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1.
Gender and local soil knowledge: Linking farmers' perceptions with soil fertility in two villages in the Philippines 
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下载免费PDF全文 Maria Elisa Christie Mary Parks Michael Mulvaney 《Singapore journal of tropical geography》2016,37(1):6-24
Scientists often turn to farmers to understand soil management. This process reveals differences and overlaps between local and scientific soil knowledge but rarely considers women and gender issues. This paper examines men's and women's local knowledge of soils in upland, smallholder farms in two villages in Mindanao, the Philippines, using focus group discussions, semi‐structured household interviews, field visits, GIS and soil testing. Farmers' field areas were calculated and delineated based on their perceptions of the different types of soils on their land. Men and women chose the same plots for what they considered their best soil but differed on what they felt were their worst. The fertility of the soils that women considered to be the best and worst was not significantly different from that of the men's respective choices. There was a difference in fertility, however, between the best and worst soils regardless of gender. Although soil fertility analyses showed that the women's chosen soils were similar to men's, analyses of qualitative data showed that their knowledge of soils was different and was based in part on a gendered division of labour. A multidisciplinary approach helped bridge the gap between sociocultural and physical research. 相似文献
2.
LUCIANA MARTINS 《Geographical review》2012,102(2):225-244
In this article I reexamine Alexander Hamilton Rice's seventh expedition to Amazonia (1924–1925) in order to highlight the ways in which the image of the modern explorer was constructed through various technologies of visualization, including maps, still photography, and film. The Rice expedition was equipped with the latest surveying instruments, among them a hydroplane especially adapted for taking aerial photographs, and it was the first to attempt shortwave radio communication in the Tropics. However, the expedition's efforts to reach the headwaters of the Rio Branco ended in failure. I investigate Rice's heavy investment in making a visual record of the expedition in the context of his academic ambitions. Despite his influence in learned societies in the United States and Europe, his questionable reputation within academic circles was difficult to overcome: His reliance on publicity to enhance his academic career had adverse consequences. The retelling of Rice's tale here also sheds light on the role of indigenous local knowledge and agency in the history of exploration. All the modern surveying technology employed notwithstanding, local support remained crucial for Amazonian exploration. 相似文献
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Presented is a detailed characterization of the present state and pollution of soil cover in the influence area of the Dzhidinskii tungsten-molybdenum plant which takes into consideration the spatial geological inhomogeneity and the functional purpose of urban territories. As part of the investigation, we determined the content levels of heavy metals and metalloids in background soils, and the elements which are the main pollutants of urban soils in the zones of different functional purposes, ascertained the degree of technogenic geochemical transformation of soil cover in the city of Zakamensk, and identified the leading soiland landscape-geochemical factors for accumulation of heavy metals and metalloids in the urban topsoil (0?10 cm) horizons. An assessment was also made of the ecological hazard of soil pollution by a set of heavy metals and metalloids in the main functional zones of the city. A soil-geochemical survey was carried out, and the ICP-MS method was used to determine the total content levels of 14 heavy metals and metalloids of hazard classes I?III as well as Be, Sn, Cs and Bi. The elements were determined, which are the main pollutants of the soils in Zakamensk: W, Bi, Cd, Pb and Mo. The study revealed a need to take into account the metallogenic specific character and geological inhomogeneity of the area by using the local coefficients of concentration (EF l ) and dispersal (DF l ) which must be calculated not with respect to the average regional background but from the individual (for each parent material) background value in order to more accurately determine the degree of technogenic geochemical transformation of soils, and the ecological hazard of pollution. It is suggested that the ecological hazard should be assessed on the basis of the Integrated Pollution Index (IPI) which is calculated with respect to the world’s average concentrations of heavy metals and metalloids in soils and takes into account hazard classes of elements. 相似文献
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In seasonally frozen regions, freezing-and-thawing action is the main cause responsible for the destruction of canals, which is closely linked to the temperature gradient and water transport. To investigate the behaviour of soils under freezing-and-thawing actions, many numerical models have been established that consider the important coupling of moisture transport and temperature evolution; but they contain excessive parameters, some of which are rather difficult to determine. Based on the well-known Harlan''s theory, a simple moisture-heat coupling model was recently proposed to quantify the coupled moisture-heat transport performance of soils in terms of the central temperature and porosity. The mathematical module of COMSOL Multiphysics was further employed to solve the governing equations numerically. To validate our model, a thorough experimental scheme was carried out in our lab. The measured temperature distribution was found to be consistent with the predicted results. 相似文献
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《自然地理学》2013,34(1):78-96
Soil erosion has been recognized as one of the major forms of human-induced soil degradation. Due to land use changes in Iran, erosion has increased 800% between 1951 and 2002, calling for urgent action. But erosion research and policy development are hampered by a lack of information on the underlying factors controlling erosion. Soil types vary in their inherent susceptibility to erosion; but, like most countries, Iran lacks a network of field plots where erodibility is measured. A proxy for erodibility based on existing data and supplemented by an easily measured minimum data set is therefore needed. In this study, we use geological mapping and cluster, principal component, and factor analysis to group soils in the Taleghan Drainage Basin in Iran and subsequently determine their erodibility. First, a geological map of the area was prepared by photogeological methods and on-the-ground verification. Then, three soil profiles were investigated within similar landform units of each geological formation, and soil samples were taken. Physical and chemical properties that might impact soil erodibility (soil texture, pH, electrical conductivity, CaCO3, and soil organic matter) were used to create a matrix of soil properties and parent material. Application of cluster analysis and factor analysis to the data allowed identification of three geological (parent material) clusters. To investigate the mutual effect of land use and parent material on soil erodibility, a soil erodibility factor was obtained for three land use types in each cluster: rangeland, cropland (irrigated), and dry-land farming (nonirrigated). Geological cluster 1, consisting of marl, gypsum, and gypsiferous mudstone, was the most erodible; geological cluster 2, consisting of recent alluvium, alluvial fan, and landslip deposits, was of intermediate erodibility; and geological cluster 3, consisting of igneous rocks, dolomite, and conglomerate, was the least erodible. Within each geological cluster, dry-land farming was the most erodible, cropland was medium erodible, and rangeland was least erodible. The study suggests that geological and land use maps provide a useful framework for assessing soil erodibility. This work can guide future soil erosion studies and direct soil conservation policy to areas most susceptible to erosion. 相似文献
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《Geography and Natural Resources》2008,29(4):348-353
We determined the rates of anthropogenic degradation of vegetation cover, soils, the river network, the slope type of terrain, and of the geological framework of landscapes. A decrease of the anthropogenic transformation rate of the component composition of geosystems was revealed in the biogenic components – bio-inert components – abiogenic components series was revealed. The time of complete exhaustion of the natural-resource potential is forecast from the components of the physical-geographical environment. 相似文献
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Zhang Zhenxiang Yang Jin Ou Qibin Zhang Yichi Qu Ximo Guo Yafei 《Natural Resources Research》2021,30(6):4807-4824
Natural Resources Research - The Ledong area is a typical high temperature and high pressure area in the South China Sea's Yinggehai Basin. The geological structure of this basin is complex,... 相似文献
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Huge volcanic landslides are one of the most hazardous geomorphological processes that can occur during the evolution of volcanic ocean islands. The causes of these phenomena, however, are very complex and combine non-volcanic and volcanic factors. In the Canary Islands, more than 20 events have been detected during the last decades. A detailed analysis was carried out for La Orotava amphitheatre on Tenerife in order to understand the relationship between geomorphological and geological aspects and huge volcanic landslides. The results indicated four major features that play a significant role in such mass movements: deep erosive canyons, high coastal cliffs, widespread residual soils and structural axes. High coastal cliffs and deep erosive canyons locally reduce the stability conditions and control both the seaward and the lateral boundary of the landslide. Weak residual soils formed above phonolitic pyroclastic deposits occur repeatedly in the stratigraphic column of La Orotava and are characterised by their large extent. Thus, one of these soils may have evolved into the slip surface of the failure. Part of the head scarp of the amphitheatre is defined by a volcanic rift zone, as indicated by the measurement of dike orientation and a density map of eruptive vents. The four features are not able to trigger a failure, but to destabilise the volcano flank and determine the boundary of the slide. Therefore, information on depth and orientation of canyons; location and height of coastal cliffs; stratigraphic repetition, extension and thickness of residual soils and orientation and density of dikes and eruptive vents along structural axes should be incorporated into a hazard assessment on large landslides on volcanic islands. 相似文献
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SOIL CATENAS,TROPICAL DEFORESTATION,AND ANCIENT AND CONTEMPORARY SOIL EROSION IN THE PETéN,GUATEMALA
Timothy Beach 《自然地理学》2013,34(5):378-405
The Petexbatún region of Guatemala's Petén tropical forest lowlands has been largely deforested since the early 1980s as landless peasants have turned even national parks into milpas. The soils of these tropical forest, karst landscapes are known mainly from small-scale maps and archaeological investigations. This paper investigates soil catenas and natural slope processes from the region's last virgin tropical forests and compares these with catenas and processes on slashed and burned slopes. Soils were sampled and analyzed for physical, fertility, and taxonomic measures. This primary forest toposequence forms a typical downward translocation catena, with the thickest soils (>200 cm) in depressions, the thinnest soils on shoulder slopes, and moderately thin soils on the crests and backslopes. Most crest and sloping soils are Lithic Rendolls and contain simple O-A-C horizon sequences, and most soils have little sign of either eluviation or illuviation. A few deeper soils on the slopes are Vertic Rendolls and have moderate slick-ensides, whereas footslopes and seasonally drained depressions are well developed Vertisols. The primary forest soil catena was compared with two slash-and-burn milpas, one with comparable slopes and one with steeper slopes. The comparably sloped milpa had soil thicknesses that were 7.9 to 13.8 cm thinner, truncated horizons, and physical evidence of erosion. The steeper milpa had soil thicknesses that were 11.1 to 18.2 cm thinner and also had truncated horizons and physical evidence of erosion. Where ancient Maya terraces (Late Classic, ca. 550 to 830 A.D.) are present in the slash-and-burn landscape, an average of 25 to 46.5 cm soil remain upslope and 9.3 to 16.1 cm remain downslope. The findings show high soil truncation rates and erosion to bedrock in a decade in one place, though ancient Maya terraces are still holding 2.7 to 3.6 times more soil than the surrounding hillslopes. Despite high modern erosion, lake sediments show surprisingly low soil losses in the Maya Late Classic during the period of the most intensive land use. In contrast, studies at Copán, Honduras and in the northern Petén, where terrace evidence is scant, show high rates of erosion during this period. [Key words: soil catenas, tropical deforestation, milpa, soil erosion, Maya Lowlands.] 相似文献
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Investigation of Soil Shear-Strength Parameters and Prediction of the Collapse of Gully Walls in the Black Soil Region of Northeastern China 总被引：1，自引：0，他引：1
《自然地理学》2013,34(2):161-178
The collapse of gully walls is an important mode of gully erosion, and it depends strongly on two soil shear-strength parameters: cohesion and the internal friction angle. However, little research has examined these parameters in China's black soil region. In the present study, we sampled six groups of surface soils from four different land uses, and two groups of soils at depths of 30 cm and 60 cm. The cohesion (c) and internal friction angle (φ) of each group were determined at 10 levels of water content. The results show that c increased with increasing water content until a certain level (12% for the surface soils, and 14% for the deeper soils), after which c decreased. Internal friction angle generally decreased with increasing water content. We developed a model predicting collapse of gully walls based on four parameters: dry bulk density, water content, crack depth, and the width of the soil collapse. The model predicts that soil collapse would occur at two levels of water content: dry and wet conditions. Field data showed that collapse only occurred under the wet condition; the critical mass water content given by the model is between 31.0% and 33.8% moisture. 相似文献
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Karl Raitz 《Geographical review》1998,88(3):363-387
ABSTRACT. Federal support for planning and building roads provided an opportunity to create a new kind of place, the American roadside. The roadside grew up beside the public road as a distinct private space, yet the two were linked as road travelers came to depend on the services provided by people who lived at the road's edge. Federal road-improvement legislation brought discipline to the surveying, construction, and configuration of roads. But roadside structures remained largely the creation of local people, who built a vernacular landscape that was undisciplined and in strong contrast to the road's regimentation. The roadside became a new kind of space occupying the unstable zone between the discipline of the road and the informality of the countryside, a spatial contradiction that gave license to a new, free-wheeling, mercantile logic, an improvisational departure from the staid formality of Main Street. 相似文献
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Studies of soil productivity must compensate for the effects of temporal trends in order to examine the pattern of crop yields along spatial gradients. An analysis of the published yield estimates for 30 soils in 233 counties, however, did not find consistent yield increases over the past three decades. On the contrary, the yield estimates for many soils were markedly uniform since 1972. The uniformity appears to have two causes: the acknowledged difficulty of making yield estimates in a time of increasing variability in soil and crop management, both within and between regions, and surveyors' awareness of data stored in a national soils data base. The effect is to cast doubt on soil productivity data reported in county soil surveys published between 1973 and 1988. 相似文献
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《极地研究》1990,1(1):49-57
It is the main task of the antarctic surveying expedition to establish the surveying system. In three times of the antarctic surveying research expeditions, a complete and accurate surveying system has been established in the Chinese Great Wall Station area. The surveying system includes geodetic coordinate system, elevation system and gravity reference system. In this paper, the surveying methods and the mathematical models for establishing these systems are discussed, and the accuracy of results is analysed. 相似文献
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Michael E. Folkoff 《自然地理学》2013,34(4):328-336
In previous studies, models of the climatic controls on pH in the A (pHA) and B horizons (pHB) of U.S. soils were developed which differ in the functional forms and variables incorporated into each model. This study suggests that the differences in the models are explained by climate's control over the soil properties that determine pH buffering. Climatic control of pHA and pHB buffering in most acid soils is through its control over clay mineralogy. However in very acid soils, organic matter content (OM) is a stronger buffer of pHA than is clay mineralogy because in these highly leached soils, OM contents are very high and most OM is concentrated in the A horizon. In basic soils, climate dominates buffering through its control over the chemical reactions involving calcium carbonate (CaCO3) formation. The pHA model suggests that in basic soils as moisture decreases CaCO3 content increases causing pHA buffering to increase. In contrast, the pHB model suggests that as moisture decreases pHB buffering decreases. Although leaching of basic soils is limited, when it occurs a highly-concentrated pulse of calcium (Ca2+) is illuviated to the B horizon, causing pHB to increase. As leaching decreases, the magnitude of this pulse of Ca2+ increases because more Ca 2+ is available for leaching and depth of leaching of Ca2+ decreases. Studies of basic soils support only the results of the pHA model, but they are based mainly on laboratory studies which do not consider the influence of climate on B horizon chemistry. [Key Words: Soil acidity, pH buffering, climate, modeling, U.S. soils.] 相似文献
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Almost half of the 16,942 km2 of South Africa's subtropical thicket with a substantial Portulacaria afra (spekboom) component has been heavily degraded by domestic herbivores. The subtropical thicket biome is a drought-prone and water-stressed area, and many of the region's watersheds comprise of eroded landscapes clothed in degraded spekboom thicket. The objective of this study was to determine the impact of degradation of spekboom thicket on hydrological processes. We hypothesised that degradation of spekboom thicket would reduce infiltration and, hence, reduce soil moisture retention and increase run-off and erosion. We tested this hypothesis by collecting data on rainfall, infiltration, soil moisture retention and run-off in degraded thicket, and – as a reference site – in an adjacent stand of relatively intact thicket. The results showed clear trends in the impacts of spekboom thicket degradation on hydrological processes. The more than hundred-fold lower infiltration in soils associated with degraded thicket relative to the soils beneath the intact, spekboom canopy, resulted in lower levels and less retention of soil moisture, almost double the amount of runoff, and an almost six-fold increase in sediment load. Thus, restoring degraded thicket will reduce erosion and likely improve baseflows, in addition to sequestering carbon. 相似文献
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钙网蛋白（calreticulin,CRT）是参与多种细胞过程的高度保守的内质网伴侣蛋白。1974年,它首次被鉴定为钙离子结合蛋白,随后CRT与肿瘤之间信号通路相关关系被广泛的研究。另外,在人类多种肿瘤中,细胞表面的CRT被认为是1个"促吞噬"信号,由此CRT与癌细胞的巨噬细胞吞噬免疫系统的相关研究,有望为肿瘤综合治疗提供新的理论依据和策略。也有越来越多的证据表明CRT在不同肿瘤中的异常表达,将为CRT成为一种新的肿瘤标志物提供许多依据。以及CRT对各种肿瘤的发展具有很重要的影响且CRT对肿瘤形成和进展的影响取决于细胞类型和临床阶段。 相似文献
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Wilfred H. Theakstone Frank M. Jacobsen & N. Tvis Knudsen 《Geografiska Annaler: Series A, Physical Geography》1999,81(4):767-776
The most labour-intensive and time-consuming part of many mass balance programmes is the acquisition of snow depth data. The standard technique, which involves probing the snow cover at intervals along a series of profiles, generally by an individual on skis, may involve more than 300 discrete measurements along a total of more than 20 km of profiling at a single glacier. Kinematic surveying with a global positioning system (GPS) in differential mode provides much more information about changes of glacier surface level and snow thickness between surveys. The positions of a large number of points can be fixed in a relatively short time by GPS surveying, and the technique is usable in adverse weather conditions. With real-time kinematic GPS surveying, it is possible to return to the same positions (longitude, latitude) during successive field programmes, and a previously followed route can be retraced precisely. GPS surveying facilitates the production of accurate glacier maps for mass balance programmes. Data obtained by snow depth probing and GPS surveying in 1995 at Austre Okstindbreen, the largest glacier of the Okstindan area, Norway (66°N), indicate that repeated GPS surveys are likely to provide a large amount of information on withinyear and between-year changes of surface topography and are not subject to the errors in mass balance calculations which arise from probing snow depths along selected profiles. Kinematic GPS surveying of several glaciers within an area would overcome the difficulties arising when mass balance studies are confined to a single glacier within a particular area. 相似文献
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Geomorphological characteristics of slope failures in northeast Viti Levu island,Fiji, triggered by Tropical Cyclone Winston in February 2016 下载免费PDF全文
下载免费PDF全文 The highways circumnavigating Viti Levu play a pivotal role in Fiji's socioeconomic development, and are a crucial link to transport aid during disasters. Slope failures triggered by heavy rainfall and tropical cyclones have led to considerable damage and fatalities along Viti Levu's main roads in the past. Knowledge of slope instability mechanisms is key for the successful identification and management of slope failure hazards, however, there is a paucity of such information for Fiji's main roads. Severe Tropical Cyclone (STC) Winston was the strongest cyclone on record to make landfall in Fiji and affected the Fiji Islands from the early hours of 20 February until 3 am, 21 February, 2016. We present a field reconnaissance examining the characteristics and mechanisms of slope failures induced by STC Winston along a 35 km stretch of the northern part of the Viti Levu's ring road, “Kings Road”. Approximately 61 distinct shallow, small‐scale slope failures were identified most of which were of a complex type and included earth and debris slides (planar and rotational) with a minor flow component. The trigger for the slope failures was the ~258 mm of rainfall in 24 hours after 30‐days of antecedent rainfall totalling 482 mm. This caused rapid increases in porewater pressures, especially at the contact of residual soils and the underlying weathered basement rock. Evidence of recurring slips along Kings Road indicates that contemporary slope instability is likely caused by elevated porewater pressure during high intensity rainfall events in clay‐dominated soils. 相似文献