Influence of wetland networks on bat activity in mixed-use landscapes

Parks and other protected lands can provide important source habitat and act as valuable dispersal corridors in urbanizing environments. However, most wetlands within protected areas are managed in isolation without consideration of the broader landscape connections. We studied the importance of wetland habitat connectivity and landscape context to bat activity in five National Parks along a gradient of increasing urbanization within the Mid-Atlantic United States. Ninety-six Anabat stations were set up throughout the parks, from which we derived the characteristic spatial scales at which bat activity was associated with wetlands. This information was used in a graph theoretic framework to construct network models of potential landscape connectivity for those species that had positive associations with wetland land cover. We found that the importance of wetlands as a predictor of bat activity varied on a species-by-species basis and increased when network measures were used that accounted for connected area in a broad spatial context. The results demonstrate that both area and connectivity of wetland foraging habitat may act as orthogonal variables to availability of roosting habitat in explaining the distribution of highly mobile species. We use the results to illustrate the value of network analysis to guide the coordinated management of two of the parks’ most valued natural resources - wetlands and bats.     

Hypotheses to explain patterns of population change among breeding bird species in England

Population declines are now evident across many taxa, but within each assemblage there is often considerable variation in constituent population trends. We used bird population trends produced from the BTO/JNCC Common Birds Census (CBC) and the RSPB/BTO/JNCC Breeding Bird Survey (BBS), to test five main hypotheses to explain population changes of 59 breeding species in England (1967-2006): (1) breeding habitat, (2) predation risk to nest sites, (3) species climatic niche, (4) migration strategy, and (5) over-wintering bioclimatic zones of migrants, accounting for additional demographic and ecological traits. In absence of phylogenetic inter-relatedness, farmland species declined more than woodland species, most pronounced prior to 1986, probably reflecting agricultural intensification (1). We found limited support that ground nesters have declined more than above-ground or cavity nesters (2), and there was some indication that species with more northerly European distributions showed larger declines than more southerly-distributed species (3). Larger population declines were recorded for Afro-tropical migrants than species wintering in Europe or in the UK, most notable prior to 1986 (4). However, declines were not uniform across all migrants (5) - species over-wintering in the arid savannah bioclimatic zone of Africa decreased in population between 1967 and 1976, whereas species wintering in humid West African forest and savannah declined more after 1987. These results suggest both breeding and over-wintering factors influenced population trends. European countries signed to the Convention on the Conservation of Migratory Species of Wild Animals are required to protect and conserve populations of migrants. Understanding connectivity between breeding and over-wintering populations, and similar environmental pressures experienced within over-wintering areas may be a useful step towards mitigating against further declines in migrants.     

Massive Hepatic Necrosis and Nodular Regeneration in Largemouth Bass Fed Diets High in Available Carbohydrate

Largemouth bass Micropterus salmoides are piscivorous fish raised on farms then sold live in Asian fish markets on the east and west coasts of the United States. In the winter of 1998, a major producer of feed‐trained bass suffered a significant increase in fish mortality both during shipping and while the fish were still in ponds. No bacterial, viral, or significant parasitic pathogens were found at necropsy. Livers of affected fish were pale and translucent with 3–10 mm pink nodules on their surface and deeper in the parenchyma. Histological examination of these livers showed that the translucent regions of the liver contained few hepatocytes and were composed of tissue consistent with a chronic inflammatory response. Also present were eosinophils, islands of pancreatic and biliary cells, and granulomas that did not stain positively for mycobacteria. The pink nodules were areas of multifocal regeneration of normal hepatocytes. Sequential studies of bass in ponds revealed that the bass were progressively accumulating glycogen in their hepatocytes to an extent sufficient to explain the massive necrosis of that organ. In order to determine the effect of diets varying in available carbohydrate on fish growth, survival, and liver glycogen content, a 12‐wk feeding trial was conducted in aquaria with juvenile largemouth bass. Nitrogen‐free extract values indicated that an extruded trout diet, a steelhead trout diet, and a diet designed to contain 45% protein and 25% fat, contained 35, 27, and 21% carbohydrate, respectively. Weight gain was lowest in fish fed the extruded trout diet, while liver glycogen was significantly higher in fish fed diets with >27% carbohydrate than in fish fed the diet with 21% carbohydrate. The farmer switched to a diet similar to the 45–25 diet used in our trial. Subsequently, 16‐mo‐old fish examined in October 2000 had no hepatic nodules or necrosis, were significantly larger and less variable in size than previous crops, and the farmer experienced no significant losses in ponds or during shipping.     

禽用谷物品质的预测和改善

小麦、大麦和黑小麦等谷物在营养价值方面(例如代谢能)的变化已被业界人士广为了解,这种营养价值的变异造成了肉鸡料肉比不可预测及在某些情况下能产生粘湿的粪便.现已充分认识到,上述谷物中所含的可溶性长链阿拉伯木聚糖和β-葡聚糖是引起肠道食糜高粘性等问题的主要原因.非淀粉多糖酶,如木聚糖酶和β-葡聚糖酶,能通过部分的破坏上述物质的纤维结构从而有效地减少肠内的粘性.这种作用的衍生效应是成倍的,而最终结果是增加了养分的利用率.自80年代末期开始,使用小麦、大麦和黑小麦作为饲料能源谷物的国家便已经商业化地使用非淀粉多糖酶来提高养殖的经济效益,而最近研发的小麦品质快速测定法(芬兰饲料国际公司的AvicheckTM 应用软件)能使饲料厂根据小麦的品质和用量来优化酶制剂的最佳添加量,从而达到最大的利润.     

Negotiating local livelihoods: Scales of conflict in the Se San River Basin

Abstract: The Se San is an important tributary river basin of the Mekong. In 1993, Vietnam began building the Yali Falls Dam 80 kilometres upstream of the point at which this westward flowing river enters Cambodia. Ninety indigenous communities along the Se San River in two provinces of north‐eastern Cambodia have been impacted severely by flooding, and a dramatically altered hydrological regime that affects fisheries and all other aspects of livelihood, such as river bank agriculture. Since 2000, when the first turbines were commissioned, the affected communities have been increasingly vocal regarding the impacts of Yali and the plans for several more dams on upper reaches of the river. A complex set of actors including non‐governmental organisations, village, district and provincial authorities, national committees in Cambodia and Vietnam, the Mekong River Commission and a range of international players have become involved in a two‐track process, which has nevertheless allowed little space for negotiation over the Se San River on the part of those most directly affected. This case has fundamental implications for governance and conflict management in the Mekong and more widely. The Australian Mekong Resource Centre has been working with local actors to document the Se San case as part of an international project on River Basin Management: a negotiated approach, in support of six cases that involve up‐scaling of grassroots river basin initiatives in Africa, Latin America and Asia. In this article, we illustrate the significance of and problematise negotiation as a socially and politically embedded conflict management principle, with reference to the Se San case.     

The Call of the Wild: Call Centers and Economic Development in Rural Areas

This paper attempts to reflect critically on the role which telephone call centers might play in the economic development of rural places in the ‘information age’, drawing mainly on a case study of the Highlands and Islands of Scotland. It argues that although call center employment tends mainly to be urban‐based, the growth of this form of work does present opportunities for some rural areas. The paper considers the locational factors rural areas would have to possess or develop in order to attract such work. It suggests call centers can make a valuable, though limited, contribution towards rural economic development, principally through the creation of additional employment opportunities and the stimulation of new skills and competencies. It also suggests that call centers do not represent a panacea for rural areas and that, indeed, it would be dangerous for rural areas to become over‐reliant on employment in this sector.     

Does Public Lands Policy Affect Local Wage Growth?

The effects on wage growth of management practices applied on public lands in the Northern Forest region of the United States are quantified. A central objective is to determine if the management of public lands for preservationist uses results in lower average wages. This is a frequent claim made by critics of land preservation who argue that preservationist management, by prohibiting resource extraction, causes the composition of employment to shift from high‐wage jobs in resource‐based manufacturing to low‐wage jobs in the service sector. A model of simultaneous employment and net migration growth is estimated with data on non‐metropolitan counties over the period 1990 to 1999 and applied in a recursive relationship to wage growth. In earlier studies, models of this type have typically been specified in levels. Time‐series evidence that supports a preference for growth rates is provided as the form for such models. Exogenous variables in this model include the 1990 shares of the county land base that are publicly owned and managed for preservationist (non‐extractive) uses and multiple (including extractive) uses. It was found that wage growth rates are not significantly affected by the shares of land under either management regime. As well, recent declines in national forest timber sales are found to have no effect on wage growth.