Fencerows, Edges, and Implications of Changing Connectivity Illustrated by Two Contiguous Ohio Landscapes

We evaluated the amounts and implications of changes in habitat connectivity on rural landscapes by modeling the colonization success and subsequent habitat colonization of a model edge organism within real landscapes. We first inventoried the changes in the fencerow and forest-edge network of two contiguous Ohio (U.S.A.) landscapes, an agriculturally dominated till plain and a more diverse and dynamic moraine landscape, from 1940 to 1988. On the moraine the number of fencerows changed little from 1940 to 1971. The number increased by 86 during 1971–1988 as marginal farms were subdivided. The total length of fencerows on the moraine increased 2.5-fold over 48 years. On the till plain the number and total length of fencerows remained relatively constant through the study period. The sum of fencerows and forest edges was used as a measure of total ecotonal edge. On the moraine total edge increased through the study period, whereas on the till plain it decreased. We selected two levels of landscape connectivity, low and high, to model animal habitat colonization success. As connectivity increased the earliest successful colonists preempted an increasingly large proportion of the total suitable habitat, and the probability of successful colonization by later-arriving individuals decreased. The changes in connectivity that resulted from changes in both the fencerow network and the proportion of forested land have resulted in contiguous landscapes that present very different colonization potentials to organisms with long-distance dispersal capability. Given the current uncertainty of the effects of corridors on species-preservation efforts, we suggest that further modeling of this type prior to field testing will add useful insights, especially if conducted using specific species and landscape types.     

CYCLICAL INSTABILITY: A GROWING THREAT TO METAL PRODUCERS AND CONSUMERS

This article first identifies the underlying features of the supply and demand for metals responsible for market instability. These include the unresponsiveness of supply in the short term to increases in price once output approaches the limits of existing capacity, the unresponsiveness of demand in the short term to changes in price and the shifts in demand over the business cycle due to changes in income. The consequences of cyclical volatility are examined next. In some industries, market instability is reflected by frequent and sharp fluctuations in price. In others, producers set prices and keep them relatively stable. Even these industries, it is argued, suffer from cyclical volatility. The latter simply manifests itself in other ways. Finally, two developments are considered that suggest the problem of cyclical volatility may be growing more acute over time. The first concerns the willingness of metal producers, fabricators, and others to vary their inventories so that metal stocks are drawn down when consumption is relatively high and built up when consumption is down. The second development involves the trend over time in the magnitude and synchronization of business cycles in the major industrialized countries. Cet article commence d'abord par déterminer les caractéristiques de l'offre et de la demande concemant les métaux qui sont responsables de l'instabilité du marché - le manque d'élasticité de l'offre à court terme aux augmentations de prix lorsque le montant de la production approche les limites de sa capacité, le manque d'élasticité de la demande à court terme aux changements de prix et l'ajustement de la demande aux variations des revenue pendant le cycle industriel. Les conséquences de la volatilité cyclique sont examinées ensuite. Dans quelques industries, l'instabilité du marché se reflète par de fréquentes et violentes fluctuations dans les prix. Dans d'autres, les producteurs fixent les prix et les maintiennent relativement stables. Mais, même ces industries souffrent des fluctuations cycliques. Ces dernières simplement se manifestent d'autres façons. Finalement, l'article étudie deux éléments qui suggèrent que le problème des fluctuations cycliques peut devenir plus aigu avec le temps. Le premier concerne la volonté des producteurs de métaux, des transformateurs et autres d'adapter leurs inventaires de façon à ce que les stocks de métaux baissent lorsque la consommation est relativement élevée et augmentent lorsque celle-ci décroît. Le deuxième élément comprend la tendance en fonction du temps concernant l'importance et la synchronisation des cycles industriels dans les principaux pays industrialisés. Este artículo identifica primero los aspectos subyacentes en la oferta y demanda de metales que son responsables de la inestabilidad del mercado, tales como la falta de reacción de la oferta en el corto plazo al incremento de precio cuando el nivel de producción se aproxima a la capacidad límite de producción, la inelasticidad de la demanda en el corto plazo y el desplazamiento de la demanda durante el ciclo económico debido a cambios en el nivel de ingreso. Luego se examinan las consecuencias de la “volatilidad” cíclica. En algunas industrias la inestabilidad del mercado se refleja en frecuentes y bruscas fluctuaciones de precio. En otras, los productores fijan los precios y los mantienen relativamente estables. Se dice que aún en estas industrias ocurre la “volatilidad” cíclica la que se manifieste en forma distinta. Finalmente se consideran dos tendencias que sugieren que el problema de la “volatilidad” cíclica está tomándose cada vez más aguda. La primera se refiere al deséo de los productores de metales, fabricantes y otros de variar sus inventarios de manera que éstos disminuyan cuando el consumo es relativamente alto y aumenten cuando el consumo es bajo. La segunda se refiere a la tendencia que está siguiendo la magnitud y sincronización de los ciclos económicos de los principales países industrializados.     

An Account of Co-ordination Mechanisms for Humanitarian Assistance During the International Response to the 1994 Crisis in Rwanda

This paper examines the co-ordination strategies developed to respond to the Great Lakes crisis following the events of April 1994. It analyses the different functions and mechanisms which sought to achieve a co-ordinated response – ranging from facilitation at one extreme to management and direction at the other. The different regimes developed to facilitate co-ordination within Rwanda and neighbouring countries, focusing on both inter-agency and inter-country co-ordination issues, are then analysed. Finally, the paper highlights the absence of mechanisms to achieve coherence between the humanitarian, political and security domains. It concludes that effective co-ordination is critical not only to achieve programme efficiency, but to ensure that the appropriate instruments and strategies to respond to complex political emergencies are in place. It proposes a radical re-shaping of international humanitarian, political and security institutions, particularly the United Nations, to improve the effectiveness of humanitarian and political responses to crises such as that in the Great Lakes.     

Home Range Size and Choice of Management Strategy for Lynx in Scandinavia

Annual and seasonal home ranges were calculated for 47 Eurasian lynx in four Scandinavian study sites (two in Sweden and two in Norway). The observed home ranges were the largest reported for the species, with study site averages ranging from 600 to 1400 km² for resident males and from 300 to 800 km² for resident females. When home range sizes were compared to the size of protected areas (national parks and nature reserves) in Scandinavia, it was concluded that very few protected areas contained sufficient forest to provide space for more than a few individuals. As a direct consequence of this, most lynx need to be conserved in the multiuse seminatural forest habitats that cover large areas in Scandinavia. This conservation strategy leads to a number of conflicts with some land uses (sheep and semidomestic reindeer herding, and roe deer hunters), but not all (forestry and moose harvest). Accordingly research must be aimed at understanding the ecology of these conflicts, and finding solutions.     

Establishing Representative No-Take Areas in the Great Barrier Reef: Large-Scale Implementation of Theory on Marine Protected Areas

Abstract:  The Great Barrier Reef Marine Park, an area almost the size of Japan, has a new network of no-take areas that significantly improves the protection of biodiversity. The new marine park zoning implements, in a quantitative manner, many of the theoretical design principles discussed in the literature. For example, the new network of no-take areas has at least 20% protection per "bioregion," minimum levels of protection for all known habitats and special or unique features, and minimum sizes for no-take areas of at least 10 or 20 km across at the smallest diameter. Overall, more than 33% of the Great Barrier Reef Marine Park is now in no-take areas (previously 4.5%). The steps taken leading to this outcome were to clarify to the interested public why the existing level of protection was inadequate; detail the conservation objectives of establishing new no-take areas; work with relevant and independent experts to define, and contribute to, the best scientific process to deliver on the objectives; describe the biodiversity (e.g., map bioregions); define operational principles needed to achieve the objectives; invite community input on all of the above; gather and layer the data gathered in round-table discussions; report the degree of achievement of principles for various options of no-take areas; and determine how to address negative impacts. Some of the key success factors in this case have global relevance and include focusing initial communication on the problem to be addressed; applying the precautionary principle; using independent experts; facilitating input to decision making; conducting extensive and participatory consultation; having an existing marine park that encompassed much of the ecosystem; having legislative power under federal law; developing high-level support; ensuring agency priority and ownership; and being able to address the issue of displaced fishers.     

Landscape Characteristics of Fragmented Shrubsteppe Habitats and Breeding Passerine Birds

We examined the influence of local and landscape-level attributes of fragmented habitats in shrubsteppe habitats on the breeding distributions of Sage ( Amphispiza belli ) and Brewer's ( Spizella breweri ) Sparrows, Sage Thrashers ( Oreoscoptes montanus ) Horned Larks ( Eremophila alpestris ), and Western Meadowlarks ( Sturnella neglecta ) in the Snake River Plains of southwestern Idaho. We developed habitat (resource) selection models for each species by combining bird counts conducted from 1991 through 1933 with local vegetation characteristics and landscape attributes derived from satellite imagery. Site selection by shrubsteppe species (Sage and Brewer's Sparrows, and Sage Thrashers) depended on local vegetation cover and landscape features, such as the patch size of shrub habitats or the spatial similarity of sites. Marginal sites for these species (with species present in one of three years) were intermediate between unoccupied (never present) and occupied sites along environmental gradients characterized by increasing size of shrub habitat patches and total shrub cover and by decreasing disturbance. Horned Larks and Western Meadowlarks, typical grassland species, were not sensitive to landscape features, and their occupancy depended on the amount of grassland or shrub cover. In contrast to shrubsteppe species, sites that varied by occupancy rates of Western Meadowlarks did not significantly differ in vegetation or landscape components. Our results demonstrate that fragmentation of shrubsteppe significantly influenced the presence of shrub-obligate species. Because of restoration difficulties, the disturbance of semiarid shrubsteppe may cause irreversible loss of habitat and significant long-term consequences for the conservation of shrub-obligate birds.     

Impacts of Alternative Timber Harvest Practices on Leaf-Chewing Herbivores of Oak

Abstract:  Studies of the effects of logging on Lepidoptera rarely address landscape-level effects or effects on larval, leaf-feeding stages. We examined the impacts of uneven-aged and even-aged logging on the abundance, richness, and community structure of leaf-chewing insects of white ( Quercus alba L.) and black ( Q. velutina L.) oak trees remaining in unharvested areas by sampling 3 years before and 7 years after harvest. After harvest, white oaks in uneven-aged sites had 32% fewer species of leaf-chewing insects than control sites. This reduction in species richness may have resulted from changes in microclimate (reducing plant quality and/or changing leaf phenology) that affected a much larger total area of each site than did even-aged cuts. For black oak after harvest, species richness in uneven- and even-aged sites increased relative to levels before harvest. Harvesting did not alter total insect density or community structure in the unlogged habitat for either oak species with one exception: insect density on black oak increased in the oldest forest block. Community structure of herbivores of black and white oaks in clearcut gaps differed from that of oaks in intact areas of even-aged sites. Furthermore, both richness and total insect density of black oaks were reduced in clearcut gaps. We suggest that low-level harvests alter herbivore species richness at the landscape level. Treatment effects were subtle because we sampled untreated areas of logged landscapes, only one harvest had occurred, and large temporal and spatial variation in abundance and richness existed. Although the effects of logging were greater in uneven-aged sites, the effects of even-aged management are likely to increase as harvesting continues.     

Evaluation of Two Kurdish Refugee Camps in Iran, May 1991: The Value of Cluster Sampling in Producing Priorities and Policy

Following the end of the Gulf war in March 1991, Kurdish refugees from Iraq crossed the border into Western Iran. To plan public health interventions and to assist in priority setting for scarce resources, a rapid epidemiological assessment of two camps, Hafez and Kaliche, was conducted in May 1991. A 30 cluster sampling method was used to determine the demographics of the camp population, the morbidity and mortality from certain diseases, and the nutritional status of the children <5 years of age. The estimated population of the camps at the time of the survey was 28,500 and 22,500 for Hafez and Kaliche respectively; children < 5 years of age accounted for approximately 25 per cent of both camp populations. The mortality rate was highest in Hafez and estimated to be 2.5/10,000 per day (95%CI:0.3–5) for adults (> 14 years of age) and 4.9/10,000 per day (95%CI:2.4–7.4) for children. Diarrhoeal and respiratory diseases accounted for major morbidity in both camps with diarrhoea the commonest stated cause of death. Little malnutrition was found but it was greater in Hafez where 6 per cent (19/327) of the children between 1 and 5 years of age had a mid upper arm circumference (MUAC) <12 cm and eleven (5.2 per cent) of the 211 children measured for height and weight were below 80 per cent of the median (95%CI:2.6%;7.8%). The survey identified that morbidity and mortality were less severe than in the Kurdish camps on the Turkish border and provided information for camp authorities to plan appropriate relief interventions.