The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Emilio Custodio - One of the best experts on this subject based on the ideXlab platform.
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aquifer Overexploitation what does it mean
Hydrogeology Journal, 2002Co-Authors: Emilio CustodioAbstract:Groundwater Overexploitation and aquifer Overexploitation are terms that are becoming common in water-resources management. Hydrologists, managers and journalists use them when talking about stressed aquifers or some groundwater conflict. Overexploitation may be defined as the situation in which, for some years, average aquifer abstraction rate is greater than, or close to the average recharge rate. But rate and extent of recharge areas are often very uncertain. Besides, they may be modified by human activities and aquifer development. In practice, however, an aquifer is often considered as overexploited when some persistent negative results of aquifer development are felt or perceived, such as a continuous water-level drawdown, progressive water-quality deterioration, increase of abstraction cost, or ecological damage. But negative results do not necessarily imply that abstraction is greater than recharge. They may be simply due to well interferences and the long transient period that follow changes in the aquifer water balance. Groundwater storage is depleted to some extent during the transient period after abstraction is increased. Its duration depends on aquifer size, specific storage and permeability. Which level of "aquifer Overexploitation" is advisable or bearable, depends on the detailed and updated consideration of aquifer-development effects and the measures implemented for correction. This should not be the result of applying general rules based on some indirect data. Monitoring, sound aquifer knowledge, and calculation or modelling of behaviour are needed in the framework of a set of objectives and policies. They should be established by a management institution, with the involvement of groundwater stakeholders, and take into account the environmental and social constraints. Aquifer Overexploitation, which often is perceived to be associated with something ethically bad, is not necessarily detrimental if it is not permanent. It may be a step towards sustainable development. Actually, the term aquifer Overexploitation is mostly a qualifier that intends to point to a concern about the evolution of the aquifer-flow system in some specific, restricted points of view, but without a precise hydrodynamic meaning. Implementing groundwater management and protection measures needs quantitative appraisal of aquifer evolution and effects based on detailed multidisciplinary studies, which have to be supported by reliable data.
Eric F Lambin - One of the best experts on this subject based on the ideXlab platform.
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the demise of caterpillar fungus in the himalayan region due to climate change and overharvesting
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Kelly A Hopping, Stephen M Chignell, Eric F LambinAbstract:Demand for traditional medicine ingredients is causing species declines globally. Due to this trade, Himalayan caterpillar fungus (Ophiocordyceps sinensis) has become one of the world’s most valuable biological commodities, providing a crucial source of income for hundreds of thousands of collectors. However, the resulting harvesting boom has generated widespread concern over the sustainability of its collection. We investigate whether caterpillar fungus production is decreasing—and if so, why—across its entire range. To overcome the limitations of sparse quantitative data, we use a multiple evidence base approach that makes use of complementarities between local knowledge and ecological modeling. We find that, according to collectors across four countries, caterpillar fungus production has decreased due to habitat degradation, climate change, and especially Overexploitation. Our statistical models corroborate that climate change is contributing to this decline. They indicate that caterpillar fungus is more productive under colder conditions, growing in close proximity to areas likely to have permafrost. With significant warming already underway throughout much of its range, we conclude that caterpillar fungus populations have been negatively affected by a combination of Overexploitation and climate change. Our results underscore that harvesting is not the sole threat to economically valuable species, and that a collapse of the caterpillar fungus system under ongoing warming and high collection pressure would have serious implications throughout the Himalayan region.
Maurice W Sabelis - One of the best experts on this subject based on the ideXlab platform.
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local dynamics Overexploitation and predator dispersal in an acarine predator prey system
Oikos, 1999Co-Authors: S H Pels, Maurice W SabelisAbstract:We studied the impact of dispersal of predatory arthropods on local predator-prey dynamics, Two types of dispersal strategies are distinguished: the Killer-strategy in which predators only disperse after a local prey population went extinct, and the Milker-strategy in which predators also disperse in the presence of prey. Theory predicts that Killers are favoured by selection when local predator populations are started by multiple, unrelated foundresses, whereas Milkers are favoured by selection when the number of foundresses is sufficiently low. To determine which of these strategies prevails in wild populations of predatory arthropods, we did replicated experiments on local dynamics and dispersal in a system of bean leaves, herbivorous mites (Tetranychus urticae) and various field-collected strains of predatory mites (Phytoseiulus persimilis). The experiments showed that all strains tend to drive local prey populations to extinction. Furthermore, we found two isofemale lines that showed consistent differences with regard to the onset of dispersal. In one linc predators did not disperse until after extermination of the local prey population, but in another some adult females dispersed when there were still prey present. The earlier predator dispersal was associated with a longer interaction period and a larger overall prey population. Interestingly, the Milker-type line originated from a population that was much more isolated from other populations than the one from which the Killer-type line was obtained. This result provides qualitative support for the so-called Milker-Killer hypothesis. Another observation was that near to prey elimination there is first a peak of dispersing juvenile predators, followed 1-3 d later by a peak of dispersing adult males and females. Dispersal continued up to 10 d after prey extermination. To explain why the predators stay so long in an area devoid of prey it is hypothesised that cannibalism on the younger and weaker stages motivates adult predators to delay dispersal, and or provides juveniles the means to reach maturity.
Juan Puigdefabregas - One of the best experts on this subject based on the ideXlab platform.
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assessing Overexploitation in mediterranean aquifers using system stability condition analysis
Ecological Modelling, 2008Co-Authors: Javier Quesada Ibanez, Jaime Martinez Valderrama, Juan PuigdefabregasAbstract:This paper analyses competitive groundwater exploitation for irrigation by means of a special case of a dynamic predator–prey or human-resource theoretical model. On the human side, the model considers both farmers’ rational behaviour and a set of economic parameters. Then the model explicitly links these issues to the dynamics of the natural resource. Equilibrium states are evaluated, and the drivers and conditions for final states leading to groundwater Overexploitation are assessed. The theoretical model finally serves to discuss the long-term sustainability of the processes of transformation from traditional to highly intensive pumping-based agricultural systems. These are processes now taking place in aquifers of southern Spain and Maghreb oases.
Vinceti Barbara - One of the best experts on this subject based on the ideXlab platform.
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Diversity under threat: Connecting genetic diversity and threat mapping to set conservation priorities for Juglans regia L. populations in Central Asia
Frontiers Media S.A., 2020Co-Authors: Gaisberger Hannes, Legay Sylvain, Andre Christelle, Loo Judy, Aaliev Sagynbek, Bobokalonov Farhod, Muhsimov Nurullo, Kettle, Chris J., Vinceti BarbaraAbstract:Central Asia is an important center of diversity for common walnut (Juglans regia L.). We characterized the genetic diversity of 21 wild and cultivated populations across Kyrgyzstan, Tajikistan and Uzbekistan. A complete threat assessment was performed evaluating the short-term threats from Overexploitation, overgrazing, landslides, and fragmentation as well as long-term threats from climate change. Based on key indicators of genetic diversity and threat magnitude, we developed an approach to identify wild populations for priority conservation and defined appropriate measures to conserve their genetic diversity based on the specific threat magnitudes. We propose (i) ex-situ conservation in areas with ‘severe threat level’ due to climate change and (ii) in-situ conservation in areas with ‘minor threat level’ due to climate change. In addition, we suggest (iii) assisted natural regeneration in areas where ‘minor threat levels’ from climate change coincide with ‘severe threat levels’ from one or more short-term threats. Our research shows high levels of genetic diversity as well as high threat levels in the walnut populations examined across three countries. Overgrazing and Overexploitation were identified as the two most important threats whereas climate changed turned out to be of minor concern in the near future. Four out of the five populations selected for priority conservation are severely threatened: Kara-Alma (KGP3) and Sariosiyo (UZP4) by Overexploitation and overgrazing, Vanj (TJP2) by landslides and fragmentation and Bostanlyk_2 (UZP2) by Overexploitation. Only the Baljuvon population (TJP4) in Tajikistan shows minor threat levels in the short and long term. Thus, for all five priority populations the most appropriate conservation approach appears to be in-situ conservation. Spontaneous natural regeneration should be sufficient to ensure the long-term survival of the Baljuvon population (TJP4), while for the other four priority populations assisted natural regeneration may be needed. This network of five sites represents the minimum number of conservation areas for wild walnut in the three countries that should be established to capture a significant amount of the species genetic diversity. Conservation efforts could be extended to home gardens, which are a valuable genetic reservoir for the wild diversity found in the region.Peer Revie
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Diversity Under Threat: Connecting Genetic Diversity and Threat Mapping to Set Conservation Priorities for Juglans regia L. Populations in Central Asia
'Frontiers Media SA', 2020Co-Authors: Gaisberger Hannes, Legay Sylvain, Andre Christelle, Loo Judy, Aaliev Sagynbek, Bobokalonov Farhod, Muhsimov Nurullo, Kettle, Chris J., Azimov Rashid, Vinceti BarbaraAbstract:Central Asia is an important center of diversity for common walnut (Juglans regia L.). We characterized the genetic diversity of 21 wild and cultivated populations across Kyrgyzstan, Tajikistan, and Uzbekistan. A complete threat assessment was performed evaluating the short-term threats from Overexploitation, overgrazing, landslides, and fragmentation as well as long-term threats from climate change. Based on key indicators of genetic diversity and threat magnitude, we developed an approach to identify wild populations for priority conservation and defined appropriate measures to conserve their genetic diversity based on the specific threat magnitudes. We propose (i) ex situ conservation in areas with “severe threat level” due to climate change and (ii) in situ conservation in areas with “minor threat level” due to climate change. In addition, we suggest (iii) assisted natural regeneration in areas where “minor threat levels” from climate change coincide with “severe threat levels” from one or more short-term threats. Our research shows high levels of genetic diversity as well as high threat levels in the walnut populations examined across three countries. Overgrazing and Overexploitation were identified as the two most important threats whereas climate change turned out to be of minor concern in the near future. Four out of the five populations selected for priority conservation are severely threatened: Kara-Alma (KGP3) and Sariosiyo (UZP4) by Overexploitation and overgrazing, Vanj (TJP2) by landslides and fragmentation and Bostanlyk_2 (UZP2) by Overexploitation. Only the Baljuvon population (TJP4) in Tajikistan shows minor threat levels in the short and long term. Thus, for all five priority populations the most appropriate conservation approach appears to be in situ conservation. Spontaneous natural regeneration should be sufficient to ensure the long-term survival of the Baljuvon population (TJP4), while for the other four priority populations assisted natural regeneration may be needed. This network of five sites represents the minimum number of conservation areas for wild walnut in the three countries that should be established to capture a significant amount of the species genetic diversity. Conservation efforts could be extended to home gardens, which are a valuable genetic reservoir for the wild diversity found in the region.ISSN:2296-701
