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1.
K. Biro B. Pradhan M. Buchroithner F. Makeschin 《Land Degradation \u0026amp; Development》2013,24(1):90-102
Several decades of intensive dry land farming in the Gadarif region, located in the Eastern part of Sudan, has led to rapid land use/land cover (LULC) changes mainly due to agricultural expansion, government policies and environmental calamities such as drought. In this paper, an attempt has been made to analyse and monitor the LULC changes using multi‐temporal Landsat data for the years 1979, 1989 and 1999 and ASTER data for the year 2009. In addition, efforts were made to discuss the impact of LULC changes on the selected soil properties. For this, a post‐classification comparison technique was used to detect LULC changes from satellite images. Primarily, three main LULC types were selected to investigate the properties of soil, namely, cultivated land, fallow land and woodland. Moreover, soil samples were also collected at two depths of surface soil from ten sample plots for each of the LULC type. For these soil samples, various soil properties such as texture, bulk density, organic matter, soil pH, electrical conductivity, sodium adsorption ratio, phosphorous and potassium were analysed. The results showed that a significant and extensive change of LULC patterns has occurred in the last three decades in the study area. Further, laboratory tests revealed that soil properties were significantly affected by these LULC changes. The change of the physical and chemical properties of the soil may have attributed to the changes in the LULC resulting in land degradation, which in turn has led to a decline in soil productivity. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
2.
H. Alphan 《Land Degradation \u0026amp; Development》2012,23(3):278-292
This study classified land cover conversions by using quantitative change detection methods in the eastern Mediterranean coastal wetlands of Turkey. Three Landsat TM scenes acquired in 1984, 1998 and 2007 were analysed using image pairs of consecutive dates. The amounts of change were calculated for the periods from 1984 to 1998 and from 1998 to 2007, using binary change masks and supervised image classifications, in which eleven a priori defined land cover classes were used. Change areas accounted for 14.81 and 15.64 per cent of the total area, in the first and second periods, respectively. Conversions from/to sand dunes, mud flats and afforestation were by far the most extensive changes. Sand dunes and mud flats decreased, while afforestation and agriculture areas increased in the 23‐year period between 1984 and 2007. Five types of qualitative change were identified on the basis of land cover transformations within and between natural and anthropogenic systems. Type I changes, which indicated conversions from (semi)natural to anthropogenic systems, took place as agricultural expansion over coastal sand dunes, while Type II changes mostly occurred within agricultural systems. Type III changes included changes in human uses, leading to conversions from one anthropogenic system to another. Conversions between semi(natural) systems such as salt marshes and mud‐flats were typical Type IV changes. Type V changes were mainly due to conversions from agriculture to wetland categories or other semi(natural) cover types. Implications of these changes were discussed for management of coastal environmental resources. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
A. K. Braimoh 《Land Degradation \u0026amp; Development》2004,15(1):37-47
When farmers migrate yearly to a village to carry out intense farming during the rainy season, and thereafter return to a more permanent place of abode this is referred to as seasonal migration. The impact of such migration on land‐use/land‐cover change in an area within the Volta Basin of Ghana was examined using satellite image analysis and socioeconomic surveys. The most drastic land‐cover change involved the conversion of woodland to agricultural land, while there was also a general transition to less vegetation cover. Socioeconomic surveys revealed that most of the migration occurred during the post‐structural adjustment period in Ghana with declining soil fertility accounting for the highest per cent of causes of migration. Multiple regression results highlighted the role of population size and distribution, marketing of agricultural produce and technological evolution of the household in determining agricultural land‐use change. Policy initiatives that could lead to environment conservation are suggested. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
4.
Soil aggregate stability (SAS) is an indicator for soil condition and is greatly influenced by land use or land cover (LULC) type and other soil and environmental attributes. This study investigated the soil aggregate-size distribution, SAS, aggregate-associated organic carbon (AAOC) and the relative importance of factors affecting SAS and AAOC. Based on conditioned Latin hypercube sampling, soil aggregate samples were collected from the “A” horizon and wet sieved into large macroaggregates (>2.0 mm), small macroaggregates (0.25–2.0 mm), microaggregates (0.053–0.25 mm) and mineral fraction (<0.053 mm). The large macroaggregates accounted for 86% to 93% of the total aggregates under all LULC types except under dry land (64%) and paddy land (35%). The SAS under different LULC decreased in the order fir > shrubland > natural grassland > orchard > blue pine > broadleaf > mixed conifer > dry land > paddy land. The AAOC of the large macroaggregates constituted for 76%–90% of the total AAOC under all LULC types except under dry land (65%) and paddy land (38%). While SAS was largely influenced by the AAOC of small macroaggregates, microaggregates and large macroaggregates and LULC type, the AAOC of different aggregate fractions was mostly affected by LULC type, altitude and slope. SAS did not exhibit any significant relationship with the AAOC of different aggregate fractions under the natural LULC types but showed a strong relationship under the agricultural land indicating that AAOC is more critical for SAS under the agricultural land than under the natural LULC. 相似文献
5.
Land degradation is a natural and socioeconomic cause–effect phenomenon that is widespread all over the world. This study investigated the socioeconomic factors and causes of land degradation (e.g. population growth and urbanization, poverty, overgrazing, pollution, biodiversity, erosion) in the eastern part of the Mediterranean region. The study revealed a significant land use change from agricultural and natural vegetation to urbanized areas due to the high population increase during the last ca. 80 years (51‐times the magnitude of the total built‐up area). The high poverty rate that exists in the area (57 per cent of the population can be classed as ‘poor’) has resulted in damaging environmental practices (overgrazing and intensive usage of natural plants); we found 83 per cent of the farmers admitted to the adoption of these practices. Poverty has also resulted in an inverse and significant correlation (at the 95 per cent confidence level) between holding size and the sale of land for urban uses. We also noted that 75 per cent of the smallholder farmers surveyed had sold their lands for immediate benefits to cope with poverty. This relation was affected by the education level of the farmers; we found a direct and significant (95 per cent confidence level) correlation existed between these factors. Overgrazing was practised by 70 per cent of the farmers and was found to be one of the most important environmental consequences of land use change (1600 ha have been transformed from natural grazing to built‐up (urban) in the study area). Socio‐economic induced land degradation demands efforts to improve farmer environmental awareness as well as environmental standards, laws and bylaws and the reduction of mismanagement of land. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
6.
N. Gnanavelrajah R. P. Shrestha D. Schmidt‐Vogt L. Samarakoon 《Land Degradation \u0026amp; Development》2008,19(3):242-256
The organic carbon pool in agricultural land‐uses is capable of enhancing agricultural sustainability and serving as a potential sink of atmospheric carbon dioxide. A study was carried out to estimate and map carbon stock of different agricultural land‐uses in a sub‐watershed of Thailand and to assess the land‐use sustainability with respect to carbon management. A quadrat sampling methodology was adopted to estimate the biomass and its carbon content of 11 different land‐uses in the study area. Existing soil data were used to calculate the soil carbon. GIS was used for integrating biomass carbon, soil carbon and carbon stock mapping. Roth carbon model was used to project the soil carbon of present land‐uses in the coming 10 years and based on which the sustainability of land‐uses was predicted. The total carbon stock of agricultural land‐uses was estimated to be 20·5 Tg, of which 41·49 per cent was biomass carbon and 58·51 per cent was soil carbon. Among the land‐uses, para rubber had the highest average biomass C (136·34 Mg C ha−1) while paddy had the lowest (7·08 Mg C ha−1). About four‐fifths of agricultural land‐uses in the watershed are sustainable in maintaining the desired level of soil carbon in coming 10 years while one‐fifths are unstable. Such information on carbon stock could be valuable to develop viable land‐use options for agricultural sustainability and carbon sequestration. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
7.
Continued conversion of woodlands into grazing and farmland is seriously undermining the natural ecosystem of the dry and fragile Rift Valley areas of Ethiopia. This study investigated the effects of land‐use change on soil organic carbon (SOC), total nitrogen (N), pH, exchangeable bases, cation exchange capacity (CEC) and base saturation (per cent) in three adjacent land‐use types: controlled grazing, open‐grazing and farmland. A total of 81 soil samples were collected and analysed. Contents of SOC and total N decreased drastically in open‐grazing and farmland (p < 0·001), and were significantly higher in the top 0·2 m than in the subsurface soil layer. Compared with the controlled grazing, reductions in the contents of SOC and total N in the top 1 m soil layer were 22–30 and 19 per cent, respectively, due possibly to the decrease in plant biomass input into the soil and the fast decomposition of organic materials. Long‐term cultivation had significantly increased the concentration of exchangeable K. Exchangeable Na was high in the lower layers, while Mg was higher in the top surface soil. CEC also varied with soil depth (p = 0·016); it was higher in the topsoil than in the subsurface soil, which may be, among others, due to the differences in soil organic matter distribution with depth. Although these semi‐arid soils are known to have low organic carbon and CEC levels, the values from the current study area are critically low, and may indicate the further impoverishment of the soils under high agricultural and grazing pressures. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
8.
利用ASTER遥感资料提取南京城郊土地利用信息的研究 总被引：8，自引：3，他引：5
土地资源是社会经济发展最基本的物质基础,利用遥感技术可对土地资源进行分类调查。在对地观测方面,高光谱遥感与一般遥感影像相比,能提供更高质量的信息源。先进的空间热辐射反射计(ASTER)覆盖可见光、近红外、短波红外和热红外的14个波段,分辨率从15 m到90 m,对长江流域环境监测、地表覆盖变化、短期气候预测、自然灾害监测等,对于了解该区资源、生态与环境具有重要的意义。该文利用2001年ASTER数据对南京城郊地区进行了土地利用分类,首先采用多元统计方法提取分类特征波段。然后以非监督分类获得初始训练样本,对训练区进行多次像元提纯后,运用监督分类方法对南京城郊土地利用信息进行分类。研究表明,多种分类方法相结合可从ASTER影像更好地提取土地利用信息,达到较好得分类精度。 相似文献
9.
P. Zdruli 《Land Degradation \u0026amp; Development》2014,25(4):373-384
The Mediterranean region covers about 854 million ha, but only 118 million (or 14 per cent) are suitable for agricultural production. In North Africa and the Middle East (MENA), agricultural land covers about 5 per cent; in Egypt and Algeria, it occupies less than 4 per cent and, in Libya, less than 2 per cent of the total national land area. Across the Mediterranean region land use divides between natural pastures/rangelands (ca. 15 per cent), forests and woodlands (ca. 8 per cent), with the ca. 63 per cent remaining desert sands, shallow, rocky, saline, sodic soils and areas effectively sealed by urbanisation. Land degradation is a severe problem in most Mediterranean countries. Estimates for the period 1961 to 2020 show that although the Mediterranean population is likely to more than double, ca. 8.3 million ha of agricultural land (7 per cent) may be lost as a result of continued urbanisation and land degradation. If these estimates are correct, agricultural land per capita would more than halve from ca. 0.48 ha (1961) to ca. 0.21 ha in 2020. Food security is likely to become increasingly problematic, especially in the MENA countries, which require a major reassessment of their agricultural development policy. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
10.
科学揭示土地利用/土地覆被的时空演变特征及其驱动机制,对推进草原生态文明建设和高质量发展具有重要意义。以位于中国北疆的锡林郭勒草原为研究区,基于2000-2020年遥感、气象等多源数据资料,运用土地利用变化指数、频次统计、桑基图可视化模型、网格单元等方法探讨了近20年锡林郭勒草原土地利用/土地覆被的时空变化特征,并利用地理探测器分析自然地理条件和社会经济发展对草原土地利用/土地覆被变化的影响机制。结果表明：1）2000-2020年间锡林郭勒草原的土地利用/土地覆被类型以草地和沙地为主（面积占比约98%）,区域土地覆被变化主要发生在中东部的沙-草交错区。2）2005年后区域沙地面积持续减少,而沙地转入率在近10年间仍接近5%,说明草原生态环境总体向好,但生态脆弱性水平仍较高。3）社会经济的快速发展是驱动锡林郭勒草原土地利用/土地覆被变化的主要因素,气候因素的驱动作用次之,地形因素影响相对较小。研究结果可为锡林郭勒草原的生态保护和可持续发展提供科学依据。 相似文献
11.
L.&#x;O. Olang P.&#x;M. Kundu G. Ouma J. Fürst 《Land Degradation \u0026amp; Development》2014,25(3):267-277
The effects of conceptual land cover change scenarios on the generation of storm runoffs were evaluated in the Nyando Basin. The spatial scenarios represented alternatives that vary between full deforestation and reforestation. Synthetic storm events of depths 40, 60 and 80 mm were formulated according to the rainfall patterns and assumed to have durations corresponding to the runoff times of concentration. The Natural Resource Conservation Service–Curve Number model was used to generate runoff volumes within the sub‐catchments, which were subsequently routed downstream to obtain effects in the whole basin. The simulated land cover change impacts were evaluated relative to values obtained from the actual land cover state of the basin in the year 2000. From the results, an agricultural land cover scenario constituting of about 86 per cent of agriculture indicated increased runoff volumes in the entire basin by about 12 per cent. An agricultural‐forested land cover scenario with 40 and 51 per cent of forest and agriculture respectively revealed reduced runoff volumes by about 12 per cent. Alternatively, a scenario depicting a largely forested land cover state with about 78 per cent of forests reduced the runoff volumes by about 25 per cent according to the model estimates. Runoff volumes in the basin were also likely to reduce by about 15 per cent if the appropriate land cover scenario for the respective sub‐catchments were to be assumed for runoff management purposes. Considering the prevalent data uncertainty, the study effectively highlights the potential hydrological vulnerability of the basin. The results obtained can form a basis for appropriate catchment management of the area. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
12.
《Land Degradation \u0026amp; Development》2017,28(1):116-127
Landsat images acquired in 1987, 1999 and 2008 were selected to evaluate land use and land cover changes in three different ecological zones in the Republic of the Sudan: savannah (North Kordofan), semi‐desert (River Nile) and desert (Northern State). Maps of soil, vegetation and non‐photosynthetic material were built by spectral mixture analysis using endmembers spectra derived from images. Multitemporal comparison techniques were then applied to vegetation and soil maps to estimate the long‐term land degradation/re‐growth dynamics and to emphasize land cover variation over time and in space. Multitemporal comparisons have shown that site‐specific interactions between natural processes, climate variation and human activity played a pivotal role in land use and land cover change. In savannah, human activities strongly affected degradation phenomena. Expansion of villages triggered a change in land use and mismanagement of the natural resources, mainly caused by deforestation to supply wood for domestic uses. The degradation then promoted sand encroachment and dune migration. On average, 48% of the total area was subjected to medium (25–50%) and high (50–75%) land degradation. Differently, climatic constraints drove increasing degradation processes in semi‐desert and desert zones. The phenomenon was particularly severe in the desert zone. In each site, an inversion of the general trend was due to a land use change where forestry or agricultural projects were established, partly sustained in savannah by the positive rainfall trend of the last two decades. Site‐specific strategies that take into account the interactions of the driving factors at local scale are thus necessary to combat land degradation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
13.
H. L. Long G. K. Heilig J. Wang X. B. Li M. Luo X. Q. Wu M. Zhang 《Land Degradation \u0026amp; Development》2006,17(6):589-603
Soil erosion in the upper reaches of the Yangtze River in China is a major concern and the Central Government has initiated the Grain‐for‐Green Programme to convert farmland to forests and grassland to improve the environment. This paper analyses the relationship between land use and soil erosion in Zhongjiang, a typical agricultural county of Sichuan Province located in areas with severe soil erosion in the upper reaches of the Yangtze River. In our analysis, we use the ArcGIS spatial analysis module with detailed land‐use data as well as data on slope conditions and soil erosion. Our research shows that the most serious soil erosion is occurring on agricultural land with a slope of 10∼25 degrees. Both farmland and permanent crops are affected by soil erosion, with almost the same percentage of soil erosion for corresponding slope conditions. Farmland with soil erosion accounts for 86·2 per cent of the total eroded agricultural land. In the farmland with soil erosion, 22·5 per cent have a slope of < 5 degrees, 20·3 per cent have a slope of 5∼10 degrees, and 57·1 per cent have a slope of > 10 degrees. On gentle slopes with less than 5 degrees inclination, some 6 per cent of the farmland had strong (5000∼8000 t km−2 y−1) or very strong (8000∼15000 t km−2 y−1) erosion. However, on steep slopes of more than 25 degrees, strong or very strong erosion was reported for more than 42 per cent of the farmland. These numbers explain why the task of soil and water conservation should be focused on the prevention of soil erosion on farmland with steep or very steep slopes. A Feasibility Index is developed and integrated socio‐economic assessment on the feasibility of improving sloping farmland in 56 townships and towns is carried out. Finally, to ensure the success of the Grain‐for‐Green Programme, countermeasures to improve sloping farmland and control soil erosion are proposed according to the values of the Feasibility Index in the townships and towns. These include: (1) to terrace sloping farmland on a large scale and to convert farmland with a slope of over 25 degrees to forests or grassland; (2) to develop ecological agriculture combined with improving the sloping farmland and constructing prime farmland and to pay more attention to improving the technology for irrigation and cultivation techniques; and (3) to carry out soil conservation on steep‐sloping farmland using suggested techniques. In addition, improving ecosystems and the inhabited environment through yard and garden construction for households is also an effective way to prevent soil erosion. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
14.
M. C. Runnstrm 《Land Degradation \u0026amp; Development》2003,14(2):189-202
Degradation of the dry semiarid ecosystems in the Mu Us Sandy Land of north central China was explored using high‐resolution satellite images from 1978, 1987 and 1996. This study monitored both changes in grassland biomass production and reclamation activities to detect the nature and scale of land degradation since major economic reforms were introduced in 1978. The position of the high‐resolution images within the vegetation cycles was inspected from National Oceanographic and Atmospheric Administration (NOAA) NDVI images at 10‐day repetition and seasonal precipitation patterns. A model was developed to categorize changes in the vegetation signal activity from 30 × 30 m pixels into vegetation cover development and land‐use changes between 1987 and 1996. A general increase of biomass production was evident despite the rapid increase in numbers of grazing animals. This increase in biomass was confirmed by the NOAA time series, which also revealed annual variability related to the amount and pattern of the seasonal rains. Rangeland conversion to farmland was detected, and this process has increased the area of cultivation almost fivefold. The classified area of cultivation corresponds with reported statistical records, also showing that irrigation features in virtually 100 per cent of the sown area. Signs of declining biological production, indicating land degradation processes, are few. Biomass production has increased, with a gain in the economic output from both crop and animal production. The early start of active measures to halt desertification has increased vegetation cover and lowered wind erosion potential and grasslands seems to be managing the high levels of grazing pressure. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
15.
A. Geymen 《Land Degradation \u0026amp; Development》2013,24(2):156-169
Istanbul, one of the largest metropolitan cities in the world, experienced rapid industrialization and urbanization in the second‐half of the 20th century. The City grew at an average annual growth rate of 4.5 per cent between 1950 and 2000. Growth of settlements and the transportation system have damaged the natural environment. Istanbul is located on both sides of the Bosporus Strait that divides Europe from Asia. Recently an alternative to the planned third bridge for the Istanbul metropolitan area has been selected. The transportation infrastructure which has been constructed has drastically changed the land use profile and caused negative impacts on the environment. The proposed third bridge route threatens agricultural areas, forests, waterbodies and water collection areas that form the open‐space systems of Istanbul. The aim of this study was to analyse the effects of existing Bosporus bridges on the spatial development and the natural resources of the metropolitan area of Istanbul. With the new transportation axis focused on the bridge route, the potential impacts on vital open spaces such as the northern forest regions, the existing agricultural lands and the waterbodies and catchments are evaluated. These changes are explored using a geographical information system and five sets of Landsat satellite images from 1975, 1990, 1995, 2000 and 2005. This should provide a better understanding of the main reasons for the effects and will support city administrators planning similar projects. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
16.
J.F. Desprats D. Raclot M. Rousseau O. Cerdan M. Garcin Y. Le Bissonnais A. Ben Slimane J. Fouche D. Monfort‐Climent 《Land Degradation \u0026amp; Development》2013,24(1):22-32
Mapping and monitoring linear erosion features (LEFs) over large areas is fundamental for a better understanding of the main erosion processes and for planning suitable protection measures. The advent of very high‐resolution satellite imagery has expanded the range of satellite LEF identification to moderate‐size elements. After determining the relationship between satellite imagery resolution and the ability to detect LEFs, we discuss a highly automated method for extracting such LEFs from a very high spatial resolution image (0.61 m resolution). The method is based on a two‐stage strategy: (1) extraction of all linear features visible on the satellite image using filters and photo‐interpretation; (2) filtering these linear features according to geometric criteria (e.g. orientation relative to slope, sinuosity, position in landscape, etc.) so as to retain only those relative to linear erosion. A series of three images with increasing spatial resolution (10.5 and 0.61 m) was prepared for an area on the Cap Bon peninsula (Tunisia). This predominantly agricultural area has a high density of LEFs with very varied geometric characteristics. The area's problems are both onsite for the agriculture itself, and offsite with the silting up of hillside reservoirs. Respectively 22 per cent, 37 per cent and 73 per cent of the site's LEFs, with respective average widths of 2.8, 3.0 and 2.2 m, are visible on the 10, 5 and 0.61 m resolution images. Gully identification should help to identify the most threatened areas to help land use planning and management or to validate erosion models whether at regional or local (drainage basin) scale. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
In the deserts of Kuwait in general and in Al‐Salmi area in particular, soil compaction and sealing are the most significant mechanisms of land degradation. In the present study, soil compaction and sealing in the Al‐Salmi area are assessed. The study is based on analysis of satellite images and aerial photographs, besides field measurements and laboratory investigations. Based on this study, a recent map is prepared for the concerned area. It shows three different soil classes. These are highly compacted (8\8 per cent), slightly compacted (1\7 per cent), and almost non‐compacted or natural (89\5 per cent). Soil compaction in Al‐Salmi area causes adverse changes in soil physical properties, e.g. infiltration rate, bulk density and soil strength. The infiltration capacity of the compacted soils has decreased by 18\46 to 91\96 per cent in comparison with non‐compacted soils. The bulk density for the compacted soil varies between 1\6 and 1\7 g cm−3, whereas it varies between 1\2 and 1\35 g cm−3 in the non‐compacted soils, that is an increased of 29\97 per cent. In some sites, the physical properties show small or no difference between compacted and natural soils due to the effect of soil sealing (crustation). Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
18.
《Land Degradation \u0026amp; Development》2017,28(1):175-180
The agricultural use of natural ecosystem is increasing in the Middle East because of population growth in the most countries. The type of cultivation could affect the content of soil organic matter in the rangeland use changes into agriculture. Therefore, we compared soil organic matter fractions of semi‐arid rangelands with agricultural lands (wheat‐land, pea‐land and orchard) where have been changed from semi‐arid rangelands to agriculture 15 years before. The results showed that in general, total and particulate organic matter (TOM and POM) and total nitrogen (TN) were highest in the rangeland compared with the three‐agricultural lands in intact soil, macro‐aggregates and micro‐aggregates (p < 0·05). Nevertheless, TOM content in orchard (1·45%) was higher than the two other land uses, and there was no significant difference of TN between natural rangeland and orchard in intact soil. The highest values of POM were obtained in the rangeland (0·23%) and orchard (0·22%), and the lowest value of POM was obtained in the pea‐land (0·14%) and wheat‐land (0·08%) in macro‐aggregates. In micro‐aggregates, TOM, POM and TN were highest in the rangeland (1·77%, 0·23% and 0·19%, respectively) and showed similar pattern in the three‐agricultural lands. We discussed that compared with pea‐land and wheat‐land, orchard was received less negative impact on soil qualitative parameters in land use changes projects from rangeland into agriculture. We conclude that orchard could be a better option in rangeland use changes into agriculture compared with the other cultivations. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
19.
Knowledge of the effects of land use on soil moisture variations is necessary to improve land and agricultural water management in the semi‐arid Chinese Loess Plateau. However, previous studies are insufficient to guide management practice in this area and improvement is needed to help with the development of the ‘Grain for Green’ programme. As part of the ‘Grain for Green’ programme, we examined the effects of five land uses (fallow, grassland, cropland, 3‐year and 8‐year jujube orchards) on soil water variations in a small catchment on the Loess Plateau. Soil moisture at 0–160 cm depth was monitored approximately weekly at 47 sites from 17 August to 19 October 2009 and from 4 April to 27 September 2010 using a portable time domain reflectometer. Results indicated that mean soil water profiles in different land uses varied with time, land use induced spatial variations of soil water but exerted negligible influence on soil water temporal patterns, and soil water content was of the greatest spatial variability with moderate means (approximately 20 per cent). Furthermore, the relationship between standard deviation and mean water content was dependent on soil depth, although it was negligibly affected by land use. Profile soil water for five land uses was different in various seasons, precipitation infiltration depth exhibited a positive correlation with precipitation, and the whole profile soil moisture (0–160 cm) was complemented following a 93·5‐mm rainfall event. The findings presented here provide helpful information for land and agricultural water management in this area. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
20.
I. Ouedraogo P. Savadogo M. Tigabu R. Cole P. C. Odn J.‐M. Ouadba 《Land Degradation \u0026amp; Development》2009,20(2):217-230
There is growing evidence that population pressure on the land has become the most intractable problem in the developing countries where demand for food exceeds the food production capacity of the land. Southern Burkina Faso has experienced rapid population growth, mostly driven by immigration of farmers. This study was carried out in Sissili Province and used satellite images acquired over 31‐year period, census and survey data to capture migration patterns and its impacts on land use change. Results showed that migrant population which accounted for only 3 per cent in the study area in 1976 shifted to 57 per cent in 2007. Migrant people were using improved technology to progressively convert forest land to cropland. Cropland increased at an annualized rate of 0·46 per cent to the detriment of the dense forest and woodland which decreased at 0·57 per cent per annum. Population growth was highly correlated with increasing area of cropland (r2 = 0·95, p = 0·014) and declining dense forest (r2 = 0·78) and woodland (r2 = 0·95) covers. It can be concluded that rural migration, driven by the relatively good soil and rainfall conditions in the recipient area, is accounted for deforestation in the study area. If rural migration is not checked, it will seriously degrade the environment. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献