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1.
Conversion of cropland to forestry and grassland is an important method to reduce soil erosion and improve the biophysical environment in the Loess Plateau. The feasibility, methods, and environmental effects of cropland conversion were studied based on 11 typical watersheds of national experimental bases instead of different geographic areas of the Loess Plateau. Between 1986 and 2000,cropland, sloping cropland and non-agricultural land decreased by 8%, 92.5% and 8% respectively,while forestry increased by 15.7%. The land use change not only decreased annual soil erosion by 74%, but also increased vegetation coverage by 100% and improved the soil condition and biodiversity. This can be achieved by building basic farmland, increasing capital and scientific input,and planting trees and grasses according to the natural biophysical restrictions.  相似文献   

2.
1 Introduction The soilerosion in Loess Plateau is mostserious on the globe mainly due to the destroying of naturalvegetation and cultivation on slope land overextensive areas(Yang and Yu,1992;Jiang, 1997).To convertsloping cropland (cropped land on slope…  相似文献   

3.
刘宇  傅伯杰 《干旱区地理》2013,36(6):1097-1102
基于16 d合成MODIS NDVI数据提取的时间序列植被覆盖度数据,采用一元线性回归趋势分析,对黄土高原2000-2008年植被覆盖度的时空变化及其地形分异、土地利用/覆被变化的影响进行了定量分析。结果表明:(1)研究时段黄土高原植被覆盖度整体呈快速上升趋势,局部下降;(2)黄土高原植被覆盖度变化存在明显的地形分异,陡坡等植被恢复、重建和保育的主要区域植被覆盖度增速显著;(3)土地利用/覆被变化对植被覆盖度的增加影响突出,土地利用/覆被类型变更区植被覆盖度增速显著高于未变化区域,退耕还林还草区增速尤其突出;(4)土地利用/覆被类型未变化区域植被覆盖度总体上也呈增加趋势,但因植被覆盖度水平相对较高,增速明显低于土地利用/覆被类型变化区。上述结果表明,黄土高原植被保育、植被恢复和重建在植被覆盖度提升方面取得了明显成效。  相似文献   

4.
Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change (LUCC) in Ningwu County, located in the eastern Loess Plateau of China, from 1990 to 2010. We found that grassland, woodland, and farmland were the main land use types in the study area, and the area of each type changed slightly from 1990 to 2010, whereas the area of water, construction land, and unused land increased greatly. For the whole area, the net change and total change were insignificant due to weak human activity intensity in most of the study area, and the LUCC was dominated by quasi-balanced two-way transitions from 1990 to 2010. The insignificant overall amount of LUCC appears to have resulted from offsetting of rapid increases in population, economic growth, and the implementation of a program to return farmland to woodland and grassland in 2000. This program converted more farmland into woodland and grassland from 2000 to 2010 than from 1990 to 2000, but reclamation of woodland and grassland for use as farmland continued from 2000 to 2010, and is a cause for concern to the local government.  相似文献   

5.
黄土高原地区景观格局演变研究综述   总被引:9,自引:1,他引:9  
研究黄土高原地区景观格局演变对认识该地区整个生态系统结构和变化,乃至全球变化,具有至关重要的作用。本文在剖析景观格局和土地利用格局概念与内涵的基础上,从定量化分析、时空特征和尺度效应等方面对黄土高原地区景观格局演变研究进展进行了阐述,深入分析了当前研究在景观数据选择与应用、尺度依赖性分析和标准确定等方面的现状特征与不足之处,并对今后在景观格局演变方面的发展趋势进行了展望,以期为未来景观格局与过程研究提供参考。  相似文献   

6.
Land use/cover change(LUCC)is a major factor affecting net primary production(NPP).According to the LUCC of the Loess Plateau from 2005 to 2015,the LUCC patterns in 2025 in three scenarios were predicted by using the Future Land Use Simulation(FLUS)model.Furthermore,taking the average NPP of various land use/cover types in 16 years as the reference scale,the changes in NPP in multi-scenario simulations are predicted and an-alyzed,and the impact of different land use/cover transfers on NPP is quantified.The results are as follows:(1)The land use/cover changes greatly in the baseline and fast development scenarios,and changes relatively little in the ecological protection scenarios.(2)The changes in NPP in different scenarios reflected the significant difference in the ecological protection effect.All the three scenarios promote an NPP increase,but the ecological protection sce-nario can promote NPP increases the most.(3)The changes in NPP caused by LUCC in the three scenarios reflected the significant difference in the various land use/cover types pro-tection effect.Analyzing and predicting NPP changes in multi-scenario LUCC simulations in the future can provide a theoretical basis for decision makers to judge the future changes in ecological environments and ecological protection effects against different policy back-grounds.  相似文献   

7.
XU Yong  TANG Qing 《地理学报》2009,19(5):577-586
At present, land use optimization at small watershed scale is the key measure to control soil erosion, restore the eco-environment and improve the farmers’ living standard on the Loess Plateau, China. Based on the land use survey maps of 1966, 1988, 1997, 2003 and the digital topographic map of 1984 in Yangou watershed, and assisted by spatial techniques of GIS, the basic characteristics and driving forces of land use change in Yangou watershed are analyzed. According to the summarization of land-use optimization characteristics since 1997, and with the help of continuous monitoring data for years and farmer investigation data, this paper appraises eco-environmental benefits, economic benefits and sustainability of Yangou watershed. We have used sediment reduction benefits, coverage ratio of permanent vegetation, per capita food production and per capita income of farmers as indices. The results show that Yangou watershed project has successfully controlled the soil and water loss and the farmers’ living standard has been improved markedly by reasonable adjustment to land use structure. The benefit of sediment reduction is higher than 80% and the coverage ratio of permanent vegetation reaches 61.03%. In 2006, the per capita income increased by 1493 yuan compared with the year 1998.The successful measures and experiences of Yangou watershed are worth promoting on the Loess Plateau.  相似文献   

8.
黄土高原小流域土地利用优化调控   总被引:2,自引:0,他引:2  
At present, land use optimization at small watershed scale is the key measure to control soil erosion, restore the eco-environment and improve the farmers’ living standard on the Loess Plateau, China. Based on the land use survey maps of 1966, 1988, 1997, 2003 and the digital topographic map of 1984 in Yangou watershed, and assisted by spatial techniques of GIS, the basic characteristics and driving forces of land use change in Yangou watershed are analyzed. According to the summarization of land-use optimization characteristics since 1997, and with the help of continuous monitoring data for years and farmer investigation data, this paper appraises eco-environmental benefits, economic benefits and sustainability of Yangou watershed. We have used sediment reduction benefits, coverage ratio of permanent vegetation, per capita food production and per capita income of farmers as indices. The results show that Yangou watershed project has successfully controlled the soil and water loss and the farmers’ living standard has been improved markedly by reasonable adjustment to land use structure. The benefit of sediment reduction is higher than 80% and the coverage ratio of permanent vegetation reaches 61.03%. In 2006, the per capita income increased by 1493 yuan compared with the year 1998. The successful measures and experiences of Yangou watershed are worth promoting on the Loess Plateau.  相似文献   

9.
In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that: 1) Land use changed significantly in the period 1998-2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57%of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998.2) Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including (a) low-coverage grassland to medium-coverage grassland, (b) medium-coverage grassland to high-coverage grassland, (c) farmland to other woodland, and (d) farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3) The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relatively stable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China.  相似文献   

10.
2000—2016年黄土高原不同土地覆盖类型植被NDVI时空变化   总被引:3,自引:1,他引:3  
了解植被覆盖的时空变化对区域环境保护及生态环境建设具有重要意义。基于MOD13A1数据,辅以Sen+Mann-Kendall、变异系数、Hurst指数,通过分析2000—2016年间黄土高原NDVI年最大值(NDVIymax)和生长季均值(NDVIgsmean)时空变化特征及趋势,以了解黄土高原实施退耕还林(草)等生态工程后的植被覆盖恢复情况。结果表明:① 2000—2016年植被NDVIymax和NDVIgsmean呈现波动式增长趋势,增长率分别为0.0070/a(P<0.01)和0.0063/a(P<0.01),生态环境整体不断改善。② NDVIymax和NDVIgsmean显示黄土高原植被覆盖呈增加趋势的面积远高于呈减少趋势的面积(93.42%和96.22%、6.58%和3.78%),植被覆盖状态正在不断改善。2种数据变化趋势下,不同土地覆盖类型表现略有差异,森林极显著增加趋势面积最大(73.02%和82.60%),其次为耕地(47.87%和67.43%),再次为裸地(47.03%和61.68%)。③ NDVIgsmean的变异系数小于NDVIymax的变异系数,相对稳定区域面积比分别为63.31%与56.64%,2种数据分析下森林变异系数最小,植被稳定性最好。④ 从植被NDVI变化趋势与Hurst组合结果得出,NDVIymax未来呈现改善趋势面积占41.35%,退化趋势面积占58.65%;NDVIgsmean呈现改善趋势面积占49.19%,退化趋势面积占50.81%。2种数据下,灌木地未来发展趋势最好,森林和耕地退化趋势面积超过了50%。研究人员应持续关注退化趋势地区的植被状态。  相似文献   

11.
李美娇  何凡能  杨帆  赵亮 《地理研究》2020,39(2):447-460
基于明代册载田亩、屯田和人口数据,以及相关赋役制度和土地制度等史料,考察了明代册载田亩和屯田数据的合理性,辨识了导致明代册载数据失实的主要因素,重建了明代典型时点省域耕地面积。结果表明:① 册籍讹误、官民田和卫所屯田的分类统计及山、塘、湖、荡等非耕地的登册起科,是导致洪武和万历年间册载数据失实的主要原因。② 洪武年间河南和湖广册载田亩数据人均耕地面积畸高,其原因为“册籍讹误”,订正后的数值分别为41万今亩和18万今亩;该时期研究区阙载的屯田总额约为5620万今亩。③ 非耕地的登册起科主要出现在南方地区,且洪武和万历年间浙江、南直隶、江西、湖广等省的册载田土数据中非耕地占比分别为24.7%、23.3%、4.4%、3.7%和28.9%、16.2%、19.2%、11.6%。④ 洪武二十六年(1393年)至万历十一年(1583年),研究区耕地总量由49 550万今亩增至75 430万今亩;省域土地垦殖变化呈现明显的区域差异,河南和山东两省垦殖率增量超过15个百分点,湖广和四川超过3个百分点,而其余各省增量低于1个百分点。区域历史时期土地利用/覆被变化数据重建,不仅是区域生态环境效应模拟的客观需求,也可为充实和完善全球数据集提供参考。  相似文献   

12.
Li  Yurui  Li  Yi  Fan  Pengcan  Sun  Jian  Liu  Yansui 《地理学报(英文版)》2019,29(5):719-729
Journal of Geographical Sciences - Exploring the impact of land consolidation on the changes of local land use and the landscape patterns is important for optimizing land consolidation models and...  相似文献   

13.
In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that: 1) Land use changed significantly in the period 1998-2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57% of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998. 2) Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including (a) low-coverage grassland to medium-coverage grassland, (b) medium-coverage grassland to high-coverage grassland, (c) farmland to other woodland, and (d) farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3) The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relatively stable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China.  相似文献   

14.
Recent changes in hydrological processes and soil erosion in the Loess Plateau, China, are immediate responses to cropland abandonment for revegetation, which lead to a long-term decrease in runoff generation and soil erosion. However, detailed hydrological responses and soil erosion changes have not been clearly evaluated. In this study, two issues were focused on the plot scale. The first issue relates to changes in vegetation cover and soil properties during the early stages of revegetation. Given the occurrence of soil compaction, it was hypothesized that runoff increased during this period and the soil erosion did not significantly decline, even though vegetation increased. The second issue is the effect of scale on runoff and soil erosion. Three plot groups of three vegetation types and two restoration stages were established for comparative experiments. The results from these experiments confirmed that the soil compaction occurred during revegetation in this region. Greater runoff was produced in plot group that experienced both a longer restoration time and with higher vegetation cover (such as Groups 2 and 3 in this study) than that with a shorter restoration time and lower vegetation cover (Group 1). In addition, the total soil loss rates of all plot groups were rather low and did not significantly differ from each other. This indicates that a reduction in runoff generation and soil erosion, as a result of revegetation, was limited in the early stages of restoration following the cropland abandonment. With increasing plot area, the runoff coefficient decreased for the plot group with a longer revegetation time (Groups 2 and 3), but gently increased for the one with a shorter restoration time (Group 1). In Groups 2 and 3, soil loss rate decreased when plot area enlarged. In Group 1, it decreased before a plot area threshold of 18 m2 was exceeded. However, the increase occurred when plot area crossed the threshold value. In conclusion, the high vegetation cover alone did not lead to reduction in the runoff coefficient during the early stages of revegetation. When evaluating hydrological and soil erosion responses to revegetation, the soil compaction processes should be considered. Additionally, the effect of scale on runoff and soil erosion was found to be dependent on restoration extent, and thus on restoration time.  相似文献   

15.
Soil erosion has become a major global environmental problem and is particularly acute on the Loess Plateau (LP), China. It is therefore highly important to control this process in order to improve ecosystems, protect ecological security, and maintain the harmonious relationship between humans and nature. We compared the effects of rainfall and land use (LU) patterns on soil erosion in different LP watersheds in this study in order to augment and improve soil erosion models. As most research on this theme has so far been focused on individual study areas, limited analyses of rainfall and LU patterns on soil erosion within different- scale watersheds has so far been performed, a discrepancy which might influence the simulation accuracies of soil erosion models. We therefore developed rainfall and LU pattern indices in this study using the soil erosion evaluation index as a reference and applied them to predict the extent of this process in different-scale watersheds, an approach which is likely to play a crucial role in enabling the comprehensive management of this phenomenon as well as the optimized design of LU patterns. The areas considered in this study included the Qingjian, Fenchuan, Yanhe, and Dali river watersheds. Results showed that the rainfall erosivity factor (R) tended to increase in these areas from 2006 to 2012, while the vegetation cover and management factor (C) tended to decrease. Results showed that as watershed area increased, the effect of rainfall pattern on soil erosion gradually decreased while patterns in LU trended in the opposite direction, as the relative proportion of woodland decreased and the different forms of steep slope vegetation cover became more homogenous. As watershed area increased, loose soil and craggy terrain properties led to additional gravitational erosion and enhanced the effects of both soil and topography.  相似文献   

16.
Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate (12.1–11.0 ka BP). The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP. After a brief episode of a cool and wet climate (9.8–9.6 ka BP), a relatively mild and dry condition prevailed during the early Holocene (9.6–7.6 ka BP). The most favourable climate of warm and humid period occurred during mid-Holocene (7.6–~4.0 ka BP) marked by forest-steppe landscape and vegetation alternatively changed between steppe and desert- steppe from ~4.0 to ~1.0 ka BP.  相似文献   

17.
Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP.Before 12.1 ka BP,steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate(12.1-11.0 ka BP).The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP.After a brief episode of a cool and wet climate(9.8-9.6 ka BP),a relati...  相似文献   

18.
作为火的代用指标—炭屑在过去生态环境变化及人类活动研究中具有重要意义,基于孢粉学方法开展的微体炭屑—火的研究得到了研究者的广泛关注,但关于炭屑统计的标准目前尚未统一。通过选取黄土高原灵台剖面顶部13 m共16个样品,采用孢粉流程法提取炭屑(外加石松孢子以计算炭屑浓度),对样品进行随机分组统计。具体方法如下:统计时以50粒外加石松孢子为单组,每个样品累计统计20组,且每组中按形态(长宽比)分为长条形炭屑与近圆形炭屑,按大小划分为10~30 μm,30~50 μm,50~100 μm和>100 μm共4种粒级。结果表明20个单组中炭屑含量相近但有一定波动性(标准偏差0.06%~8.70%);当石松孢子累计统计500粒(10组)以上时,炭屑浓度、各粒径炭屑所占百分比均趋于稳定(相关系数r=0.99);当石松孢子累计统计300粒(6组)以上时,炭屑的长/圆比值趋于稳定(标准偏差0.01~0.24,r=0.87)。基于以上结果,建议在黄土高原微体炭屑研究中统计500±50粒的石松孢子,以确保数据稳定。以此为基础,初步发现灵台地区自165 ka以来,火事件较为频繁,草本较木本植被更占优势,此结果与该地区黄土—古土壤中元素碳含量等数据有较好对应关系,表明该地区的古火发生与环境变化具有较强联系。  相似文献   

19.
黄土高原不同生态类型NDVI时空变化及其对气候变化响应   总被引:1,自引:0,他引:1  
孙锐  陈少辉  苏红波 《地理研究》2020,39(5):1200-1214
了解植被的时空变化及其气候主控因子可为植被保护和恢复提供重要的理论依据。基于MOD13A1和气象数据,分析了黄土高原Normalized Difference Vegetation Index (NDVI)时空变化特征,探讨了NDVI对水热条件在不同时间尺度的响应特征。结果表明:黄土高原植被覆盖状态正在不断的改善,气候呈暖湿的发展趋势;83.77%的植被退化区(退化区面积占研究区总面积的5.79%)海拔<2000 m且退化类型以不显著减少为主,不同覆被类型的退化区海拔分布及退化比例差异明显,湿地的退化面积比最高(23.91%)、其次耕地(11.88%)。年尺度上,NDVI与降水呈正相关的面积高于气温,约75.06%的区域受水分条件控制;灌木地(海拔分布<2200 m)、耕地(<3000 m)、草地(<3000 m)和裸地(600~3700 m)等植被生长受水分条件影响;森林(<1000 m、1700~3700 m)和湿地(>2500 m)的植被生长受热量影响。月尺度上,黄土高原植被NDVI对热量响应以滞后1个月为主,不同植被对水热响应的滞后性差异明显,草地、湿地、耕地和裸地对热量响应以滞后1个月为主;森林和灌木地则表现水热同期的特征。伴随滞后时间的推移,水分主控面积逐渐降低,热量成为影响植被生长的主要因素,水热主控及响应滞后性分布受海拔影响明显。  相似文献   

20.
黄土丘陵小流域土壤物理性质的 空间变异   总被引:43,自引:2,他引:43  
邱扬  傅伯杰  王军  陈利项 《地理学报》2002,57(5):587-594
黄土丘陵小流域土壤物理性质在景观尺度上的空间变异以质地、容重和饱和含水量最小,稳定入渗率最大,团稳性与粘结力居中,不同土地利用类型之间诸项物理性质都存在显著差异,土壤质地以林地的砂粒含量显著偏低但粉粒含量显著高于其它土地利用类型,休闲地的粉粒含量显著较低;容重以林地显著偏大,耕地较小;饱和含水量以灌木地较大,林地显著偏低,土壤团稳性以林地显著偏高,耕地显著偏低;土壤粘结力以灌木地,林地,荒地和休闲地显著较强,耕地显著较弱;稳定入渗率以灌木地显著较高,间作地显著较低,就坡形来说,垂直与水平凹形坡的砂粒含量都显著较低而粉粒含量比较高,相反直形坡的砂粒比较高而粉粒含量显著较低;饱和含水量与稳定入渗率都是以垂直直形坡较高,垂直凹形坡则较低,就坡向而言,偏东坡的土壤粘结力显著低于偏西坡;偏北坡土壤质地比偏南坡粘性强,但稳定入渗率低,稳定入渗率还随坡度的增大而增高,随着海拔的升高,土壤砂粒含量与稳定入渗率增高,而粘粒含量与团稳性呈降低趋势。  相似文献   

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