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1.
Water, Air, & Soil Pollution - The Problem: Over-use of the automobile, in transportation jobs for which it is neither technologically nor economically qualified. This over-use causes...  相似文献   

2.
Forests and grassy vegetation (savannas and grasslands) are alternative ecosystem states in many tropical landscapes. Relative to forests the grassy ecosystems are poorly known and poorly conserved, partly because they were thought to be products of forest clearance. However many grasslands have proved to be ancient. Commensurate with their antiquity, grassy biomes have distinct suites of plant and animal species that contribute a large fraction of the diversity of forest-grassland mosaics. Grasslands differ strikingly from forests in their ecology and in the nature of threats to their future. Here we highlight the high biodiversity value of grassy biomes and, in contrast to tropical forests, we illustrate the importance of fire in maintaining these systems. We discuss the major threats to, and consequences for, biodiversity in these regions including land clearance and elevated CO2-driven forest expansion. Finally we focus on the difficulties of grassland restoration. A new approach to understanding and conserving grassy ecosystems, free from cultural prejudices of the past, is long overdue.  相似文献   

3.
Pink Lady apples were harvested at commercial maturity and stored at 1 degrees C and 92% relative humidity under either air or controlled atmosphere conditions (2 kPa O 2:2 kPa CO 2 and 1 kPa O 2:1 kPa CO 2) for 27 weeks. Data on the emission of volatile compounds and on the activity of some related enzymes in both skin and flesh tissues were obtained during subsequent shelf life at 20 degrees C. Major effects of storage atmosphere and poststorage period were observed on the emission of volatile esters and their precursors. Changes in the production of volatile esters were partly due to alterations in the activity of alcohol o-acyltransferase, but the specific esters emitted by fruit after storage also resulted largely from modifications in the supply of the corresponding substrates. Samples stored under air were characterized by higher availability of acetaldehyde, whereas those stored under CA showed enhanced emission of the alcohol precursors ethanol and 1-hexanol (2 kPa O 2) and 1-butanol (1 kPa O 2), with accordingly higher production of ethyl, hexyl, and butyl esters. Multivariate analysis revealed that a large part of the observed differences in precursor availability arose from modifications in the activity of the enzymes considered. Higher pyruvate decarboxylase activity in air-stored fruit possibly accounted for higher acetaldehyde levels in these samples, while storage under 1 kPa O 2 led to significantly decreased lipoxygenase activity and thus to lessened production of 1-hexanol and hexyl esters. Low acetaldehyde availability together with enhanced hydroperoxide lyase and alcohol dehydrogenase levels in these fruits are suggested to have led to higher emission of 1-butanol and butyl esters.  相似文献   

4.
Root-associated plant growth promoting rhizobacteria (PGPR) interact with the plant roots and influence plant health and soil fertility. Plant growth promoting rhizobacteria play an important role in plant growth by exerting various mechanisms such as biological nitrogen fixation, growth hormone production, phosphate solubilization, siderophore production, hydrolytic enzyme production, antagonistic activity against fungal pathogens etc. Hence, these are employed as inoculants for biofertilizer and biocontrol activities. This review summarizes various mechanisms of PGPR and their potential for use as inoculants. It shows that their use is a worthwhile approach for exploring disease management in conjunction with other strategies.  相似文献   

5.
Morphogenetic features of soils on the selected plots in the Cat Tien National Park in southern Vietnam have been studied with the use of a set of morphological, analytical, and instrumental methods. The lithological factor and topographic position play the leading role in the development of the particular genetic soil features. The soils can be subdivided into four groups according to these factors. The soils developing from volcanic deposits with a predominance of tephra can be classified as thin clayey brown tropical soils (Dystric Skeletic Rhodic Cambisols (Clayic)), and the soils developed from less weathered colluvial derivatives of basalts with some admixture of tephra can be classified as dark-humus clayey tropical soils (Skeletic Greyzemic Umbrisols (Clayic)). Very poor soils developed from the eluvium of argillites are classified as thin weakly developed clayey tropical soils (Dystric Regosols (Clayic)). The soils forming from the alluvial sediments of different textures are classified as alluvial loamy sandy soils (Dystric Fluvisols (Arenic, Drainic)) and as alluvial clay loamy soils (Eutric Fluvisols (Episiltic, Endoclayic)).  相似文献   

6.
We used models integrating road maps, traffic volume, and snake movements to examine the potential for roads to contribute to mortality in two species of water snakes that differ in their vagility, use of terrestrial habitats, and conservation status. Road networks and traffic volumes typical of three regions in Indiana, USA, may account for mortality of 14-21% of the population per year in the more vagile, terrestrial, and imperiled copperbelly water snake (Nerodia erythrogaster neglecta) but only 3-5% mortality in the more sedentary, aquatic, and common northern water snake (Nerodia sipedon). The majority (>91%) of road crossings and associated mortality are predicted to occur during overland migrations to other wetlands, suggesting roads bisecting travel routes between wetlands may function as mortality sinks. Our models highlight the proportionately greater risk of mortality for the more vagile and imperiled species, N. e. neglecta, and suggest current wetland conservation strategies that focus on the wetland alone are unlikely to adequately protect wetland biodiversity from certain types of anthropogenic habitat modification. What is needed is a landscape approach to wetland conservation that considers not only the quality of wetlands and nearby terrestrial habitats, but also ensures that terrestrial corridors between wetlands remain permeable and offer safe passage for wildlife.  相似文献   

7.
Since the advent of sequencing technologies,the determination of microbial diversity to predict microbial functions,which are the major determinants of soil functions,has become a major topic of interest,as evidenced by the 900 publications dealing with soil metagenome published up to 2017.However,the detection of a gene in soil does not mean that the relative function is expressed,and the presence of a particular taxon does not mean that the relative functions determined in pure culture also occur in the studied soil.Another critical step is to link microbial community composition or function to the product analyzed to determine flux rates.Indeed,flux rates might not only be highly dynamic,but several metabolites can depend on different reactions,which makes the link to one process of interest difficult or even impossible.This review also discusses biases caused by sampling,storage of samples,DNA extraction and purification,sequencing(amplicon-vs.metagenome sequencing),and bioinformatic data analysis.Insights and the limits of predicting microbial interactions by network inference methods are critically discussed,and finally,future directions for a better understanding of soil functions by using measurements of microbial diversity are presented.  相似文献   

8.
Parks represent spatially and socially heterogeneous conservation units, yet are often assessed and managed using spatially homogeneous approaches. This paper represents an effort to focus on the larger social-ecological landscapes within which protected areas are embedded, to understand why conservation succeeds and fails in different parts of the landscape. In a wildlife sanctuary in the central plains of India (Tadoba Andhari Tiger Reserve), we address: (i) how people living within and immediately outside a park differentially impact its resources and (ii) how the park differentially impacts communities living within. Using forest plots, satellite imagery and interviews, we evaluate park conservation by assessing plant diversity, land cover change, forest fragmentation, and attitudes of local communities towards conservation. We find that interior villages have a negative impact on regeneration, but there is a decline in tree species diversity, and increased forest cover change and fragmentation at the park periphery. Interior villages suffer greatly from crop and livestock depredations by wildlife and consider park rules to be unfairly devised. Yet, they affirm the importance of the park for conservation, and are willing to work with park authorities for stricter protection. Park authorities largely focus on resettlement of interior villages, when they should also pay attention to protecting the peripheral areas of the park from severe degradation by surrounding villages. In summary, we find that different parts of the park landscape face different conservation challenges. Taking into account spatial variations in the factors influencing conservation can greatly benefit the management of protected areas.  相似文献   

9.
Species of Salix characterized by particular physiological adaptations and ecological resilience are predisposed to use in conservation and environmental projects in many climatic zones and adverse microsite conditions. The economic importance of Salix is currently increasing and emerging in a wide array of practical applications to restore damaged ecosystems. Here we describe the ecology, physiological characteristics and agricultural requirements of Salix and present an integrated picture based on literature review, of current uses for willows well beyond wetland and riparian situations. These uses include ecosystem restoration, phytoremediation (phytoextraction, phytodegradation, rhizofiltration and phytostabilization), bioengineering (water and wind erosion, and protective structures), and biomass production for both fuel and fiber.  相似文献   

10.
This paper addresses the question, when are threatened or endangered species really recovered? The US Endangered Species Act enables the de-listing of species once demographic criteria are met. In the Greater Yellowstone ecosystem, two protected apex carnivores, grizzly bears (Ursus arctos) and wolves (Canis lupus), face removal from federal government protection due to population increases, a point at which they are expected to be integrated components of this ecosystem. We tested the assumption that these two carnivores are playing normative ecological roles in the Yellowstone ecosystem by comparing the extent to which wolves and bears have re-instilled anti-predator responses in a primary prey species, moose (Alces alces), within wolf and bear recovery zones. As a type of control, we contrasted female moose from two areas in Alaska with different predator regimes to those in Wyoming. Populations from mainland Alaska, a region with a relatively intact carnivore assemblage, responded significantly more to odors of both carnivores. In contrast, a basic anti-predator reaction was lacking in Wyoming; and responses to grizzly bear odor only nominally increased after dependent young experienced heightened mortality. Additionally, the level of response among Alaskan moose living under virtual predator-free conditions for 25+ years closely resembled that of conspecifics in Wyoming. That such striking variation in prey responses exists re-enforces critical ecological differences between predator-intact and -defunct systems. Thus, although grizzly bears and wolves in the Yellowstone area will most likely be de-listed within the next few years, whether such action would be ecologically defensible is arguable. At this point in the recovery process, these predators may currently have limited ecological impacts in large portions of this region, at least as gauged by one potentially important prey species, moose. Although our data suggest ecologically incomplete conditions, other indices of carnivore recovery that include responses of other important prey species such as elk (Cervus elaphus), may be more in tune with carnivore activities. We recommend that different types of ecological data available throughout recovery zones be used in consort with demographic criteria to evaluate when endangered carnivores are more fully integrated into their ecosystems. And, in the event of a disparity between these criteria, we also encourage a dialogue focusing on approaches towards bringing ecological conditions in concordance with demographic criteria, irrespective of whether one considers increasing population levels beyond the current target levels required for de-listing,and/or simply, additional time for the recovery process.  相似文献   

11.
12.
We apply an age- and stage-structured model incorporating varying harem sizes, paternal care and infanticide to examine the effect of hunting on sustainability of populations. Compared to standard carnivore and herbivore models, these models produce different outcomes for sustainable offtake when either adults, or adult males are harvested. Larger harem size increases sustainable offtake whereas paternal care and infanticide lowers it. Where males are monogamous, populations are vulnerable to male offtake, regardless of paternal care. Surprisingly, an incidental take of 10% of other age-sex-classes has very little effect on these findings. Indiscriminate (subsistence) hunting of all age-sex classes has a dramatic effect on certain populations. Applying these behavior-sensitive models to tourist hunting in the Selous Game Reserve, Tanzania, we find that across the Reserve hunting quotas were generally set at sustainable rates except for leopard (Panthera pardus). In certain hunting blocks within the Reserve, however, quotas for eland (Taurotragus oryx), hartebeest (Alcelaphus buselaphus), lion (Panthera leo), reedbuck (Redunca arundinum), sable antelope (Hippotragus niger), warthog (Phacochoerus aethiopicus) and waterbuck (Kobus ellipsiprymnus) are set at unsustainably high rates. Moreover, particular blocks are consistently awarded high quotas. Behaviorally sensitive models refine predictions for population viability, specify data required to make predictions robust, and demonstrate the necessity of incorporating behavioral ecological knowledge in conservation and management.  相似文献   

13.
作为新兴学科和交叉学科的动物微生态学课程,是高校动物医学和动物科学专业本科生的重要应用型专业课,学好这门课程对于拓宽学生的学术视野及实践应用能力很重要。本文提出了在动物医学和动物科学本科教育中,加强动物微生态学课程势在必行。从合理利用多媒体新手段;选择重点教学内容,合理组织教学内容和安排教学程序;灵活多样的教学方法;及时更新教材;提高教师综合素质等几方面来介绍提高该课程教学质量的一些体会。  相似文献   

14.
近十年来,集约化畜牧生产在中国的一些城市郊区有了很大发展,同时推动了畜牧工程技术的进展。这些工作表明,中国的畜牧工程技术人员已经具备了设计、建造畜牧工程与设备的能力。中国人多地少,资金与能源紧缺,发展以高投入、高能耗、精饲料型为特点的全封闭、高密度饲养方式显然不符合中国国情,而只能走适合自己的道路。在企业中任何工程措施的采用,所花代价必须由其在生产中的经济效益所补偿。在任何情况下衡量畜牧生产效益只能根据动物的生产性能,不能根据生产单位的机械化水平。在城市郊区不顾环境的承受能力,过分追求城市肉、蛋、奶自给,由于大量家畜粪尿得不到妥善处理,将构成严重的威胁。总之,中国畜牧工程的发展必须从中国国情出发,走农牧结合的道路。  相似文献   

15.
We discuss the notorious problem of order selection in hidden Markov models, that is of selecting an adequate number of states, highlighting typical pitfalls and practical challenges arising when analyzing real data. Extensive simulations are used to demonstrate the reasons that render order selection particularly challenging in practice despite the conceptual simplicity of the task. In particular, we demonstrate why well-established formal procedures for model selection, such as those based on standard information criteria, tend to favor models with numbers of states that are undesirably large in situations where states shall be meaningful entities. We also offer a pragmatic step-by-step approach together with comprehensive advice for how practitioners can implement order selection. Our proposed strategy is illustrated with a real-data case study on muskox movement.Supplementary materials accompanying this paper appear online.  相似文献   

16.
《动物性食品卫生学》课程的建设与教学实践   总被引:1,自引:0,他引:1  
在《动物性食品卫生学》的课程建设中,以课程教学内容和教学实践环节为改革重点,经过三年教学改革和实践,加强学生的实验操作技能,培养学生的综合能力和综合素质,获得较好的教学效果。  相似文献   

17.
简述了物联网的技术特点,并结合畜牧业养殖、生产、加工和畜产品安全的特殊环境和条件,介绍了物联网技术在畜牧业各主要环节应用情况和注意事项;分析了物联网技术在现代畜牧业发展的应用前景,以及目前推广物联网技术所存在的问题和建议。  相似文献   

18.
SCI收录的动物科学核心期刊   总被引:2,自引:0,他引:2  
以影响因子大小为序,根据2000年SCI(JCR-CD)中对奶制品和动物科学的收录情况,选择介绍影响因子在0.500以上的主要期刊20种,以便于该专业的科研人员投稿和检索。  相似文献   

19.
Nonpoint source pollution is the leading remaining cause of water quality problems. The extent of NPS pollution is often more difficult or expensive to monitor at the point(s) of origin, as compared to monitoring of point sources. This study evaluated the hypothesis that animal manure (chicken, cow, horse, and pig) applied to pasture contribute fecal sterols and bile acids to runoff. The study also assessed the potential benefit of fecal sterols and bile acids as biomarkers in distinguishing fecal pollution and its sources. Fecal sterol and bile acid concentrations were determined in flow-weighted composite runoff samples collected from 2.4?×?6.1 m plots (n?=?3) amended with manure. Runoff was generated from simulated rainfall (152 mm.h?1). Runoff samples from manure-amended plots showed high concentrations of fecal sterol (ranged from 13?±?1 to 1,287?±?183) and bile acid (ranged from 24?±?1 to 2,251?±?248) biomarkers. The profiles of fecal sterols and bile acids in runoff samples were similar to those of fresh manure for all selected animals. For runoff and fresh manure, chenodeoxycholic acid, deoxycholic acid, epicoprostanol, and hyodeoxycholic acid were consistent biomarkers for chicken, cow, horse, and pig, respectively, suggesting that sterols and bile acids can be used to identify sources and occurrence of fecal matter in water and sediments.  相似文献   

20.
Availability and fragmentation of habitat are today identified as key determinants of population maintenance. Disentangling their relative effects is of crucial importance to adequately manage landscapes. However, the classical use of occurrence or abundance data as proxy to assess the responses of populations could be insufficient to detect less drastic impacts than short-term population extinction. We evaluated the effects of both habitat availability and fragmentation at three spatial scales on both the occurrence and two “physiological state” indicators (body condition and level of stress hormone) reflecting the physical state of common toads (Bufo bufo). Our study showed that occurrence was negatively affected only by habitat availability at the largest spatial scale whereas the both physiological state indicators studied at the population scale are significantly altered by both habitat availability and fragmentation at the finest spatial scale. Results obtained with occurrence and physiological state approaches substantially diverge, which highlights the need to also investigate proximal processes to deeply understand how populations are threatened by landscape modifications. The use of physiological state indicators, particularly of body condition, powerful and easy to obtain, could be particularly relevant to detect early warnings of population decline allowing a management before extinction. Only a complete investigation of the potential impacts of landscape on the different population processes could offer a realistic picture of the requirements of populations to avoid drastic alterations.  相似文献   

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