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1.
This study aims to assess conservation practices in Izta-Popo National Park(Central Mexico) by evaluating the mechanisms of sediment transfer. We applied a methodology based on fallout ~(137)Cs and optically stimulated luminescence(OSL) analysis. This was tested in the upper catchment of Amalacaxco Gorge, selected for being one of the sectors of the park in which man-made actions have been implemented in last decades to favor forest growth in the alpine grassland and to reduce the effect of water runoff. We quantified the ~(137)Cs activity using gamma and beta spectrometry of fine sediment grains extracted from the surface of parcels of 0.4 m2 in areas of natural forest, natural alpine grassland, alpine grassland with conservation practices, ravines and trails. In general, ~(137)Cs values increases as local slope decreases as it was expected. The natural forest is the most stable area in terms of soil erosion and sediment accumulation and, mean ~(137)Cs activity was taken as reference to assess cumulative zones, with higher ~(137)Cs values and erosive, with lower. We found that trails are accumulative surfaces but in other areas, erosion predominates. Man-made ditches, trenches and afforestation in the alpine grassland have higher ~(137)Cs values than thenatural grassland, which indicates that conservation practices are limiting the sediment transfer from hillslopes to channels, however, soil retention is less than in the natural grassland. Additionally, we evaluated the luminescence(OSL) values obtained from samples extracted from the sediment transported in ravines that are cutting into different sectors of the study area to assess the grade of resetting of fluvial materials. These luminescence results indicated that the sediment transported in ravines that are cutting into the natural forest and alpine grassland is bleached more efficiently than the sediment transported in the alpine grassland with conservation practices. Results of fallout ~(137)Cs and luminescence strongly suggest that man-made actions in this part of the Izta-Popo National Park are dramatically modifying the natural mechanisms of sediment transfer and favoring soil erosion. We conclude that made ditches, trenches and afforestation are not an effective conservation practice in Amalacaxco Gorge because they are promoting soil erosion instead of reducing it.  相似文献   

2.
The Middle Mountains is one of the regions of Nepal most vulnerable to water erosion, where fragile geology, steep topography, anomalous climatic conditions, and intensive human activity have resulted in serious soil erosion and enhanced land degradation. Based on the 137Cs tracing method, spatial variations in soil erosion, organic carbon, and total nitrogen (TN) in terraced fields lacking field banks and forestland were determined. Soil samples were collected at approximately 5 m and 20 m intervals along terraced field series and forestland transects respectively. Mean 137Cs inventories of the four soil cores from the reference site was estimated at 574.33 ± 126.22 Bq m-2 (1 Bq (i.e., one Becquerel) is equal to 1 disintegration per second (1 dps)). For each terrace, the 137Cs inventory generally increased from upper to lower slope positions, accompanied by a decrease in the soil erosion rate. Along the entire terraced toposequence, 137Cs data showed that abrupt changes in soil erosion rates could occur between the lower part of the upper terrace and the upper part of the immediate terrace within a small distance. This result indicated that tillage erosion is also a dominant erosion type in the sloping farmland of this area. At the same time, we observed a fluctuant decrease in soil erosion rates for the whole terraced toposequence as well as a net deposition at the toe terrace. Although steep terraces (lacking banks and hedgerows) to some extent could act to limit soil sediment accumulation in catchments, soil erosion in the terraced field was determined to be serious. For forestland, with the exception of serious soil erosion that had taken place at the top of slopes due to concentrated flows from a country road situated above the forestland site, spatial variation in soil erosion was similar to the “standard” water erosion model. Soil organic carbon (SOC) and TN inventories showed similar spatial patterns to the 137Cs inventory for both toposequences investigated. However, due to the different dominant erosion processes between the two, we found similar patterns between the <0.002 mm soil particle size fraction (clay sized) and 137Cs inventories in terraced fields, while different patterns could be found between 137Cs inventories and the <0.002 mm soil particle size fraction in the forestland site. Such results confirm that 137Cs can successfully trace soil erosion, SOC and soil nitrogen dynamics in steep terraced fields and forestland in the Middle Mountains of Nepal.  相似文献   

3.
137 Cs is an artificial radionuclide with a half-life of 30.2 years,which was released into the environment as a byproduct of atmospheric testing of nuclear weapons during the period of 1950s to 1970s with a peak deposition in 1963.137 Cs fallout was strongly and rapidly adsorbed by soil particles when it deposited on the ground mostly with precipitation.Its following movements will associate with the adsorbed particles.137 Cs tracing technique has been widely used in soil erosion and sedimentation studies since 1980s.This paper introduces the basis of the technique and shows several case studies of assessment of soil erosion rates,investigation of sediment sources and dating of reservoir deposits by using the technique in the Loess Plateau and the Upper Yangtze River Basin.  相似文献   

4.
Soil conservation practices can greatly affect the soil erosion process, but limited information is available about its influence on the particle size distribution(PSD) of eroded sediment, especially under natural rainfall. In this study, the runoff, sediment yields, and effective/ultimate PSD were measured under two conventional tillage practices, downhill ridge tillage(DT) and plat tillage(PT) and three soil conservation practices, contour ridge tillage(CT), mulching with downhill ridge tillage(MDT), and mulching with contour ridge tillage(MCT) during 21 natural rainfall events in the lower Jinsha River. The results showed that(1) soil conservation practices had a significant effect on soil erosion. The conventional tillage of DT caused highest runoff depth(0.58 to 29.13 mm) and sediment yield(0.01 to 3.19 t hm-2). Compared with DT, the annual runoff depths and sediment yields of CT, MDT and MCT decreased by 12.24%-49.75% and 40.79%-88.30%, respectively.(2) Soil conservation practices can reduce the decomposition of aggregates in sediments. The ratios of effective and ultimate particle size(E/U) of siltand sand-sized particles of DT and PT plots were close to 1, indicating that they were transported as primary particles, however, values lower/greater than 1 subject to CT, MDT and MCT plots indicated they were transported as aggregates. The ratios of E/U of claysized particles were all less than 1 independently of tillage practices.(3) The sediments of soil conservation practices were more selective than those of conventional tillage practices. For CT, MDT and MCT plots, the average enrichment ratios(ERs) of clay, silt and sand were 1.99, 1.93 and 0.42, respectively, with enrichment of clay and silt and depletion of sand in sediments. However, the compositions of the eroded sediments of DT and PT plots were similar to that of the original soil. These findings support the use of both effective and ultimate particle size distributions for studying the size selectivity of eroded sediment, and provide a scientific basis for revealing the erosion mechanism in the purple soil area of China.  相似文献   

5.
Accelerated soil erosion and land degradation represent major environmental problems for agricultural lands.Reliable information on the rates of soil loss is urgently needed.The traditional techniques for documenting rates of soil loss may meet this need,but face many limitations.The fallout radionuclides,especially 137 Cs and 210 Pb ex,are increasingly used as effective tracers to quantify soil erosion rates,and they represent a valuable complement to the existing classical methods.This paper aims to introduce the basis for assessing soil erosion rates on cultivated and uncultivated slopes by using 137 Cs and 210 Pb ex measurements,to compare the 137 Cs and 210 Pb ex reference inventories,and to report several case studies undertaken in the hilly area of Sichuan Basin and the Three Gorges area of China.  相似文献   

6.
Reservoir sedimentation dynamics were interpreted using Cs-137 activity,particle size and rainfall erosivity analysis in conjunction with sediment profile coring.Two sediment cores were retrieved from the Changshou reservoir of Chongqing,which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an acrylic tube with an inner diameter of 6 cm.The extracted cores were sectioned at 2 cm intervals.All sediment core samples were dried,sieved(2 mm) and weighed.137 Cs activity was measured by γ-ray spectrometry.The particle size of the core samples was measured using laser particlesize granulometry.Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends.The peak fallout of 137 Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B.The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982,1989,1998 and 2005,respectively.Sedimentation rates were calculated according to the sediment profile chronological controls of 1956,1963,1982,1989,1998 and 2005.The highest sedimentation rate was around 2.0 cm?a~(-1) between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented,leading to accelerated soil erosion in the Longxi catchment.Since 1990 s,andparticularly since 2005,sedimentation rates clearly decreased,since a number of soil conservation programs have been carried out in the catchment.The combined use of 137 Cs chronology,particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration.Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.  相似文献   

7.
The well-known Three Gorges Dam(TGD) within the Yangtze catchment launched its operation in 2003. The effect of the TGD operation on the sediment size on the East China Sea shelf is rarely known. High resolution(0.5 cm sampling) grain size analysis and 137 Cs and 210 Pb dating of the DH8-1 core were conducted with core collected from the distal part of a main sink for the modern Yangtze sediment entering the sea, the Min-Zhe Coastal Mud Deposits(MZCMD) on the inner East China Sea shelf. The 137 Cs dating results show that the core DH8-1 formed during 1946–2012 with a mean deposition rate of 0.65 cm yr~(-1), indicating that the 0.5 cm sampling for grain size analysis in this local area could reflect environmental changes generally on a one-year time scale. The mean grain size of DH8-1 core sediment that deposited after 2003 is significantly larger than that deposited during 1988–2002. After ruling out other possible factors, we infer that the sediment coarsening of DH8-1 core after 2003 is attributed to the TGD operation which causes the erosion of the Yangtze subaqueous delta. Specifically, the TGD operation significantly intensifies the declining trend of the Yangtze sediment loads to the sea despite no decreased water discharge, which results in extensive erosion of the Yangtze subaqueous delta. The relatively coarse sediment of the subaqueous delta is eroded and resuspended by ocean dynamics and then transported by coastal current, finally depositing on the MZCMD area. In addition, the general sediment fining of core DH8-1 that deposited during 1988–2002, comparing with 1946–1987, is mainly caused by dam construction and soil and water conservation within the Yangtze catchment. Our findings are helpful for better understanding the effects of such a huge dam as the TGD on a sediment sink like the MZCMD of such a large river as the Yangtze River.  相似文献   

8.
Soil erosion and associated off-site sedimentation are threatening the sustainable use of the Three Gorges Dam.To initiate management intervention to reduce sediment yields,there is an increasing need for reliable information on soil erosion in the Three Gorges Reservoir Region(TGRR).The purpose of this study is to use 137 Cs tracing methods to construct a sediment budget for a small agricultural catchment in the TGRR.Cores were taken from a pond and from paddy fields,for 137 Cs measurements.The results show that the average sedimentation rate in the pond since 1963 is 1.50 g cm-2 yr-1 and the corresponding amount of sediment deposited is 1,553 t.The surface erosion rate for the sloping cultivated lands and the sedimentation rate in the paddy fields were estimated to be 3,770 t km-2 yr-1 and 2,600 t km-2 yr-1,respectively.Based on the estimated erosion and deposition rates,and the area of each unit,the post 1970 sediment budget for the catchment has been constructed.A sediment delivery ratio of 0.5 has been estimated for the past 42 years.The data indicate that the sloping cultivated lands are the primary sediment source areas,and that the paddy fields are deposition zones.The typical land use pattern(with the upper parts characterized by sloping cultivated land and the lower parts by paddy fields) plays an important role in reducing sediment yield from agricultural catchments in the TGRR.A 137 Cs profile for the sediment deposited in a pond is shown to provide an effective means of estimating the land surface erosion rate in the upstream catchment.  相似文献   

9.
Soilerosionisoneofthemostseriousenvironmentalproblemsinthepresentworld.Itnotonlyrestrictstheproductionofagriculturebadly,butalsothreatensthenaturalenvironmentonwhichhumanbeinglive.Andthismakethemankindconfrontedwithtremendouschallenge.OntheLoessPlateau,soilandwaterlossisterrible,environmentisweak,anditshighsandyieldmakestheriverwayinthelowerreachesoftheHuanghe(Yellow)Riverfilledup,riverbeddrivenup,floodthreatprickedup,andresultsingreathiddentroublestothecontrollingoffloodandtherunningofirrig…  相似文献   

10.
Assessment of soil erosion by compensatory hoeing tillage in a purple soil   总被引：2，自引：0，他引：2  
This study explores the role of a traditional tillage method,i.e.,compensatory hoeing,for sustainable agro-ecosystem management in the hilly areas of the Chongqing municipality,south-western China.To validate the effects of compensatory tillage on the terraced slopes,the tillage method of noncompensatory hoeing was conducted on a linear slope.To acquire information about 137 Cs inventories and soil texture,soil samples were collected by a core sampler with a 6.8-cm diameter at 5.0-m intervals along the toposequence and the linear slope in the dry season(March) of 2007.Meanwhile,a tillage erosion model was used for evaluating the spatial pattern of tillage erosion.The 137 Cs data showed that on the terraced slope,soil was lost from the upper slope,and soil deposition occurred at the toe slope positions on each terrace.As a result,abrupt changes in the 137 Cs inventories of soil were found over short distances between two sides of terrace boundaries.Results obtained from the tillage erosion model and the 137 Cs data indicate that soil redistribution mainly results from tillage erosion in the terraced landscape.Consecutive non-compensatory tillage caused soil redistribution on the linear slope,resulting in thin soil profile disappearing at the top and soil accumulating at the bottom positions of the linear slope.This result further validates that compensatory tillage could avoid the complete erosion of the thin soil layer at the summit position.Therefore,this traditional tillage.method,i.e.,compensatory tillage,has maintained the soil quality at the summit of the slope in the past decades.  相似文献   

11.
Assessing the contribution of sediments from different sources is essential to understand erosive processes and formulate further soil conservation strategies to address environmental problems.In this study,we combined the source fingerprinting approach with geochemistry,including comparison of potential sources,and distribution pattern of major elements,to estimate the different land-use relative contributions to streambed sediment in the Luowugou catchment(13.5 km~2)located on the Heishui River,the first branch of the Jinsha River,China.A total of 57 samples from stream bank,cropland,grassland,forest land,and sediments were collected,and then,15 elements were analyzed foreach sample.The fingerprinting results demonstrated that the stream bank(62.4%)had the greatest relative contribution to the bed sediment yield,while cropland,grassland,and forest land contributed 18.6%,14.9%,and 4.1%to the bed sediments,respectively.In comparison to the fingerprinting method,even though the results upon geochemistry only provide a qualitative assessment,the ranking of sediment contributions based on geochemistry was consistent with the sediment fingerprinting ranking,that is,stream bankcroplandgrasslandforest land.Our findings suggest that the focal point for sediment control practices should be the stream bank rather than cropland in the region.Geochemistry can result in an important means in validating the fingerprinting results.  相似文献   

12.
Soil erosion on sloping field has led to a lot of environmental problems. In order to reveal the seriousnessof the damage of soil erosion on sloping fields 137^Cs tracer method was used to estimate soil erosion rate. 137^Cs referenceinventory of 2200Bq/m^2 in Yixing, southern Jiangsu Province, was estimated and a model for estimating erosion of cultivat-od soil was established in order to avoid overestimating soil erosion rates. Then based on the soil erosion rates and mea-sured soil physical and chemical properties, direct and indirect impacts of soil erosion on environment were further dis-cussed. Direct impacts of erosion on environment included on-site and off-site impacts. The on-site impacts were thatsoil layer became thin, soil structure was deteriorated and soil nutrients decreased. The off-site impacts were that waterbodies were polluted. The indirect impacts of soil erosion on environment were the increase of fertilizer application andenergy consumption, and change of adaptability of land uses. Although erosion intensity was not serious in the studyarea, its environmental impacts should not be ignored because of great soil nutrient loss and coazseness of soil particles.  相似文献   

13.
Investigations of natural and artificial radioisotopes including 90Sr,137Cs, gross B and U carried out in the Yellow Sea and adjacent southeast area in 1963. 1964, 1975 and 1978 showed that radioactive pollution by 90Sr and 137Cs from atmospheric fallout had gradually decreased with time due to the cessation of atmospheric nuclear weapons tests in the 70s. The distributions of natural and artificial radioactive isotopes (U, Ra, Th. 40K and 137Cs) in sediments southwest of Jizhou Island were uniform. The more uniform may be related to the soluble species of U[Uo2(CO3)4] in the seawater.The high value of Th at stations 3 and 6 was related to the sandy clay sediment; the low value at station 8 was related to sandy sediment. The content of 137Cs in the eddy area being less than about half of that in the China inshore area showed that the source of Cs may be insufficient orthat the conditions for enriching " Cs in the circulation eddy area were not favorable.  相似文献   

14.
This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China and the Volga River Basin in Eastern Europe. In the Upper Yangtze River Basin, natural factors including topography, climate,lithology and tectonic activity are responsible for the spatial variation in the magnitude of denudation rates.Human disturbances have contributed to the temporal changes of soil erosion and fluvial SSY during the past decades. On one hand, land use change caused by deforestation and land reclamation has played an important role in the acceleration of sediment production from the central hilly area and lower Jinsha catchment; On the other hand, diverse soil conservation practices(e.g., reforestation,terracing) have contributed to a reduction of soil erosion and sediment production since the late 1980 s.It was difficult to explicitly decouple the effect of mitigation measures in the Lower Jinsha River Basindue to the complexity associated with sediment redistribution within river channels(active channel migration and significant sedimentation). The whole basin can be subdivided into seven sub-regions according to the different proportional inputs of principal denudation processes to riverine SSY. In the Volga River Basin, anthropogenic sheet, rill and gully erosion are the predominant denudation processes in the southern region, while channel bank and bed erosion constitutes the main source of riverine suspended sediment flux in the northern part of the basin. Distribution of cultivated lands significantly determined the intensity of denudation processes.Local relief characteristics also considerably influence soil erosion rates and SSY in the southern Volga River Basin. Lithology, soil cover and climate conditions determined the spatial distribution of sheet, rill and gully erosion intensity, but they play a secondary role in SSY spatial variation.  相似文献   

15.
Accurate assessment of soil erosion is an important prerequisite for controlling soil erosion.The engineering-control(E)and tillage(T)factors are the keys for Chinese Soil Loss Equation(CSLE)to accurately evaluate water erosion in China.Besides,the E and T factors can reflect the water and soil conservation effects of engineering-control and tillage practices.But in the current full coverage of soil erosion surveys in China(such as soil erosion dynamic monitoring),for the same practice,the E or T factors are assigned the same value across the country.We selected 469 E and T factors data based on runoff plots from 73 publications,and they came from six soil and water conservation regions.Correlation analysis,regression analysis,and nonparametric tests were used to determine the comparability of the data,and it was proved that the runoff plots dimensions are consistent with the local topography.The results of one-way ANOVA and nonparametric tests for E and T factors in different regions showed that the engineering-control practices have good soil and water conservation effects and weaken the regional differences of other environmental factors,so there were no significant differences in E factors between different regions.However,there were significant differences in T factors between different regions,and the geodetector was applied to explore the intrinsic driving force of the spatial distribution of T factors.The results of the geodetector showed that the dominant driving forces of the spatial distribution of different types of tillage practices were not completely the same.When using CSLE to calculate water erosion,the E factor of the same practice can be used uniformly throughout the country,and the T factor needs to be considered and selected according to regional differences.At the same time,when choosing tillage practices in each water and soil conservation region,practices with better sediment reduction benefits should also be selected according to the regional environmental conditions.  相似文献   

16.
Under conditions of a warmer climate, the advance of the alpine treeline into alpine tundra has implications for carbon dynamics in mountain ecosystems. However, the above- and below-ground live biomass allocations among different vegetation types within the treeline ecotones are not well investigated. To determine the altitudinal patterns of above-/below-ground carbon allocation, we measured the root biomass and estimated the above-ground biomass (AGB) in a subalpine forest, treeline forest, alpine shrub, and alpine grassland along two elevational transects towards the alpine tundra in southeast Tibet. The AGB strongly declined with increasing elevation, which was associated with a decrease in the leaf area index and a consequent reduction in carbon gain. The fine root biomass (FRB) increased significantly more in the alpine shrub and grassland than in the treeline forest, whereas the coarse root biomass changed little with increasing altitudes, which led to a stable below-ground biomass (BGB) value across altitudes. Warm and infertile soil conditions might explain the large amount of FRB in alpine shrub and grassland. Consequently, the root to shoot biomass ratio increased sharply with altitude, which suggested a remarkable shift of biomass allocation to root systems near the alpine tundra. Our findings demonstrate contrasting changes in AGB and BGB allocations across treeline ecotones, which should be considered when estimating carbon dynamics with shifting treelines.  相似文献   

17.
Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands？ Plant community composition and chemical properties of soil samples were compared to investigate the relationship between soil and species diversity, and the richness in Tibetan alpine grasslands. Results showed that species diversity was significantly positively related to soil organic matter （SOM）, total nitrogen （TN）, available nitrogen （AN）, total phosphorus （TP）, available phosphorus （AP）, and available potassium （AK） in the high alpine grasslands. Margalefs species richness index was also significantly positively related to SOM, TN, AN, and TP. Most soil chemical properties showed significantly positive correlation with species diversity and Margalef＇s richness index. Our results suggested that higher plant species richness index and diversity occurred in more fertile soil habitats in high altitude natural grassland community. In practice, fertilization management for the restoration of degraded grassland should be conducted with reference to the nutrient levels ofnatural grassland without the additional artificial fertilizer and with higher species-diversity and richness index.  相似文献   

18.
The Loess Plateau of China has experienced a lengthy drought and severe soil erosion.Changes in precipitation and land use largely determine the dynamics of runoff and sediment yield in this region. Trend and mutation analyses were performed on hydrological data(1981–2012) from the Yanwachuan watershed in the Loess Plateau Gully Region to study the evolution characteristics of runoff and sediment yield. A time-series contrasting method also was used to evaluate the effects of precipitation and soil and water conservation(SWC) on runoff and sediment yield. Annual sediment yield declined markedly from 1981 to 2012 although there was no significant change in annual precipitation and annual runoff. Change points of annual runoff and annual sediment yield occurred in 1996 and 1997,respectively. Compared with that in the baseline period(1981–1996), annual runoff and annual sediment yield in the change period(1997–2012)decreased by 17.0% and 76.0%, respectively, but annual precipitation increased by 6.3%. Runoff decreased in the flood season and normal season, but increased in the dry season, while sediment yield significantly declined in the whole study period. The SWC measures contributed significantly to the reduction of annual runoff(137.9%) and annual sediment yield(135%) and were more important than precipitation. Biological measures(forestland and grassland) accounted for 61.04% of total runoff reduction, while engineering measures(terraces and dams) accounted for 102.84% of total sediment yield reduction. Furthermore, SWC measures had positive ecological effects. This study provides a scientific basis for soil erosion control on the Loess Plateau.  相似文献   

19.
The impact of land-use on surface runoff and soil erosion is still poorly understood at basin scale. Thus in the Western Jilin Ecosystem (WJE), surface runoff and soil erosion were measured against identified land-use types in the basin. Due to the spatial nature of the analysis, GIS ArcMap version 9.1 and the WetSpass model were used in the simulation process. In the study, the WetSpass model was extended with the Dynamic Sediment Balance Equation (Ziegler et al., 1997), to simulate and quantify soil erosion. A hypothetical natural grassland scenario was developed for the study area and compared with the present land-use management conditions. The results indicate significant differences in runoff and soil erosion across the different land-use types both within and between the two scenarios. Calculated averages of surface runoff and soil erosion for the present land-use management were 48.03 mm/a and 83.43 kg/(m2·a) respectively. Those for the hypothetical natural grassland scenario were 24.70 mm/a and 78.36 kg/m2·a) . Thus an overall decrease in runoff and soil erosion was observed as the conditions changed from the present land-use management to the hypothetical natural grassland state. Under the present land-use management, urban settlements exhibited the highest surface runoff but one of the least soil erosions, while bare-lands showed the highest soil erosion. It was more generally observed that runoff and erosion varies with vegetation type/density. It was concluded based on the research findings that the present land-use management might not be the best scenario for the ecosystem as it showed increased basin runoff and soil erosion in comparison with the natural grassland vegetation. Since no best scenario was simulated for or advanced in the study, further research to develop a more balanced land management system is thus required. The findings of the study can assist in the identification of vulnerable/fragile ecosystems in the basin and to guide sustainable future planning and development of the basin.  相似文献   

20.
锡林郭勒盟为我国北方典型草原区,草地的退化与恢复影响生态系统的防风固沙服务功能。为了便于制定区域生态恢复的防治措施,实现草地生态系统的可持续发展与防治土壤风蚀危害,本文基于气象、遥感数据,运用RWEQ(Revised Wind Erosion Equation)模型,结合锡林郭勒盟的草地覆盖度变化对20世纪90年代以来的防风固沙服务功能的时空变化趋势进行了定量评估,并分析了草地覆盖度变化对防风固沙服务功能的影响。研究表明:锡林郭勒盟土壤风蚀以微度和轻度侵蚀为主,主要集中在植被盖度较高、降水相对较多,风场强度相对较低的东部、中部和南部地区;中度以上区域主要集中在西部的荒漠草原区与浑善达克沙地区,且侵蚀面积随侵蚀强度的增加而递减;防风固沙服务功能量的分布趋势与土壤风蚀模数的分布趋势基本一致;防风固沙服务功能保有率的分布特征与植被盖度的分布特征基本一致,表现为由西北到东南逐渐增加的趋势;在气候暖干化背景下,受京津风沙源治理工程实施的影响,以微度和轻度侵蚀为主的草地覆盖度减小区转为以微度和轻度为主的覆盖度增加区,轻度和中度以上侵蚀为主的草地覆盖度减小区转为基本持衡区;草地覆盖度的降低与增加对土壤风蚀的加剧和抑制作用明显,大部分地区的防风固沙服务功能保有率的下降(提升)与风蚀季节草地覆盖度的减小与提升呈显著正相关(r0.6,p0.05)。  相似文献   

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