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201.
In a context of continued environmental degradation of agricultural landscapes, the concept of Payments for Ecosystem Services (PES) has been attracting growing attention in both academic and policy circles. The main premise of this conservation approach is appealing: land users, who tend to be poorly, if at all, motivated to protect nature on their land, may be encouraged to do so through direct payments from ecosystem service buyers. The theoretical underpinnings of PES emanate from an environmental externality framework, in which market failures are considered the root cause of environmental degradation. While the PES concept is attractive at first sight, this article discusses some weaknesses in its conceptual foundation. It focuses on two important aspects of the market-based PES concept: the hidden political ambiguities of the externality framework and the risk that PES, especially if user-funded, may perpetuate and deepen the regressive financing of global commons by poor local communities. 相似文献
202.
The micro-ecosystem under consideration consists of three compartments forming a closed chain in which water circulates. Three trophic levels are represented in different compartments: autotrophs (algae, mainly Chlorella vulgaris), herbivores (Daphnia magna) and microbial decomposers. From a 20 years experiment with this system, data has been selected for this study. The dynamics of algae and Daphnia magna in only one of the compartments were modeled by different systems of differential and difference equations. We describe the successive steps in the process of model development, and the fitting of parameters using a Nelder-Mead simplex calibration method. Identification problems were overcome by taking values for physiological parameters in agreement with the literature. It turned out that a logistic type of model gives the best result for the structured Daphnia population because of the set up of the experiment: algae grow and reproduce in the upstream compartment. For this reason well-known plant–herbivore models did not comply with the data. The results of the parameter estimation procedure are discussed. The estimated grazing rate by Daphnia was smaller than expected. Possibly the Daphnia fed also on detritus and decomposing algae which were not measured. 相似文献
203.
Theory predicts that, with conflicting selection pressures mediated by mutualists and antagonists, alternative reproductive strategies can be maintained by negative frequency-dependent selection if it results in rare-morph advantage. We combined field experiments and surveys of natural populations to determine whether selection on floral display is frequency dependent in the self-incompatible herb Primula farinosa, which is polymorphic for inflorescence height and occurs in a short-scaped and a long-scaped morph. Among short-scaped plants, both pollination success, quantified as initiation of fruits and seeds, and seed predation were positively correlated with the relative frequency of the long-scaped morph. The relative strength of these effects and the direction of the resulting frequency-dependent selection on scape morph varied among years and populations. The results suggest that both mutualists and antagonists may mediate frequency-dependent selection and that frequency dependence may vary from positive to negative with rare-morph advantage, depending on the relative strength of these interactions. 相似文献
204.
Lina Mtwana Nordlund Maricela de la Torre-Castro Johan Erlandsson Chantal Conand Nyawira Muthiga Narriman Jiddawi Martin Gullstr?m 《Ambio》2014,43(8):1006-1019
This expert opinion study examined the current status of the intertidal zone in the Western Indian Ocean (WIO) and ranked and discussed future management approaches. Information was gathered from scientists, practitioners, and managers active in the WIO region through a questionnaire and a workshop. The experts stated that the productive intertidal environment is highly valuable for reasons such as recreation, erosion protection, and provision of edible invertebrates and fish. Several anthropogenic pressures were identified, including pollution, harbor activities, overexploitation, and climate change. The experts considered the WIO intertidal zone as generally understudied, undermanaged, and with poor or no monitoring. The most important management strategies according to the expert opinions are to develop and involve local people in integrated coastal zone management (ICZM), to increase knowledge on species–environment relationships, and to develop awareness campaigns and education programs. To improve coastal environmental management and conservation, we argue that the intertidal zone should be treated as one organizational management unit within the larger framework of ICZM.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-013-0465-8) contains supplementary material, which is available to authorized users. 相似文献205.
Reconnecting Cities to the Biosphere: Stewardship of Green Infrastructure and Urban Ecosystem Services 总被引:2,自引:0,他引:2
Erik Andersson Stephan Barthel Sara Borgström Johan Colding Thomas Elmqvist Carl Folke Åsa Gren 《Ambio》2014,43(4):445-453
Within-city green infrastructure can offer opportunities and new contexts for people to become stewards of ecosystem services. We analyze cities as social–ecological systems, synthesize the literature, and provide examples from more than 15 years of research in the Stockholm urban region, Sweden. The social–ecological approach spans from investigating ecosystem properties to the social frameworks and personal values that drive and shape human interactions with nature. Key findings demonstrate that urban ecosystem services are generated by social–ecological systems and that local stewards are critically important. However, land-use planning and management seldom account for their role in the generation of urban ecosystem services. While the small scale patchwork of land uses in cities stimulates intense interactions across borders much focus is still on individual patches. The results highlight the importance and complexity of stewardship of urban biodiversity and ecosystem services and of the planning and governance of urban green infrastructure. 相似文献
206.
Yohannes Yared Beyene Ikenaka Yoshinori Ito Gengo Nakayama Shouta M. M. Mizukawa Hazuki Wepener Victor Smit Nico J. Van Vuren Johan H. J. Ishizuka Mayumi 《Environmental science and pollution research international》2017,24(30):23763-23770
Environmental Science and Pollution Research - Ethiopia and South Africa are among the few countries to still implement indoor residual spraying with dichloro-diphenyl-trichloroethane (DDT) for... 相似文献
207.
Judith Schleicher Johanna Eklund Megan D. Barnes Jonas Geldmann Johan A. Oldekop Julia P. G. Jones 《Conservation biology》2020,34(3):538-549
The awareness of the need for robust impact evaluations in conservation is growing and statistical matching techniques are increasingly being used to assess the impacts of conservation interventions. Used appropriately matching approaches are powerful tools, but they also pose potential pitfalls. We outlined important considerations and best practice when using matching in conservation science. We identified 3 steps in a matching analysis. First, develop a clear theory of change to inform selection of treatment and controls and that accounts for real-world complexities and potential spillover effects. Second, select the appropriate covariates and matching approach. Third, assess the quality of the matching by carrying out a series of checks. The second and third steps can be repeated and should be finalized before outcomes are explored. Future conservation impact evaluations could be improved by increased planning of evaluations alongside the intervention, better integration of qualitative methods, considering spillover effects at larger spatial scales, and more publication of preanalysis plans. Implementing these improvements will require more serious engagement of conservation scientists, practitioners, and funders to mainstream robust impact evaluations into conservation. We hope this article will improve the quality of evaluations and help direct future research to continue to improve the approaches on offer. 相似文献
208.
Many chemicals in use today lack appropriate documentation on their environmental properties, fate, and effects. To counteract this lack of documentation it is vital to thoroughly investigate a compound’s fate in the environment before it comes into use. The present study is describing a novel method for assessing the reduction potential of polybrominated diphenyl ethers (PBDEs), as a part of a project aimed to create an experimental model for determination of chemical persistence. The reductive transformation of 15 PBDE congeners using sodium borohydride was determined. Pseudo-first-order reaction rate constants of the transformations were determined by monitoring the disappearance of the investigated congeners. The reductions lead primarily to formation of lower brominated PBDEs. Each PBDE congener was tested in a total of ten replicates which showed a relative standard deviation of 31% or less. The decaBDE, BDE-209 was approximately 3 times as prone to reductive transformation as BDE-207. The three nonaBDEs, BDE-206, BDE-207, and BDE-208, showed similar reductive potential. The reactivity of the tested octaBDEs was quite variable, from 5% to 24% of the reactivity of BDE-209 for BDE-196 and BDE-198, respectively. The heptaBDEs studied were in the range of the less reactive octaBDEs, except for BDE-181 which was as high as 13% of the reactivity of BDE-209. The results presented give a method for measuring the propensity of PBDEs, and possibly similar compounds, to undergo reductions. They indicate a potential route to a vital piece of information in the assessment of environmental persistence of chemicals. 相似文献
209.
Forest Fragmentation and Landscape Transformation in a Reindeer Husbandry Area in Sweden 总被引:1,自引:0,他引:1
Reindeer husbandry and forestry are two main land users in boreal forests in northern Sweden. Modern forestry has numerous
negative effects on the ground-growing and arboreal lichens that are crucial winter resources for reindeer husbandry. Using
digitized historical maps, we examined changes in the forest landscape structure during the past 100 years, and estimated
corresponding changes in suitability of forest landscape mosaics for the reindeer winter grazing. Cover of old coniferous
forests, a key habitat type of reindeer herding system, showed a strong decrease during the study period, whereas clear-cutting
and young forests increased rapidly in the latter half of the 20th century. The dominance of young forests and fragmentation
of old-growth forests (decreased patch sizes and increased isolation) reflect decreased amount of arboreal lichens as well
as a lowered ability of the landscape to sustain long-term persistence of lichens. The results further showed that variation
in ground lichen cover among sites was mainly related to soil moisture conditions, recent disturbances, such as soil scarification
and prescribed burning, and possibly also to forest history. In general, the results suggest that the composition and configuration
of the forest landscape mosaic has become less suitable for sustainable reindeer husbandry. 相似文献
210.
Humanity has entered a new phase of sustainability challenges, the Anthropocene, in which human development has reached a
scale where it affects vital planetary processes. Under the pressure from a quadruple squeeze—from population and development
pressures, the anthropogenic climate crisis, the anthropogenic ecosystem crisis, and the risk of deleterious tipping points
in the Earth system—the degrees of freedom for sustainable human exploitation of planet Earth are severely restrained. It
is in this reality that a new green revolution in world food production needs to occur, to attain food security and human
development over the coming decades. Global freshwater resources are, and will increasingly be, a fundamental limiting factor
in feeding the world. Current water vulnerabilities in the regions in most need of large agricultural productivity improvements
are projected to increase under the pressure from global environmental change. The sustainability challenge for world agriculture
has to be set within the new global sustainability context. We present new proposed sustainability criteria for world agriculture,
where world food production systems are transformed in order to allow humanity to stay within the safe operating space of
planetary boundaries. In order to secure global resilience and thereby raise the chances of planet Earth to remain in the
current desired state, conducive for human development on the long-term, these planetary boundaries need to be respected.
This calls for a triply green revolution, which not only more than doubles food production in many regions of the world, but
which also is environmentally sustainable, and invests in the untapped opportunities to use green water in rainfed agriculture
as a key source of future productivity enhancement. To achieve such a global transformation of agriculture, there is a need
for more innovative options for water interventions at the landscape scale, accounting for both green and blue water, as well
as a new focus on cross-scale interactions, feed-backs and risks for unwanted regime shifts in the agro-ecological landscape. 相似文献