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1.
加速土壤侵蚀对养分流失的影响   总被引:7,自引:0,他引:7  
ZHENG Fen-Li 《土壤圈》2005,15(6):707-715
Soil erosion and nutrient losses on newly-deforested lands in the Ziwuling Region on the Loess Plateau of China were monitored to quantitatively evaluate the effects of accelerated soil erosion, caused by deforestation, on organic matter, nitrogen and phosphorus losses. Eight natural runoff plots were established on the loessial hill slopes representing different erosion patterns of dominant erosion processes including sheet, rill and shallow gully (similar to ephemeral gully). Sediment samples were collected after each erosive rainfall event. Results showed that soil nutrients losses increased with an increase of erosion intensity. Linear relations between the losses of organic matter, total N, NH4-N, and available P and erosion intensity were found. Nutrient content per unit amount of eroded sediment decreased from the sheet to the shallow gully erosion zones, whereas total nutrient loss increased. Compared with topsoil, nutrients in eroded sediment were enriched, especially available P and NH4-N. The intensity of soil nutrient losses was also closely related to soil erosion intensity and pattern with the most severe soil erosion and nutrient loss occurring in the shallow gully channels on loessial hill slopes. These research findings will help to improve the understanding of the relation between accelerated erosion process after deforestation and soil quality degradation and to design better eco-environmental rehabilitation schemes for the Loess Plateau.  相似文献   

2.
围绕子午岭天然次生林区土壤侵蚀与生态环境演变关系的研究主题,着重讨论研究背景,研究内容和研究方法。以典型调查和定位观测相结合,分析研究植被的破坏与恢复对土壤侵蚀的影响。通过建立大型径流场,动态监测不同地形部位林地与开垦地的土壤侵蚀演变过程,包括降雨、径流、入渗和侵蚀量的变化,细沟侵蚀和浅沟侵蚀的演变,土壤侵蚀与土壤退化的演变,坡、沟侵蚀的演变;同时结合进行野外人工降雨试验,林地和开垦地小气候对比观测等。初步建立了一整套宏观与微观相结合的研究体系,在黄土高原残留林区建立了土壤侵蚀与生态环境观测站,填补了国内空白。  相似文献   

3.
沟头发生侵蚀的地形临界模型可有效预测侵蚀沟的形成条件,浅层滑坡失稳形成的洼地也是沟头形成的方式之一。为探究浅层滑坡临界起动模型的特点,以甘肃省天水市小陇山林区的降雨型浅层滑坡为研究对象,运用汇水面积-坡度关系,构建临界起动模型,与黄土高原典型侵蚀沟(浅沟、切沟)的临界起动模型进行对比分析,并探讨土地利用类型、植被类型和土壤质地对该模型的影响。结果表明:(1)浅层滑坡临界起动模型为S=3.50As-0.34,其侵蚀阈值为3.50,大于黄土高原典型浅沟(0.96)和切沟(1.54)的侵蚀阈值。研究区浅层滑坡一般发生于土层较薄的陡坡地带,其平均坡度(S=1.26)大于浅沟(S=0.35)与切沟(S=0.46),单位汇水面积(A=89.08 m2/m)小于浅沟(A=920.93 m2/m)和切沟(A=1 129.82 m2/m)。(2)汇水面积与坡度平方的乘积(AS2)代表了沟头产生侵蚀的能量指标值。研究区浅层滑坡AS2值在269.1~5 703.2 m2,平均值为1 772.97 m2,黄土高原浅沟AS2值在4.74~892.66 m2,切沟在41~814 m2,启动能量值方面,浅沟<切沟<浅层滑坡。(3)土地利用类型、植被类型和土壤质地通过影响土壤的抗冲力、渗透性和黏粒含量,从而对浅层滑坡的起动难易程度产生影响。在不同的土地利用方式中,农地最易发生侵蚀,其次是林地。油松林附近浅层滑坡的抗侵蚀能力高于日本落叶松林。研究结果为探究浅层滑坡的起动条件提供理论依据。  相似文献   

4.
为探究黄土残塬沟壑区退耕还林(草)工程等林业生态工程实施后林业资源恢复情况,以黄土高原DEM数据及2000—2020年归一化植被指数NDVI数据为基础,采用地形因子计算、水文分析、空间叠加分析等方法,划分了较为完整的黄土残塬沟壑区的范围,并利用趋势分析法、变异系数的相关理论与方法,分析了近21年来黄土残塬沟壑区NDVI时空变化特征。结果表明:(1)黄土残塬沟壑区横跨山西、陕西和甘肃3省,面积约为2.99万km2,沟壑密度为1.91~3.21 km/km2;(2)黄土残塬沟壑区NDVI从时序变化上看,全区21年总平均NDVI值为0.711,2000—2020年该区植被NDVI变化趋势呈快—慢—较快增长;从空间分布来看,植被覆盖度NDVI值总体为0.6~0.9,研究区中部地区植被覆盖度较其他地区高;(3)在时空趋势特征方面,研究区西部和东部部分地区植被覆盖改善程度明显,中部地区植被覆盖情况较为稳定;在时空波动特征方面,该区植被NDVI时序波动稳定,空间波动差异性较大,低波动区域面积占比为48.06%。整体而言,黄土残塬沟壑区主要分布在山西、陕西和甘肃3省,该区2000—2020年间植被NDVI整体呈上升态势,植被覆盖水平整体较高且波动较低,并呈持续改善趋势。研究结果可为黄土残塬沟壑区水土保持工作提供理论基础和科学依据。  相似文献   

5.
为研究黄土高原丘陵沟壑区不同植被恢复方式下的土壤水分特征,以天水典型对比小流域——桥子西沟(自然恢复的荒草地)和桥子东沟(人工恢复的刺槐林地)为例,基于2流域5-8月0~ 100 cm深度土壤质量含水量和氢氧同位素浓度,定量分析不同植被恢复方式下降水和坡向对土壤水分影响.结果表明:以刺槐林地为主的流域土壤含水量低于以荒草地为主的流域(16.72%)约3.70%,对降水量的响应较弱,各土层含水量变异系数较高.土壤水分存在临界变化深度,刺槐林地为主的流域在10 cm以下含水量趋于稳定,最大蒸发深度为55 cm,荒草地为主的流域在30 cm以下含水量开始增加,最大蒸发深度为30 cm.两流域含水量均遵循阴坡>半阴坡>半阳坡,δo18的分布不符合这一规律.以刺槐林地为主的流域含水量随坡向变化较小,而以荒草地为主的流域受坡向影响较大,坡向对土壤水分的影响受植被因子的制约.以自然恢复荒草地为主的恢复方式可以较好的增加土壤水库蓄水量,有利于流域生态的可持续发展.  相似文献   

6.
切沟侵蚀是黄土高原丘陵沟壑区水土流失的重要形式之一,然而极端暴雨条件下不同土地利用类型坡面切沟侵蚀研究还鲜见报道。该研究以陕北2017年"7·26"特大暴雨为例,研究了岔巴沟流域3种土地利用类型(农地、休闲地和撂荒地)坡面切沟发育形态特征及体积估算模型。结果表明:1)农地、休闲地和撂荒地切沟长度分布在20 m内的占比分别为55.6%、34.8%和44.8%;农地切沟平均深度为110 cm,分别比休闲地和撂荒地高18.3%、19.2%;农地和休闲地切沟平均宽深比分别为0.87和0.84,横断面呈"宽-浅型",而撂荒地切沟呈"方型"(宽深比1.01)。2)撂荒地切沟侵蚀体积分别比农地和休闲地减少47.8%和28.3%,表明植被恢复有效地削弱了极端暴雨作用下的切沟侵蚀。3)农地切沟不同坡段侵蚀体积由高到低为下坡、上坡、中坡,而休闲地和撂荒地切沟侵蚀体积沿坡长方向呈递增趋势;3种土地利用类型切沟在上坡段的沟岸拓宽速率大于下切速率,中下坡则相反。4)农地、休闲地和撂荒地切沟侵蚀体积均与切沟长度、横断面面积呈极显著幂函数关系(P<0.001),横断面面积是切沟体积估算更为有效的参数。研究结果可为黄土高原丘陵沟壑区不同土地利用类型坡面切沟侵蚀体积估算及其防治提供重要依据。  相似文献   

7.
子午岭地区植被演替的土壤碳汇效应   总被引:2,自引:0,他引:2  
为明确黄土高原地区植被长期恢复的土壤碳汇效应,采用时空互代的方法,研究子午岭地区150年以来8个植被演替序列的土壤有机碳含量及储量的变化特征,分析影响土壤有机碳储量变化的植被因素。结果表明:从农地演替到气候顶级辽东栎(Quercus wutaishanicaMary.)群落,土壤有机碳含量和储量明显增加,表现为演替前期(草本群落)快速增加,后期(乔木群落)趋向稳定的变化特征。剖面上来看,随着土层加深,土壤有机碳含量迅速减少。0—5 cm土层土壤有机碳含量与5—20,20—40 cm土层差异显著(P<0.05),表明土壤有机碳积累存在明显的表聚效应。枯落物蓄积量与细根生物量均随演替时间呈现出增加的变化特征,前者更有利于提高土壤有机碳储量。0—5 cm土层与0—20 cm土层土壤有机碳储量与演替时间均存在极显著的幂函数关系,不同土层之间土壤有机碳储量线性相关关系显著(P<0.001)。植被长期演替具有显著的土壤碳汇功能。未来黄土高原地区林、草地的恢复应根据植被带的分异规律,促进自然演替,以进一步提升该地区的土壤碳汇潜能。  相似文献   

8.
运用野外实测资料,分析研究了子午岭林区植被破坏与恢复对坡面浅沟侵蚀的影响。所得结论为:一旦植被恢复,坡面浅沟沟槽部位发生泥沙淤积,其淤积速度为0.5cm/a;浅沟沟槽部位淤积,坡面横向起伏减少,坡面向平直方向发展。人为破坏植被后的开垦地,坡面浅沟侵蚀急剧发展,浅沟侵蚀量为4400~7600t/(km2·a),占坡面侵蚀量的47%以上;当年新冲刷的浅沟沟槽宽为20~80cm,深度为10~30cm;开垦3年裸露地与林地相比,浅沟沟槽深度增加40~60cm;浅沟沟头前进速度为3~5m/a,浅沟深、宽、长的逐年发展,坡面横向起伏加大,片蚀和细沟侵蚀随之加大,又促使了浅沟侵蚀的加剧。  相似文献   

9.
以浅沟集水区为研究对象,分析了子午岭地区林地被开垦破坏15年后裸露地在不同侵蚀强度和侵蚀方式下的土壤养分流失和土壤微生物数量的变化。结果表明,林地开垦破坏后,土壤侵蚀加剧发展,侵蚀强度达159.7t/(hm2a),是林地土壤侵蚀量的上千倍。开垦破坏15年后,裸露地浅沟集水区不同地形部位表层土壤全氮、有机碳、速效磷和土壤微生物总数显著减少,同林地相比,依次分别减少37.9%~82.6%、42.7%~86.4%、24.2%~80.3%和31.8%~92.0%。在裸露地浅沟集水区梁坡随坡长的增加,表层土壤有机碳、全氮和速效磷含量及微生物总数呈显著的下降趋势,且沟槽的土壤各养分含量及微生物总数明显低于沟间。裸露地浅沟集水区土壤养分流失强度及微生物数量减少幅度在浅沟集水区的空间分布与土壤侵蚀方式和侵蚀强度相对应。林地开垦破坏15年后,土壤养分以有机碳流失最严重,其次分别为速效磷、全氮;微生物中的真菌减少幅度最大,细菌次之,放线菌减少幅度最小。  相似文献   

10.
退耕还林(草)工程的深入实施有效遏制了黄土高原水土流失,但以浅层滑坡和崩塌为主的重力侵蚀在黄土高原广泛分布,且已成为小流域侵蚀泥沙主要来源之一.为探究黄土丘陵沟壑区浅层滑坡和崩塌的形态特征和发育临界地形,在陕西省安塞区纸坊沟小流域调查了 53处浅层滑坡和40处崩塌,记录其植被特征,同时进行无人机摄影测量.结果表明:浅层...  相似文献   

11.
选择黄土高原子午岭地区植被自然恢复1-140a不同年限的阳坡墚坡地为研究对象,通过相关性分析筛选土壤表层(0-20cm)16项表征土壤物理、化学、生物学性质的指标,运用主成分分析计算土壤质量综合指数,评价子午岭地区植被恢复过程对土壤质量的影响。结果表明:土壤总孔隙度、平均重量直径(MWD)、有机质质量分数、速效磷质量分数、蔗糖酶活性、碱性磷酸酶活性、真菌数量、微生物总量构成土壤质量评价指标体系;土壤质量综合指数随植被恢复年限的增加而增加;植被自然恢复1-140a间,土壤质量综合指数变化范围为0.1559-0.8509,较裸露休闲地增加4.2-27.5倍;根据土壤质量综合指数变化规律,可将140a植被恢复过程中的土壤质量演变过程分为3个阶段,即植被恢复初期(1-20a)的土壤质量综合指数呈快速增长,植被恢复中期(20-40a)的土壤质量综合指数呈波动性增长,植被恢复后期(40-140a)的土壤质量综合指数呈稳定增长。植被演替过程中不同植被生活型土壤质量综合指数表现为乔木林地〉灌木林地〉草地。  相似文献   

12.
黄土高原不同侵蚀类型区侵蚀产沙强度变化及其治理目标   总被引:5,自引:3,他引:2  
为了确定黄土高原不同侵蚀类型区的治理目标,采取"水文—地貌法",利用98个水文站控制区和234个侵蚀产沙单元,在分析其不同治理阶段土壤侵蚀产沙变化特征与减沙幅度,不同侵蚀强度面积的变化及其空间分布的基础上,提出了未来20a黄土高原主要流失区的区域治理目标:土壤流失量控制在3.60×108 t左右,土壤侵蚀模数1 300 t/(km2.a)左右。其中,黄土峁状丘陵沟壑区为3 000t/(km2.a),黄土梁状丘陵沟壑区为2 000t/(km2.a),干旱黄土丘陵沟壑区为2 000t/(km2.a),黄土平岗丘陵沟壑区为1 000t/(km2.a),风沙黄土丘陵沟壑区为1 000t/(km2.a),黄土山麓丘陵沟壑区为1 000t/(km2.a),森林黄土丘陵沟壑区为300t/(km2.a),黄土高塬沟壑区为1 500t/(km2.a),黄土残塬沟壑区为3 000t/(km2.a),黄土阶地区为500t/(km2.a),风沙草原区为500t/(km2.a),高原土石山区为100t/(km2.a)。未来20a黄土高原的治理重点区域为黄土峁状丘陵沟壑区(2.20×104 km2)、干旱黄土丘陵沟壑区(1.50×104 km2)、黄土高塬沟壑区(8 600km2)、黄土梁状丘陵沟壑区(4 600km2)。  相似文献   

13.
Gbris   . Kertsz  L. Zmb 《CATENA》2003,50(2-4):151-164
Gully erosion can be widely observed on cultivated hillslopes in Hungary. Loose sediments covering two thirds of the total area of the country are prone to gully erosion.A detailed study of gully formation was carried out in the Rakaca catchment (58 km2), northeastern Hungary. The objectives include (1) a detailed survey of the present gullies, (2) an explanation of differences in gully distribution within the catchment, (3) clarification of the role of influencing factors like slope gradient, vegetation cover and soil type and (4) a study of changes of gully distribution and development in time over the last 200 years based on the comparison of topographic maps.The present gully distribution was first surveyed by applying 1:10 000 topographic maps and aerial photographs. The total length of the network is 70.9 km, i.e. 1.22 km/km2. Distribution inhomogeneities within the catchment can well be explained by differences in slope gradient and vegetation cover.The rate of increase of the gully length per unit area (1 km2) calculated for different time periods shows the following trends: (1) until 1860, when more than 50% of the catchment was forested, it was 5 m year−1 km−2; (2) between 1860 and 1920, when forest area dropped to almost 25% and agricultural land use was extended to slopes steeper than 25%, it still remained at roughly 5 m year−1 km−2; (3) after 1920, with 24–25% forest cover and with the extension of farming activity to the steepest slopes, it reached 10 m year−1 km−2.It could be shown that gully erosion on cultivated slopes leads to the development of gully systems in 50–60 years even if slope gradient is below 12%.To prevent further development of gully systems, it is suggested that at least 30% of the area should be forested and slopes steeper than 17% should not be cultivated at all.  相似文献   

14.
Soil organic carbon (SOC) sequestration by vegetation restoration is the theme of much current research. Since 1999, the program of “Grain for Green”has been implemented in the semi-arid Loess Plateau, China. Its scope represents the largest vegetation restoration activity in China. However, it is still unclear for the SOC sequestration effects of vegetation cover change or natural succession promoted by the revegetation efforts at different scales under the semi-arid conditions. In this study, the changes in SOC stocks due to the vegetation restoration in the middle of Loess Plateau were estimated at patch, hill slope transect and small watershed scale from 1998 to 2006. Soil samples were taken from field for the determination of cesium-137 (137Cs) and SOC contents. Vegetation cover change from 1998 to 2006 at the small watershed scale was assessed using Geographic Information System. The results showed that cropland transforming to grassland or shrubland significantly increased SOC at patch scale. Immature woodland, however, has no significant effect. When vegetation cover has no transformation for mature woodland (25 years old), SOC has no significant increase implying that SOC has come to a stable level. At hill slope scale, three typical vegetation cover patterns showed different SOC sequestration effects of 8.6%, 24.6%, and 21.4% from 1998 to 2006, and these SOC increases mainly resulted from revegetation. At the small watershed scale, SOC stocks increased by 19% in the surface soil layer at 0–20 cm soil depth from 1998 to 2006, which was equivalent to an average SOC sequestration rate of 19.92 t C y− 1 km− 2. Meanwhile, SOC contents showed a significant positive correlation (P < 0.001) with the 137Cs inventory at every soil depth interval. This implied significant negative impacts of soil erosion on SOC sequestration. The results have demonstrated general positive effects of vegetation restoration on SOC sequestration at multiple scales. However, soil erosion under rugged topography modified the spatial distribution of the SOC sequestration effects. Therefore, vegetation restoration was proved to be a significant carbon sink, whereas, erosion could be a carbon source in high erosion sensitive regions. This research can contribute to the performance assessment of ecological rehabilitation projects such as “Grain to Green” and the scientific understanding of the impacts of vegetation restoration and soil erosion on soil carbon dynamics in semi-arid environments.  相似文献   

15.
基于AnnAGNPS模型的黄土高原小流域土壤侵蚀定量评价   总被引:9,自引:3,他引:9  
以位于黄土丘陵沟壑区的砖窑沟流域为试点,利用AnnAGNPS模型进行土壤侵蚀定量评价。采用流域8次径流事件监测数据进行模型检验,径流量和沉积物量的相对误差分别为10%和-10%,AnnAGNPS模型能够比较理想地模拟流域长期的径流量和沉积物量,并可应用于黄土丘陵沟壑区的径流流失和土壤侵蚀定量评价。采用2004年土地利用状况模拟分析了流域土壤侵蚀量及其空间分布,结果表明:该流域平均片蚀和细沟侵蚀强度为3508 t/(km2·a),属中度侵蚀等级,黄土沟壑地的平均侵蚀强度最大,属极强度侵蚀等级;严重的沟道侵蚀显著增加了运移到流域出口的泥沙。  相似文献   

16.
Ephemeral gullies are widely distributed in the hilly and gully region of the Loess Plateau and play a unique role in the slope gully erosion system. Rapid and accurate identification of ephemeral gullies impacts the distribution law and development trend of soil erosion on the Loess Plateau. Deep learning algorithms can quickly and accurately process large data samples that recognize ephemeral gullies from remote sensing images. Here, we investigated ephemeral gullies in the Zhoutungou watershed in the hilly and gully region of the Loess Plateau in China using satellite and unmanned aerial vehicle images and combined a deep learning image semantic segmentation model to realize automatic recognition and feature extraction. Using Accuracy, Precision, Recall, F1value, and AUC, we compared the ephemeral gully recognition results and accuracy evaluation of U-Net, R2U-Net, and SegNet image semantic segmentation models. The SegNet model was ranked first, followed by the R2U-Net and U-Net models, for ephemeral gully recognition in the hilly and gully region of the Loess Plateau. The ephemeral gully length and width between predicted and measured values had RMSE values of 6.78 m and 0.50 m, respectively, indicating that the model has an excellent recognition effect. This study identified a fast and accurate method for ephemeral gully recognition in the hilly and gully region of the Loess Plateau based on remote sensing images to provide an academic reference and practical guidance for soil erosion monitoring and slope and gully management in the Loess Plateau region.  相似文献   

17.
黄土高塬沟壑区水土流失综合治理范式   总被引:3,自引:0,他引:3       下载免费PDF全文
 黄土高原是中华农耕文化的发祥地,其主要地貌类型区之一的黄土高塬沟壑区,其农业发展有着比黄土高原其他地区优越的自然条件。但长期以来,由于自然和人为因素的双重作用,该区水土流失十分严重,塬面径流下沟导致沟头不断前进,塬面逐年萎缩。由于沟坡坡度大而导致重力侵蚀异常活跃,侵蚀强度逐渐加强。在特殊的自然环境、人口压力以及经济发展需求的条件下,探索黄土高塬沟壑区水土流失综合治理范式成为水土保持领域科技人员和当地政府急需解决的问题之一。在解析黄土高塬沟壑区自然地理特征、水土流失特点以及社会经济发展需求的基础上,通过对该区现有的水土流失综合治理模式进行梳理,结合范式的概念,提出黄土高塬沟壑区水土流失综合治理范式。  相似文献   

18.
黄土高原生态环境建设的若干问题与研究需求   总被引:23,自引:8,他引:15  
针对目前黄土高原生态环境建设的新形势,提出了当前面临的若干问题与研究需求,包括通过退耕还林还草治理黄土高原的前景与重点治理区的选择问题、坡耕地退耕还林还草与沟壑治理相结合的问题、黄土高原不同地区植被恢复前景问题、制定黄河流域生态环境建设区划的理论基础问题、黄土高原生态环境治理后效的预测、监测与评估问题等。  相似文献   

19.
Accelerated erosion caused by deforestation and soil degradation has become the primary factor limiting sustainable utilization of soil resources on the Loess Plateau of Northwestern China. We studied the physical, chemical, and microbiological processes of soil degradation along a chronosequence of deforestation in the Ziwuling area of northwestern Shaanxi province. The results indicated that soil wet aggregate stability, mean aggregate diameter decreased with years following deforestation. Accelerated erosion resulted in soil nutrient loss, and a decrease in soil enzyme activities including notable losses of total soil N, organic C, alkaline phosphatase activity, and invertase activity. During the early time period, the rates of total soil N, organic C, alkaline phosphatase activity, and invertase activity decreasing were rapid and gradually decreased with deforestation years. Increased use of nitrogen fertilizers made determination of soil quality based on measured NO3–N and NH4–N inconclusive. The differences in measured parameters between the topsoil and subsoil horizons decreased with time since deforestation, and we concluded that soil erosion was the primary process responsible for the degradation of measured soil physical, chemical, and microbiological properties.  相似文献   

20.
黄土高原地区是我国水土流失和环境问题严重的地区之一,人工植被恢复可以有效改善土壤性质,提高土壤质量,明确长期人工植被恢复后土壤水分和养分性质的响应差异,有利于进一步有效改善生态环境。选取晋西黄土区自然恢复的次生林地、人工刺槐林地、人工油松林地3种典型植被恢复类型为研究对象,通过测定土壤物理性质以及有机碳、氮磷钾元素含量等土壤养分,对比分析长期不同人工林恢复条件下的差异。结果表明:(1)次生林地、刺槐林地和油松林地在0-20 cm浅层土壤的容重分别1.15,1.04,1.06 g/cm3,次生林地的容重最大,土壤容重随着土层深度的增加而增大;(2)次生林地在浅层的土壤水分状况优于刺槐林地和油松林地,土壤水分消耗期(生长季开始前)过渡到积累期(生长期开始)时,次生林土壤水分动态变化更剧烈;(3)次生林地土壤碳储量较高,油松林地土壤氮、磷储量较高。3种林地土壤养分垂直变化差异显著,且均具有明显的表聚性,有机碳、全氮、全磷、速效氮和速效钾含量均随着土层深度的增加而减少,而速效磷含量随着土层深度的变化表现为先增大再减小。以水养条件为依据,建议在植被恢复过程中多以保育次生林为主来达到较好的水碳储量等生态效益,有利于优化晋西黄土区的林分管理,促进植被恢复和生态建设。  相似文献   

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