictable results. This constitutes a limitation for the projections. Also, the impact of the incomplete occurrences data on the projections, especially records for the regions, is unavoidable. In the scope of this PhD thesis, it was aimed to construct a modeling framework by the utilization of correlative species distribution and agent-based modeling methods in tandem to simulate biological invasions under climate change. The framework was implemented to make projections for I. glandulifera invasion in North America for 2020-2050 period under RCP 4.5 scenario. In accordance with the conducted spatiotemporal analysis on the projections, invasion patterns were determined and the potential impacts on the invasive range were evaluated. The results were observed to be in concert with the historical invasion patterns of I. glandulifera in Europe and the climatic and environmental projections for North America. In this regard the framework can be considered a promising tool to be utilized for making projections which can be used for determination of the areas under invasion risk.
Investigating the genomic differentiation landscape of the large mouse-eared bats

(Graduate School, 2024-05-23) Şensoy, Bengisu ; Çoraman, Emrah ; 601211001 ; Earth System Science

Interspecific gene flow, through shaping the evolution of species over time, plays a pivotal role in evolutionary biology. Often complex and multifaceted, this process presents a rich area to explore the intricate dynamics that drive the evolution of species. The large mouse-eared bats, specifically Myotis myotis and M. blythii, present a particularly intriguing species complex for studying interspecific gene flow. Myotis myotis and M. blythii have substantially overlapping ranges across Europe and Anatolia. These species also exhibit evidence of gene flow, identified in the previous studies. Their shared mitochondrial lineage suggests past hybridization events. Additionally, nuclear marker based analyses identified evidence of recent gene flow events. Despite their sympatric distribution coupled with past and present hybridization events, the mechanism underlying the maintenance of separate gene pools remains an intriguing question. This study aims to contribute in the understanding of the evolutionary history of the large Myotis bats through a whole-genome approach. In this regard, genomic differentiation landscapes were considered within and between Large Myotis bats. For the genomic analysis, whole-genome shotgun sequencing data was generated from a total of thirty-four samples, representing M. myotis, M. blythii, and their closely related species, M. punicus. To assess the population structures and differentiation levels, Principal Component and Admixture analyses were conducted. Both analyses identified three distinct clusters in accordance with the three large Myotis taxa. Within M. blythii, a further split separating the individuals from Kyrgyzstan and Mongolia from the rest was present. Genomic landscapes of differentiation were explored through Manhattan plots of fixation index, nucleotide diversity and genomic divergence. The genomic differentiation assessments supported the nuclear divergence of M. myotis and M. blythii. Within M. blythii, East and West populations exhibited a significant divergence, although not to a level comparable to the divergence seen between two different species. Potentially introgressed genomic regions were investigated. Although a slightly increased gene flow signal was observed across the entire genome between M. myotis and Eastern M. blythii, localized introgression regions that would indicate recent hybridization could not be detected. Further exploration of introgressed genomic regions may reveal the genomic basis for species differentiation. This study contributes to future studies on large Myotis bats and other cryptic species complexes, while also demonstrating the power of whole-genome data in unraveling the complex processes that shape the evolution of species.
Phylogeography of the Savi's pipistrelle (Vespertilionidae, chiroptera) complex based on whole mitochondrial genome analysis

(Graduate School, 2024-07-01) Ergöl, Yeliz ; Çoraman, Emrah ; 601211010 ; Earth System Science

Understanding the phylogeography of species provides insight into the historical processes that lead the formation of their current geographic distributions and also how they evolve and adapt to variable environments over time. Intraspecific and interspecific genetic variations stand as a great indicator for elucidation of the evolutionary history of organisms in diverged phylogeographical patterns. Bats represent an immensely diverged group among mammals. They inhabit a wide variety of ecosystems, with the tropical belt hosting the highest number of bat species, similar to many other life forms. While the oldest known fossil of Chiroptera is approximately 52 million years old, they are hypothesized to be evolved around the Cretaceous-Tertiary boundary. During their evolution, they settled to the nocturnal niche. Echolocation and flight capabilities have affected the phylogenetic classification in the era of morphological and physiological taxonomy. However, the taxonomic classification of Chiroptera is a more complex phenomenon. The developments of modern genetic techniques transformed the historical perception of taxonomy. The introduction of high-throughput sequencing, which enables the sequencing of an organism's whole genetic material, has made genomic studies increasingly popular in biodiversity research. This powerful technique has revealed that organisms can exhibit significant genetic variation, even when their phenotypic characteristics do not reflect this diversity. Cryptic species, which arise from the discordance between morphological similarity and genetic divergence, exemplify this phenomenon. Resolving cryptic diversity is cruicial for identying evolutionary significant units and provides a new dimension for investigating the ecological dynamics of species. Furthermore, it is a significant concept in biodiversity assessment and monitoring, essential for inforimg conservation actions. Past studies have showned that the Palearctic Region hosts a rich fauna with signifacnt cryptic diversity, including among bats. Savi's Pipistrelle, Hypsugo savii, is a small-sized, vespertilionid bat species with a broad distribution range across various ecoregions in Europe, Asia, and North Africa. The accumulation of studies showing intraspecific variation within the species has drawn attention to the investigation of possible divergence within the taxon. Several studies idenfied deeply diverged mitochondrial lineages of H. savii. Two of such lineages have been proposed as distinct species statuses, H. darwinii and H. stubbei, based on their significant divergence from H.savii. Hypsugo savii hosts possibly further cryptic diversity. It is composed of deeply diverged clades, with sympatric occurences in Northwestern Africa, the Iberian Peninsula, Italy, and some Mediterranean islands (Sardinia, Sicily, and Malta). These studies, however, are based on limited sampling from a very broad geographical range. Furthermore, they utilize realtively short mitochondrial markers and marker selection is not usually consistent among studies. This study aims to invesitage the whole mitogemones of the previously identified H. savii lineages and the recently suggested related species. There are three main objectives: 1) establishing a reproducible workflow to de novo assemble mitogenome from whole genome sequencing data; 2) de novo assembling complete mitogenome of H. savii and the related species; and 3) reconstructing their phylogenetic relationships based on whole mitogenome sequences. Thirty samples from various regions including Central Asia, Sinai Peninsula, North Africa, continental Europea, and Mediterranean islands were analysed. High-throughput shotgun sequencing data was used for the analysis. The analysis workflow covers data filtering, de novo assembling of complete mitogenomes, and annotating the obtained mitogenomes. Complete mitochondrial genomes were succesfully de novo assembled for thirty samples, representing all of the previously identified lineages, as well as the closely related species, H. stubbei and H. alaschanicus. Mitochondrial genes were annotated on the assembled genomes. The read pool of each sample was mapped to the assembled mitogenomes to assess their coverage and also to edit possible misallignments and gaps. The samples which had uncircular genomes were manual edited and circularized. The tRNA profiles were analyzed with tRNAscan-SE. Phylogenetic relations of the analysed samples were investigated reconstructing phylogenetic trees. The sequences were aligned and the pairwise distance of the sequences were calculated with MEGA11. The phylogenies were obtained with Maximum-Likelihood model with IQ-TREE and RAxML tools. The trees were visualized with FigTree abd iTOL WebServer. The alignments were analysed with PopArt for a haplotype network analysis. The highly variable non-coding D-loop regions were removed from the sequences for all these analysis . All thirty-seven mitochondrial genes were annotated: two of them were ribosomal RNAs; twenty-two were transfer RNAs; and thirteen were protein-coding genes. D-loop regions of mitogenomes were also annotated. The secondary stuctures of the tRNA profiles were calculated and illustrated. The tRNA for serine amino acid was lacking the D- arm in the secondary stucture, which had no significant impact on its functionality. Phylogenetic analysis revealed that there are three main H. savii lineages in the Western Palearctic region. The related species, H. ariel, H.alaschanicus, and H. stubbei, also formed three distinct clusters. The latter was identified in Kyrgyzstan, which is outside of its known range. The distribution of Hypsugo savii lineages were in three main regions: Eastern Mediterranean, Western Mediterranean, and North African-Southwestern Mediterranean. In Sardinia, the latter of these three lineages were found together. The pairwise genetic distance between the clades in Europe were between 8 and 10%, close to the difference observed between H. alaschanicus and the other species. Similar levels of divergences were also found between newly proposed species, H. stubbei, and the European clades. These observed high levels of mitogenomic differences suggest that the H. savii complex probably harbours further cryptic diversity.
Pollen-based quantitative reconstruction of vegetation cover in Turkey

(Graduate School, 2024-06-27) Erdoğmuş Ergin, Esra ; Dalfes, Nüzhet H. ; 601172001 ; Earth System Science

Vegetation is a critical component of the climate system that influences and is influenced by climate through physical and chemical processes. Vegetation affects regional and local climate dynamics by contributing to energy and water vapor exchanges and is also affected by these dynamics. Incorporating vegetation into climate models improves the accuracy of global climate change predictions. Paleoecological and paleoclimate data provide insights into historical vegetation, land use, and climate patterns, helping us understand long-term changes. Fossil pollen data preserved in lakes, peatlands, and marshes are essential for reconstructing and understanding vegetation dynamics. However, interpreting pollen data is limited due to the non-linear relationships between pollen percentages and plant abundances. Taxonomic differences in pollen production, dispersal and deposition, changes in the spatial structure of vegetation, and differences in the size and type of the sediment basin are not considered in traditional pollen analysis methods. Additionally, before interpreting a pollen record, it is necessary to have an idea about the pollen source area of the studied site. Therefore, model-based methods play an essential role in correcting for factors that influence pollen representation of vegetation and in linearizing the pollen-vegetation relationship. The Landscape Reconstruction Algorithm (LRA) quantitatively reconstructs vegetation abundance at regional and local scales using fossil pollen counts. The REVEALS model, a part of the LRA, reconstructs past vegetation cover based on pollen data and relies on Relative Pollen Productivity estimates (RPP) and pollen fall speed values (FSP). Although the REVEALS model has been applied in various regions, its use in the Mediterranean is limited due to the lack of region-specific RPP values. The primary objective of this thesis is to understand the vegetation dynamics of southwestern Turkey during the late glacial period and the Holocene. To achieve this goal, the study aims first to acquire RPP values for Turkey and then to conduct quantitative vegetation reconstructions in southwestern Turkey using the REVEALS model. Studies on Holocene vegetation changes in southwestern Anatolia indicate increased human activities such as agriculture, grazing, and fires. Lake Gölhisar is located in southwestern Turkey with its rich palynological and archaeological evidence of human-induced vegetation changes. This study focuses on a 50 km radius around Lake Gölhisar in the Oro-Mediterranean vegetation zone. This area includes forests of Pinus brutia, Pinus nigra, and Juniperus, high mountain steppes, and Quercus coccifera shrublands. Sampling sites were randomly selected within a 50 km radius using QGIS software, ensuring a minimum distance of 1500 m between each location to prevent autocorrelation. Moss samples were collected from 21 accessible sites, and vegetation surveys were conducted within a 100 m radius of each site. These data were used to create land cover maps for distances up to 5000 m, and pollen extraction from moss samples was performed according to standard procedures. The ERV model was applied to estimate RPPs for different plant taxa by focusing on species well represented in both vegetation and pollen samples. Specific pollen types were selected for analysis, with Quercus coccifera used as the reference taxon. The RSAP was determined to be 102 m. Five taxa, including Q. coccifera, Juniperus, Fabaceae, Pinus, and Poaceae, were used for the final analysis, and RPP values were produced for these taxa. In the second part of the study, the REVEALS model was used with the produced RPP values. The study focused on the Oro-Mediterranean vegetation zone and utilized fossil pollen data from the Neotoma Paleoecology Database. Fossil pollen data were converted into REVEALS input files, and the model was run using the RPP values. Results indicated that some taxa not well represented in pollen proportions were better captured by the REVEALS model. This highlights the model's ability to provide a more comprehensive and accurate reconstruction of vegetation by compensating for biases and limitations in raw pollen data. By integrating all available records and using the Mediterranean taxa set, the REVEALS model offers a robust framework for understanding past vegetation dynamics, even in the presence of time gaps and varying pollen counts. Throughout the Holocene, human activities and climate changes in southwestern Anatolia have led to significant changes in vegetation structure. Agriculture, grazing, and fires have greatly influenced vegetation dynamics in the region. Records obtained from Lakes Gölhisar and Söğüt provide detailed insights into the impact of human activities on vegetation. Pollen analyses show an increase in agricultural activities and deforestation processes, especially during the late Holocene. The REVEALS model quantitatively evaluates these impacts, providing a more accurate reconstruction of past vegetation. Integrating REVEALS-based reconstructions with traditional pollen data offers new insights into the extent and nature of human impact on vegetation over thousands of years. Human activities such as agriculture, grazing, and fires have caused significant changes in vegetation dynamics. These changes can be tracked and analyzed through pollen records. Particularly during the late Holocene, increased agricultural activities and deforestation processes have greatly affected the vegetation structure in the region. This study enhances the understanding of historical vegetation dynamics in southwestern Turkey and underscores the importance of region-specific RPP research for accurate vegetation reconstructions. This comprehensive approach provides a clearer picture of human-induced changes and their long-term effects on biodiversity. Future research, covering a wider geographical area and including more sampling points, could further improve RPP values and contribute to a more detailed understanding of vegetation dynamics. In conclusion, this thesis takes a crucial step in understanding the vegetation dynamics of southwestern Turkey and sheds light on the paleoecological and climatic history of the region. By providing a comprehensive analysis of historical vegetation changes, it helps us understand the long-term effects of human impact. Moreover, these findings contribute to the accuracy and reliability of future climate and vegetation models.
Potential implications of sea-level rise in Türkiye and its vicinity

(Graduate School, 2022-10-08) Alabay, Ebru ; Karaca, Mehmet ; Baykara, Metin ; 601201007 ; Earth System Sciences

In the last century, the sea-level rise has accelerated due to anthropogenic climate change. With the growing population, the consequences of climate change have become more adverse. As in the rest of the world, the population pressure is high on the Turkish Coasts, where 45 million people live in. Türkiye, which has a long shoreline with 8333 km covered with seas on three sides will be affected adversely by the consequences of accelerated sea-level rise (e.g. flooding, salt intrusion, erosion, etc.). In addition to physical hazards, also socio-economic losses will have consequences. The purpose of this study is to determine the potential implications of the sea-level rise on Turkish coasts. For this purpose, the monthly sea-level data in the Turkish Seas (the Black Sea, the Marmara Sea, the Aegean Sea, and the Mediterranean Sea) are received from the Permanent Service for Mean Sea Level. However, some tide gauge stations have data gaps and insufficient data for determining long-term sea-level change. Therefore, cubic interpolation was applied to eliminate the data gaps, also the tide gauge station data in the same sea are combined to create a longer time series of sea-level change. Thus, the mean sea-level rise rates in the Black Sea, the Marmara, the Aegean, and the Mediterranean Sea are calculated at 5,31 mm/yr in 1874-2018, 8,79 mm/yr in 1984-2009, 0,844 mm/yr in 1969-2019, 0,8455mm/yr in 1923-2019, respectively. It is determined that sea-level rise has accelerated in recent decades. The accelerated sea-level rise causes the increasing frequency and intensity of disaster floods, inundations, coastal erosion, landslides, saltwater intrusion, and even storm surges. The main economic activities in this region are tourism, agriculture, fishing, port, and industry sectors. In Turkey, the coastal low-lying delta areas (i.e. Cukurova, Bafra, Carsamba, Meric, Goksu, etc.) are important in agricultural production. Especially one-third of Samsun is covered with agricultural lands its agricultural contribution to the economy is approximately $1 billion. Thanks to their long sandy beaches, the Mediterranean and the Aegean are among the destinations that attract a lot of international tourists and play an important role in the development of the region locally and nationally. Another popular destination for international tourists is Istanbul with its natural beauty, rich culture, and historical places. Hence, the socio-economic factors on the Turkish coast were examined. The contribution of the coastal region is estimated at two-thirds of the Turkish Gross Domestic Product (GDP): the Marmara, the Aegean, the Mediterranean, and the Black Sea coastal regions' contributions are 44.5%, 8.3%, 8.4%, and %4.7 respectively. As a result, these economically active regions are essential to be protected against sea-level rise. In this study, adaptation strategies have been determined for the protection of coastal areas from the destructive consequences of sea-level rise. In addition, the adaptation costs for agricultural areas (Bafra and Carsamba) in Samsun, and the sandy beaches are also examined.
Sparse identification of non-linear dynamics (SINDy) of landscape evolution model simulations

(Graduate School, 2024-07-01) Birol, Özgür Doğan ; Yetemen, Ömer ; 601211007 ; Earth System Science

This study, titled "Sparse Identification of Nonlinear Dynamics (SINDy) of Landscape Evolution Model (LEM) Simulations" explores the linear inference of differential physical processes simulated by the LEM called Landlab by using the SINDy toolkit. The research aims to enable LEM researchers to incorporate data trained models to explain nonlinear phenomena alongside the traditional approach of physical equations. The study employed an iterative approach to investigate explanation of the non-linear Taylor diffusion process from simulation data using a sparse, linear model. The data was collected from the simulations run by the LEM model Landlab which incorporated a non-linear hillslope and a fluvial flux process. Results suggest that the underlying nonlinear dynamic could be identified with a trained SINDy model in a relatively sparse manner with a median average percentage error as low as 0.097%. Although, the simulations ran with the trained model exhibited drift from the original course of model data. This is expected due to stochasticity of non-linear models. The findings of this study reveal that soil elevation at a node in a spatial grid can be inferred using the elevation values of the neighboring nodes as model features. This has important implications for LEM modelling providing viable employable alternatives to representative physical equations. Additionally, this study contributes to the existing body of knowledge in earth sciences by showing that it is possible to linearize a process in spatial domain simulations when treated as a dynamical system. Furthermore, the study highlights the challenge of reducing number of terms in a linear model to just a few, which can contribute to further research in this area. In conclusion, this study sheds light on treating differential physical processes in a spatial domain as sparse linear models and providing valuable insights for researchers who design or employ LEM's in their studies.
Studying the ancient settlement of Hacılar Büyük Höyük with integrated methods

(Graduate School, 2022) Özdoğru, İnci Nurgül ; Arıkan, Bülent ; Küçükdemirci, Melda ; 714414 ; Earth System Science Programme

Archaeology has great potential to illustrate the long-term human-environment interactions especially when it is supported by other disciplines and computational modeling. This holistic perspective provides a detailed analysis of landscape with a multidisciplinary framework that might provide an understanding of complex systems, including land use, interactions of the elements, and adaptation. The Hacılar Büyük Höyük, a major Early Bronze Age-I (ca. 3100 – 2900 BC) site in Burdur, (Turkey), has been the focus of this thesis. It has significant contribution to the knowledge of the Early Bronze Age-I (EBA-I, hereafter) and II phases in Southwest Anatolia with its settlement plan, defense system, archaeological remains, and its material culture. The primary goal of this research is to assess the long-term human-environment interactions at the site from an interdisciplinary perspective. In this research, three different digital-computational approaches have been used to assess the long-term changes in landscape around the site; GIS-based morphometric analysis, Ground Penetrating Radar (GPR, hereafter), and Agent Based Modelling (ABM, hereafter). Data was collected via unmanned aerial vehicle (UAV, hereafter) photography, and sub-surface geophysical measurements. Through the use of GPR and GIS-based morphometric analyses, I will calculate the scale of settlement and its agro-pastoral (i.e., farming and herding) catchment areas. I will then integrate cultural, economic, and environmental parameters into an agent-based modeling platform where I will visualize the spatio-temporal impacts of human activities (e.g., de-vegetation, erosion, deposition) at the site. The geomorphometric analysis is used to figure out how geomorphological features on and around the settlement are distributed. To gain a better understanding of the landscape, the sky-view factor (SVF, hereafter) map and red relief image mapping (RRIM, hereafter) approaches were applied. A combination of morphometric analysis and field observation provides complementary information about the site, land, and surroundings. Then, GPR data were implemented and results analyzed. The geomorphic units are mapped and the estimated agricultural catchment area is identified based on the slope of the area and distance from the settlement as the flat area limited by the river considering the geomorphic units were similar with modern data. Based on the site's layout, it is possible to calculate the approximate population of the settlement considering that the casemates surround the mound. ABM is used to evaluate the effects of land use on surface processes as well as to calculate agricultural catchment areas based on precipitation and population data. The Macrophysical climate model (MCM) results were used in the model as the input climate data. The ABM used in this study is Medland Modeling Laboratory (MML, hereafter) to simulate how dry farming and ovicaprid-based, site-tethered pastoralism affected the landscape around the site. As a result of the study, possible archaeological structures buried underground were determined by using GPR. Then, model results show agricultural exploitation of the landscape and husbandry practices between 3100-2900 BC had varying degrees of impact on the environment and that population density is the most critical factor. Within the scope of the study, GPR and geomorphological analyses enabled to visualize to combine incorporate unearthed archaeological remains in the ABM for calculating the approximate human and animal population of the settlement. Then, four scenarios have been tested by changing the climate and increasing population variables for 200 years. The cumulative changes in the woodland vegetation, erosion, and deposition provide critical information about the land use patterns and anthropogenic impacts around the Hacılar Büyük Höyük during EBA-I. This thesis study illustrates that integrating the existing archaeological and anthropological data with the numerical models can benefit the interpretation of social structure at the settlement.
Systematics and biostratigraphic implications of micromammals (Rodentia) from selected pliocene-quaternary basins along the North Anatolian Fault Zone

(Graduate School, 2023-07-20) Erdal, Ozan ; Dalfes, H. Nüzhet ; Şen, Şevket ; 601122006 ; Earth System Sciences

Anatolia plays an important role as a bridge between Africa, Europe and Asia for the evolutionary course of vertebrates. It is potentially rich in fossil bearing deposits which would greatly serve to contribute the understanding of vertebrate evolution. However, paleontological research conducted in Turkey is mainly focused on Paleogene and Miocene deposits. Although it is obvious that any studies of mammalian paleontology dealing with any interval of Cenozoic in Anatolia is worthful because of its potential, one must point out that Quaternary mammalian fauna is still not well known when compared to European equivalent. In this manner, it is not difficult to estimate how micromammalian paleontology is less dealt. The introduction of the present thesis deals with some general definitions and fields of application of micromammals besides a brief summary of all conducted or ongoing studies on the Quaternary micromammalian fauna in Anatolia. One of the main motivations of this study is to underline the potential contribution of micromammal paleontology to Quaternary research in Turkey. On the following sections, a detailed study is provided on rodent remains which were collected from diverse localities in three adjacent basins on the North Anatolian Fault Zone (NAFZ), the depositional ages of which are estimated spanning from the Pliocene to the late Pleistocene. I investigated small mammal faunas of these basins by means of systematic paleontology, biochronology with proper stratigraphic positions, and studied their inference on paleoclimate and paleoenvironment of the localities. The North Anatolian Fault Zone (NAFZ) forms the boundary between the Anatolian and Eurasian plates and hosts many tectonic basins. The chronology of the NAFZ basin deposits is established mostly by pollen and partly by mammalian fauna studies. Nonetheless, the formation history of these basins starting in the Late Miocene to the Pleistocene and actively continuing today is still incompletely known because biochronological data are still scarce. The previous studies on the Tosya Basin by many authors and on its several aspects revealed detailed information on the structure of the basin (Barka and Hancock, 1984; Şengör et al, 1985; Andrieux et al, 1995; Dhont et al, 1998). The earliest deposition within the basin, the Devrez Formation, is claimed to date of Early-Middle Miocene but no fossil findings are discovered so far. According to Ünay and de Bruijn (1998), the only paleontological work on the area despite the lack of stratigraphic position nor systematic description, an Early Pliocene age (late Ruscinian-MN15) is suggested based on micromammal fauna from one locality at Ortalıca Village. In the same study, they proposed Early Pleistocene (MN17) age for a locality at Karasapaca Village to the West of Ortalıca, based on micromammal remains. Unfortunately, stratigraphic positions of these localities are uncertain. In the present study, the occurrence of Mimomys cf. polonicus at the Sapaca locality points out the early late Villanyian (MN16b) age for the locality which is older than previously studied locality Karasapaca by Ünay and de Bruijn (1998), situated at the north-eastern to the Sapaca village. At the Ortalıca locality, the co-occurence of Pliomys destinatus, Apodemus atavus and Mesocricetus primitivus within their stratigraphic position, supports rather the transition from MN15 (late Ruscinian) to early Villanyian (MN16a), slightly younger than age proposed by Ünay and de Bruijn (1998). On the other hand, the newly discovered Kumkapı locality, at the SW of Ortalıca and Sapaca-Karasapaca, surprisingly indicates a much younger age, late Toringian with remains of Microtus (M.) arvalis and Mus cf. macedonicus which provide a profile well younger than the Umurlu locality findings from the Niksar Basin. Finally, the finding in this basin reveals a more or less continuous deposition, where the faunal succession from the Early Pliocene (MN15) toward the Late Pleistocene follows the opening of the basin in a NE–SW direction, in almost 4 Ma. Indeed, the surprising young age of Kumkapı deposits is subjected to further geological studies in the near future. The abundance of Pliomys and Apodemus species in Ortalıca, in overall, points out rather forested, wooded and humid environment rather than grassland. (Sen, 1977; Suata-Alpaslan, 2010; Hoek Ostende et al. 2015b; Popov, 2018). However, the presence of Mesocricetus remains together with Pliomys and Apodemus would indicate that for a while between MN15b–MN16a (Pliocene), there have been cooler climatic conditions occurred, which resulted in steppe environment (Sen, 1977; Hoek Ostende et al. 2015a; Popov, 2018) may be with sparse forested area for the food sources. Sapaca locality which is younger than Ortalıca but much older than the Kumkapı localities yielded only Mimomys species, which are generally reported from relatively warm and arid, open steppe environment (e.g. Rabeder, 1981; Montuire et al, 1994; Popov, 2017). Finally, the Kumkapı locality with the presence of recent species of Microtus and Mus, is not much different from the present climate and environmental condition of the studied area such as mixture of open environment with meadows and grasslands with warm climate, as pointed out in previous studies (e.g. Montuire et al, 1994; Çolak et al, 2016; Erdal et al, 2018, 2019). The Suluova Basin is a prominent member of a wide transtensional Amasya Shear zone, located at the central part of the North Anatolian Shear Zone. Analysis of detailed stratigraphic sections, faulting data and mammal paleontology reveals that the Suluova Basin has started to evolve as a closed half-graben along the NE-SW trending, SW dipping basin bounding fault zone with normal slip at early Quaternary. Within this tectonic environment, the sedimentary assemblages were various facies of a river dominated alluvial fan network. As faults propagated westwards, the basin deepened and a fresh water lake started to develop at the basin depocenter. The initiation of E-W trending southern tectonic boundary of the basin caused further extension. Each basin boundary fault zones witnessed clockwise rotation in time. Marking an increasing water income, the Suluova Basin has evolved into a vast fresh water lake during the Middle Pleistocene (~1.7–0.8 Ma) acting as a refugia for a potential rich faunal assemblage of large and small land mammals. Thus far, micro- and macromammal remains studied from several localities in the basin comprise Kalymnomys sp. and Sivatherium sp. from late Villanyian of Kurnaz; Microtus (Allophaiomys) aff. nutiensis, Mimomys aff. pliocaenicus and Apodemus cf. dominans from late Villanyian–early Biharian of Kerimoğlu; Mesocricetus aff. arameus from early Biharian of Kızıleğrek, and Mesocricetus cf. brandti and Arvicola cf. mosbachensis from early Toringian of Yolpınar, in addition to some fragments of Equus sp. The faunal association from five localities would allow to make some assumptions concerning the past environment. For instance, the paleoenvironment of Sivatherium is reported as grasslands and well-watered landscape with much warmer temperature for the early part of Early Pleistocene (MN17–MNQ18); Kalymnomys on the other hand, is not well known but based on actual relatives (e.g., Lagurus lagurus) it is thought that should be rather dry steppe environments (Alçiçek et al, 2017, p.242). The floodplain deposits at the Kurnaz locality would support the former hypothesis in addition to environmental changes with the presence of a paleolake at the younger Kerimoğlu locality which would point out rather warmer climate. The Kerimoğlu locality, as it is important for the formation of a paleolake which is also supported by the remains of unidentified fossil fish teeth, represents an environment surrounded with deciduous woodland and bushy vegetation covers with streams and marsh-like areas by the presence of a large vole Mimomys aff. pliocaenicus and Apodemus cf. dominans. (Siori and Sala 2007; Hoek Ostende et al, 2015a; Erdal et al, 2018; Sen et al, 2018). The macromammal remains at Kamışlı has been previously reported by Sickenberg and Tobien (1971, p.60–61) where faunal elements including Equus sp. point out steppe environment crossed by forest along the water courses and lakes. The presence of Mesocricetus spp. at Kızıleğrek and Yolpınar localities would indicate somewhat dry, semi-arid steppes covered by sparse vegetation (Krystufek and Vohralik 2009). Note that Anatolia is playing an important role for the evolution of the hamster Mesocricetus during the Middle Pleistocene, which is favoured by alternating dry periods and spreading lakes causing steppe-corridors for hamsters' dispersals and adaptations (Neumann et al, 2017). On the other hand, the water vole Arvicola findings together with Mesocricetus as at the Niksar Basin, demonstrate rather a mixture of steppe-like environments with water streams for that youngest locality to the east of the Suluova Basin. A new micromammalian faunal assemblage from four horizons at the Umurlu locality (Niksar Basin, Tokat-Turkey) has been investigated; it improves our knowledge about the chronology of this basin infill. According to the stratigraphic range of the recorded species (Mesocricetus cf. brandti, Cricetulus migratorius, Arvicola cf. mosbachensis, Microtus arvalis, M. (Terricola) subterraneus, Clethrionomys cf. glareolus, Apodemus flavicollis, Nannospalax cf. xanthodon) the age of the deposit is constrained between early Middle Pleistocene and Late Pleistocene (i.e., 480–130 ka). The fossil assemblage indicates a mixture of open environments with meadows and grasslands associated with forested and bushy vegetation covers. This fauna and the implied environment are typical for an interglacial period, most probably within the interval of MIS 12–5. The studied rodent assemblage with elements of several paleobiogeographic affinities shows once more the key position of Anatolia as a bridge between the Old World continents. It improves our knowledge on Quaternary micromammals of Anatolia, which is still poorly documented, and provides a well-constrained age of the investigated localities.
Temporal and spatial investigation of maritime accidents in the strait of Istanbul in the perspective of navigational safety

(Graduate School, 2022-10-24) Kodak, Gizem ; Ünal, Alper ; Acarer, Tayfun ; 601142001 ; Earth System Sciences

The Strait of Istanbul is located on the primary routes of international maritime transport. The strait, which is the second busiest waterway in the world with average of 50.000 ships per year, has four times more maritime traffic than the Panama Canal and three times more than the Suez Canal. When compared to its peer waterways the biggest threat in the Strait, the risk of accidents created by difficult navigational conditions. Some of the accidents that took place in the strait in the recent past have caused worldwide concern due to the environmental disaster they have caused. Considering that today, ships carrying dangerous goods serve at much larger capacities compared to the past, the maritime traffic in the region poses a risk both for the ships passing and for the city and people of Istanbul, which is densely populated on its shores. In this context, the development of solutions to reduce maritime accidents in the region plays a key role in strengthening navigational safety. In this study, the accidents that took place in the strait were discussed in terms of temporal/spatial and were examined simultaneously with the environmental factors affecting the navigational safety. For this purpose, hourly wind speed and wind direction data of Sarıyer and Atatürk meteorology stations located on the traffic route in the strait were obtained from the Turkish State Meteorological Service and wind dynamics affecting maritime traffic were examined. On the other hand, accidents also were evaluated in terms of the number of ships passing and the effect of maritime traffic on accidents were examined with the regression analysis. In this direction the monthly movement of international ship traffic in the strait was examined on a micro scale with the data of the Directorate General of Coastal Safety and accident rate per passing ship was calculated. In addition to dynamic factors such as wind speed, wind direction and traffic flow, another factor affecting the occurrence of accidents in the strait is the navigational regulations carried out in relation to the traffic order. In this context, the regulations for maritime traffic in the strait were examined chronologically and compared with the accident data. Thus, not only the effects of the regulations regarding navigational safety on the accidents were observed, but also the strengths and weaknesses of the developed solution proposals were revealed. The results of the study have shown that patrol tugs can be an effective solution to prevent accidents when the wind and current dynamics in the region and the spatial distribution of the accidents are evaluated together. In this direction, the response time of the proposed patrol tugboats to a possible accident was calculated and the response options were evaluated under two different scenarios as parallel to the current and antiparallel.
The impact of paleoclimatic changes on the archaeological settlement patterns in the Gediz Graben (Western Türkiye) during the late pleistocene and holocene

(Graduate School, 2024-05-28) Kolbüken, Mesut ; Arıkan, Bülent ; 601192009 ; Earth System Science

The Gediz Graben has been an attractive area for human occupation due to its suitable geographical features such as the large arable land coupled with water sources that supported animals and plants attracted human groups and societies at different archaeological periods. The graben is one of the highly sensitive areas in the Anatolian Peninsula to climatic changes as the climatic patterns in the region have been controlled by both polar and tropical circulation systems. Therefore, the area provides a great opportunity to assess human-climate interaction. This research aims to reconstruct paleoclimate dynamics of the Gediz Graben since the late Last Glacial covering the last 21 ka and to contextualize human-environment interactions in archaeological settlement patterns in the region by using a multiple approach through different paleoclimate models (the Macrophysical Climate Model and CHELSA-TraCE21k) for paleoprecipitation and paleotemperature patterns and a new palynological record from core MAR03-02C in the Aegean Sea for the reconstruction of paleovegetation patterns with paleoclimate interpretations in the surrounding landmass. Based on the results of the paleoclimate models, in the late Last Glacial Period and the early Holocene, the climatic conditions of the graben were wetter (except paleoprecipitation of the CHELSA-TraCE21k) and colder than today. During the middle and late Holocene, the climate was generally stable, and near-modern patterns prevailed around 7 ka in the graben while the climatic shifts occurred at smaller amplitudes for shorter time periods in comparison to the previous periods. This pattern was recorded in variations in Mediterranean/temperate forests and herb/steppe plants. In the cold and dry late Last Glacial Period, low amounts of arboreal pollen and high percentages of cold/drought-tolerant Pinus and Cedrus trees with high amounts of herbaceous and steppe pollen, including Artemisia, Cyperaceae, and Asteraceae Cichorioideae were recorded. Warm-temperate and Mediterranean trees, consisting of mainly deciduous Quercus and Quercus ilex-type trees, reached their maximum from the onset of the Holocene at ~11.7 to 6 ka, corresponding to the Holocene Climate Optimum. Subsequently, general aridity trends and nearly modern climate patterns prevailed. Variations in the paleovegetation, the paleoprecipitation and paleotemperature patterns indicate major climatic shifts associated with the Greenland Stadial 2, the Bølling-Allerød, the Younger Dryas, and the Holocene Climatic Optimum and some rapid climate changes, such as the 11.1, 9.4 8.2, 5.9, and the Little Ice Age cold events; a short warm interval of the Medieval warm period during the Holocene. In Gediz Graben, the patterns from the paleoclimate models and the palynological record show similarity with local and regional proxy data in the eastern Mediterranean. The archaeological settlements in the plain, which increased from the Neolithic to the Bronze Age except the Iron Age, gathered around water resources. The results suggest that the paleoenvironmental processes (the paleolakes, paleoclimatic conditions, paleovegetation patterns) contributed to the decisions concerning the locales of archaeological settlements on the Gediz Plain. Anthropogenic indicators plants with the onset of the Neolithic come into slight in the region. Especially, during the last 3.5 ka when cultivated plants became prominent in the pollen records (e.g., Olea europea and Pistacia), with a significant decline in warm-temperate trees until 1.2 ka, suggesting that the Beyşehir Occupation Phase is also recorded in the palynological records of core MAR03-02C in the Aegean Sea. As a result of this study, significant findings regarding paleoenvironmental changes in the region and human-environment interactions have been obtained. The results underscore the importance of making future plans regarding human-environment relationships in the Eastern Mediterranean Basin, where Türkiye is prominently located, which notably demonstrates the impacts of the current climate change crisis. This highlights the necessity of taking measures to mitigate the effects of the climate crisis, strengthening societal resilience, and conserving natural resources.

Gözat

Başlık ile LEE- Yer Sistem Bilimi Lisansüstü Programı'a göz atma

Sayfa başına sonuç

Sıralama Seçenekleri