首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
Soil erosion is a severe problem on China's Loess Plateau due to its fine‐grained soils and the increasing frequency of extreme rainfall events. Accordingly, this study used a 100‐year frequency rainstorm dataset to analyse sediment deposition and sources in a 27‐km2 catchment with a dam field area of 0·14 km2 based on the hypothesis that sediments were intercepted by the dam (before collapse) during the rainstorm event and deposited in the dam field. This study applied composite fingerprinting, which revealed the sediment source contributions and estimated sediment deposition. Sediment deposition (626·4 kg m−2) decreased linearly or exponentially with increasing distance from the dam. Composite fingerprints based on the optimal parameters revealed relative sediment contributions of 44·1% ± 25·5%, 37·7% ± 35·0%, 9·0% ± 11·4% and 9·2% ± 11·5% by bare ground, croplands, grassland and forests, respectively. The 5‐year cumulative sediment deposition from normal rainfall was 2·3 × 104 t less than the extreme rainstorm. Bare grounds and croplands were the dominant sediment sources following both the extreme rainstorm and normal erosive rainfall events but varied at different areas of the check‐dam. Erosion patterns and start times depended on land use type, thereby affecting sediment profiles in the dam field. Furthermore, severe erosion from bare ground that were all gully slopes and gully walls occurred throughout the rainfall, whereas grasslands and forest erosion occurred earlier and croplands later. Finally, extreme rainfall promoted mass wasting on slopes, gully slopes and gully walls, which are important in determining extreme rainstorm erosion pattern variation. This study aimed to reveal erosion pattern variation under extreme rainstorm events. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

2.
The effects of grazing and cultivation management on infiltration, runoff and sediment yield on storm basis were quantified for summer rangeland in the Matash mountains (Talesh Region), northern Iran. The infiltration experiments were made using double cylinder infiltrometer with five replicates within each study treatment. The runoff generation and sediment yield were measured using standard plots (1·83 m × 22·18 m) in three replications. The peak and the terminal instantaneous infiltration, and runoff and sediment rates were compared using independent and paired sample t‐test in two aforesaid treatments, respectively. The terminal and the peak instantaneous infiltration rates of 39·6 and 342·9 mm/h showed a respective significant increase (p < 0·001) of 32 and 39 per cent in cultivated areas compared to those in open grazing treatments. The results of runoff analysis also showed that there was a significant difference (p < 0·001) in runoff generation in two above‐mentioned areas. The runoff water was also found to be 5·63‐folds more in case of open grazing treatment in comparison with that generated by cultivated plots. A significant difference (p < 0·001) in sediment yield between two study treatments was also proved by the results obtained through sediment yield study. The soil loss in open grazing treatment was found to be 26·6 times more than of that occurred in cultivated plots. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

3.
The catchments in the western Rift Valley escarpment of northern Ethiopia are highly responsive in terms of hydro‐geomorphic changes. With deforestation, dense gully and scar networks had developed by the 1980s on the escarpment between the towns of Alamata and Korem, transporting huge amounts of runoff and sediment down to the fertile and densely populated Raya Valley. To reverse this problem, catchment‐scale rehabilitation activities were initiated in the mid‐1980s. In this study, we examine the major hydro‐geomorphic response of streams after catchment rehabilitation. Scar networks in 20 adjacent catchments were mapped on Google Earth imagery of 2005, and their density was explained in terms of its corresponding Normalized Difference Vegetation Index and slope gradient. Soil and water conservation measures and vegetation recovery have reduced discharge and sediment flow which in turn resulted in various hydro‐geomorphic changes. In a multiple regression analysis, scar density was negatively related with Normalized Difference Vegetation Index and positively with average gradient of very steep slopes (r2 = 0·53, p < 0·01, n = 20). The size and amount of sediment supply to streams decreased, and various channel adjustments occurred. Notably, previously braided streams have changed to single thread streams, lateral bars have been stabilized and stream channels are narrowing and incising. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

4.
Catchment scale sediment budgeting models are increasingly being used to target remediation works aimed at controlling erosion and improving water quality. Gully erosion is often a major sediment source and needs to be accounted for in such models in a manner consistent with the scale of analysis and available data. Using 130 measurements of gully cross-sectional area and 45 measurements of gully wall sediment texture, the variability in gully dimensions and particle size distribution for the Lake Burragorang catchment in Australia is examined. The distribution of gully cross-sectional area measurements is log-normally distributed and modelling indicates a representative value of 23 m2 be used in catchment sediment budgeting applications. The proportion of gully eroded sediment contributing to the bedload budget (defined as particles > 63 μm diameter) of a river link is approximately half, though may be higher in igneous landscapes. A continental scale spatially distributed subsoil texture dataset provided limited capacity to predict the finer scale spatial variation in the proportion of sediment contributing to bedload from gully erosion within the Lake Burragorang catchment.  相似文献   

5.
The lower Himalayan regions of north‐west India experienced a severe land‐use change in the recent past. A study was thus conducted to assess the effect of grassland, forest, agricultural and eroded land uses on soil aggregation, bulk density, pore size distribution and water retention and transmission characteristics. The soil samples were analysed for aggregate stability by shaking under water and water drop stability by using single simulated raindrop technique. The water‐stable aggregates (WSA) >2 mm were highest (17·3 per cent) in the surface layers of grassland, whereas the micro‐aggregates (WSA < 0·25 mm) were highest in eroded soils. The water drop stability followed the similar trend. It decreased with the increase in aggregate size. Being lowest in eroded soils, the soil organic carbon also showed an adverse effect of past land‐use change. The bulk density was highest in eroded lands, being significantly higher for the individual aggregates than that of the bulk soils. The macroporosity (>150 µm) of eroded soils was significantly (p < 0·05) lower than that of grassland and forest soils. The grassland soils retained the highest amount of water. Significant (p < 0·05) effects of land use, soil depth and their interaction were observed in water retention at different soil water suctions. Eroded soils had significantly (p < 0·05) lower water retention than grassland and forest soils. The saturated hydraulic conductivity and maximum water‐holding capacity of eroded soils were sufficiently lower than those of forest and grassland soils. These indicated a degradation of soil physical attributes due to the conversion of natural ecosystems to farming system and increased erosion hazards in the lower Himalayan region of north‐west India. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

6.
Soil erosion is a key factor affecting sustainable agriculture on Chinese Loess Plateau. A 2‐year study was conducted on jujube trees in a controlled study to compare effects of clean cultivation (CC) with jujube branch mulch (WJBM), strip white clover cover (SWC), strip shallow tillage (ST), jujube branch mulch under tree canopy + strip white clover cover (JBM + SWC) and jujube branch mulch under tree canopy + strip shallow tillage (JMB + ST). The study was on sloping soil (26·7%) in mesocosms (2·0 m × 0·8 m × 0·8 m) using a rainfall simulator. Runoff volume and sediment yield were significantly larger under CC than other treatments (p < 0·05), and were least under WJBM. Water infiltration under CC was significantly less than other treatments (p < 0·05), while it was the largest under WJBM. The available nitrogen (AN) and available phosphorus (AP) runoff loss under CC were significantly larger than others (p < 0·05), and least under WJBM. No differences in soil AN, AP and water‐soluble organic carbon (WSOC) concentrations were detected among all treatments. The soil AN and WSOC concentration under all treatments decreased during the growing season and slightly increased during fallow, while AP concentrations fluctuated but decreased slowly. The WJBM was the best management in this sloping jujube orchard study. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

7.
Land degradation is recognized as a major environmental problem in rainfed fruit orchards on the Chinese Loess Plateau. Six treatments were used to investigate surface runoff and soil moisture by means of simulated rainfall experiments: (i) a control (clean cultivation) (CC); (ii) strip cock's foot (Dactylis glomerata L.) cover (SCF); (iii) strip crown vetch (Coronilla varia L.) cover (SCV); (iv) strip bird's foot trefoil (Lotus corniculatus L.) cover (SBF); (v) strip white clover (Trifolium repens L.) cover (SWC); and (vi) complete white clover cover (WCC). The time to runoff was significantly longer under WCC than under other treatments (p < 0·05). The total runoff volume and sediment yield were significantly greater under CC than under the vegetation cover treatments (p < 0·05). The mean infiltration rate under WCC and CC was the largest and lowest and differed significantly from that under other treatments (p < 0·05). The change of soil water storage was the largest under WCC and the least under CC. The soil moisture was significantly greater under SCF than under other treatments (p < 0·05). Treatment SCF seemed to be the best groundcover for rainfed sloping jujube orchards on the Chinese Loess Plateau. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

8.
Runoff is the key factor to understand the land degradation causing high risk of soil erosion and can reduce the water available for human societies and ecosystems. The dynamics of runoff and suspended sediment transport are not completely understood. In this study, we examined the trends, breaking point and regime changes for the runoff and sediment load at different temporal scales using 50 years of continuous observational data from a highly erodible sub‐catchment with an area of 7,325 km2 in the Beiluo River basin on the Loess Plateau, China. At the annual scale, the runoff and sediment load declined significantly (p < 0·05) with decreasing rates of −0·23 mm y−1 and −164·9 Mg km−2 y−1, respectively. Abrupt changes in the runoff and sediment load series were detected between 1979 and 1999; thus, the data were divided into intervals of 1960–1979, 1980–1999 and 2000–2009. The flow duration curve analysis indicated increasing low‐flow values and decreasing daily runoff and sediment discharge peaks, which suggested that soil and water conservation measures reduced the volume of runoff and the sediment load. This led to a more uniform runoff regime. At the flood event scale, we investigated the relationship between runoff and the suspended sediment load based on 123 flood events, which showed clearly that the magnitude and frequency of hyper‐concentrated sediment flows decreased in 2000–2009 compared with 1960–1999. The annual erosive rainfall exhibited non‐significant changes throughout the entire study period. We conclude that soil and water conservation measures (e.g. afforestation, grassing, terraces and check dams) have played major roles in the changes in runoff and the sediment load in the Beiluo River catchment. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

9.
This study aimed to determine microbial biomass carbon and microbial abundance immediately after, and two years after, forest soil erosion, so as to estimate the degree of damage, including the rate of recovery of microorganisms, in each area. It also aimed to determine the community diversity, and to establish relationships between microbial biomass, microbial abundance and the physico‐chemical properties of the soil. Three different study areas in Hiroshima Prefecture, Japan, were used. One undisturbed area and two eroded areas (one immediately after and one two years after erosion). The analysis of variance showed a highly significant difference in microbial biomass carbon and abundance between the study areas. The undisturbed area showed the highest value, followed by the area eroded two years ago, then lastly the area studied immediately after the erosion. The biomass carbon was highly correlated with gram positive bacteria with r2 = 0·983, p < 0·01. The biomass carbon and microbial population were shown to be significantly correlated to the soil's physico‐chemical properties, such as pH, moisture content, water‐holding capacity and CN ratio. However, CN ratio proved to be closely correlated to biomass carbon with r2 = −0·978, p < 0·01, to Gram‐positive bacteria with r2 = −0·977, p < 0·01, to Gram‐negative bacteria with r2 = −0·989, p < 0·01 and to fungi with r2 = −0·977, p < 0·01. The undisturbed area showed a highly diverse community in both of the restriction enzymes used, followed by the area affected by erosion two years ago, then the area immediately after erosion. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

10.
In southern China, collapsing gully erosion produces massive deposits of sediment on the plough layer of alluvial fan farmland, leading to reduced nutrients, increased erodibility, and even desertification. The aim of this study was to investigate soil erodibility (the factor K in the universal Soil Loss Equation, USLE) and physicochemical properties of the alluvial fans of the most severe collapsing gully erosion areas (Hubei, Jiangxi, Fujian, and Guangdong provinces) in southern China. The soils of the collapsing gully alluvial fans had a higher bulk density, but a lower total porosity, saturated water content, and silt and clay fractions than the control (CK) soils from the farmland without desertification. Soil quality gradually decreased from fan edge to fanhead. Significant decreases were found in soil pH, organic matter, cation exchange capacity, and total potassium, nitrogen, and phosphorus, as well as available nitrogen, phosphorus, and potassium, resulting in a gradual decrease in soil nutrients from the fanedge to the fanhead. Soil erodibility was greatest in the fanhead, and soil erodibility K values of the alluvial fans were 53.71%, 66.28%, 67.53%, and 71.68 % greater than that in those of the CK soils of Hubei, Jiangxi, Fujian, and Guangdong, respectively, indicating a significant correlation between the soil erodibility K values and physicochemical properties, particularly sand fraction and organic matter content. The results provide new insights into the relationship between soil physicochemical properties and erodibility of alluvial fans, and suggest that improving soil structure might increase soil fertility in the collapsing gully alluvial fan farmland.  相似文献   

11.
Gully erosion reduces agricultural productivity by destroying valuable land resources, increases sediment concentrations, reduces water quality, and fills up reservoirs. Gully rehabilitation has proven to be challenging especially in the high‐rainfall areas of the Ethiopian Highlands and has therefore had limited success. This paper describes a successful low‐cost gully rehabilitation effort with community participation in the Birr watershed in the Blue Nile basin that begun in early 2013. Initially, farmers were reluctant to participate for religious reasons, but with the aid of local priests and respected elders, community discussions, and a visit to a rehabilitated gully, a consensus was reached to rehabilitate a 0·71‐ha upland gully. The rehabilitation measures consisted of regrading the gully head at a 45° slope, constructing low‐cost check dams from locally available materials, and planting Pennisetum purpureum grass and Sesbania sesban. At the end of the first post‐implementation rainy season, 2,200 tons of soil was conserved by the constructed check dams and newly planted vegetation, compared with soil losses of 680 and 560 tons in two untreated, nearby gullies. In 2014, an additional 3,100 tons of soil was conserved. In 2013, the marginal rate of return (MRR) on the gully rehabilitation investment was 2·6 based on the value of increased forage production alone. When we include trapped soil nutrient values, the rehabilitation MRR was increased to 10. Although these numbers are impressive, the best proof of the success was that farmers on their own initiative rehabilitated an additional five gullies in 2014. Copyright © 2015 John Wiley & Sons, Ltd.  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.
野牛沟为大渡河流域中段具代表性的一条泥石流沟,其充足的物源储备和地形条件为泥石流的再次暴发提供了有利条件。通过对3种频率下野牛沟泥石流一次冲出固体物质方量、流量和扇形地的沟床条件3个方面的研究,对传统的堵河经验公式进行了修正,并通过对野牛沟泥石流的研究对修正后的经验公式进行了验证。结果表明,在P=1%(100年一遇泥石流)条件下,野牛沟发生泥石流会完全堵塞金汤河;P=2%时(50年一遇泥石流),可能会堵河或部分堵塞;P=5%时(20年一遇泥石流),野牛沟泥石流不会造成堵河。研究结果验证了修正后堵河公式在研究区域内的通用性,为泥石流灾害提前识别和预防提供了可靠的方法。  相似文献   

14.
Data populations of Corixidae in 55 water bodies are considered. There is a significant correlation (p0·07 ? <0·001) between the distribution of each of six species of Corixidae and the conductivity of water bodies. Similarly, two species show significant correlations (p 0·07 ? <0·001) with a function of lake area and shape. There is also a significant correlation (p <0·001) between conductivity and bicarbonate ion-chloride ion ratios. It is argued that corixid populations may give an indication of the nature of water bodies and provide a valuable means of comparison for both investigation and conservation. A quantitative method of data treatment is described which facilitates comparison.  相似文献   

15.
Soil degradation is a serious problem in the central and northern Highlands of Ethiopia. It has been so for several decades as a result of over exploitation and mismanagement. Relocation of a portion of the population from these regions to the relatively less populated Southwestern Highlands has taken place for decades to try to address the problem. However, such mass resettlements have caused severe soil degradation problems in many destination areas in the Southwestern Highlands. The aim of this study was to assess the problem of soil degradation using the caesium‐137 isotope and to test its value for erosion study in the region. The adapted USLE was applied to compare results from the caesium‐137 isotope studies. Along a deforestation continuum, fields cultivated for various years were studied for erosion. From a reference grazing land plot, total caesium‐137 fallout of 2026 ± 176 Bq m−2 with a CV of 24·6 per cent was recorded showing the presence of sufficient fallout to apply the technique. Erosion in cultivated fields was estimated against this reference using conversion models. Results from the Proportional Model |−13·9 ± 2·7|and the adapted USLE |12·3 ± 2·6| were not significantly different (p < 0·05), meaning the technique provides reliable results. A positive relationship was observed between severity of erosion and time of cultivation after forest clearing (R2 = 0·78). The mean annual loss of soil from cultivated land, 14·9 ± 2·9 t ha−1 y−1, is already beyond the tolerable threshold and might exacerbate further clearing of forests for cultivation if the land is not properly managed. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

16.
Agricultural soils are considered to have great potential for carbon sequestration through land‐use change. In this paper, we compiled data from the literatures and studied the change in soil organic carbon (SOC) following the ‘Grain‐for‐Green’ Programme (GGP, i.e., conversion from farmland to plantation, secondary forests and grasslands) in China. The results showed that SOC stocks accumulated at an average rate of 36·67 g m−2 y−1 in the top 20 cm with large variation. The current SOC storage could be estimated using the initial SOC stock and year since land use transformation (Adjusted R2 = 0·805, p = 0·000). After land use change, SOC stocks decreased during the initial 4–5 years, followed by an increase after above ground vegetation restoration. Annual average precipitation and initial SOC stocks had a significant effect (p < 0·05) on the rate of change in SOC, while no significant effects were observed between plantation and natural regeneration (p > 0·05). The ongoing ‘Grain‐for‐Green’ project might make significant contribution to China's carbon sequestration. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
Based on a 28‐year in situ experiment, this paper investigated the impacts of organic and inorganic fertiliser applications on soil organic carbon (SOC) content and soil hydraulic properties of the silt loam (Eumorthic Anthrosols) soils derived from loess soil in the Guanzhong Plain of China. There were two crop (winter wheat and summer maize) rotations with conventional tillage. The treatments included control without fertiliser application, organic manure application (M), chemical fertiliser application (NP), and the application of organic manure with chemical fertiliser (MNP). The results showed that the 28‐year organic manure applications (M and MNP) significantly (p < 0·05) increased SOC content at surface layer (0–10 cm), but the effect of chemical fertilisers alone on SOC was not significant. Organic manure treatments (M and MNP) apparently improved soil hydraulic properties. Compared with control, field capacity and total porosity significantly (p < 0·05) increased while soil bulk density significantly (p < 0·05) decreased for organic manure applications. The M and MNP treatments increased soil water retentions by 3·2–10·8%, which was dependent of suction tensions. However, the NP treatment had no significantly impact on soil water retention compared with control. Neither organic nor inorganic fertiliser applications significantly changed saturated hydraulic conductivity. However, a clear difference was observed for unsaturated hydraulic conductivity between the M and the control at 0–5 cm. Overall, long‐term applications of organic manuring increased SOC content and amended soil hydraulic properties. However, the effects of chemical fertilisers on these soil properties were limited. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

18.
Overgrazing contributes to rangeland degradation altering plant community composition, erosion and biodiversity. Little unanimity in the literature exists on the effects of livestock grazing on soil carbon and biodiversity, in part, due to uncontrolled grazing pressure from native and feral animals. Paired paddock contrasts at three, long‐term (>8 years) study locations in the southern Australian rangelands were used to examine the effects of managing grazing intensity through the use of exclusion fencing and rotational grazing on soil organic carbon (SOC), soil nitrogen (TN), ground cover and biodiversity (flora and invertebrates). Grazing management had no effect on SOC or TN on grey soils (Vertisols), but for red soils (Lixisols), significantly higher levels of SOC were found for both the 0 to 5 and 5 to 10‐cm soil depths (0·3% and 0·27% respectively) and associated with increased TN. We found strong and consistent relationships among SOC and higher perennial (p < 0·001), higher litter (p < 0·05) cover and close proximity to trees (p < 0·05). Managing grazing intensity resulted in significantly higher perennial ground cover (p < 0·001) on Vertisols (8·9 to 11%) and Lixisols (12·5 to 15%) and higher plant diversity (both native and exotic) but negatively impacted invertebrate diversity, indicating trade‐offs between production and resources. We provide evidence that the effects of grazing management on SOC are mediated by ground cover and increased organic matter supply and/or reduced soil carbon redistribution (erosion), which indicates that the management of grazing intensity may provide a tool to avoid soil carbon loss in rangelands. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

19.
Soil erosion is a major threat to food security in rural areas of Africa. Field experiments were conducted from 2011 to 2014 in Majulai and Migambo villages with contrasting climatic conditions in Usambara Mountains, Tanzania. The aim was to investigate the effectiveness of mulching in reducing soil erosion and restoring soil fertility for productivity of maize (Zea mays) and beans (Phaseolus vulgaris) under miraba, a unique indigenous soil conservation measure in the area. Soil loss was significantly higher (p < 0·05) under miraba sole than under miraba with mulching, for example, 35 versus 20 and 13 versus 8 Mg ha−1 y−1 for Majulai and Migambo villages, respectively, in 2012. Soil fertility status was significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, for example, 0·35 versus 0·25% total N, 37 versus 22 mg kg−1 P and 0·6 versus 0·2 cmol(+) kg−1 K for the Majulai village; and 0·46 versus 0·38 total N, 17·2 versus 10·2 mg kg−1 P and 0·50 versus 0·2 cmol(+) kg−1 K for the Migambo village. Maize and bean yields (Mg ha−1) were significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, 2·0 versus 1·3 for maize and 0·9 versus 0·8 for beans in Majulai; and 3·8 versus 2·6 for maize and 1·0 versus 0·8 for beans in the Migambo village in 2012. This implies that Tughutu mulching is more effective in improving crop yield than Tithonia, although both could potentially protect the arable land from degradation caused by water erosion under miraba. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

20.
Climatic warming is presumed to cause topsoil drought by increasing evapotranspiration and water infiltration, and by progressively inducing land degradation in alpine meadows of the Qinghai–Tibetan Plateau. However, how soil moisture and temperature patterns of degraded alpine meadows respond to climate warming remains unclear. A 6‐year continuous warming experiment was carried out in both degraded and undegraded alpine meadows in the source region of the Yangtze River. The goal was to identify the effects of climatic warming and land degradation on soil moisture (θ ), soil surface temperature (T sfc ), and soil temperature (T s ). In the present study, land degradation significantly reduced θ by 4·5–6·1% at a depth of 0–100 cm (p  < 0·001) and increased the annual mean T sfc by 0·8 °C. Warming with an infrared heater (radiation output of 150 W m−2) significantly increased the annual mean T sfc by 2·5 °C (p  < 0·001) and significantly increased θ by 4·7% at a depth of 40–60 cm. Experimental warming in degraded land reversed the positive effects of the infrared heater and caused the yearly average θ to decrease significantly by 3·7–8·1% at a depth of 0–100 cm. Our research reveals that land degradation caused a significant water deficit near the soil surface. Experimental warming aggravated topsoil drought caused by land degradation, intensified the magnitude of degradation, and caused a positive feedback in the degraded alpine meadow ecosystem. Therefore, an immediate need exists to restore degraded alpine meadow grasslands in the Qinghai–Tibetan Plateau in anticipation of a warmer future. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号