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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Nuevos datos y problemas sobre el Paijanense en el Chicama: aportes para una evaluación de la ocupación temprana en el norte del Perú

Gálvez, César 10 April 2018 (has links)
New Evidence and Problems Concerning the Paijanense in the Chicama Valley: Contributions to an Evaluation of Early Occupation in Northern PerúRecent information on the Paijanense in the Chicama valley is presented complementing the available data in the archaeological literature. In a review on spacial occupation, the information about the resources and the bioindicators, as well as the mobility through natural corridors, the problem of the settlement paterns and the probabilities for the early sedentarism is discussed. The function of projectile points for hunting as well as the necessity for more intensive investigations on this culture of the Early Archaic Period is also proposed. / Se presenta información reciente sobre el Paijanense en el valle de Chicama que complementa la existente en la literatura arqueológica. En base a una revisión acerca de la ocupación del espacio, la información sobre los recursos y los bioindicadores, y la movilidad a través de corredores naturales, se discute el problema de los asentamientos y las probabilidades de un sedentarismo temprano. Se evalúa la función de las puntas de proyectil paijanenses para la caza y la necesidad de mayores investigaciones sobre esta cultura del Arcaico Temprano.
22

Ecological Role of Dry-Habitat Chimpanzees (Pan troglodytes schweinfurthii) at Issa, Ugalla, Tanzania

January 2013 (has links)
abstract: Identifying the ecological role, or niche, that a species occupies within their larger community elucidates environmental adaptability and evolutionary success. This dissertation investigates the occupied niche of chimpanzees (Pan troglodytes schweinfurthii) living in an open, dry savanna-woodland environment by examining patterns of resource use and interspecific interactions. Data were collected October 2010--November 2011 at Issa, in the Ugalla region of western Tanzania, which is one of the driest, most open, and seasonal habitats inhabited by chimpanzees. Unlike most primatological studies which employ methods that include focal follows, this study focused instead on observing 'resource patches' for chimpanzees. Patch focals allow for the observation of all animals within a study area; capture resources that are not used by the study species; and are particularly well suited for unhabituated communities. In order to better understand relationships between environment and behavior, data collected at Issa are compared with published data from other chimpanzee populations. Issa chimpanzees were expected to have broader resource use than forest chimpanzees, as well as increased competition with other fauna, due to fewer available resources. However, in contrast to the assumption of food scarcity in dry habitats, dietary resources were available throughout the year. Like other populations, the diet of Issa chimpanzees consisted of mostly fruit, but unlike at other sites, the majority of plants consumed were woodland species. Additionally, although chimpanzees and other fauna shared spatial and dietary resources, there was only nominal overlap. These results point to extremely low levels of indirect competition between chimpanzees and other fauna. Despite extensive study of forest chimpanzees, little is known about their role within their faunal community in open, dry habitats, nor about how greater seasonality affects resource use. This project addresses both of these important issues and fosters novel approaches in anthropological studies, especially in reference to chimpanzee ecology and evolution. Understanding current chimpanzee behavioral relationships with their environments shapes hypotheses about their pasts, and also informs predictions about behaviors of similar taxa in paleo-environments. Lastly, examining the ecological role of chimpanzees within their larger communities will influence the formation of, as well as evaluate, conservation strategies. / Dissertation/Thesis / Ph.D. Anthropology 2013
23

Invasão, competição e uso de recursos por uma gramínea nativa e uma gramínea invasora do cerrado / Invasion, competition and resource use by a native and invasive grass in the Brazilian savanas

Talita Marques Zupo 08 December 2010 (has links)
No Brasil, varias espécies de gramíneas africanas introduzidas se tornaram importantes invasoras dos cerrados e constituem uma das principais ameaças para a sua biodiversidade. Atributos envolvendo trade-offs evolutivos que influenciam na adaptabilidade das espécies - aquisição, alocação e perda de recursos pelas plantas por meio de competição, facilitação, estresse e distúrbio - irão influenciar o desempenho dos indivíduos e a manutenção das populações nas comunidades vegetais. Deste modo, e de extrema importância entender quais os mecanismos que levam uma espécie invasora a ter um desempenho melhor sobre as espécies nativas. Comparações envolvendo características entre espécies exóticas e nativas podem levar a uma melhor compreensão sobre o processo da invasão. Diante disso, este trabalho procurou identificar algumas das estratégias competitivas adotadas por uma gramínea invasora, Urochloa decmbens, e por uma gramínea nativa, Echinolaena inflexa, em ecossistema de cerrado. Para verificar aspectos relativos às estratégias de colonização das espécies foram analisadas suas fenologias reprodutivas, as taxas de viabilidade e de germinação das sementes. Em um experimento com plantas envasadas, sementes de ambas as espécies foram semeadas em diferentes proporções relativas uma a outra. Três censos foram realizados durante o período de um ano para avaliar a sobrevivência, crescimento e fecundidade das espécies. Medidas da capacidade fotossintética e das taxas de assimilação foram tomadas para ambas as espécies tanto em parcelas puras quanto em parcelas mistas; também foi quantificada a área foliar especifica e total das espécies. No experimento com as plantas envasadas, quando sementes de ambas as espécies foram colocadas juntas, a nativa teve seu crescimento suprimido pela invasora. Nos tratamentos puros, os indivíduos da espécie nativa cresceram em tamanho, mas somente três se tornaram reprodutivos. No entanto, muitos indivíduos da espécie invasora cresceram em tamanho e se reproduziram em todos os tratamentos, mostrando uma alocação de recursos tanto para crescimento quanto para reprodução. A espécie invasora apresentou uma taxa fotossintética maior, porem ambas as espécies tiveram sua capacidade fotossintética e sua taxa fotossintética reduzida nos parcelas mistas, sugerindo que a competição afeta tanto a espécie nativa como a espécie invasora. Uma vez que a espécie nativa possui área foliar especifica menor em relação à espécie invasora, espera-se que ela apresente uma perda menor de nutrientes e, conseqüentemente, uma maior conservação/retenção dos nutrientes, o que favoreceria sua persistência em ambientes como o cerrado. No entanto, com a ocorrência de distúrbios e possíveis alterações na disponibilidade de nutrientes, a gramínea nativa pode ser deslocada pela invasora, que apresenta maior capacidade de colonizar novas áreas por meio de maiores taxas de germinação e estabelecimento; e maior produtividade, apresentando maiores taxas fotossintéticas, sendo mais eficiente no uso do nitrogênio. / Many African grasses have been introduced in Brazil and have invaded areas of Brazilian savannas, thus becoming a major threat to the biological diversity of this biome. Traits involving evolutionary trade-offs that influence the species adaptive strategies, such as differences in nutrient uptake, nutrient loss and biomass allocation in response to plant competition and facilitation, and environmental stress and disturbance, will influence individual performance and population maintenance in plant communities. Therefore, it is extremely important to identify the mechanisms associated with invasiveness that lead to a better performance of exotic species over co-occuring natives. Comparisons involving traits of both native and exotic species may lead to a better understanding concerning the success of invasions. This study sought to recognize possible competitive strategies adopted by an invasive grass, Urochloa decmbens, and a native grass, Echinolaena inflexa, in a Brazilian savanna. In order to identify aspects relative to their colonization strategies, the reproductive fenologies and seed viability and germination rates of both species were analyzed. An experiment with potted plants was performed where seeds of both species were sown in different relative proportions to each other. Three census were carried out during a period of 12 months to evaluate survival, growth and fecundity of both species. Gas exchange and chlorophyll fluorescence were quantified for each species in pure and mixed stands in the field; total and specific leaf area for both species were also measured. In the potted experiment, when seeds of both species were sown together, the growth of the native species was suppressed by the exotic species. In pure treatments, however, individuals of the native species grew in size, but only 2% reproduced. On the other hand, individuals of the exotic species grew in size and reproduced in all treatments, demonstrating that this species allocated enough resources for both growth and reproduction. The photosynthetic rates were greater for the invasive species, however, in mixed stands, both species had their photosynthetic rates and capacities decreased. The smaller specific leaf area of the native species suggests lower rates of nutrient loss than the invasive species, which would favor its persistence in nutrient poor environments, as the Brazilian savannas. Yet, with the occurrence of disturbances and variable nutrient availabilities, the native species might be displaced by the invasive species, since the later possesses traits leading to a higher competitive ability in such conditions.
24

A review and comparative assessment of existing approaches to calculate material footprints

Lutter, Franz Stephan, Giljum, Stefan, Bruckner, Martin 16 April 2016 (has links) (PDF)
Effective implementation of resource policies requires consistent and robust indicators. An increasing number of national and international strategies focussing on resource efficiency as a means for reaching a green economy call for such indicators. As supply chains of goods and services are increasingly organised on the global level, comprehensive indica-tors taking into account upstream material flows associated with internationally traded products need to be compiled. Particularly in the last few years, the development of con-sumption-based indicators of material use also termed material footprints has made considerable progress. This paper presents a comprehensive review of existing methodol-ogies to calculate material footprint-type indicators. The three prevailing approaches, i.e. environmentally extended input-output analysis (EE-IOA), coefficient approaches based on process analysis data, and hybrid approaches combing elements of EE-IOA and process analysis are presented, existing models using the different approaches discussed, and advantages and disadvantages of each approach identified. We argue that there is still a strong need for improvement of the specific approaches as well as comparability of re-sults, in order to reduce uncertainties. The paper concludes with recommendations for further development covering methodological, data and institutional aspects.
25

Trophic Ecology and Habitat Use of Atlantic Tarpon (<i>Megalops atlanticus )

Kurth, Benjamin Neal 02 November 2016 (has links)
Fish can have complex life histories and use multiple habitats and resources throughout their life span. Consequently, their life histories are often poorly understood. The Atlantic Tarpon, Megalops atlanticus, is a large, typically migratory, elopomorph fish that is both ecologically and economically important. Atlantic Tarpon are under threat due to regional exploitation, loss of natal and juvenile habitat, poor water management, and offshore impacts. In addition, little is known about its lifelong habitat and resource use. In Chapter 1, I used stable isotope analysis of eye lens δ13C and δ15N values to explore patterns in trophic history and habitat use of 16 Atlantic Tarpon from West-Central Florida and Louisiana. The stable isotope chronologies showed 100% use of backcountry habitats during the early life history and an ontogenetic habitat shift to coastal waters at approximately 10 years of age and 140 cm total length. During the coastal phase Atlantic Tarpon displayed among-individual variability and within-individual consistency in basal resource use. In Chapter 2, mark-recapture data from a multi-year genetic tagging program were used to investigate survival and growth rates, ontogenetic habitat use, and migration of juvenile Atlantic Tarpon in Florida. The study found that juvenile Atlantic Tarpon take approximately 10 years to reach the length associated with maturity, and appear to have a high survival rate (~80%), possibly due to effective use of habitats with reduced competition and predation. Atlantic Tarpon underwent several ontogenetic habitat shifts throughout the juvenile phase. In addition, juvenile Atlantic Tarpon did not migrate long distances but instead showed fidelity to systems wherein only short movements were needed to shift habitat types. This work serves to fill critical gaps in our knowledge of Atlantic Tarpon life history and may aid in better management and conservation of the species.
26

Att mäta och kommunicera hållbart : en analys av ett svenskt jordbruk

Levin, Anna January 2011 (has links)
Tools that highlight the human impact on ecosystems and the accelerating depletion of natural resources are essential in the strife towards a more sustainable way of living. Emergy analysis is a scientific and robust method to assess the degree of sustainability of human as well as natural systems. Despite the advantages of the method, its public breakthrough has been slow. One reason could be that the results of an emergy analysis are difficult to grasp. In contrast, ecological footprint is a concept that has a widespread impact, much due to its pedagogical disposition. Ecological footprint made use of the vision to develop a method to well communicate the magnitude of human effect on nature. Another more recently created method suitable in this context is ecosystem services. Ecosystem services as a concept is not yet so well developed methodologically, but its use of mainstream concepts point toward a promising application. The main purpose of this study is to make the emergy analysis and ecosystem services methods more accessible and also to facilitate effective communication of the results from these methods. The second part of the study aims to assess the degree of sustainability ofan agricultural system in central Sweden by means of emergy analysis and ecosystems services. By demonstrating the results of the emergy analysis as a foot- and fingerprint, a better understanding of the outcome may be achieved. The footprint, here called emergy-based footprint, visualizes all resources used in the production system. An emergy-based fingerprint identifies the resources of the most important items in the system. Furthermore, ecosystem services are evaluated from a data matrix and presented by means of a radar diagram. Alternative scenarios for the agricultural system were created in the study, each presented as an emergy-based foot- and fingerprint, as well as by means of a radar diagram to visualize the values of the ecosystem services. Together, these methods demonstrate the sustainability characteristics of the different production systems. Results from this study suggest the agricultural system analysed, as well as the developed scenarios, not to be sustainable. The use of emergy analysis combined with ecosystem services and the visualization methods developed in this study, serve to provide accessible and effective communication methods when aiming to transform agricultural systems towards sustainability. The communication methods developed in this study are alsoapplicable in systems other than agriculture.
27

Predicting Length of Stay and Non-Home Discharge: A Novel Approach to Reduce Wasted Resources after Cardiac Surgery

Pattakos, Gregory January 2011 (has links)
No description available.
28

Natural Resource Use in Madagascar

Reuter, Kim E. January 2015 (has links)
The anthropogenic use of natural resources has become a major cause of biodiversity loss and habitat degradation throughout the world. Deforestation - the conversion of forests to alternative land covers - has led to a decrease in local biodiversity directly through a decrease in habitat, and indirectly through habitat fragmentation. Likewise, defaunation – the loss of animals both directly through hunting and indirectly through deforestation – has led to the empty forest syndrome and subsequent deterioration of forest ecosystems. In many cases, areas where anthropogenic use of natural resources is high overlap with areas of high biodiversity value. Therefore, the present series of studies aims to better understand the impacts that different types of natural resources use and habitat degradation have on biodiversity. This dissertation details the results of five studies, which aimed to: 1) examine the effects of habitat degradation on plant-frugivore networks; 2), understand the live capture and extent of ownership of lemurs in Madagascar; 3) understand the micro- and macro-level drivers of wild meat consumption in Madagascar; 4) describe the capture, movement, and trade of wild meat in Madagascar; and 5) the impacts of habitat changes on the diets and vertical stratification of frugivorous bats. For the first study, our objectives were to understand the effects of habitat degradation on (1) community structure, (2) network structure, and (3) seed dispersal services. We focused on fruit-bearing trees and frugivores (two lemur and five bird species) across a three-point gradient of habitat degradation in a tropical dry forest in Madagascar. Our objectives were to understand the effects of habitat degradation on (1) community structure, (2) network structure, and (3) seed dispersal services. We focused on fruit-bearing trees and frugivores (two lemur and five bird species) across a three-point gradient of habitat degradation in a tropical dry forest in Madagascar. Data on fruit consumption by frugivores were collected over 592 hours of observations at 13 fruiting tree species. We found that as habitat became more degraded: (1) the community structure of both frugivores and fruiting tree communities changed; (2) the mutualistic network structure became less complex and less connected; (3) the interaction strengths of pair-wise interactions changed and the asymmetries of these interactions shifted; and (4) seed dispersal decreased by 91% in the secondary forest, compared to the primary forest. In addition, we show that frugivores: (1) sometimes stopped eating fruit in the degraded forest, even when they had consumed it in other forests; and (2) appeared to avoid some fruiting tree species while showing preference for others. The mutualistic network studied in this paper appeared sensitive to anthropogenic disturbance and a novel measure of effectiveness helped quantify these changes. For the second study, our objectives were to provide the first quantitative estimates of the prevalence, spatial extent, correlates and timing of lemur ownership, procurement methods, within-country movements, and numbers and duration of ownership. Using semi-structured interviews of 1,093 households and 61 transporters, across 17 study sites, we found that lemur ownership was widespread and affected a variety of taxa. We estimate that 28,253 lemurs have been affected since 2010. Most lemurs were caught by owners and kept for either short (≤1 week) or long (≥3 years) periods. The live capture of lemurs in Madagascar is not highly organized but may threaten several endangered species. For the third study, we investigated the role of wild meat in food security in Madagascar, a country where wild meat consumption is poorly understood in urban areas and at regional scales. Using semi-structured interviews (n = 1339 heads-of-households, 21 towns), we aimed to: 1) quantify the amount and purpose of; 2) understand the drivers behind; and, 3) examine recent changes in wild meat consumption in Madagascar. Few respondents preferred wild meat (8 ± 3%) but most had eaten it at least once (78 ± 7%), and consumption occurred across ethnic groups, in urban and rural settings. More food insecure areas reported higher rates of recent consumption of wild meat. However, consumption was best explained by individual preferences and taboos. Few respondents (&lt;1 ± &lt;1%) had increased rates of consumption during their lifetimes, and wild meat prices showed no change from 2005-2013. Most consumption involved wild pigs and small-bodied animals, though these animal groups and lemurs were consumed less in recent years. Given these data, wild meat is unlikely to enhance food security for most Malagasy people in urban and well-connected rural areas. For the fourth study, and to improve understanding of the wild meat trade in Madagascar, our objectives were to: (1) quantify the volume of consumption, transport, and sale for different animal groups, compared to domestic meat; (2) describe the methods of capture and hunting for different animal groups; (3) analyze the patterns of movement of wild meat from the capture location to the final consumer, compared to domestic meat; and (4) examine how the prices of wild meat change depending on the venue through which the consumer purchases it. Data was collected in May-August 2013 using semi-structured interviews of consumers (n = 1343 households, 21 towns), meatsellers (n = 520 restaurants, open-air markets stalls, and supermarkets, 9 towns), and drivers of inter-city transit vehicles (n = 61, 5 towns). We found that: (1) a wide range of hunting methods were used, though their prevalence of use differed by animal group; (2) wild meat traveled distances of up to 166 km to reach consumers, though some animal groups were hunted locally (&lt;10 km) in rural areas; (3) most wild meat was procured from free sources (hunting and receiving meat as a gift), though urban respondents who consumed bats and wild pigs were more likely to purchase those meats; and (4) wild meat was consumed at lower rates than domestic meat, though urban respondents consumed twice as much wild meat as rural respondents. We conclude that urban and rural respondents differ in how they interact with the wild meat commodity chain. We also believe that the consumption and trade of wild meat in Madagascar is likely more formalized that previously thought. Finally, for our fifth study, we used stable isotope analysis to examine how foraging by three fruit bat species in Madagascar, Pteropus rufus, Eidolon dupreanum, and Rousettus madagascariensis, are impacted by habitat change across a large spatial scale. Our results indicated that the three species had broadly overlapping diets. Differences in diet were nonetheless detectable and consistent between P. rufus and E. dupreanum, and these diets shifted when they co-occurred, suggesting resource partitioning across habitats and vertical strata within the canopy to avoid competition. Changes in diet were also correlated with a decrease in forest cover, though at a larger spatial scale in P. rufus than in E. dupreanum. These results suggest fruit bat species exhibit differing foraging strategies in response to habitat change. They also highlight the key threats that fruit bats face from habitat change, and clarify the spatial scales at which conservation efforts should be implemented to mitigate threats for these bat species in Madagascar. / Biology
29

ENHANCING RESOURCE-USE EFFICIENCY FOR INDOOR FARMING

Fatemeh Sheibani (16649382) 03 August 2023 (has links)
<p>Vertical farming (VF) as a newer sector of controlled-environment agriculture (CEA) is proliferating as demand for year-round, local, fresh produce is rising. However, there are concerns regarding the high capital expenses and significant operational expenses that contribute to fragile profitability of the VF industry. Enhancing resource-use efficiency is a strategy to improve profitability of the VF industry, and different approaches are proposed in the three chapters of this dissertation. LEDs are used for sole-source lighting in VF, and although they recently have significantly improved electrical efficiency and photon efficacy, the Lambertian design of the illumination pattern leads to significant loss of obliquely emitted photons beyond cropping areas. In chapter 1, close-canopy lighting (CCL) is proposed as one effective energy-saving strategy, through which unique physical properties of LEDs were leveraged, and two CCL strategies (energy efficiency and yield enhancement) were characterized at four different separation distances between light-emitting and light-absorbing surfaces. Dimming to the same light intensity at all separation distances resulted in the same biomass production while significant energy savings occurred at closer distances. Significantly higher light intensity and yield were achieved under closer separation distances in the yield-enhancement strategy for the same energy input. The energy-utilization efficiency (g fresh/dry biomass per kWh of energy) was doubled in both scenarios when the separation distance between LED emitting surface and crop surface was reduced maximally. At reduced separation distances, the chance of photon escape from growth areas is less, and canopy photon capture efficiency is improved.</p><p>Optimizing environmental conditions for indoor plant production also helps improve resource-use efficiency for the nascent vertical-farming industry. Although significant technical advancements of LEDs have been made, use of efficient far-red (FR) LEDs has yet to be exploited. As a recent proposed extension to traditional photosynthetically active radiation (PAR, 400-700 nm), FR radiation (700-750 nm) contributes to photosynthesis as well as photomorphogenesis when added to shorter wavelengths of traditional PAR. However, the interaction of FR with other environmental parameters such as CO2 is less studied. In chapter 2, the interaction effect of four FR fluxes (as substitution for red) in combination with three different CO2 concentrations were investigated at three distinctive stages of young-lettuce production. The highest biomass achieved at all stages occurred at 800 mmol mol-1 CO2 compared to 400 and 1600 mmol mol-1. A photomorphogenic effect of FR to promote leaf length was pronounced at the earliest stages of development, at which FR did not contribute to higher biomass accumulation. At more developed stages, 20 mmol m-2 s-1 of FR substituting for red contributed to biomass accumulation similar to shorter wavelengths of traditional PAR, whereas higher fluxes of FR in the light recipe resulted in undesirable quality attributes such as longer leaves.</p><p>Optimizing environmental conditions for indoor production with emphasis on light intensity and CO2 concentration at four distinctive stages of lettuce production was investigated in chapter 3. Utilizing the Minitron III gas-exchange system, light and CO2 dose-response profiles were characterized at four distinctive crop-development stages through instantaneous gas-exchange measurements at crop level. At all developmental stages, as CO2 concentration increased, photosynthesis increased up to 500 mmol mol-1, above which the incremental rate of photosynthesis was reduced. Light-dose response profiles were characterized at 400 or 800 mmol mol-1 CO2, and as light intensity increased, photosynthesis increased up to 650 mmol m-2 s-1. However, when instantaneous power (Watts) consumed for lighting was taken into consideration, power-use efficiency as the ratio of output photosynthesis increment to input power increment (to increase light intensity), decreased at higher light intensities. Vertical farming as a nascent and growing industry is facing limitations including marginal and even elusive profitability. Optimizing environmental conditions for indoor plant production such as these will help improve resource-use efficiency and profitability of the vertical farming industry.</p>
30

Elephant space use in relation to ephemeral surface water availability in the eastern Okavango Panhandle, Botswana

Makati, Anastacia 03 July 2023 (has links) (PDF)
The movement and distribution of elephants can be influenced by environmental factors over time (Foley, 2002). Examining how features in the landscape such as vegetation productivity, water sources and anthropogenic activities drive the movement of elephants can help in understanding patterns of movement. It can also help to inform the establishment and alignment of protected areas, wildlife corridors and identification of tourism hotspots as well as policy interventions to manage Human-Elephant Conflict (HEC). The Okavango Panhandle in Botswana is a HEC hotspot and the focus of My study. A number of strategies to address HEC are underway in the area, however one longer term strategy that has been proposed in this area involves provision of artificial water sources to influence elephant movements and keep animals away from fields during the cropping season. However, an improved understanding of how elephants utilize their habitats in relation to natural ephemeral surface water and other factors that influence their movements from dryland habitats to the Okavango Delta resources is needed to inform such management decisions. My study seeks to establish the role of ephemeral surface water on elephant distribution in the eastern Okavango Panhandle, Botswana as well as assess the movement distribution of elephants in relation to the seasonality, proximity and spatial extent of water presence represented by ephemeral surface water. Time series analysis of water extent on ephemeral surface water of the eastern Okavango panhandle will be developed and overlaid with elephant movement datasets. Elephant collar data from 15 elephants (5 males and 10 females) in the eastern Okavango Panhandle, Botswana have been analysed and Home Range (HR) sizes estimated using Kernel Density Estimation (KDE). The relative importance/probability of environmental variables in determining elephants' movement based on the Utilization Distribution (UD) were computed using Generalized Linear Mixed Models (GLMMs). I utilized a remote sensing spectral index, namely the Automated Water Extraction Index (AWEI) to delineate ephemeral surface water in dryland (excluding permanent waters) of the study area. The results reveal that during the wet season, elephants were evenly spread out all over the study area until the early dry season (April-June) when the ephemeral waterholes dried up. Elephants moved southwards towards the permanent waters of the Okavango River, where there are many human settlements and farms. Male HR sizes were found to be bigger than those of female elephants. Wet season (early and late) home range sizes were also bigger when compared to dry season (early and late) HR size. Mean daily distances were computed to investigate the effect of season on elephant daily distances and the distances ranged between 5km and 6.8km in the late wet and in the early wet and late dry season respectively. The Resource Selection Function (RSF) analysis shows that water adjacent sites are preferred over distant ones and both sexes prefer areas with high NDVI, with this preference being more pronounced in males. The seasonal variation of water use is notable in that it affirms the importance of proximity to water for elephants and has implications for their management and HEC. For example, I found that ephemeral surface water has a significant role in influencing elephant spatial use in the area, particularly during the early and late wet season. As ephemeral pans dried and NDVI (vegetation greenness) decreased, elephants started to move closer to the Okavango Delta and consequently human settlements and fields. However, further investigations into the timing of movements away from ephemeral waterholes and the influence of other environmental factors on elephant movements in the area would be needed before any recommendations can be made regarding artificial water provision in this area.

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