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41.
Steven J Phillips Paul Williams Guy Midgley Aaron Archer 《Ecological applications》2008,18(5):1200-1211
We introduce a new way of measuring and optimizing connectivity in conservation landscapes through time, accounting for both the biological needs of multiple species and the social and financial constraint of minimizing land area requiring additional protection. Our method is based on the concept of network flow; we demonstrate its use by optimizing protected areas in the Western Cape of South Africa to facilitate autogenic species shifts in geographic range under climate change for a family of endemic plants, the Cape Proteaceae. In 2005, P. Williams and colleagues introduced a novel framework for this protected area design task. To ensure population viability, they assumed each species should have a range size of at least 100 km2 of predicted suitable conditions contained in protected areas at all times between 2000 and 2050. The goal was to design multiple dispersal corridors for each species, connecting suitable conditions between time periods, subject to each species' limited dispersal ability, and minimizing the total area requiring additional protection. We show that both minimum range size and limited dispersal abilities can be naturally modeled using the concept of network flow. This allows us to apply well-established tools from operations research and computer science for solving network flow problems. Using the same data and this novel modeling approach, we reduce the area requiring additional protection by a third compared to previous methods, from 4593 km2 to 3062 km , while still achieving the same conservation planning goals. We prove that this is the best solution mathematically possible: the given planning goals cannot be achieved with a smaller area, given our modeling assumptions and data. Our method allows for flexibility and refinement of the underlying climate-change, species-habitat-suitability, and dispersal models. In particular, we propose an alternate formalization of a minimum range size moving through time and use network flow to achieve the revised goals, again with the smallest possible newly protected area (2850 km2). We show how to relate total dispersal distance to probability of successful dispersal, and compute a trade-off curve between this quantity and the total amount of extra land that must be protected. 相似文献
42.
43.
This paper outlines the importance of the policy context for monitoring with and for raptors, and, conversely, of the importance of such monitoring for policy. It then outlines two key areas of European Union (EU) environmental policy most relevant to monitoring for and with raptors, namely biodiversity policy and pollution policy. For each of the policy areas, the pertinent objectives and actions of the current EU policy are identified, and their relevance for raptor monitoring is discussed. The potential contribution of raptor monitoring to the further development of these policy areas is also addressed. 相似文献
44.
An integrated assessment of estrogenic contamination and biological effects in the aquatic environment of The Netherlands 总被引:18,自引:0,他引:18
Vethaak AD Lahr J Schrap SM Belfroid AC Rijs GB Gerritsen A de Boer J Bulder AS Grinwis GC Kuiper RV Legler J Murk TA Peijnenburg W Verhaar HJ de Voogt P 《Chemosphere》2005,59(4):511-524
An extensive study was carried out in the Netherlands on the occurrence of a number of estrogenic compounds in surface water, sediment, biota, wastewater, rainwater and on the associated effects in fish. Compounds investigated included natural and synthetic hormones, phthalates, alkylphenol(ethoxylate)s and bisphenol-A. The results showed that almost all selected (xeno-)estrogens were present at low concentrations in the aquatic environment. Locally, they were found at higher levels. Hormones and nonylphenol(ethoxylate)s were present in concentrations that are reportedly high enough to cause estrogenic effects in fish. Field surveys did not disclose significant estrogenic effects in male flounder (Platichthys flesus) in the open sea and in Dutch estuaries. Minor to moderate estrogenic effects were observed in bream (Abramis brama) in major inland surface waters such as lowland rivers and a harbor area. The prevalence of feminizing effects in male fish is largest in small regional surface waters that are strongly influenced by sources of potential hormone-disrupting compounds. High concentrations of plasma vitellogenin and an increased prevalence of ovotestes occurred in wild male bream in a small river receiving a considerable load of effluent from a large sewage treatment plant. After employing in vitro and in vivo bioassays, both in situ and in the laboratory, we conclude that in this case hormones (especially 17 alpha-ethynylestradiol) and possibly also nonylphenol(ethoxylate)s are primarily responsible for these effects. 相似文献
45.
Nasonova Alla Levy Guy J. Borisover Mikhail 《Environmental science and pollution research international》2020,27(34):42644-42655
Environmental Science and Pollution Research - Land application of composts affects concentration and composition of dissolved organic matter (OM) which plays important roles in soil functioning... 相似文献
46.
Akinwumi A. Adesina David Mbila Guy Blaise Nkamleu Dominique Endamana 《Agriculture, ecosystems & environment》2000,80(3)
Slash-and-burn agriculture continues to expand in many parts of the forest zone of Cameroon. One alternative land use to slash-and-burn system is alley farming. This paper quantifies, using an econometric model, the factors determining farmers’ adoption and use of alley farming variants in southwest of Cameroon, based on a survey of 156 farmers in 11 villages in the region.The analysis showed that male farmers are more likely to adopt than women. Adoption is higher for farmers with contacts with extension agencies working on agroforestry technologies. Adoption is higher for farmers belonging to farmers’ groups. Adoption is lower for farmers in areas with very high population pressure, as farmers in such areas may have greater labor productivity from use of less labor intensive natural resource management technologies like chemical fertilizers. Adoption is higher for farmers in areas facing fuel wood scarcity. Farmers have made adaptations to the conventional alley farming technology recommended by researchers, the most significant adaptation being the introduction of fallow periods into the system. Farmers use alley farming as a land use option, not as a replacement for the slash-and-burn system, since land supply is still relatively elastic. Achieving increased impact with alley farming variants requires effective targeting. Results showed that econometric modeling using farmer and village characteristics, socioeconomic and institutional variables can lead to more effective targeting to farmers and locations where higher adoption rates may occur. 相似文献
47.
Jérôme Buhl Jean Louis Deneubourg Anne Grimal Guy Theraulaz 《Behavioral ecology and sociobiology》2005,58(1):9-17
Many ant species adjust the volume of their underground nest to the colony size. We studied whether the regulation of the volume of excavated sand could result from an interplay between recruitment processes and ant density. Experiments were performed with different group sizes of workers in the ant Messor sancta. When presented with a thin homogeneous sand disk, these groups excavated networks of galleries in less than 3 days. The excavation dynamics were logistic shaped, which suggests the existence of a double feedback system: a positive one resulting in an initial exponential growth phase, and a negative one leading the dynamics to a saturation phase. The total volume of excavated sand was almost proportional to the number of workers. We then developed a model in which we incorporated the quantitative behavioral rules of the workers digging activity. A positive feedback was introduced in the form of a recruitment process mediated by pheromones. The model predicts that the excavation dynamics should be logistic shaped and the excavation should almost stop despite the absence of any explicit negative feedback. Moreover, the model was able to reproduce the positive linear relationship between nest volume and colony size.Communicated by K. Ross 相似文献
48.
The evaluation of toxicological effects at the cellular and molecular levels in organisms are often used to determine sites subjected to contamination problems that pose a threat to the long-term survival of organisms. However, the integration of multiple measurements on the health status of organisms into a model for site discrimination is challenging. This study compares two discrimination methods which are based on rule inference: rough sets (RS) analysis and classification trees (CT) with classical multivariate discriminant analysis (DA). Site classification was attempted with six biomarkers of effects: metallothionein levels, lipid peroxidation, DNA damage, levels of lipophosphoproteins (i.e., vitellins), phagocytosis activity and haemocyte cell viability on clam (Mya arenaria) populations from the Saguenay River fjord (Quebec, Canada). Rule based methods have the advantage of complete independence from data distribution constraints in contrast to the classification methods from multivariate analysis that are more commonly used in ecotoxicology. Results show that RS and CT gave better classifications than DA because they do not require strong distributional assumptions. Moreover, RS provided classification rules that could identify the most important biomarker(s) for site discrimination. RS and CT were shown to be simple and efficient methods for classifying multivariable ecotoxicological data. This methodology would be especially useful when freedom from distributional assumptions is required. 相似文献
49.
Mosleh YY Paris-Palacios S Couderchet M Biagianti-Risbourg S Vernet G 《Environmental pollution (Barking, Essex : 1987)》2005,135(1):73-82
Laboratory studies were conducted to determine the effects of different concentrations of fenhexamid (0.1, 1, and 10 mg L(-1)) on growth, oxidative stress, protein, glycogen, and metallothionein (MT) contents in Tubifex tubifex after an exposure of 2, 4, and 7 days. In addition, residues of the fungicide were followed in water and in the worms. In water, fenhexamid concentration decreased slowly (maximum -2 +/- 0.03% after 2 days for 1 mg L(-1)). In the worms, it increased after 4 days and decreased thereafter, confirming that the worms were exposed to the fungicide and not to a degradation product. LC50 values were between 95.22 +/- 5.36 and 32.11 +/- 1.8 mg L(-1) depending on exposure time. Exposure to fenhexamid had a negative effect on T. tubifex growth (maximum effect -12.2 +/- 0.8% after 7 days with 10 mg L(-1)) demonstrating the toxic effect of the pesticide. This growth rate decrease was accompanied by a reduction in protein and glycogen contents. The activity of catalase (CAT), and glutathione reductase (GR) increased in response to the fungicide demonstrating an oxidative stress in the worms. In contrast glutathion-S-transferase activity (GST) decreased. Exposure to fenhexamid also induced synthesis of MT (maximum +78 +/- 8% after 2 days for 10 mg L(-1)). The specificity of MT concentration increase in response to metals is discussed. 相似文献
50.
Mercier G Duchesne J Carles-Gibergues A 《Environmental pollution (Barking, Essex : 1987)》2002,118(3):285-296
Lead pollution is an environmental priority. The evaluation of contaminated soils was often based on the results of the toxicity characteristic leaching procedure (TCLP) or the synthetic precipitation leaching procedure (SPLP). This paper presents a simple and fast screening test to detect soil contaminated by lead. The test is based on the chemistry of the stomach (Cl- concentration, pH 2, T = 37 degrees C) and simulates the incidental oral ingestion of soil by young children. The gastric juice simulation test (GJST) and the TCLP were applied to six size fractions from five soils. The GJST solubilized more Pb (up to 169 mg/l) than the TCLP especially for the smallest size fraction. Particle size had less effect on the TCLP. The percentage of lead released with the GJST, was most significant for the <63 microm size fraction and varied from 18 to 74% of the total lead content. Lead leached during the TCLP as a function of the total lead content showed poor linear regression coefficient (R) values for soils <250 microm. R values were significant for all size fractions with the GJST. The pH of approximately 5 in the TCLP limits the solubilization of lead in the small size fractions. The five soils exceeded the toxicity threshold of 10 microgPb/dl of blood for a significant fraction of children between 0 and 36 months using the EPA's IEUBK model (Integrated Exposure Uptake Biokinetic). But the TCLP did not detect lead contamination in two of these five soils. The GJST proved to be a better estimator of lead bioaccessibility in the gastrointestinal tract. 相似文献