跨国土地利用及其生态影响

在全球食物价格不断上涨,粮食安全已经威胁到经济安全的环境下,跨国农用地投资成为国际浪潮。跨国农用地投资推动着各国的土地资源向全球化资源转变,对土地的跨国利用成为全球土地资源优化配置的必然。在对跨国土地利用的背景及现状进行阐述的基础上,指出\"代理性农业耕作\"方式对区域生态环境可能造成的影响。同时,新型农业科技与跨国土地利用的结合,也在推动着农业经济发展的同时,改变着传统的土地利用模式,进而改变着区域生态环境。最后,指出需要对跨国土地利用做出理性分析并建立相关的国际规则,从而维护可持续粮食安全及生态安全。     

Strategies for farmers and policy makers to control nitrogen losses whilst maintaining crop production

The nitrogen (N) cycle is essentially 'leaky'. The losses of small amounts of nitrate to waters and of ammonia and nitrous oxide to the atmosphere are a part of the global biogeochemical N cycle. However, intensive agricultural production, industry and vehicle use have more tem change and health concerns. Research has identified agricultural practices that cause large losses of N and, in some cases, developed solutions. This paper discusses the problems of maintaining productivity while reducing N losses, compares conventional with low input (integrated) and organic farming systems, and discusses wider options. It also looks at the need to integrate studies on N with other environmental impacts, set in the context of the whole farm system, to provide truly sustainable agricultural systems.     

与环境管理有关的生态学研究展望

当今世界 ,自然资源和环境管理间有许多问题需要解决。决策者们不断寻求能够实现环境质量改善和有效、持续利用资源的途径和手段。而环境资源的有限性和稀缺性也决定了必须进行有效的环境管理 ,这就需要借助生态学知识作出有效可行的管理决策 [10 ,11]。然而 ,在我国目前的条件下 ,生态学家和环境管理人员之间通常缺乏联系 ,在许多方面难以达成共识。其原因 ,既有人为造成的 ,也有历史发展的原因。在解决有关生态保护、环境管理和可持续发展之间的种种问题时 ,对生态学研究所处的地位和作用缺乏理论上的探索。另一方面 ,生态系统管理比我们…     

Strategies for farmers and policy makers to control nitrogen losses whilst maintaining crop production

The nitrogen (N) cycle is essentially 'leaky'. The losses of small amounts of nitrate to waters and of ammonia and nitrous oxide to the atmosphere are a part of the global biogeo-chemical N cycle. However, intensive agricultural production, industry and vehicle use have more than doubled the amount of 'reactive' N in the environment, resulting in eutrophication, ecosystem change and health concerns. Research has identified agricultural practices that cause large losses of N and, in some cases, developed solutions. This paper discusses the problems of maintaining productivity while reducing N losses, compares conventional with low input (integrated) and organic farming systems, and discusses wider options. It also looks at the need to integrate studies on N with other environmental impacts, set in the context of the whole farm system, to provide truly sustainable agricultural systems.     

Application of a Demographic Model for Evaluating Proposed Oyster-Restoration Actions in Chesapeake Bay

A demographic model was developed for oyster populations in the Chesapeake Bay, USA, to explore population responses to proposed management actions in support of an Environmental Impact Statement and Environmental Risk Assessment for oyster restoration. The model indicated that high natural mortality due to disease strongly controlled the population of native Eastern oysters. Continuing restoration effort at recent levels was predicted not to increase oyster populations. An enhanced restoration program that included habitat improvement and stocking would likely increase populations, particularly in areas with lower salinity where disease prevalence was lower. However, population numbers would likely reach a plateau much less than the restoration goal a few years after enhanced restoration efforts ended. A harvest moratorium was predicted to have a smaller positive effect than enhanced restoration. A moratorium likely would take much longer than the 10-year restoration period to meet restoration goals given the present high natural mortality rates. The proposed introduction of non-native Suminoe oysters was not modeled because insufficient data existed with which to parameterize the model. These results were used semi-quantitatively in the Ecological Risk Assessment to evaluate population trajectories and speculate about population changes more than 10 years after implementation of a management action.     

Integrating Concern for Animals into Personal Values

Recent scholarship in human–animal relationships demonstrates that new theoretical insights emerge when these relationships are seriously considered. We suggest that the most prominent measures of values in the environmental decision-making research literature, the Schwartz approach, may not adequately capture key aspects of how individuals value animals. Our research used confirmatory factor analysis and ordinary least squares regression techniques on data collected from an Amazon Mechanical Turk online survey. It expands on the values commonly used in the environmental decision-making literature to consider whether there is a distinct value dimension focused on animals. Our suggestion that a “concern for animals” value orientation constitutes a motivation that is separate from the other values commonly used in research on environmental decision-making finds support in our data. Traditional scaling methods indicate that the items we created have high reliability when used to form an unweighted additive scale. The results of confirmatory factor analysis are consistent with the argument that this “concern for animals” value orientation is distinct from biospheric altruism, humanistic altruism, self-interest, traditionalism, openness to change, and hedonism. Finally, our regressions using values and demographic, social, and political characteristics as controls show that an animal-focused value orientation and biospheric altruism have different relationships with identification with the animal rights movement than with identification with the environmental movement.     

Environmental impact of former gold mining on the Orangi river,Serengeti N.P., Tanzania

The Orangi river is an important all-year source of water for wildlife in the northern part of the Serengeti National Park. At two points along the river in the Banagi area, tributaries draining the adit and tailings of the Kilimafeza mine impact the Orangi. The former Au-Cu mine is subject to occasional wet season flooding leading to the release of iron ochres from the adit and physical as well as chemical mobilization of tailings material. The unpolluted river chemistry is essentially Na-Ca-HCO₃^– and well-buffered. Drainage water; from the tailings are characterized by low pH (2.3) and high concentration of sulphate (up to 3280 mg/l), aluminium (275 mg/l), arsenic (324 mg/l), copper (125 mg/l), iron (622 mg/l), lead (21 mg/l), manganese (65 mg/l), and zinc (126 mg/l). Adit-drainage waters are typically of a lower pH (4.6) and have a lower concentration of sulphate (up to 1840 mg/l) and metals (up to 25 mg/l Al, 92 mg/l As, 42 mg/l Cu, 258 mg/l Fe, 9.6 mg/l Pb, 53 mg/l Mn, and 102 mg/l Zn). Mixing of these acidic waters with the alkaline river leads to rapid metal precipitation as Fe-ochre coatings on clastic sediment. This effect is more noticeable in the dry season. Consequently, although the tributaries draining the two sources are heavily contaminated, the effective buffering of the mine drainage waters restricts any potential pollution to within 1 km of the mine workings. Faecal coliforms show an antipathetic relationship to low pH and high metal conditions. The only mobile metals in the water outside this area are Mn and Zn and their contamination can be biologically monitored using a protozoan-based bioassay.     

Paths to last in mixed crop–livestock farming: lessons from an assessment of farm trajectories of change

Mixed crop–livestock systems, combining livestock and cash crops at farm level, are considered to be suitable for sustainable intensification of agriculture. Ensuring the survival of mixed crop–livestock systems is a challenge for European agriculture: the number of European mixed crop–livestock farms has been decreasing since 1970. Analysis of farming system dynamics may elucidate past changes and the forces driving this decline. The objectives of this study were (i) to identify the diversity of paths that allowed the survival of mixed crop–livestock farming and (ii) to elucidate the driving forces behind such survival. We analysed the variety of farm trajectories from 1950 to 2005. We studied the entire farm population of a case study site, located in the ‘Coteaux de Gascogne’ region. In this less favoured area of south-western France, farmers have limited specialisation. Currently, half of the farms use mixed crop–livestock systems. The data set of 20 variables for 50 farms on the basis of six 10-year time steps was collected through retrospective surveys. We used a two-step analysis including (i) a visual assessment of the whole population of individual farm trajectories and (ii) a computer-based typology of farm trajectories on the basis of a series of multivariate analyses followed by automatic clustering. The European Common Agricultural Policy, market globalisation and decreasing workforce availability were identified as drivers of change that favoured the specialisation process. Nevertheless, farmers’ choices and values have opposed against these driving forces, ensuring the survival of some mixed crop–livestock farming systems. The trajectories were clustered into five types, four of which were compatible with mixed crop–livestock systems. The first type was the maximisation of autonomy by combining crops and livestock. The second type was diversification of production to exploit economies of scope and protect the farm against market fluctuations. The other two types involved enlargement and progressive adaptation of the farm to the familial workforce. The survival of mixed crop–livestock systems in these two types is largely dependent on workforce availability. Only one type of trajectory, on the basis of enlargement and economies of scale, did not lead to mixed crop–livestock systems. In view of the current evolution of the driving forces, maximising autonomy and diversification appear to be suitable paths to deal with current challenges and maintain mixed crop–livestock systems in Europe.