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In Mexico, as in many other parts of the world, industrial agriculture is dramatically changing rural landscapes and altering relationships with the land. This paper draws on community‐based research from a collaborative international research project that examined the perceived health implications of the agricultural industry for Indigenous peoples in the state of Jalisco, Mexico. Thirty interviews were conducted in a Nahuas community experiencing expanding agribusiness industries. The results of this study show that the implications of export‐oriented agricultural industry for this Nahuas community are complex and, at times, contradictory: employment in the agricultural industry provides community members with much‐needed sources of income, but it is precarious work. At the same time, community members are concerned about the long‐term health and environmental implications, such as increased exposure to chemicals, depletion of the soil and water, and loss of traditional food and lifeways. These results suggest that to better understand the costs and benefits of large‐scale agriculture for Indigenous health, a broad lens of health that is situated in the context of colonial legacies and the particularities of relationships with the land is required.  相似文献   

3.
A major advantage of satellite remote sensing is that the imagery acquired provides a synoptic view of the landscape. Thus, repeat coverage by the satellite on a regular basis permits the detection of changes in land‐cover over time. This study demonstrates the application of remote sensing technology to the monitoring of mining activities at the Athabasca Oil Sands region of Alberta, Canada. First, we describe the techniques used to match a time sequence of Landsat imagery, both spatially and spectrally, to ensure that the spectral changes through time are due to land‐cover variations. A series of spectral trajectories were then extracted to assess changes in land‐cover through time. Secondly, a land‐cover classification was produced from the baseline 1984 imagery and, using historic and future mine extents, the classification was analyzed to determine the proportion of each land‐cover type affected through development. Results of the analysis indicate that since 1984 there has been a larger reduction in mixedwood dense and broadleaf vegetation classes than mixedwood sparse or dense conifer stands in the area. Based on the delineations of mine‐site activity, the area of woodland and wetland habitat subject to development has increased from approximately 2,520 hectare (ha) in 1984 to 32,930 ha in 2005.  相似文献   

4.
Starting from an econometric model of local employment growth, applied to Canada (1971–2001), residuals—relative to model predictions—are analyzed over time and over space, in turn allowing us to draw a distinction between general explanatory variables and factors of a more local, cyclical or accidental nature. The model's explanatory power grows over time, founded on variables such as urban size, market access and industrial structure, allowing us to conclude that local employment growth in Canada follows an increasingly geographically predictable pattern. However, an examination of the residuals reveals more localized processes. Growth volatility is most manifest in Alberta and British Columbia, home to the most erratic local economies. Emerging patterns are visible in the last period, most notably the underperformance of Northern Ontario and of non‐metropolitan communities between Windsor and Québec City, lying along the Great Lakes and the Saint Lawrence. The over‐performance—compared to model predictions — of small and mid‐sized towns in south‐eastern Québec can, on the other hand, be interpreted as a sign of truly local social processes, generally associated with a particularly dynamic local entrepreneurial class.  相似文献   

5.
Changes in the prices of homes and the reasons for those changes may be more accurately predicted from repeat sales of the same homes after controlling for their changed attributes and differences in time between their sales and resales. This paper analyzes 346 of 583 sold houses in the Glengarry neighbourhood in Windsor, Ontario, that were sold more than once between 1981 and mid‐2017, and a corresponding 414 of 737 sold houses in the city's Wellington‐Crawford neighbourhood, sold more than once between 1986 and mid‐2017. After comparing types of resold homes with once‐sold ones, a repeat sales model predicts a first period of increasing annual percentage changes in resale prices compared to sale prices during the 1980s, followed by a second period of stagnation and possible decreases until 2011, and then increases during a third period after that. In addition, changes in resold homes’ attributes of the dwelling unit and neighbourhood are a second type of neighbourhood change in two inner‐city neighbourhoods during the past 30 or more years.  相似文献   

6.
Freeze‐thaw cycles are most common at the beginning or near the end of the winter season. These cycles have various effects on the ecosystems of Eastern Canada, affecting both biotic and abiotic components of temperate cold environments. Using air temperature minima and maxima from four meteorological stations close to Québec City, we determined the frequency of daily freeze‐thaw cycles for the last 30 years. The results show no significant increase in the number of freeze‐thaw cycles despite a small increase in air temperature. Polynomial curves describing the relationship between mean air temperatures and the number of freeze‐thaw cycles were calculated. Based on these equations and anticipating a climate change scenario, we projected future freeze‐thaw cycles. Assuming a 5 °C increase in mean air temperatures by 2100, we estimated that the number of days with a freeze‐thaw cycle could increase by approximately 20 days per winter. The increase in the number of such cycles will be concentrated during the coldest months of the winter (January and February).  相似文献   

7.
Depuis plus d'un siècle, l'agriculture québécoise en général, et la production maraîchère en particulier, ont subi d'importantes transformations. Cette étude historique vise à comprendre comment la production maraîchère a évolué par rapport aux changements dans l'environnement décisionnel général de l'agriculture entre 1940 et 1990. L'analyse des données statiques de superficie, de production et de rendement pour 12 légumes ont permis d'identifier trois périodes, intercalées d'années transitoires, dans l'évolution de la production maraîchère référant chacune à une stratégie agricole particulière. La première (1940–1957) correspond à une stratégie agricole de type familial traditionnel; la seconde (1963–1975), à une agriculture marchande spécialisée fondée sur la maximisation des revenus à court terme par intensification; la troisième (1980–1990), à une agriculture marchande diversifiée fondée également sur une maximisation à court terme. Les facteurs externes de l'environnement décisionnel qui ont entraîné ces changements sont identifiés et discutès. For more than a century, Quebec agriculture in general, and market-gardening production in particular, have experienced important changes. This study, using a historical perspective, seeks to understand how market gardening evolved in relation to changes in the broad decision environment for agriculture between 1940 and 1990. Statistical analysis of data on the areas cultivated, production levels, and yields for 12 vegetable crops revealed three distinct periods, separated by periods of transition, in the evolution of market gardening. Each period is characterized by a particular type of agricultural development strategy. The first period (1940–1957) is characterized by a focus on the traditional family form; the second (1963–1975), by a specialized market agriculture driven by short-term income-maximization intensification; the third (1980–1990), by a diversified marketoriented agriculture, also based on short-term income maximization. External environmental factors that stimulated these changes are identified and discussed.  相似文献   

8.
Next to agriculture, road development is one of the most significant sources of stress to wetlands in Prairie Canada. However, there currently exists limited guidance for incorporating direct, indirect, and induced effects to wetlands in impact assessment and mitigation planning for small and often routine developments, including access roads or highway improvement initiatives. Based on the Louis Riel Trail, Highway 11 North twinning project in Saskatchewan, Canada, this article demonstrates a methodological approach and decision support framework for assessing and managing direct, indirect, and induced effects to wetlands from linear developments. No regulatory‐based environmental assessment was required for the highway project; effects were deemed to be insignificant under current wetland mitigation practices. However, our results show that 1115 ha of potentially affected wetlands are located within a 500 m impact zone on either side of the proposed highway. More than 50 percent of these wetlands are seasonal, less than 1 ha in size, and typically not included in mitigation planning. An expert‐based multi‐criteria evaluation of impact and mitigation options for wetlands in the study area indicated “no net loss” as a planning priority, and a preference for a spatially ambitious mitigation plan focused on direct, indirect, and potentially induced impacts. In practice, however, mitigation is often restrictive, focused on mitigating only direct impacts within the project's right‐of‐way, in this case less than 50 ha of wetlands, resulting in the potential for significant net loss of wetland habitat and function. If the risk to wetlands is to be given due consideration in project planning and development for roads and road improvement initiatives, then structured assessment methods and decision support frameworks should be sensitive to the time and resource constraints of small projects and screening‐type assessments. This requires also that wetland mitigation policies are developed and implementation plans formulated as part of project planning and assessment initiatives for linear developments.  相似文献   

9.
Numerous anthropogenic stressors have impacted the region surrounding Sudbury, Ontario, leading to pronounced vegetation and landscape change. Few long‐term records exist to understand the nature or timing of this change. We use pollen analysis from radiometrically dated sediments of Clearwater Lake to compare pre‐ and post‐settlement vegetation. Beginning ~1850 CE, the record shows major shifts in forest composition, coincident with settlement and the beginnings of lumbering. These changes are unprecedented for the past ~5000 years, and consist of increases in diversity and abundance of deciduous tree taxa and herbaceous disturbance indicators. While evidence of mining appears as early as 1900 CE, little effect is seen in the pollen record until ~1930 CE, when sedimentation rates increased and acidification of the lake also began. At this time, further increases in palynological disturbance indicators and minimum sediment organic matter levels indicate the period of maximum vegetation loss. As a result of reduced emissions since the 1970s, water quality began to improve in Clearwater Lake and there are some decreases in the abundances of shade‐intolerant disturbance indicators in the pollen record. However, the fact that the pollen assemblages do not resemble those prior to 1850 suggests lasting vegetation changes.  相似文献   

10.
Snow cover is often measured as snow‐water equivalent (SWE), which refers to the amount of water stored in a snow pack that would be available upon melting. Snow cover and SWE represent a source of local snow‐melt release, and are sensitive to regional and global atmospheric circulation, and changes in climate. Monitoring SWE using satellite‐based passive microwave radiometry has provided nearly three decades of continuous data for North America. The availability of spatially and temporally extensive SWE data enables a better understanding of the nature of space‐time trends in snow cover, changes in these trends and linking these trends to underlying landscape and terrain characteristics. To address these interests, we quantify the spatial pattern of SWE by applying a local measure of spatial autocorrelation to 25 years of mean February SWE derived from passive microwave retrievals. Using a method for characterizing the temporal trends in the spatial pattern of SWE, temporal trends and variability in spatial autocorrelation are quantified. Results indicate that within the Canadian Prairies, extreme values of SWE are becoming more spatially coherent, with potential impacts on water availability, and hazards such as flooding. These results also highlight the need for Canadian ecological management units that consider winter conditions.  相似文献   

11.
In this paper, we provide a spatial analysis of agriculture in three mid‐sized French cities, with a particular focus on professional farms. The existence of important agricultural spaces inside the cities is confirmed. We reveal the persistence of a field‐based, market‐oriented agriculture in French mid‐sized cities, often ignored in studies on urban agriculture, and usually made invisible. Our results highlight the farms' diversity, as well as a diversity of farmers' viewpoints on the relations between urban and agricultural places. We emphasise the importance of three main determinants in the observed dynamics: the cities' geographies; the impact on farmers of land speculation and urbanisation; and the implementation of resistance and adaptation processes by some farmers. These results are discussed in relation to the literature on urban and peri‐urban agriculture.  相似文献   

12.
In recent years, aridity and drought have become crucial issues at the global scale because of their environmental and socio‐economic implications. On the one hand, aridity causes a reduction in the biological and economic productivity of terrestrial ecosystems, and represents a serious threat to ecological, biogeochemical, and hydrological processes. On the other hand, human use (and abuse) of vulnerable dry land ecosystems may lead to unsustainable land management. Based on these considerations, this paper analyses the recent land cover changes observed in Latium (Italy) during the exceptionally dry period 2000–2007. More than 50% of the area investigated was classified as dry in 2004–2007 compared with 0% in 2000–2003. Moreover, climatic aridity impacted differently on semi‐natural, agricultural, and built‐up land. These findings illustrate a possible scenario for suburban Mediterranean regions: increasing aridity (mainly due to rising temperatures) mainly impacting on peri‐urban land.  相似文献   

13.
This study assesses the overall spatial variations and neighbourhood‐level “hot spots” of low birth weight and preterm birth incidence within three public health units in Ontario, Canada. The analysis uses a stepwise approach of intra‐class correlation analysis, a spatial scan statistic, and multilevel spatial modeling. Results show that neighbourhood level variation accounts for only 2–3 percent of the total variation of adverse birth outcomes in the study area. However, strong spatial autocorrelation is observed at the neighbourhood level, and spatial clusters of relatively high adverse birth outcome rates exist in areas that are associated with environmental risks, including pollution sources and proximity to highways. Thus, although estimated neighbourhood impacts on adverse birth outcomes are small compared with those of individual‐level risks, local high potential environmental risk areas are identifiable. Environmental surveillance and spatial statistical analysis should be conducted regularly by local health authorities to identify and monitor the impact of environmental changes on health in general and on birth outcomes in particular. Specific community‐oriented health interventions may be required to reduce observed local health impacts.  相似文献   

14.
Effective catchment monitoring requires an integrative approach for selecting remotely sensed data to monitor land‐cover change. Catchment analyses and monitoring requirements in the Maroochy and Mooloolah River Catchments (south‐east Queensland) were addressed by linking government and community information needs to appropriate scales of remotely sensed data and processing routines. A hybrid image classification approach applied to Landsat Thematic Mapper image data acquired in 1988 and 1997 provided catchment scale land‐cover maps (with accuracies of 73% and 84%). Land‐cover change maps derived from post‐classification comparison provided information on the spatial distribution and type of land‐cover changes between 1988–1997. Land‐cover change was dominated by activities related to urban residential expansion (suburban and rural residential) and agricultural expansion (sugar cane farms). Significant spatial variations in the geometric registration accuracy of the image data sets and classification accuracies produced moderate to low change detection accuracies. However, the framework and community consultation used for selecting and processing data ensured the resource managers and community groups were fully aware of the limitations of the land‐cover change mapping process and that the output images were suitable for incorporating in resource monitoring activities.  相似文献   

15.
Given the importance of contextual factors—physical, social and institutional environments—for understanding health landscapes, this article examines the situation in the province of Québec and suggests a spatial typology at the scale of the health and social services centres (CSSS). These CSSS provide services for 95 areas which are the finest territorial delineation in terms of health policies since a reform instituted in 2003. While delivery of primary health and social services is defined at this local scale, overall health policy is decided at the provincial scale. The challenge for stakeholders is to supplement their local knowledge with that of the broader context. In this article, we use principal components analysis and hierarchical cluster analysis to identify eight profiles of CSSS. The final results of the cluster analysis demonstrate that two‐thirds of the health and social services centres correspond with two marginally differentiated profiles and the remaining third shows specificities that are highly spatially anchored.  相似文献   

16.
The geography of the Canadian economy has long been dominated by heartland‐hinterland contrasts, with manufacturing identified as the dominant function of most heartland cities in analyses of the 1961 and 1971 census data. However, the proportion of employment in manufacturing has been declining in the heartland provinces of Ontario and Quebec over the past fifty years and some geographers argue that the heartland‐hinterland dimension of the regional economy is being overridden by city‐regions that are integrated into global networks of production and trade. The heartland‐hinterland trends are examined using multifactor partitioning (MFP), an advanced shift‐share methodology, for the period of 2001–2006. This is the first intercensal period in which Canadian business has faced the full impact of the removal of North American tariff protection and the increased globalization of the Canadian economy. The data covers employment by eighteen industry sectors for the seventy‐three economic regions defined by Statistics Canada. MFP measures the region and industry‐mix effects, which are interpreted as in the traditional shift‐share model (though they are derived more accurately) and, in addition, an interaction effect. The results demonstrate that the broad heartland‐hinterland differences in the distribution of population and employment growth are increasing not decreasing and that the hinterland is in fact falling further behind the heartland in employment growth. However the Calgary‐Edmonton corridor and the Lower Mainland of British Columbia are emerging as a western heartland. The population size of cities does affect their rates of employment growth, but so too does their location: the growth of heartland cities is outpacing those in the hinterland. The Appendix provides the equations for two‐variable multifactor partitioning.  相似文献   

17.
Farmer–herder conflicts in Africa are often presented as being driven by ‘environmental scarcity’. Political ecologists, however, argue that these conflicts should be analysed within a broader historical and policy context. This article presents a case study of a local conflict in the Kilosa District in Tanzania that tragically culminated in the killing of thirty‐eight farmers on 8 December 2000. To understand the conflict, the authors argue that it is necessary to study the history of villagization and land use in the District, as well as national land tenure and pastoral policies. Attempts at agricultural modernization have fostered an anti‐pastoral environment in Tanzania. The government aim is to confine livestock keeping to ‘pastoral villages’, but these villages lack sufficient pastures and water supplies, leading herders to search for such resources elsewhere. Pastoral access to wetlands is decreasing due to expansion of cultivated areas and the promotion of agriculture. The main tool that pastoralists still possess to counteract this trend is their ability to bribe officials. But corruption further undermines people's trust in authorities and in the willingness of these authorities to prevent conflicts. This leads actors to try to solve problems through other means, notably violence.  相似文献   

18.
We consider the history of woodland clearing in central western New South Wales, Australia, which has led to the present highly cleared and fragmented landscape. A combined approach is used examining available historical land‐use data and using regression analysis to relate the pattern of cleared and wooded areas in the recent landscape to environmental variables, taking into account the contagious nature of clearing. We also ask whether it would be possible to apply a simple simulation modelling approach to reconstruct a credible historical sequence of clearing in the study area. The historical data indicate that annual clearing rates have varied substantially in the study area and selective tree removal (ringbarking and thinning) has been common. These findings make it unlikely that a simple simulation approach would replicate the spatial and temporal sequence of woodland loss. Our regression results show that clearing patterns can be related to environmental variables, particularly annual rainfall and estimated pre‐European vegetation type, but that patterns are dominated by contagion.  相似文献   

19.
North American cities have undergone dramatic changes over the last century. Locations that were once inconvenient have become accessible through extensive road networks leading to population decentralization from the traditional urban centre to suburbia, creating polycentric sprawls from once monocentric communities. Hamilton, Ontario is one such city. The decentralization and urban decline of the city is widely attributed to sprawling development. This change in the sociospatial structure creates challenges for transportation planners as we see greater automobile dependency, greater commuting distances and increased congestion. Smart growth policies such as urban residential intensification (URI) aim to increase population densities in the urban core. This exploratory study estimates the benefits of such policies from a transportation aspect. It is predicted that the City of Hamilton will experience household growth of approximately 80,000 households over the period 2005–2031. Using IMULATE, an integrated urban transportation and land‐use model, a variety of development scenarios model this anticipated growth. Changes in vehicular emissions, traffic congestion and energy consumption as a result of URI are examined. Models of the land‐use/transportation relationship demonstrate how increasing population densities within a city's urban centre drastically reduce congestion, emissions and gasoline consumption.  相似文献   

20.
Until recently, the Pokot in the highlands of the Baringo area in Kenya have practised semi‐nomadic pastoralism. Today they are rapidly sedentarizing and in many areas suitable for farming, they are adopting rain‐fed agriculture. As a result of these dynamics, claims to individual property on de facto communal rangelands have arisen, and to such an extent that they seriously threaten the peace of the community. This article explores the conflicts that emerge in the transition from common property to private tenure. Using locally prominent land disputes as exemplary cases, it focuses on the role of traditional gerontocratic authorities in the attempt to resolve a growing number of land disputes; on the emerging power of patrilineal clans and local elites in the enforcement of access to land; and on the incompetence of government agencies to intervene. The failure of customary institutions to ensure land tenure security leads to a situation in which women and marginalized actors in particular are threatened with displacement, and in which most local actors want the state to intervene and establish formal property rights.  相似文献   

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