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Letteratura scientifica selezionata sul tema "Ecosystème aride"

Autore: Grafiati

Pubblicato: 28 settembre 2024

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Articoli di riviste sul tema "Ecosystème aride"

Santana, Otacilio Antunes, José Imaña Encinas, Bárbara Alves de Sousa, Sandra Razana Silva do Monte e Valéria Sandra de Oliveira Costa. "Aridy index over time in five ecosystems on semiarid". Journal of Hyperspectral Remote Sensing 9, n. 3 (11 dicembre 2019): 138. http://dx.doi.org/10.29150/jhrs.v9.3.p138-145.

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The local climate change was registered over time (1992-2018) on different land use ecosystems, in Brazilian Semiarid area. The aimed of this work was to analyze aridity index in five ecosystems (Wild Caatinga, Caatinga on management, Cactaceae field, Eucalyptus reforestation, and Fabaceae crop), and to compare this index with environment variables. Meteorological towers and measures with porometer and psychrometers were carried out to collect the data. The main result was that the studied areas are hotter and drier. The Fabaceae crop and Eucalyptus reforestation studied ecosystems already are on Arid classification according with registered aridity index. Wild Caatinga and Cactaceae field ecosystems are on Semiarid classification, and over time Caatinga on management ecosystem pass from Semiarid to Arid classification. The five ecosystems together are classified on Arid climate. The VPD and Ψsoil were the variables more directly proportional with Aridity index to analyzed ecosystems.

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Kirey, Vladimir V. "GLOBAL SYSTEMS OF ENVIRONMENTAL-ECONOMIC ACCOUNTING". EKONOMIKA I UPRAVLENIE: PROBLEMY, RESHENIYA 11/2, n. 140 (2023): 82–88. http://dx.doi.org/10.36871/ek.up.p.r.2023.11.02.011.

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Throughout history, people have treated natural resources as infinite and free, which has led to their overexploitation and degradation of ecosystems. At present, society and industry are facing challenges caused by the degradation of ecosystems and the reduction of ecosystem service flows. With ecosystem accounting, we now have the ability to incorporate the value of biodiversity into policy and decision-making. Clear consideration of ecosystem contributions as to current ecosystems Market production, as well as the broader benefits accruing to individuals and society, contributes to a broader understanding of the role of ecosystems and the impacts that can arise when the scale and condition of ecosystems change. The purpose of this article is to provide stakeholders with a brief overview of existing classification systems and assessment frameworks for ecosystem accounting. To do this, we analyses four different ecosystem classification systems, including the Millennium Ecosystem Assessment, the Economics of Ecosystems and Biodiversity, the Common International Classification of Ecosystem Services, and the Intergovernmental Scientific Classification. - Policy Platform on Biodiversity and Ecosystem Services. This review will help to determine the most appropriate models for assessing ecosystem services and natural capital for use in Russia.

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Zhou, Yanqing, Yaoming Li, Wei Li, Feng Li e Qinchuan Xin. "Ecological Responses to Climate Change and Human Activities in the Arid and Semi-Arid Regions of Xinjiang in China". Remote Sensing 14, n. 16 (12 agosto 2022): 3911. http://dx.doi.org/10.3390/rs14163911.

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Understanding the impacts and extent of both climate change and human activities on ecosystems is crucial to sustainable development. With low anti-interference ability, arid and semi-arid ecosystems are particularly sensitive to disturbances from both climate change and human activities. We investigated how and to what extent climate variation and human activities influenced major indicators that are related to ecosystem functions and conditions in the past decades in Xinjiang, a typical arid and semi-arid region in China. We analyzed the changing trends of evapotranspiration (ET), gross primary productivity (GPP) and leaf area index (LAI) derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite product and the Breathing Earth System Simulator (BESS) model in Xinjiang for different climate zones. We separated and quantified the contributions of climate forcing and human activities on the trends of the studied ecosystem indicators using the residual analysis method for different climate zones in Xinjiang. The results show that GPP and LAI increased and ET decreased from 2001 to 2015 in Xinjiang. Factors that dominate the changes in ecosystem indicators vary considerably across different climate zones. Precipitation plays a positive role in impacting vegetation indicators in arid and hyper-arid zones and temperature has a negative correlation with both GPP and LAI in hyper-arid zones in Xinjiang. Results based on residual analysis indicate that human activities could account for over 72% of variation in the changes in each ecosystem indicator. Human activities have large impacts on each vegetation indicator change in hyper-arid and arid zones and their relative contribution has a mean value of 79%. This study quantifies the roles of climate forcing and human activities in the changes in ecosystem indicators across different climate zones, suggesting that human activities largely influence ecosystem processes in the arid and semi-arid regions of Xinjiang in China.

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Gu, Qing, Hui Zheng, Li Yao, Min Wang, Mingguo Ma, Xufeng Wang e Xuguang Tang. "Performance of the Remotely-Derived Products in Monitoring Gross Primary Production across Arid and Semi-Arid Ecosystems in Northwest China". Land 9, n. 9 (22 agosto 2020): 288. http://dx.doi.org/10.3390/land9090288.

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As an important component to quantify the carbon budget, accurate evaluation of terrestrial gross primary production (GPP) is crucial for large-scale applications, especially in dryland ecosystems. Based on the in situ data from six flux sites in northwestern China from 2014 to 2016, this study compares seasonal and interannual dynamics of carbon fluxes between these arid and semi-arid ecosystems and the atmosphere. Meanwhile, the reliability of multiple remotely-derived GPP products in representative drylands was examined, including the Breathing Earth System Simulator (BESS), the Moderate Resolution Imaging Spectroradiometer (MODIS) and data derived from the OCO-2 solar-induced chlorophyll fluorescence (GOSIF). The results indicated that the carbon fluxes had clear seasonal patterns, with all ecosystems functioning as carbon sinks. The maize cropland had the highest GPP with 1183 g C m−2 y−1. Although the net ecosystem carbon exchange (NEE) in the Tamarix spp. ecosystem was the smallest among these flux sites, it reached 208 g C m−2 y−1. Furthermore, distinct advantages of GOSIF GPP (with R2 = 0.85–0.98, and RMSE = 0.87–2.66 g C m−2 d−1) were found with good performance. However, large underestimations in three GPP products existed during the growing seasons, except in grassland ecosystems. The main reasons can be ascribed to the uncertainties in the key model parameters, including the underestimated light use efficiency of the MODIS GPP, the same coarse land cover product for the BESS and MODIS GPP, the coarse gridded meteorological data, and distribution of C3 and C4 plants. Therefore, it still requires more work to accurately quantify the GPP across these dryland ecosystems.

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Tate, Robert L. "Arid Ecosystems". Soil Science 160, n. 6 (dicembre 1995): 453. http://dx.doi.org/10.1097/00010694-199512000-00015.

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Ávila Flores, Diana Yemilet, Dora Alicia García García e David Castillo Quiroz. "Caracterización ecológica en parcelas afectadas por incendios en el sureste de Coahuila, México". E-CUCBA 10, n. 20 (29 giugno 2023): 114–20. http://dx.doi.org/10.32870/ecucba.vi20.303.

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Among the factors that influence the composition, structure, functioning and dynamics of ecosystems, fire is one of the mostimportant and widespread in the world. Knowledge about the dynamics of post-fire recovery of the vegetation constitutes the basisfor the management of areas impacted by forest fires; the above is more important when it comes to areas with little information onthe response of vegetation to fire, such as the vegetation of semi-arid ecosystems. The objective of this study was to characterize thebiodiversity of the vegetation in experimental plots, which were affected by a forest fire, through the ecological parameters ofabundance (ARi), dominance (DRi), frequency (FRi) and importance value index. (IVI) in order to determine the floristiccomposition of post-fire areas in semi-arid zones. Despite the fact that biodiversity has been affected as shown by the resultsobtained, since these are dominated by a single species (Quercus pringlei Seemen ex Loes.), the tendency they show is to recovernaturally as indicated by the results, values of ecological importance where Yucca carnerosana (Trel.) McKelvey stands out as anelement that gives support and structure to the ecosystem. The study of post-fire recovery dynamics in semi-arid areas of Mexico isof the utmost importance, since it is valuable information that contributes to knowledge to address the risks that may arise during aforest fire, to generate initiatives for its conservation.

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Schreieck, Maximilian, Manuel Wiesche e Helmut Krcmar. "From Product Platform Ecosystem to Innovation Platform Ecosystem: An Institutional Perspective on the Governance of Ecosystem Transformations". Journal of the Association for Information Systems 23, n. 6 (2022): 1354–85. http://dx.doi.org/10.17705/1jais.00764.

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Incumbent companies across industries such as banking, insurance, and enterprise software have begun transforming their existing product platform ecosystems into innovation platforms ecosystems to increase generativity in their ecosystems. Such ecosystem transformations not only entail technological challenges as the underlying platform technology changes but also organizational challenges in that ecosystem actors such as partners and customers need to become part of the transformed ecosystem. To study how incumbent companies can govern ecosystem transformations successfully, we interpret ecosystems as organizational fields and ecosystem transformations as changes to the fields’ institutional infrastructure. Based on a multiyear, grounded theory study of the transformation of SAP’s on-premises ERP system, we first identify institutionalization challenges that arise when institutional infrastructure is changed during an ecosystem transformation. We then show how field-level governance mechanisms address these challenges and how the new institutional infrastructure gains legitimacy among ecosystem actors, ultimately leading to the institutionalization of the transformed ecosystem. These findings contribute to the literature on ecosystem transformations and platform governance by highlighting the role that institutional forces play in ecosystem transformations. Furthermore, we add to the literature on institutional theory by providing insights into the dynamics of institutional infrastructure as it becomes infused with digital technologies.

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Atazadeh, Ehsan, Andrew Barton, Mozhgan Shirinpour, Mahdi Zarghami e Abbas Rajabifard. "River management and environmental water allocation in regulated ecosystems of arid and semi-arid regions – A review". Fundamental and Applied Limnology / Archiv für Hydrobiologie 193, n. 4 (23 giugno 2020): 327–45. http://dx.doi.org/10.1127/fal/2020/1286.

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Rivers make a significant contribution in providing goods and services for human well-being. Today, many rivers and streams have been heavily regulated to ensure adequate provision of water resources for anthropogenic uses. Riverine ecosystems, especially those in arid and semi-arid regions, are experiencing severe stress due to the increasing demands on the ecosystem services they provide, coupled with anthropogenic catchment-scale impacts and factors associated with natural and human-induced climate variability and change. In this paper, the various flow components in regulated riverine ecosystems and the methods to determine environmental flows are reviewed. The review also focuses on the concurrent developments of eco-hydrological models and on the new opportunities for improving environmental flows of rivers by sustainably adjusting consumptive flows to fine-tune environmental flows and maximize the ecological benefit. In fact, the present paper highlights the role of consumptive flows, towards improving environmental flows, which has largely been neglected by river scientists and water managers. Indeed, consumptive flows can provide an opportunity to improve and support environmental flows in regulated riverine ecosystems. Addressing these challenges may aid water management efforts in finding sustainable solutions in riverine ecosystems by balancing environmental/ecological and human water requirements.

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Glettler, Christiana, e Gregor Torkar. "First-Year Pre-service Primary School Teachers’ Conceptual Structure of Ecosystem Ecology Concepts". Action Research and Innovation in Science Education 4, n. 1 (1 ottobre 2021): 25–31. http://dx.doi.org/10.51724/arise.41.

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Science education research has been increasingly concerned with students’ and teachers’ conceptions of central scientific concepts over the past decades. However, science teaching today should not only convey knowledge but also values and science practices in order to empower students to become responsible citizens in a world that is facing ecological as well as social problems. Thus, a profound understanding of ecology and systems thinking skills are seen as paramount. This paper explores first-year pre-service primary school teachers’ conceptual understanding of ecology through the use of a word association test. Students were given four stimulus words and asked to provide five response words to each stimulus. Furthermore, they were asked to formulate a sentence related to biology, using each stimulus word. Response words were categorised and the frequency of the words was calculated. The findings show very limited understanding of the ecological concepts and their interrelatedness. Furthermore, the students showed numerous misconceptions regarding energy flow and food chain relationships. Thus our findings support other authors’ propositions that students often struggle with understanding ecology concepts. The findings further imply that the instruction students receive at school is not successful in replacing existing misconceptions with accurate science concepts.

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Guan, K., S. P. Good, K. K. Caylor, H. Sato, E. F. Wood e H. Li. "Continental-scale impacts of intra-seasonal rainfall variability on simulated ecosystem responses in Africa". Biogeosciences 11, n. 23 (11 dicembre 2014): 6939–54. http://dx.doi.org/10.5194/bg-11-6939-2014.

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Abstract. Climate change is expected to modify intra-seasonal rainfall variability, arising from shifts in rainfall frequency, intensity and seasonality. These intra-seasonal changes are likely to have important ecological impacts on terrestrial ecosystems. Yet, quantifying these impacts across biomes and large climate gradients is largely missing. This gap hinders our ability to better predict ecosystem services and their responses to climate change, especially for arid and semi-arid ecosystems. Here we use a synthetic weather generator and an independently validated vegetation dynamic model (SEIB-Dynamic Global Vegetation Model, DGVM) to virtually conduct a series of "rainfall manipulation experiments" to study how changes in the intra-seasonal rainfall variability affect continent-scale ecosystem responses across Africa. We generate different rainfall scenarios with fixed total annual rainfall but shifts in (i) frequency vs. intensity, (ii) rainy season length vs. frequency, (iii) intensity vs. rainy season length. These scenarios are fed into SEIB-DGVM to investigate changes in biome distributions and ecosystem productivity. We find a loss of ecosystem productivity with increased rainfall frequency and decreased intensity at very low rainfall regimes (<400 mm year−1) and low frequency (<0.3 event day−1); beyond these very dry regimes, most ecosystems benefit from increased frequency and decreased intensity, except in the wet tropics (>1800 mm year−1) where radiation limitation prevents further productivity gains. This result reconciles seemingly contradictory findings in previous field studies on the impact of rainfall frequency/intensity on ecosystem productivity. We also find that changes in rainy season length can yield more dramatic ecosystem responses compared with similar percentage changes in rainfall frequency or intensity, with the largest impacts in semi-arid woodlands. This study demonstrates that intra-seasonal rainfall characteristics play a significant role in influencing ecosystem function and structure through controls on ecohydrological processes. Our results suggest that shifts in rainfall seasonality have potentially large impacts on terrestrial ecosystems, and these understudied impacts should be explicitly examined in future studies of climate impacts.

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Più fonti

Tesi sul tema "Ecosystème aride"

Maurice, Kenji. "Structuration des communautés et des réseaux microbiens des sols et des plantes dans un écosystème aride". Electronic Thesis or Diss., Université de Montpellier (2022-....), 2024. http://www.theses.fr/2024UMONG006.

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La diversité, la composition et les assemblages du microbiome du sol et des plantes sont conditionnés en partie par l’environnement et les interactions biotiques. L’oasis d’AlUla, située dans le désert d’Arabie Saoudite, est caractérisé par de fortes contraintes abiotiques, liées à un pH hyper alcalin et à la faible disponibilité en eau et en nutriments. L’activité et la croissance des organismes est donc soumise à cette disponibilité ponctuelle et spatialement hétérogène des ressources. En résulte une répartition spatiale discontinue des végétaux, les îlots de fertilité, qui influencent la composition du sol et des communautés microbiennes. Les plantes sont également associées dans des relations symbiotiques à des microorganismes, qui vont influencer leur santé, leur résistance à la sècheresse, améliorer l’acquisition des ressources minérales et en eau, et sont particulièrement critiques dans ces milieux à fortes contraintes. Enfin, ces écosystèmes, déjà fragilisés par le changement climatique, sont également soumis à des pressions agricoles importantes qui conduisent à une dégradation des sols et de leur biodiversité associée. La biodiversité des écosystèmes chauds et arides est aujourd’hui peu connue, particulièrement concernant l’Arabie Saoudite, un pays aux frontières longtemps restées fermées.Le but de cette thèse est de caractériser le microbiome bactérien et fongique du sol et des plantes, en lien avec son environnement, et sa réponse à différents usages des terres par le biais de séquençage d’amplicons. Afin de dépasser le cadre analytique de l’étude de la diversité et de la composition des communautés, j’ai cherché à utiliser les métriques des réseaux de co-occurrence et explorer de nouvelles méthodologies pour leur étude. Dans un premier chapitre, l’influence mutuelle des plantes, du sol et des microorganismes dans un micro-environnement, les îlots de fertilité, est caractérisée. Puis, une campagne d’échantillonnage sur le terrain au cours de deux saisons m'a permis de réaliser une analyse extensive du microbiome des plantes par l’approche des réseaux de co-occurrence. En se focalisant sur les relations intra- et inter-royaumes microbiens des taxons symbiotiques, il y est démontré la redondance de l’assortativité des champignons mycorhiziens, et de l’intégration des bactéries fixatrices d’azote dans le microbiome étendu des plantes. La réponse du microbiome à un événement simulé de précipitation sur le terrain a également permis de caractériser la réponse taxonomique du microbiome à la disponibilité en eau dans le sol. Dans un troisième chapitre, la réponse du microbiome face à des contingences historiques de nature anthropique ou naturelle, décrit comment des cycles de dessiccation et d’inondation affectent les communautés microbiennes contemporaines. Par l’étude de la stabilité de leur interaction, il y est montré comment l’activité agricole passé impacte de manière durable la structure du microbiome. Enfin, la quantification des processus d’assemblage des communautés a permis de déterminer l’effet de perturbations anciennes sur les processus de sélection bactérienne et fongique.Collectivement, les résultats de cette thèse permettent d’améliorer la compréhension de l’assemblage et de la structure du microbiote du sol et des plantes dans un écosystème désertique encore peu connu. De plus, les analyses de cooccurrence se sont révélées un outil précieux dans la formulation de nouvelles hypothèses fondamentales sur le rôle fondateur des symbioses, et de la réponse du microbiote aux perturbations. La poursuite de l’étude de la stucture complexe des réseaux, complémentée par l’étude des fonctions microbiennes et d’approches réductionnistes pour lier les relations de covariance aux processus écologiques promet de prochaines avancées majeures en écologie microbienne
The diversity, composition and assemblages of the soil and plant microbiome are partly determined by the environment and biotic interactions. The AlUla oasis, located in the Saudi Arabian desert, is characterized by strong abiotic constraints, linked to a hyper-alkaline pH and low availability of water and nutrients. The activity and growth of organisms is therefore subject to this punctual and spatially heterogeneous availability of resources. This leads to a spatially discontinuous distribution of plants, known as islands of fertility, which influence soil composition and microbial communities. Plants also form symbiotic relationships with microorganisms, which influence their health, resistance to drought and the acquisition of mineral and water resources, and are particularly critical in this ecosystem. Finally, these ecosystems, already weakened by climate change, are also subject to significant agricultural pressures, leading to soil degradation and associated biodiversity loss. Little is known at present about the biodiversity of hot, arid ecosystems, particularly in Saudi Arabia, a country whose borders have long remained closed.The goal of this thesis is to characterize the bacterial and fungal microbiome of soil and plants in relation to its environment, and its response to different land uses through amplicon sequencing. In order to extend the analytical framework of the study of community diversity and composition, I have sought to use co-occurrence network metrics and explore new methodologies for their study. In a first chapter, the mutual influence of plants, soil and microorganisms in a micro-environment, the fertility islands, is characterized. Then, a field sampling campaign over two seasons enabled me to carry out an extensive analysis of the plant microbiome using the co-occurrence network approach. Focusing on the intra- and inter-kingdom relationships of symbiotic taxa, this work demonstrated the redundant assortativity of mycorrhizal fungi, and the integration of nitrogen-fixing bacteria into the extended plant microbiome. The microbiome's response to a simulated precipitation event in the field was also used to characterize the microbiome's taxonomic response to water availability in the soil. In the third chapter, the microbiome's response to historical contingencies of an anthropogenic or natural nature, describes how cycles of desiccation and flooding affect contemporary microbial communities. By studying the stability of their interactions, it shows how past agricultural activities has had a lasting impact on the structure of the microbiome. Finally, the quantification of community assembly processes has made it possible to determine the effect of past disturbances on bacterial and fungal selection processes.Collectively, the results of this thesis improve our understanding of the assembly and structure of soil and plant microbiota in a little-known desert ecosystem. In addition, co-occurrence analyses have proven to be a valuable tool in the formulation of new fundamental hypotheses on the founding role of symbioses, and the response of the microbiota to disturbance. Continued study of the complex structure of networks, complemented by the exploration of microbial functions and reductionist approaches to be able to couple covariance relationships to ecological processes, promises major advances in microbial ecology in the future

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Wellens, Jane. "Monitoring and modelling rangeland vegetation in Tunisia using satellite and meteorological data". Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359492.

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Lee, Enhua School of Biological Earth &amp Environmental Science UNSW. "The ecological effects of sealed roads in arid ecosystems". Awarded by:University of New South Wales. School of Biological, Earth and Environmental Science, 2006. http://handle.unsw.edu.au/1959.4/26265.

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The effects of roads on landscapes and wildlife and their ecological processes are substantial and represent a major anthropogenic disruption to the natural environment. Current understanding of the impacts of roads for their strategic management is hampered by a lack of information on 1) the influence of the ecosystems on road effects, 2) the effects of roads on higher-order ecosystem responses (populations and communities), and 3) the overall impacts of roads on ecosystems and their wildlife (on both abiotic and biotic ecosystem components). This study used the Silver City Highway in arid New South Wales, Australia, as a model for a typical road in an arid ecosystem to investigate the ecological effects of arid-zone roads and their management. The study examined the spatial variation of soil, vegetation, kangaroo and small mammal variables in relation to the road, explored the factors contributing to these respective spatial variations, investigated the effects of arid-zone road management on vegetation, assessed the fragmentation effect of the arid-zone road on small mammals, and determined the patterns, causes and effects of kangaroo-vehicle collisions. The study revealed that the arid-zone road influenced most of the variables measured, skewed the population demographics of two kangaroo species, and altered the community composition of small mammals, with two small mammal species listed as threatened in NSW and of national significance (Sminthopsis macroura and Leggadina forresti) negatively impacted by the road. Increases in the amount of water along the road edge drove many of the subsequent effects of the arid-zone road as arid-zone flora and fauna are adapted to exploiting limited and patchily distributed resources. However, current arid-zone road management also influenced vegetation quality, microclimates around the road influenced kangaroo densities and small mammal communities, and kangaroo flight behaviour and temporal variations in traffic volume affected roadkill frequency. Together, these results suggest that roads have a high overall ecological impact in arid ecosystems. Conservation managers need to first rank the impacts of arid-zone roads in order of their conservation importance and need for mitigation, and from there, devise relevant informed management frameworks to target these impacts.

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Potts, Daniel Lawrence. "Rainfall Variability and Carbon Cycling in Semi-Arid Ecosystems". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1338%5F1%5Fm.pdf&type=application/pdf.

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Lee, Enhua. "The ecological effects of sealed roads in arid ecosystems". Connect to this title online, 2006. http://www.library.unsw.edu.au/~thesis/adt-NUN/public/adt-NUN20070315.091920/.

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Sanchez, Cohen Ignacio. "Evaluating strip farming systems for arid ecosystems: A stochastic approach". Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186696.

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The objectives of this study were: (a) to delineate a methodology for determining the feasibility of a water harvesting system for an arid ecosystem, (b) to develop a simulation model for the water balance of a water harvesting strip farming system, and (c) to perform a sensitivity analysis of the simulation model. The discussion focuses on the feasibility as constrained by risk. A computer program was developed for the computations. The results indicate that light textured soils cannot be used for this type of farming system since their hydrodynamic characteristics do not allow runoff from light rains (i.e. the threshold value is high). Medium textured soils require a minimum of 50% of initial soil water content and a CCAR of 2:1. Heavy soils require a minimum of 20% of initial soil water content and a CCAR greater than 5:1. As a general rule, the system is more efficient, in terms of water use efficiency (eᵤ), as the conditions become dryer. In this way, for CCAR ranging from 0 to 5 eᵤ is around 95% for all three textures. Beyond that point, as the CCAR increases eᵤ decreases being more efficient light soils and less efficient heavy soils. The shapes of the curves of profit, reflect the impact of weather conditions on the response of output to varying CCAR. Lack of rainfall prior to and during the growing season results in poor outputs. The risk (probability of loss) will depend on both the farmers own criteria and the economical situation. Thus, these criteria can be divided into two broad categories: risk-taking (those farmers who pursue a high level of investment relative to the probability of failure), and risk-adverse (those farmers with low level of investment relative to the probability of failure). Curves of minimum risk-maximum net benefit (minimax) were developed as a guide for decision making processes. According to the minimax curves, for medium soils, the minimum risk maximum net benefit is achieved with CCAR 2:1 and initial soil water content of 100%. This implies a risk of 0.2 and net benefit of $510.00. For heavy textured soils, the minimum risk maximum net benefit is achieved with CCAR 10:1 and initial soil water content of 100% with a risk of 0.55 and net benefit of $580.00. The sensitivity analysis indicate that the model is sensitive to: (1) initial soil water content, (2) soil depth and (3) soil texture in terms of reduction on yield (actual/potential yield).

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Zachmann, Luke J. "Drivers of Plant Population Dynamics in Three Arid to Subhumid Ecosystems". DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/544.

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Understanding the relative importance of density-dependent and density-independent factors in driving population dynamics is one of the oldest challenges in ecology, and may play a critical role in predicting the effects of climate change on populations. We used long-term observational data to describe patterns in plant population regulation for 57 forb and grass species from three different ecosystems (arid desert grassland, semiarid sagebrush steppe, and subhumid mixed-grass prairie). Using a hierarchical partitioning approach, we (i) quantified the relative influence of conspecific density, heterospecific composition, and climate on temporal variation in population growth rates, and (ii) asked how the relative importance of these drivers depends on site aridity, species growth form and life expectancy, and abundance and spatial patterns. The data from one of the sites in this analysis are presented in one of the chapters of this thesis. We found that density-dependence had the strongest effect on species. Climate often had a significant effect, but its strength depended on growth form. Community composition rarely explained significant variation in growth rates. The relative importance of density, composition, and climate did not vary among sites, but was related to species' life histories: compared to forbs, grasses were more sensitive to climate drivers. Abundance and spatial clustering were negatively correlated with the importance of density dependence, suggesting that local rarity is a consequence of self-limitation. Our results show that interspecific interactions play a weaker role than intraspecific interactions and climate variability in regulating plant populations. Forecasting the impacts of climate change on populations may require understanding how changes in climate variables will affect the strength of density-dependence, especially for rare species.

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Abubeker, Hassen. "Characterization and evaluation of Indigofera species as potential forage and cover crops for semi-arid and arid ecosystems". Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-03292006-171339.

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Giardina, Mariah. "Challenges and Strategies for Spring Ecosystem Restoration in the Arid Southwest". Arizona-Nevada Academy of Science, 2011. http://hdl.handle.net/10150/296987.

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Whittington-Jones, Gareth Morgan. "The role of aardvarks (Orycteropus afer) as ecosystem engineers in arid and semi-arid landscapes of South Africa". Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1005445.

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Arid and semi arid environments are characterised by extreme fluctuations in temperature and low rainfall which present significant challenges to the animals inhabiting these areas. Mammals, such as aardvarks (Orycteropus afer, Pallas 1766), excavate burrows in order to avoid predators and climatic extremes and are termed “ecosystem engineers” as they physically modify their environment and in doing so create new habitats and alter the availability of resources to other species. In this study I assessed the microhabitat conditions (maximum and minimum temperature, relative humidity and seed abundance) of aardvark burrows in relation to paired control sites. In addition, I evaluated the use of aardvark burrows by other vertebrate and invertebrate species and investigated the impact of aardvark burrow mounds on landscape scale floristic diversity. Maximum temperatures were significantly lower (p < 0.05) and minimum temperatures and midday humidity were significantly higher (p < 0.05) inside the burrows at the three study sites, Kwandwe Private Game Reserve (Kwandwe), Mountain Zebra National Park (MZNP) and Tswalu Kalahari Reserve (Tswalu). There were no significant differences between the concentration of seeds, the average numbers of unique individual small mammals, trap success or small mammal species richness recorded inside the burrows compared to outside (p > 0.05). At all three sites, small mammal species diversity was higher in the burrows but this result was also not significant (p > 0.05 for all). Trap success and the number of individuals captured was higher at Tswalu than the other two sites (p < 0.05 for both). The different methods used in this study revealed a total of 25 mammal, seven bird, one amphibian and six reptile species utilising aardvark burrows. There were significant differences in insect community assemblages between the burrows and open control areas at Kwandwe and Tswalu (p < 0.05 for both) but not at MZNP (p > 0.05). The parasitic guild was more prominent inside the burrows than outside but their abundance was not as high as anticipated, possibly due to the placement of traps closer to the burrow entrances than the sleeping chambers. The complex structure of the burrows prevented the placement of traps in close proximity to the sleeping chambers. As expected, the amount of bare earth was significantly higher on active and recently abandoned burrow mounds compared to the old burrow mounds and reference plots at all three sites (p < 0.05 for all), with the exception of the active burrows at Tswalu. Overall, the different plot types were characterised by significantly different plant communities during all the seasons at MZNP, during three of the seasons at Kwandwe and only during winter at Tswalu. The total species richness recorded on the reference plots was higher than on the burrow mounds at all three sites. However, species diversity on the reference plots was not significantly higher than the burrows at any of the sites (p > 0.05 for all sites). Although the results were not significant, the overall species diversity at a site level was greater than the reference patches at Kwandwe and Tswalu (p > 0.05 for both). Aardvarks fulfil the criteria of a significant ecosystem engineer and their presence in arid and semi-arid environments is likely to be critical to the survival of other individual organisms and species, particularly when alternative burrowing animals are either absent or restricted in their activities. Thus, aardvark populations should be considered a conservation priority in arid and semi-arid ecosystems.

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Libri sul tema "Ecosystème aride"

Hans-Peter, Blume, e Berkowicz Simon M, a cura di. Arid ecosystems. Cremlingen-Destedt, Germany: Catena, 1995.

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Breckle, Siegmar-W., Aaron Yair e Maik Veste, a cura di. Arid Dune Ecosystems. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-75498-5.

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S, Faroda A., e Arid Zone Research Association of India., a cura di. Management of arid ecosystem. Jodhpur: Arid Zone Research Association of India and Scientific Publishers, 1999.

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G, Kepner William, United States. Environmental Protection Agency. Environmental Monitoring and Assessment Program e Environmental Monitoring Systems Laboratory (Las Vegas, Nev.), a cura di. Arid ecosystems 1992 pilot report. Las Vegas, Nev: Environmental Monitoring Systems Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 1994.

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1935-, Kolarkar A. S., Joshi D. C. 1943- e Sharma K. D. 1950-, a cura di. Rehabilitation of degraded arid ecosystem. Jodhpur: Scientific Publishers, 1992.

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Xiaoling, Pan, Zhongguo hai yang xue hui., Society of Photo-optical Instrumentation Engineers., United States. National Aeronautics and Space Administration. Earth Science Technology Office. e Guo jia yao gan zhong xin (China), a cura di. Ecosystems dynamics, ecosystem-society interactions, and remote sensing applications for semi-arid and arid land: 24-27 October 2002, Hangzhou, China. Bellingham, Wash., USA: SPIE, 2003.

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Partnership for Arid Lands Stewardship (PALS), a cura di. Arid lands: Teacher handbook. [Richland, Wash: Partnership for Arid Lands Stewardship, 1999.

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N, Tewari D. Desert ecosystem. Dehra Dun, India: International Book Distributors, 1994.

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W, Hoekstra T., e Shachak Moshe, a cura di. Arid lands management: Toward ecological sustainability. Urbana: University of Illinois Press, 1999.

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Breman, Henk, e Jan-Joost Kessler. Woody Plants in Agro-Ecosystems of Semi-Arid Regions. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79207-6.

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Capitoli di libri sul tema "Ecosystème aride"

Gallacher, David. "Drone-Based Vegetation Assessment in Arid Ecosystems". In Sabkha Ecosystems, 91–98. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-04417-6_7.

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Boone, Randall B., Shauna B. BurnSilver e Russell S. Kruska. "Comparing Landscape and Infrastructural Heterogeneity within and between Ecosystems". In Fragmentation in Semi-Arid and Arid Landscapes, 341–67. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-4906-4_14.

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Coughenour, Michael B. "Causes and Consequences of Herbivore Movement in Landscape Ecosystems". In Fragmentation in Semi-Arid and Arid Landscapes, 45–91. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-4906-4_3.

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Stahl, Bernd Carsten. "AI Ecosystems for Human Flourishing: The Recommendations". In SpringerBriefs in Research and Innovation Governance, 91–115. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69978-9_7.

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AbstractThis chapter develops the conclusions that can be drawn from the application of the ecosystemmetaphor to AI. It highlights the challenges that arise for the ethical governance of AI ecosystems. These provide the basis for the definition of requirements that successful governance interventions have to fulfil. Three main requirements become apparent: the need for a clear delimitation of the boundaries of the ecosystem in question, the provision and maintenance of knowledge and capacities within the ecosystem, and the need for adaptable, flexible and careful governance structures that are capable of reacting to environmental changes. Based on these requirements, the chapter then spells out some recommendations for interventions that are likely to be able to shape AI ecosystems in ways that are conducive to human flourishing.

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Ibáñez, Carles, e Nuno Caiola. "Impacts of Water Scarcity and Drought on Iberian Aquatic Ecosystems". In Drought in Arid and Semi-Arid Regions, 169–84. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6636-5_9.

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BurnSilver, Shauna B., Jeffrey Worden e Randall B. Boone. "Processes of Fragmentation in the Amboseli Ecosystem, Southern Kajiado District, Kenya". In Fragmentation in Semi-Arid and Arid Landscapes, 225–53. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-4906-4_10.

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Hobbs, N. Thompson, Robin S. Reid, Kathleen A. Galvin e James E. Ellis. "Fragmentation of Arid and Semi-Arid Ecosystems: Implications for People and Animals". In Fragmentation in Semi-Arid and Arid Landscapes, 25–44. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-4906-4_2.

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Overton, Ian C., e Tanya M. Doody. "The River Murray-Darling Basin: Ecosystem Response to Drought and Climate Change". In Drought in Arid and Semi-Arid Regions, 217–34. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6636-5_12.

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Jafari, Mohammad, Ali Tavili, Fatemeh Panahi, Ehsan Zandi Esfahan e Majid Ghorbani. "Characteristics of Arid and Desert Ecosystems". In Environmental Science and Engineering, 21–91. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54828-9_2.

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Wickens, Gerald E. "Arid and Semi-Arid Regions and Ecosystems of the World". In Ecophysiology of Economic Plants in Arid and Semi-Arid Lands, 17–103. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-662-03700-3_3.

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Atti di convegni sul tema "Ecosystème aride"

Howari, Fares M., Manish Sharma, Cijo M. Xavier, Yousef Nazzal, Imen Ben Salem e Fatima Al Aydaroos. "Remote sensing and GIS based approaches to estimate evapotranspiration in the arid and semi-arid regions". In Remote Sensing for Agriculture, Ecosystems, and Hydrology XXIII, a cura di Christopher M. Neale e Antonino Maltese. SPIE, 2021. http://dx.doi.org/10.1117/12.2599899.

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Moglia, A., L. Bracco, M. Chiolo e M. Buffagni. "E&P Operations in Water Stressed Areas: An Approach to the Identification, Selection and Implementation of Initiatives for a Sustainable Water Management, Withdrawal Reduction and Water Valorization". In SPE International Health, Safety, Environment and Sustainability Conference and Exhibition. SPE, 2024. http://dx.doi.org/10.2118/220301-ms.

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Water is one of earth's most critical resources, and water scarcity represents an increasing problem worldwide. Demographic growth and economic development are putting unprecedented pressure on water resources, especially in arid regions. Water is crucial for many sectors, and it is also fundamental to meet personal and household needs, for energy and industrial production, to maintain important water-dependent ecosystems and ecosystem services. Water plays a key role in all the phases of the Oil and Gas business, because of the large amounts of this resource that should be managed, both with respect to withdrawals and to disposal. For these reasons, it is essential to adopt a well-defined and sound approach in order to protect the water resource, also considering that often Oil and Gas activities take place in arid regions. All these aspects require an integrated and inclusive approach, able to build resilience against worsening factors.

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Alhamad, Mohammad N., e Shefaa M. Abdullah. "MODELING OF RANGELAND ECOSYSTEMS IN NORTHERN JORDAN". In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/3.1/s12.12.

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Grasslands is globally important vegetation type for providing feed resources for grazing animals. An improved understanding of the factors affecting the long-term productivity of the ecosystems will be beneficial, as well as to developing a better understanding of the role these ecosystems play in global environmental change. Arid and semi-arid Mediterranean grasslands provide valuable forage for grazing animals in the eastern part of the Mediterranean area and have been subjected to long-term unsustainable grazing practices, leading to degeneration of productivity and impacts plant community structure. The present study aimed to discover the validity of using Phytomass Growth Simulator Model (Phygrow) to simulate arid grassland ecosystems. The purpose is to build a Phygrow simulation model that can accurately estimate important eco-hydrological processes in arid grassland ecosystems. The weather parameter was taken from the NASA (National Aeronautics and Space Administration). Important vegetation parameters and other key processes were simulated during the period 1981�2021 using the Phygrow model. The simulation was conducted for a grassland community within the Jordan University of Science and Technology JUST Campus. The model was able to reproduce all the general trends found in the study area, where peak growth is reached during the spring and ceased during the summer for annual spring growing species. The model has been successfully able to simulate leaf area index, evapotranspiration, soil moisture, leaf water storage, water stress, and temperature stress from 1981 to 2021.

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Zhao, Xin, Jia Jin, Haiying Guan e Sinan Zhang. "Spatial pattern of soil microbial biomass in a typical arid ecosystem". In International Conference on Environment and Sustainability. Southampton, UK: WIT Press, 2014. http://dx.doi.org/10.2495/ices140441.

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Dan Luo e Nai'ang Wang. "Notice of Retraction: Simulations for vegetation cover in an arid ecosystem". In 2010 International Conference on Computer Application and System Modeling (ICCASM 2010). IEEE, 2010. http://dx.doi.org/10.1109/iccasm.2010.5620721.

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Pan, Xiaoling, Fengxue Gu, Wei Gao, Weiqing Li, Subai Anabiek e Michelle M. Glantz. "Stability study of oasis ecosystems in arid land areas of western China". In Third International Asia-Pacific Environmental Remote Sensing Remote Sensing of the Atmosphere, Ocean, Environment, and Space, a cura di Xiaoling Pan, Wei Gao, Michael H. Glantz e Yoshiaki Honda. SPIE, 2003. http://dx.doi.org/10.1117/12.466610.

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Chabrillat, Sabine, Hermann J. Kaufmann, Alicia Palacios-Orueta, Paula Escribano e Andreas Mueller. "Development of land degradation spectral indices in a semi-arid Mediterranean ecosystem". In Remote Sensing, a cura di Manfred Ehlers, Francesco Posa, Hermann J. Kaufmann, Ulrich Michel e Giacomo De Carolis. SPIE, 2004. http://dx.doi.org/10.1117/12.565252.

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Aralova, Dildora, Kristina Toderich, Ben Jarihani, Dilshod Gafurov, Liliya Gismatulina, Babatunde A. Osunmadewa e Majdaldin Rahamtallah Abualgasim. "Environmental resilience of rangeland ecosystems: assessment drought indices and vegetation trends on arid and semi-arid zones of Central Asia". In SPIE Remote Sensing, a cura di Ulrich Michel, Karsten Schulz, Manfred Ehlers, Konstantinos G. Nikolakopoulos e Daniel Civco. SPIE, 2016. http://dx.doi.org/10.1117/12.2242563.

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Lipka, Oksana, G. Mazmaniants, Maria Isupova, A. Aleynikov, Dmitry Zamolodchikov e Vladimir Kaganov. "USING OF THE ILI RIVER DELTA ECOSYSTEM SERVICES FOR ADAPTATION TO CLIMATE CHANGE". In Land Degradation and Desertification: Problems of Sustainable Land Management and Adaptation. LLC MAKS Press, 2020. http://dx.doi.org/10.29003/m1700.978-5-317-06490-7/158-165.

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Ecosystem-based adaptation can be applied as an option for sustainable land management. Methodologies that not only prevent land degradation but also contribute to the maintenance of a hydrological regime have become a priority in arid Central Asian climate. Large river deltas can be used as a natural counter-regulator, which accumulates water in wet seasons/years and gradually gives it back to low-water ones. To do so the land-use regime must prevent the degradation of ecosystems and the reduction of their functions. The hystorical anthropogenic damage must be eliminated. In the case of the Ili River delta the restoration of tugai forests is required on an area of at least 30% of the territory, i.e. more than 200 thousand hectares. Afforestation can lead to an increase in the underground water supply of the river at 30 - 70%. The groundwater supply to the river branches in the delta can increase by 1.26 - 2.94 km3/year (up to 21% annual river flow), which, in turn, will lead to additional water supply to Lake Balkhash and reduce the risk of the Aral Sea crisis repetition.

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Azlaoui, Mohamed, Salah Karef, Rachid Zegait, Nadjib Haied, Atif Foufou e Imed Eddine Nezli. "Hydrochemical Characterization of Groundwater in a Semi-Arid Zone; Algeria". In 2023 1st International Conference on Renewable Solutions for Ecosystems: Towards a Sustainable Energy Transition (ICRSEtoSET). IEEE, 2023. http://dx.doi.org/10.1109/icrsetoset56772.2023.10525410.

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Rapporti di organizzazioni sul tema "Ecosystème aride"

Fischer, Richard A. Ecosystem Management and Restoration. January 2003. Riparian Restoration and Management Needs in the Arid and Semi-Arid Western United States. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2003. http://dx.doi.org/10.21236/ada410913.

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Juy-abad, Fatemeh Khani, Parisa Mohammadi e Mahbubeh Zarrabi. The Identification of Some Phototrophic Microorganisms from a Semi-arid Ecosystem in Iran. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, dicembre 2018. http://dx.doi.org/10.7546/crabs.2018.12.06.

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Peters, Jan. Plant diversity patterns at different spatial scales in a semi-arid savanna ecosystem in central Namibia. BEE-Press, ottobre 2010. http://dx.doi.org/10.7809/thesis.diplom.003.

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Sharp, Jonathan. Final Report: Mechanistic and predictive understanding of needle litter decay in semi-arid mountain ecosystems experiencing unprecedented vegetation mortality. Office of Scientific and Technical Information (OSTI), agosto 2020. http://dx.doi.org/10.2172/1712688.

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Razdan, Rahul. Unsettled Issues Regarding Autonomous Vehicles and Open-source Software. SAE International, aprile 2021. http://dx.doi.org/10.4271/epr2021009.

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As automobiles morph from stand-alone mechanical objects to highly connected, autonomous systems with increasing amounts of electronic components. To manage these complex systems, some semblance of in-car decision-making is also being built and networked to a cloud architecture. This cloud can also enable even deeper capabilities within the broader automotive ecosystem. Unsettled Issues Regarding Autonomous Vehicles and Open-source Software introduces the impact of software in advanced automotive applications, the role of open-source communities in accelerating innovation, and the important topic of safety and cybersecurity. As electronic functionality is captured in software and a bigger percentage of that software is open-source code, some critical challenges arise concerning security and validation.

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Raymond, Kara, Laura Palacios, Cheryl McIntyre e Evan Gwilliam. Status of climate and water resources at Chiricahua National Monument, Coronado National Memorial, and Fort Bowie National Historic Site: Water year 2019. National Park Service, maggio 2022. http://dx.doi.org/10.36967/nrr-2293370.

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Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and water quality and quantity is central to assessing the condition of park biota and key cultural resources. The Sonoran Desert Network collects data on climate, groundwater, and surface water at 11 National Park Service units in southern Arizona and New Mexico. This report provides an integrated look at climate, groundwater, and springs conditions at Chiricahua National Monument (NM), Coronado National Memorial (NMem), and Fort Bowie National Historic Site (NHS) during water year (WY) 2019 (October 2018–September 2019). Overall annual precipitation at Chiricahua NM and Coronado NMem in WY2019 was approximately the same as the normals for 1981–2010. (The weather station at Fort Bowie NHS had missing values on 275 days, so data were not presented for that park.) Fall and winter rains were greater than normal. The monsoon season was generally weaker than normal, but storm events related to Hurricane Lorena led to increased late-season rain in September. Mean monthly maximum temperatures were generally cooler than normal at Chiricahua, whereas mean monthly minimum temperatures were warmer than normal. Temperatures at Coronado were more variable relative to normal. The reconnaissance drought index (RDI) indicated that Chiricahua NM was slightly wetter than normal. (The WY2019 RDI could not be calculated for Coronado NMem due to missing data.) The five-year moving mean of annual precipitation showed both park units were experiencing a minor multi-year precipitation deficit relative to the 39-year average. Mean groundwater levels in WY2019 increased at Fort Bowie NHS, and at two of three wells monitored at Chiricahua NM, compared to WY2018. Levels in the third well at Chiricahua slightly decreased. By contrast, water levels declined in five of six wells at Coronado NMem over the same period, with the sixth well showing a slight increase over WY2018. Over the monitoring record (2007–present), groundwater levels at Chiricahua have been fairly stable, with seasonal variability likely caused by transpiration losses and recharge from runoff events in Bonita Creek. At Fort Bowie’s WSW-2, mean groundwater level was also relatively stable from 2004 to 2019, excluding temporary drops due to routine pumping. At Coronado, four of the six wells demonstrated increases (+0.30 to 11.65 ft) in water level compared to the earliest available measurements. Only WSW-2 and Baumkirchner #3 have shown net declines (-17.31 and -3.80 feet, respectively) at that park. Springs were monitored at nine sites in WY2019 (four sites at Chiricahua NM; three at Coronado NMem, and two at Fort Bowie NHS). Most springs had relatively few indications of anthropogenic or natural disturbance. Anthropogenic disturbance included modifications to flow, such as dams, berms, or spring boxes. Examples of natural disturbance included game trails, scat, or evidence of flooding. Crews observed 0–6 facultative/obligate wetland plant taxa and 0–3 invasive non-native species at each spring. Across the springs, crews observed six non-native plant species: common mullein (Verbascum thapsus), spiny sowthistle (Sonchus asper), common sowthistle (Sonchus oleraceus), Lehmann lovegrass (Eragrostis lehmanniana), rabbitsfoot grass (Polypogon monspeliensis), and red brome (Bromus rubens). Baseline data on water quality and water chemistry were collected at all nine sites. It is likely that that all nine springs had surface water for at least some part of WY2019, though temperature sensors failed at two sites. The seven sites with continuous sensor data had water present for most of the year. Discharge was measured at eight sites and ranged from < 1 L/minute to 16.5 L/minute.

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Raymond, Kara, Laura Palacios, Cheryl McIntyre e Evan Gwilliam. Status of climate and water resources at Saguaro National Park: Water year 2019. A cura di Alice Wondrak Biel. National Park Service, dicembre 2021. http://dx.doi.org/10.36967/nrr-2288717.

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Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and water quality and quantity is central to assessing the condition of park biota and key cultural resources. The Sonoran Desert Network collects data on climate, groundwater, and surface water at 11 National Park Service units in south-ern Arizona and New Mexico. This report provides an integrated look at climate, groundwater, and springs conditions at Saguaro National Park (NP) during water year 2019 (October 2018–September 2019). Annual rainfall in the Rincon Mountain District was 27.36" (69.49 cm) at the Mica Mountain RAWS station and 12.89" (32.74 cm) at the Desert Research Learning Center Davis station. February was the wettest month, accounting for nearly one-quarter of the annual rainfall at both stations. Each station recorded extreme precipitation events (>1") on three days. Mean monthly maximum and minimum air temperatures were 25.6°F (-3.6°C) and 78.1°F (25.6°C), respectively, at the Mica Mountain station, and 37.7°F (3.2°C) and 102.3°F (39.1°C), respectively, at the Desert Research Learning Center station. Overall temperatures in WY2019 were cooler than the mean for the entire record. The reconnaissance drought index for the Mica Mountain station indicated wetter conditions than average in WY2019. Both of the park’s NOAA COOP stations (one in each district) had large data gaps, partially due to the 35-day federal government shutdown in December and January. For this reason, climate conditions for the Tucson Mountain District are not reported. The mean groundwater level at well WSW-1 in WY2019 was higher than the mean for WY2018. The water level has generally been increasing since 2005, reflecting the continued aquifer recovery since the Central Avra Valley Storage and Recovery Project came online, recharging Central Arizona Project water. Water levels at the Red Hills well generally de-clined starting in fall WY2019, continuing through spring. Monsoon storms led to rapid water level increases. Peak water level occurred on September 18. The Madrona Pack Base well water level in WY2019 remained above 10 feet (3.05 m) below measuring point (bmp) in the fall and winter, followed by a steep decline starting in May and continuing until the end of September, when the water level rebounded following a three-day rain event. The high-est water level was recorded on February 15. Median water levels in the wells in the middle reach of Rincon Creek in WY2019 were higher than the medians for WY2018 (+0.18–0.68 ft/0.05–0.21 m), but still generally lower than 6.6 feet (2 m) bgs, the mean depth-to-water required to sustain juvenile cottonwood and willow trees. RC-7 was dry in June–September, and RC-4 was dry in only September. RC-5, RC-6 and Well 633106 did not go dry, and varied approximately 3–4 feet (1 m). Eleven springs were monitored in the Rincon Mountain District in WY2019. Most springs had relatively few indications of anthropogenic or natural disturbance. Anthropogenic disturbance included spring boxes or other modifications to flow. Examples of natural disturbance included game trails and scat. In addition, several sites exhibited slight disturbance from fires (e.g., burned woody debris and adjacent fire-scarred trees) and evidence of high-flow events. Crews observed 1–7 taxa of facultative/obligate wetland plants and 0–3 invasive non-native species at each spring. Across the springs, crews observed four non-native plant species: rose natal grass (Melinis repens), Kentucky bluegrass (Poa pratensis), crimson fountaingrass (Cenchrus setaceus), and red brome (Bromus rubens). Baseline data on water quality and chemistry were collected at all springs. It is likely that that all springs had surface water for at least some part of WY2019. However, temperature sensors to estimate surface water persistence failed...

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Raymond, Kara, Laura Palacios e Evan Gwilliam. Status of climate and water resources at Big Bend National Park: Water year 2019. A cura di Tani Hubbard. National Park Service, settembre 2022. http://dx.doi.org/10.36967/2294267.

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Climate and hydrology are major drivers of ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, streamflow, and water quality is central to assessing the condition of park resources. This report combines data collected on climate, groundwater, and springs at Big Bend National Park (NP) to provide an integrated look at climate and water conditions during water year (WY) 2019 (October 2018–September 2019). However, this report does not address the Rio Grande or its tributaries. Annual precipitation was higher than normal (1981–2010) for Big Bend NP at four of the five National Oceanic and Atmospheric Administration Cooperative Observer Program weather stations: 111% of normal for Chisos Basin, 122% of normal for Panther Junction, 155% of normal for Persimmon Gap, and 124% of normal for Rio Grande Village. Castolon had 88% of normal annual precipitation. All five stations had higher than normal rainfall in October and December, while rainfall totals were substantially below normal at all stations in November, February, and March. Monthly precipitation totals for April through September were more variable from station to station. Mean monthly maximum air temperatures were below normal in the fall months, with Panther Junction as much as 7.5°F below normal in October. Monthly temperatures from January through July were more variable. Temperatures in August and September were warmer than normal at every station, up to +9.4°F at Rio Grande Village and +8.7°F at Chisos Basin in July. The reconnaissance drought index values indicate generally wetter conditions (based on precipitation and evaporative demand) at Chisos Basin since WY2016 and at Panther Junction and Persimmon Gap since WY2015, except for WY2017. This report presents the manual and automatic groundwater monitoring results at nine wells. Five wells had their highest water level in or just before WY2019: Panther Junction #10 peaked at 99.94 ft below ground surface (bgs) in September 2018, Contractor’s Well peaked at 31.43 ft bgs in November 2018, T-3 peaked at 65.39 ft bgs in December 2018, K-Bar #6 Observation Well peaked at 77.78 ft bgs in February 2019, and K-Bar #7 Observation Well peaked at 43.18 ft bgs in February 2019. This was likely in response to above normal rainfall in the later summer and fall 2018. The other monitoring wells did not directly track within-season precipitation. The last measurement at Gallery Well in WY2019 was 18.60 ft bgs. Gallery Well is located 120 feet from the river and closely tracked the Rio Grande stage, generally increasing in late summer or early fall following higher flow events. Water levels in Gambusia Well were consistently very shallow, though the manual well measurement collected in April was 4.25 ft bgs—relatively high for the monitoring record—and occurred outside the normal peak period of later summer and early fall. The last manual measurement taken at TH-10 in WY2019 was 34.80 ft bgs, only 0.45 ft higher than the earliest measurement in 1967, consistent with the lack of directional change in groundwater at this location, and apparently decoupled from within-season precipitation patterns. The last water level reading in WY2019 at Oak Springs #1 was 59.91 ft bgs, indicating an overall decrease of 26.08 ft since the well was dug in 1989. The Southwest Network Collaboration (SWNC) collects data on sentinel springs annually in the late winter and early spring following the network springs monitoring protocol. In WY2019, 18 sentinel site springs were visited at Big Bend NP (February 21, 2019–March 09, 2019). Most springs had relatively few indications of natural and anthropogenic disturbances. Natural disturbances included recent flooding, drying, and wildlife use. Anthropogenic disturbances included flow modifications (e.g., springboxes), hiking trails, and contemporary human use. Crews observed one to seven facultative/obligate wetland plant...

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Walker, David, e Jeffrey Renfrow. Toxicological reconnaissance of Arsenal? use along the Rio Grande River through Big Bend National Park: Final report. National Park Service, 2024. http://dx.doi.org/10.36967/2302769.

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This study examined the biological response of aquatic organisms, collected in situ and from laboratory toxicity testing of water and soil to the herbicide Arsenal? primarily used to decrease the invasive species Arundo donax in the Rio Grande River through Big Bend National Park in Texas (USA). Biological, toxicological, physicochemical, and flow data were collected before, during, and after an Arsenal? treatment from 4 reference and 3 treatment sites. Significant differences existed in ecoregion 24 B-IBI scoring, and in toxicity testing of water and sediment, between treatment and reference sites. Greater toxicity, and a higher inverse relationship to B-IBI scoring, was observed in sediment samples compared to water samples. This could be due to the surfactant nonylphenol ethoxylate (NPE), added to the Arsenal? formulation rather than the active ingredient imazapyr. Care must be implemented with the results of this research due to many confounding variables that occurred during the study period including flash flooding. Although flashy hydrology is relatively common to the region, it can influence aquatic macroinvertebrate assemblage structure, function, and species richness measures with these dropping due to scour and downstream displacement within a reach during, and for some period following, flooding. Therefore, flash flooding would be expected to have some effect on aquatic macroinvertebrate assemblages and subsequent B-IBI scoring. Additionally, flooding will cause some displacement, and deposition, of sediment throughout the study area. This flooding could impact the sediment toxicity results as sediment-bound contaminants could be spread some distance from their origin. Arsenal? treatment occurred during this study near sites Treatment 1 and Treatment 2 on 5/29 and 5/31 2022 respectively. This represented an extreme condition as far as concentration of potential toxicants in the water are concerned and these relatively high concentrations would be expected to have decreased within a relatively short period of time, especially in the water. It was outside of the scope and budget of this project to obtain concentrations of imazapyr or surfactants from sediment or water. Therefore, exact doses of imazapyr or surfactant for response curves could not be obtained. No sample site exists in isolation rather, influences from one reach can significantly impact downstream areas. This is especially true for aquatic ecosystems in arid regions that often exhibit flashy hydrology. However, we believe the findings from this study provide indication of potential toxicity of some magnitude as well as provide direction for management. Decisions of whether the toxic effects of herbicide use to aquatic macroinvertebrates outweigh the beneficial effects of Arundo donax control should be carefully considered.

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Menuz, Diane, e Rebekah Downard. Opportunity for Improved Wetland Mitigation in Utah - In-Lieu Fee Mitigation Potential in Utah. Utah Geological Survey, settembre 2023. http://dx.doi.org/10.34191/ofr-756.

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Wetlands play a crucial role in watersheds and provide critical ecosystem functions, most notably, water quality improvement, fish and wildlife habitat, flood attenuation, drought mitigation, and carbon sequestration. Wetlands in Utah are regulated primarily by the federal government under the Clean Water Act (CWA), which requires mitigation to replace ecological services that are lost to permitted activities. Utah House Bill 118 (2022) directed the Utah Geological Survey to explore the potential for an In-Lieu Fee (ILF) mitigation program to improve wetland resources in Utah. An ILF program would allow entities seeking CWA permits to pay a fee to mitigate impacts to streams and wetlands rather than having to develop their own mitigation plans. To research the possible consequences of an ILF, we conducted document research and interviews with mitigation practitioners and wetland stakeholders and analyzed ten years of permit data. Interview participants agreed that an ILF would improve the quality of wetland mitigation projects, which currently are often small, isolated, and overrun with weeds. An ILF would also improve coordination between the various entities involved in natural resource protection, permitting, and restoration. Further, permittees would benefit from an ILF because it would streamline the permitting process. Research and input from current practitioners showcased that there were many options for running an ILF program that can work for Utah, which has few permitted wetland impacts compared to other, less arid states. The most effective way to build an ILF in Utah is to support a full-time ILF administrator to establish the program and develop and maintain strong relationships with regulators, restoration specialists, and those seeking permits. Based on historical permit rates, such a position could be funded by program fees after the program is established. The future of a self-sustaining ILF program is uncertain, however, due to the recent Sackett v. Environmental Protection Agency (EPA) Supreme Court decision which limited the types of wetlands that are regulated by the federal government. The expected reduction in wetland permitting creates a more challenging environment in which to operate an ILF program because permit fees will likely no longer support a full-time ILF administrator’s salary. At the same time, ensuring high quality mitigation will be more important than ever because there will be more unpermitted and thus unmitigated wetland impacts, leading to loss in ecological functions. Given these considerations, we recommend establishing a position for a wetland mitigation and restoration coordinator who can explore multiple options to preserve and restore wetlands in Utah, coordinate among agencies, and begin to implement an ILF program at a rate and scale appropriate to the new regulatory conditions. By investing in a wetland mitigation and restoration coordinator, the state can support voluntary restoration measures to increase wetland functions while at the same time improving mitigation outcomes for permittees and projects. Together, these actions will lead to healthier, more resilient wetlands that will protect the quality of life for all Utahns.

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