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1.
Both ‘tanka’ and ‘beri’, the well-like structures made for storing drinking water fetched from distant places or superficially charged from the runoff water of the monsoon rains, are considered integral components of rural communities in the Thar Desert of Rajasthan State in north-western India.A. stephensi, the confirmed malaria vector in desert regions, breeds in these structures predominantly.  相似文献   

2.
Impacts of the forces and processes of agricultural restructuring are described in this paper through an analysis of farmers’ ‘lived experience’ in the tobacco sector of Ontario, Canada. The paper argues that the political and economic changes in the 1980s fundamentally altered tobacco farming and the broader rural community. The analysis is based upon a survey of farmers and former farmers, and includes examples of individual case histories. The results show the ways in which farmers’ well-being was affected and provides insights into coping mechanisms.  相似文献   

3.
This paper examines farmers’ ethnobotanical knowledge, innovation and rural change, and indicates one way in which indigenous technical knowledge complementing scientific knowledge may be documented for use by development planners and agencies. This paper firstly identifies plant species recognised as resources by farmers, and considers the value of these resources. Secondly, the paper documents and assesses the ethnobotanical knowledge associated with the utilisation of plant species, before turning to examine how plant resources are defined by use and culture. It also demonstrates that some components of ethnobotanical knowledge have potential for the sustainable development of plant species. The study shows that farmers have started to domesticate some of the ‘traditional’ plants, and new crops have been introduced associated with corresponding innovations in local agricultural systems. Since the farmers have a relatively strong tradition in natural resources conservation, this study suggests that it will be possible to introduce community-based gene banks linked to formal or government facilities. The paper demonstrates that it is important to combine and interweave ‘modern’ and indigenous knowledges to produce a more realistic and sensitive understanding and management of natural environmental resources for sustainable development.  相似文献   

4.
5.
The spatial distribution of UK farm-based tourist accommodation is not known in detail, although this type of facility has been an important element in the growth of rural tourism and the most common option for farm diversification. A database of farms in England and Wales offering tourist accommodation has been prepared and the individual entries georeferenced to enable their locations to be determined with respect to selected Scenic Areas (Areas of Outstanding Natural Beauty, Heritage Coasts and National Parks). Exploratory analysis of this database indicates a possible ‘neighbourhood effect’ in which the provision of farm-based accommodation within buffer zones immediately surrounding these designated areas has a higher level of penetration in the farming community than in more distant areas. Further research is outlined to examine the interaction between actors in farming and planning communities using the geographical framework presented here.  相似文献   

6.
Vegetation restoration is one of the most common and effective ways to combat desertification and prevent adjacent areas from sand encroachment in many of the desertified regions of the world. However, vegetation restoration in desertified regions is very difficult because of low rainfall, the mobile ground surface, and cost. An effective, low-cost method of afforestation is urgently required. To determine such a method, a 10-year study was carried out in the Jilantai Salt Lake area. Five different afforestation areas were established: a ‘comparison area,’ a ‘land enclosure area,’ a ‘land enclosure + irrigation area,’ a ‘leveled-afforestation area’ (the dune areas were leveled and then planted with seedlings with added irrigation), and a ‘protected afforestation area’ (the dune areas were planted with seedlings, and the surviving natural vegetation was protected as much as possible). Vegetation-related parameters (survival rate, height, trunk diameter, coverage, canopy size, and density) and environment-related factors (relative humidity, wind velocity, and amount of sand encroachment) were measured by standard methods. Results show that the protected afforestation method had the following advantages: (1) the survival rate was higher for seedlings planted in the protected afforestation area than in the leveled afforestation area; (2) vigor (height, trunk diameter, coverage, and canopy size) was better in seedlings planted in the protected afforestation area than in the leveled afforestation area, especially in the beginning period of revegetation; (3) coverage (of individual species, of all planted vegetation, and of all vegetation) was larger in the protected afforestation area than in the leveled afforestation area; (4) density of naturally germinated plant species was higher in the protected afforestation area than in the other areas, showing that the protected afforestation method provided a suitable growing environment not only for planted species but also for naturally growing species; (5) in the protected vegetation area, relative humidity of air increased and wind velocity was greatly reduced; (6) after the establishment of vegetation by the protected afforestation method, sand encroachment into the salt lake area was significantly reduced. These results suggest that protected afforestation is an effective method of vegetation rehabilitation that has the potential not only to be applied to arid lands in China but also to desertified areas throughout the world; (7) cost-effective calculation shows that the leveled afforestation area costs much more than other areas.  相似文献   

7.
Coming from a socio-cultural geography perspective this paper sets out to question the ‘essentiality’ of East/West German differences, often said to persist in Germany despite (re)unification, by analysing the way in which they are socially constructed in German television reports and films today. Particular emphasis is placed upon the social and spatial positioning of the TV producers, of those represented, and of the audience. It is suggested that television representations such as those analysed in the paper effect a marginalization of East Germans and East Germany that can be partially resisted on the basis of contradictions ‘within’ and ‘outside’ filmic texts.  相似文献   

8.
A methodological proposal for the assessment of impacts due to linear infrastructures such as motorways, railways, etc. is presented. The approach proposed includes a series of specific issues to be addressed for each geomorphological feature analysed—both ‘static’ and ‘dynamic’—as well as a series of steps to be followed in the process.Geomorphic characteristics potentially affected were initially identified on the basis of a conceptual activities/impacts model that helps to single out geomorphic impacts related to environmental concerns for the area. The following issues were addressed for each individual impact: nature of potential effects; indicators that can be used to measure impacts; criteria of ‘geomorphologic performance’; procedure for measurement/prediction of changes; translation of geomorphologic impacts into significant terms from the viewpoint of human concerns; possible mitigation and/or compensation measures.The procedure has been applied to a case study corresponding to a new motorway in the Basque Country, northern Spain. Geomorphological impacts considered in this analysis included: (1) consumable resources; (2) sites of geomorphological interest; (3) land units with high potential for use, high productivity or value for conservation; (4) visual landscape; (5) slope instability processes. The procedure has been designed for implementation in a Geographic Information System (GIS) environment. Details are given on the application of the method to each individual impact analysed and results are presented in both numerical and map form.Impacts assessed were initially expressed by means of heterogeneous magnitudes, depending on the geomorphological feature considered. Those geomorphological impacts were then translated into significant terms and homogeneous magnitudes. Integration was carried out on the basis of impact values thus obtained. Final integrated results were also expressed in numerical and map form.The method proposed enables comparison of alternatives as well as ‘prediction’ and assessment of impacts in terms directly related to geomorphic characteristics. It also facilitates the expression of those impacts in terms that allow integration with other types of environmental impacts.  相似文献   

9.
F. Sheldon  M.C. Thoms   《Geomorphology》2006,77(3-4):270
Large rivers are often considered to retain less organic material than smaller streams primarily because of a decrease in retentive structures. From our observations on the Barwon–Darling River, a semi-arid river in southeastern Australia, we suggest that geomorphic complexity plays a fundamental role in the retention of organic matter. The Barwon–Darling River has a ‘complex’ river channel cross-section with large inset benches being a prominent morphological feature within the channel. The importance of geomorphic complexity for retaining organic material is likely to be significant in dryland rivers. These rivers spend extended periods at low flow with infrequent large floods that inundate the floodplain. They do, however, experience more frequent within channel floods that inundate in-channel ‘bench’ features. In-channel geomorphic complexity and its ability to retain organic material, therefore, means that although the dominant lateral movements of organic material will still occur during large overbank flows, smaller ‘pulse’ inputs will occur with each in-channel rise and fall in water level. In dryland rivers, where large overbank flows may only occur every seven or more years, these small ‘pulse’ inputs of organic material may well be vital for the integrity of the system.This paper describes the contemporary complexity of a channel in a regulated and an unregulated reach of the Barwon–Darling and compares this with cross-sections surveyed in 1886. We show that flow regulation has greatly reduced channel complexity. We estimate the potential organic matter input to each bench level within the channel (using data collected under near natural riparian conditions) and measure the contemporary organic loads within the channel of the regulated and unregulated reach. This modelling suggests that the development of water resources has reduced the complexity of the channel in the regulated reach, resulting in a potential decrease in the retention of organic matter in this region of the river. The importance of this organic matter to the aquatic food web of the Barwon–Darling River is also demonstrated.  相似文献   

10.
Bioprotection explored: the story of a little known earth surface process   总被引:2,自引:3,他引:2  
Bioprotection is identified as an earth surface process. However, it has been little studied, little acknowledged and yet may have major implications for the operation and management of geomorphic systems. Key early observations are traced back to Darwin's ‘Voyage of the Beagle’, Geikie in the natural environment and Watson for the built environment. Recent field observations and experimental work examining bioprotection are reviewed, with a specific focus on lichens and the landscape, as are its complex interactions with other processes. A conceptual model of bioprotection is presented for the case of an epilithic lichen on a limestone surface.  相似文献   

11.
The study examines the changes in sub-Saharan's natural land cover resources for a 25 year period. We assess these changes in four broad land cover classes – forests, natural non-forest vegetation, agriculture and barren – by using high spatial resolution Earth observing satellites. Two sets of sample images, one ‘historical’ targeted at 1975 and a second ‘recent’ targeted at the year 2000, have been selected through a stratified random sampling technique over the study area, targeting a sampling rate of 1% in each of the strata. The results, presented at eco-region level and aggregated at sub-Saharan level, show a 57% increase in agriculture area at the expense of natural vegetation which has itself decreased by 21% over the period, with nearly 5 million hectares forest and non-forest natural vegetation lost per year. The impacts of these changes on the environment on one site and on the socio-economy on the other site are discussed and possible pressures on human well being are highlighted.  相似文献   

12.
This paper presents an improved method for the optical dating of Holocene sediments from a variety of geomorphic settings. We have measured the equivalent dose (De) in individual grains of quartz, using green laser light for optical stimulation, and have simulated the De distributions for multiple-grain ‘synthetic’ aliquots using the single-grain data. For 12 samples of known (independent) age, we show that application of a ‘minimum age model’ to the single-grain and ‘small’ (10-grain) aliquot De data provides the most accurate estimate of the burial dose for nine of the samples examined (3 aeolian, 5 fluvial, and 1 marine). The weighted mean De (as obtained using the ‘central age model’) gives rise to burial age overestimates of up to a factor of 10 for these nine samples, whether single grains, small aliquots, or ‘large’ (100-grain) aliquots are used. For the other three samples (two aeolian and one fluvial), application of either the minimum age model or the central age model to the single-grain, small aliquot, and large aliquot De data yields burial ages in accord with the independent age control. We infer that these three samples were well bleached at the time of deposition. These results show that heterogeneous bleaching of the optical dating signal is commonplace in nature, and that aeolian transport offers no guarantee that the sample will be well bleached at the time of deposition. We also show that grains sensitive to infrared (IR) stimulation can give rise to low De values, which will result in significant underestimation of the burial dose and, hence, of the age of deposition. We demonstrate that use of a modified single-aliquot regenerative-dose protocol incorporating IR stimulation prior to green light stimulation deals effectively with contamination by IR-sensitive grains. We conclude that application of the modified protocol to single grains or small aliquots of quartz, using the lowest De population to estimate the burial dose, is the best means of obtaining reliable ages for Holocene sediments from a wide range of depositional environments.  相似文献   

13.
Many Vertisols in Tigray, Ethiopia, typically carry a discontinuous rock fragment (RF, size 0.5–> 40 · 10− 2 m) cover with 10 to 100 RFs m− 2. Such RF mulches are of agricultural and environmental significance because they influence the water balance in the underlying soils and the crop yield. Natural RF concentrations are mostly considered as eolian or hydraulic lag deposits, or as the result of lateral transport over the soil surface from a rock outcrop, upslope. In cultivated areas RF mulches can develop by tillage.This paper presents the case of a natural RF mulch whose lithology indicates that the RFs are up-squeezed by the local Vertisol. The study site is located in the pass of Enda Maryam, Tigray, Northern Ethiopia (39°8′ E and 13°36′ N). A circular area of 10 m diameter, about 200 m away from the water divide in the valley has been cleared annually between 01/1999 and 05/2003. During this period, 625 RFs, 17 being > 7.5 · 10− 2 m in size, totalling a mass of nearly 62 kg, have been collected. After correction for measurement procedures, the rate of RF up-warping by the Vertisol at Enda Maryam is assessed at 5 RFs m− 2 in 3 years. At this rate of appearance, the formation of current RF concentrations on top of active valley Vertisols is only a matter of 101–2 years, provided the availability of RFs below the soil surface.Although important underground displacements were measured in the Vertisol between 01/1999 and 05/2002, the supposed link between up-squeezing of RFs and plastic deformations of ‘chimney’, ‘diapir’ or ‘intrusion’-like type in the Vertisol could not be evidenced. Instead, RFs are clearly concentrated on the soil surface as well as in depth, along the existing vertical desiccation cracks, often > 1 m deep which display polygonal configurations at the soil surface. Further, bundles of slickensides containing some RFs, have been mapped at the base of the Vertisol. The slickenside configuration suggests that the RF-bearing substrate is being scraped off.While the underground displacement of RFs along active slickensides seems normal, the process of RFs ascending in ‘upright’ position in the edge of desiccation cracks needs explanation. The closure of a desiccation crack is a peristaltic-like movement, following ascent or descent of the capillary fringe. It is hypothesized that this movement gradually pushes the RF to the surface or to another place or level in the soil profile where the crack closes in last instance.The apparent young age of the valley Vertisol mulches in Ethiopia might indicate the very recent formation of yearly recurrent desiccation cracks of Vertisols in the area. Available information confirms that most valleys in the study area used to be perennially marshy. Under these conditions no movements of RFs in the soil profile are expected to occur. Gullying, leading to pronounced seasonal desiccation of the Vertisols, started in several cases not more than 50 years ago.  相似文献   

14.
In the Solway Firth — Morecambe Bay region of Great Britain there is evidence for heightened hillslope instability during the late Holocene (after 3000 cal. BP). Little or no hillslope geomorphic activity has been identified occurring during the early Holocene, but there is abundant evidence for late Holocene hillslope erosion (gullying) and associated alluvial fan and valley floor deposition. Interpretation of the regional radiocarbon chronology available from organic matter buried beneath alluvial fan units suggests much of this geomorphic activity can be attributed to four phases of more extensive gullying identified after 2500–2200, 1300–1000, 1000–800 and 500 cal. BP. Both climate and human impact models can be evoked to explain the crossing of geomorphic thresholds: and palaeoecological data on climatic change (bog surface wetness) and human impact (pollen), together with archaeological and documentary evidence of landscape history, provide a context for addressing the causes of late Holocene geomorphic instability. High magnitude storm events are the primary agent responsible for gully incision, but neither such events nor cooler/wetter climatic episodes appear to have produced gully systems in the region before 3000 cal. BP. Increased gullying after 2500–2200 cal. BP coincides with population expansion during Iron Age and Romano-British times. The widespread and extensive gullying after 1300–1000 cal. BP and after 1000–800 cal. BP coincides with periods of population expansion and a growing rural economy identified during Norse times, 9–10th centuries AD, and during the Medieval Period, 12–13th centuries AD. These periods were separated by a downturn associated with the ‘harrying of the north’ AD 1069 to 1070. The gullying episode after 500 cal. BP also coincides with increased anthropogenic pressure on the uplands, with population growth and agricultural expansion after AD 1500 following 150 years of malaise caused by livestock and human (the Black Death) plagues, poor harvests and conflicts on the Scottish/English border. The increased susceptibility to erosion of gullies is a response to increased anthropogenic pressure on upland hillslopes during the late Holocene, and the role of this pressure appears crucial in priming hillslopes before subsequent major storm events. In particular, the cycles of expansion and contraction in both population and agriculture appear to have affected the susceptibility of the upland landscape to erosion, and the hillslope gullying record in the region, therefore, contributes to understanding of the timing and spatial pattern of human exploitation of the upland landscape.  相似文献   

15.
Service provision to remote rural areas is extremely costly, and only likely to be effective if the services provided are appropriate and accessible to the population. To date, little is known about the attitudes of rural residents (both townsfolk and the farming population) to various services. This study examines people's attitudes towards services generally, and health services in particular, and relates their attitudes to sociodemographic variables and geographical location. The results show the overwhelming importance attributed to health services, particularly medical services, and that attitudes differ significantly according to place of residence and by age group. These findings have major implications for those responsible for formulating policies relating to service provision for rural areas.  相似文献   

16.
Geomorphic differences between slopes backing two distinct desert piedmont types provide a proxy indicator for the kind of landform developed at the corresponding mountain base. Here, the term ‘bedrock pediment’ describes subaerial bedrock platforms that emanate from a mountain base while ‘alluvial slope’ describes suballuvial bedrock platforms that extend from the mountain. Mountain slopes backing bedrock pediments have been demonstrated to be mantled by larger clast sizes than corresponding slopes backing alluvial slopes in the Phoenix region, Arizona, USA. The present research focuses on using the disparate particle sizes between slopes backing bedrock pediments and alluvial slopes as an indicator for the piedmont form developed at the mountain base, and uses high-resolution remotely sensed digital data as a medium for quantitative landform assessments. A gravel + bedrock versus soil index developed from airborne midinfrared multispectral imagery acquired by the Thermal Infrared Multispectral Scanner (TIMS) indicates the presence of slopes mantled with larger particle sizes versus slopes mantled with smaller particle sizes and greater soil coverage. Two test areas confirm the applicability of this method and further demonstrate the usefulness of high-resolution midinfrared multispectral imagery as a geomorphic tool in arid regions.  相似文献   

17.
Schismus arabicusis a common annual with an ‘escape’ strategy of caryopsis dispersal and ‘opportunistic’ strategy of germination. It inhabits the Negev and Saharo-Arabian and Irano-Turanian phytogeographical regions. It displays a quantitative long-day response for flowering and a day length response in caryopses germinability. Germination in the dark was much higher than in light. The longer the period of light, from 0·5 h to continuous light, the lower the percentage of germination. The low percentage of germination, which is also regulated by temperature during dry storage, is important for the survival ofS. arabicusunder the unpredictable distribution and small amounts of rain in its extreme desert habitats.  相似文献   

18.
Quantifying spatial accessibility in relation to the provision of rural health services has proven difficult. This article critically appraises the two-step floating catchment area (2SFCA) method, a recent solution for measuring primary care service accessibility across rural areas of Victoria, Australia. The 2SFCA method is demonstrated to have two fundamental shortcomings – specifically the use of only one catchment size for all populations, and secondly the assumption that proximity is undifferentiated within a catchment (especially problematic when the catchment is large). Despite its advantages over simple population-to-provider ratios, the 2SFCA method needs to be used with caution.  相似文献   

19.
20.
Seven mesas (i.e. flat-topped, isolated mountains) and the Grootberg mountain in arid north-west Namibia were investigated with regard to floristic relationships in relation to environmental gradients. Relationships between mesas and their surrounding, species richness and number of mesa specialists were used as measures to explore the influence of elevation on these floristic parameters. Also soil properties were investigated along these elevation gradients. The overall questions were designed to investigate the importance, i.e. ‘special status’, of these mesas in terms of contributing to species diversity and to elucidating ecological processes in this arid landscape.With regard to special floristic status, the tops of mesas supported different plant communities than their surrounding plains, while slopes indicated various levels of intermingling with plain vegetation. Differences between mesas and plains became more pronounced with increasing elevation. There were, however, no clear vegetation belts related to elevation. Plant species richness and number of mesa specialists showed a trend of increasing numbers with elevation, but these trends were statistically poorly supported, largely due to high variability between samples.Do soil gradients and elevation, as two important environmental variables, affect this ‘special’ status? Pronounced soil gradients were evident for many soil properties. These in combination with altitudinal effects of increased moisture and lower temperatures were believed to directly influence plant species composition and richness. The soil gradients may also indicate nutrient flow from the mesas to the surrounding lowlands, a process of ecological importance, particularly should degradation due to over grazing become a problem in the lowland areas.  相似文献   

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