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1.
苏打盐碱土地区不同土地利用类型的地表水分蒸渗特征 总被引：6，自引：0，他引：6
选择东北松嫩平原西部典型地区,采用FAO56方法和实际田间定期观测相结合,分析了当地旱田和碱斑地两种主要土地利用类型地表水分蒸散和入渗特征及其对土地盐碱化的影响。结果表明:对于玉米地这样相对蒸散量比较大的旱作农田来讲,水分亏缺和盐碱化主要发生在根层,而对表层土壤,即使在偏干旱年份,仍然有足够的水分入渗量来维持盐分平衡。碱斑地随着植被的破坏,总体上表层土壤蒸发和入渗量基本平衡,但是由于土壤水分蒸发过程中盐分浓度要比入渗过程中的盐分浓度大,表层土壤依然向盐碱化方向发展。采取适当的土地利用方式,建立耗水量与该地区降雨水平相适应的植被系统是控制区域土地盐碱化发展的关键。 相似文献
2.
沙地降雨入渗水分动态 总被引：21，自引：3，他引：21
应用土壤水动力学基本原理，结合先进仪器的使用，从动力学角度，以能态观点定量研究沙地水分入渗动态。通过野外现场观测，分析不同深度含水率和吸力随时间变化过程，研究沙地降雨入渗水分传递过程，探讨入渗条件下沙地水分运动的动力学机制和特征。 相似文献
3.
In Brazil, the semi-arid tropical zone comprises approximately 12% of its territory. In this region the Caatinga is the only exclusively Brazilian biome. Nonetheless, there is a lack of knowledge about its structure and functioning. This study aimed at assessing the effective depth of the root system of the preserved Caatinga biome, as well as its temporal and spatial variation. To this end, 72 soil profiles were evaluated, both in the dry and rainy seasons, including three soils (Acrisol, Luvisol and Regosol) and four profiles per trench, with three replications. The results showed that the effective depth of the Caatinga roots range from 0.60 m to 0.78 m in non-restrictive deep soils, three times smaller than values commonly used in hydrological models. Vegetation adapted to shallow soils, presenting effective root depth as low as 0.36 m. The effective depth of the roots showed spatial homogeneity, for each soil-vegetation association, regardless of the proximity of large trees. It was also observed that the root depth in the dry season is, on average, 10 cm shorter than that of the rainy season. This can indicate an adaptation strategy, generating soil secondary porosity to enhance infiltration in the root zone. 相似文献
4.
Valdemir Antoneli Edivaldo Lopes Thomaz Joo Ansio Bednarz 《Singapore journal of tropical geography》2019,40(1):34-49
The Brazilian faxinal is a traditional agrosilvopastoral system, which combines extensive grazing, subsistence cropping and low impact forest extraction, managed within a communal property system. Today it is at serious risk of disappearing due to increasing grazing pressure and logging activities that are leading to environmental problems such as forest fragmentation and soil degradation. The objectives of the study were to: a) evaluate soil physical degradation levels in different grazing areas within the faxinal system; and b) correlate soil degradation, fodder quantity and livestock dynamics in different pasture areas according to the household's location. Landscape mapping, vegetation surveys, and livestock grazing dynamics were assessed. In addition, soil physical parameters were evaluated for each land use (e.g., resistance, bulk density, porosity, moisture, and water infiltration rates). Results showed that livestock grazing and household locations are the main driving forces that lead to forest fragmentation. The household location creates three interrelated gradients in the communal grazing land: 1) soil physical degradation decreases from the pasture areas to araucaria forests; 2) fodder quantity decreases from pastures to araucaria forests; and 3) the livestock grazing intensity decreases from pastures to araucaria forests. In addition, some management practices to mitigate land degradation, including improvement of pastures, installation of removable troughs for drinking water in the upland areas and restriction of livestock from the riparian zone, have been proposed. 相似文献
5.
绿洲是由农田、林地、沙荒地、湖泊和湿地等多种景观组成的镶嵌体,农田、林地、沙荒地是该镶嵌体的主要组成部分。探究不同土地利用土壤入渗特征对深入了解绿洲内部水循环和水转化具有重要意义。本文研究了农田、防护林地和沙荒地3种土地利用方式0—40 cm土层土壤物理性质及入渗特征,探讨不同土地利用对土壤入渗特征的影响及其驱动机制。结果表明：（1）不同土地利用土壤质地差异显著,较沙荒地,防护林地和农田0—40 cm土层土壤黏粉粒含量分别增加了100.25%和285.23%,土地利用对干密度和总孔隙度影响较小,仅防护林地表层（0—10 cm）干密度减小（1.37±0.12 g·cm-3）、总孔隙度增大（48.22%±4.56%）;（2）不同土地利用方式土壤入渗性能存在显著差异,与沙荒地相比,农田和防护林地土壤初始入渗率分别减小了75.49%和37.05%,饱和导水率分别减小了80.04%和42.02%;（3）不同土地利用方式显著影响土壤水流模式,防护林地和农田土壤水流入渗非均匀性显著高于沙荒地,其优先流比分别是沙荒地土壤的3.84倍和5.46倍;（4）土壤初始入渗率和饱和导水率与黏粉粒含量显著负相关,优先流比和长度指数与黏粉粒含量和总孔隙度显著正相关,土壤入渗性能和水流模式均受土壤质地的影响,表明土壤质地是土地利用对土壤入渗影响的关键因子。 相似文献
6.
The agricultural landscape in the semi-arid central Ebro Basin is changing from dry farming towards land abandonment. This study aims to describe quantitatively the influence of this land use change onto wind erosion susceptibility in this region. Additionally, the effects of tillage operations on wind erosion rates were evaluated. A portable wind tunnel was used to assess the relative sediment loss rates at three test sites near Zaragoza. Three different land use systems varying in crust disturbance level were investigated – (1) fallow land with undisturbed physical soil crusts, (2) simulated sheep trampling and (3) conventional tillage (dry farming).The results show that simulations on undisturbed crusted soils produce little soil loss. Consequently, wind erosion can be considered as negligible on these surfaces. Simulated sheep trampling during wind tunnel test runs produce 10 times higher sediment losses than simulations on undisturbed crusted soils. Highest sediment losses (50 times) were observed from rolled surfaces. Because of the ongoing extensification process, the distributions of physical soil crusts will most probably further increase. According to the results, this would lead to a reduction of wind erosion susceptibility in the central Ebro Basin depending on intensity and time of sheep pasturing and tillage. 相似文献
7.
John Boardman 《Applied geography (Sevenoaks, England)》1983,3(4):317-329
Few measurements of the rate of soil erosion from agricultural land in Britain have been published. Loamy soils in England may be particularly vulnerable to erosion. Thus, in a field of strawberries near Albourne at least 181 t ha−1 of fine loamy soil was eroded in a 9-month period; this is almost 100 times greater than a suggested ‘acceptable’ figure. Factors which have induced erosion at Albourne are: the removal of field boundaries; the choice of crop which left the ground bare for a prolonged period ; and the working of the land downslope. Other factors contributing to erosion are the low clay and organic matter content of the soil. The soil slakes and the resultant crust reduces the rate of infiltration of rainfall into the soil and this produces overland flow. Large amounts of rainfall are not necessary to cause erosion. Erosion in the Albourne area is probably a relatively recent phenomenon brought about by changes in land use. 相似文献
8.
于2016年7~12月和2017年4月的旱、雨季期间,以金沙江干热河谷苴那小流域内的银合欢（Leucaena Benth）林地、车桑子（Dodonaea angustifolia）灌丛地和扭黄茅（Heteropogon cantortus）草地为研究对象,通过网格法和土钻法采集并测定了（0~100 cm）土层的土壤含水量,应用经典统计法和地统计学方法分析该区域不同林草植被下坡面土壤水分的动态变化特征。结果表明：（1）研究区土壤含水量总体较低,雨季显著大于旱季,旱、雨季均表现为灌丛地>草地>林地,呈中度至强度变异（0.07~0.28之间）。（2）不同林草植被下旱、雨季土壤水分具有相似的空间自相关性,自相关系数均由正向负转变,但由正向负转变的滞后距离有所不同,且雨季大于旱季,呈中等或强等空间自相关性。（3）不同林草植被下的土壤水分空间结构不同,林地、灌丛地和草地旱雨季最佳拟合模型均为球状模型;相同林草植被下各土层旱、雨季土壤水分的空间分布特征相似,但旱季的分布格局差异更显著,不同林草植被下深层土壤水分分布比表层土壤水分的分布更为复杂,土壤水分呈明显的斑块或条带状分布,含水量高值区和低值区位置不固定。总之不同林草植被类型会改变局部地段土壤水分空间分布,降雨会加强这种差异的趋势,但土壤水分仍具一定空间连续性。 相似文献
9.
《自然地理学》2013,34(1):54-78
The sensitivity of the near-surface weather variables and small-scale convection to soil moisture for Western Kentucky was investigated with the aide of the MM5 Penn State/NCAR mesoscale atmospheric model for three different synoptic conditions in June 2006. The model was initialized with FNL reanalysis from NCEP containing soil moisture data calculated with the Noah land surface model. Dry and wet experiments were performed in order to find the influence of soil moisture specification on boundary layer atmospheric variables. Dry experiments showed less available atmospheric moisture (between 2 and 6 g kg-1) at near-surface levels during all synoptic events consistent with slightly deeper boundary layers, higher lifting condensation levels and a larger Bowen ratio. As expected, precipitation rates were generally smaller than those of the control simulation. However, during a moderately strong synoptic event in early June, the dry experiments displayed larger precipitation rates compared to the control experiment (up to 5 mm in 3 hr) as the soil volumetric fraction was decreased from 0.05 to 0.15 (m3 m-3) with respect to the control simulation. Precipitation rates in wet experiments were also modulated by characteristics of synoptic conditions. In early June, precipitation rates slightly were larger than the control run (from 0.2 mm 3 h-1 to 1.4 mm 3 h-1) while in the other periods precipitation was reduced significantly. Both dry and wet anomaly experiments experienced reduced precipitation for different reasons. It was found, lifting condensation level, CAPE and low Bowen ratio were not sensitive markers of changes in soil moisture. Equivalent potential temperature was a better indicator of precipitation changes among all experiments. The controlling factor in these responses was the soil moisture content forcing vertical velocities. Thermodynamic conditions such as local stability played a less substantial role in controlling the precipitation processes. It was found that the response of planetary boundary layer variables under a variety of soil moisture conditions can be modified due to degree of synoptic forcing. Weak-to-moderate forcing favored convection while strong synoptic forcing tended to suppress it under dry soil moisture conditions. Wetter soils did not produce a response in horizontal wind fields as large as under the drier soils. 相似文献
10.
The direct short-term impact of three rates of stocking (4, 8 and 16 small-stock units [SSU] ha?1) was quantified in terms of soil characteristics of arid Nama Karoo vegetation (subshrub/grass). Mature Merino wethers grazed in the experimental plots throughout May in 1995 and 1996 (the plots were not subjected to grazing at any other time). Stocking rate proved inversely related to initial infiltration rate. Light trampling (4 SSU ha?1) loosened the topsoil sufficiently to increase the initial infiltration rate: infiltration capacity of soil in fields stocked at 4 SSU ha?1 and 16 SSU ha?1 was 17% higher and 14% lower respectively than that of soil of ungrazed rangeland over the two grazing periods. Increased soil compaction and greater bulk density due to higher stocking rates significant decreased the infiltration rate. Compared to ungrazed rangeland stocking rates of 4, 8 and 16 SSU ha?1 over the two grazing periods increased bulk density respectively by 2.73%, 6.67% and 8.945% and compaction by 10.90%, 16.78% and 20.90%. No grazing also increased bulk density and soil compaction and decreased infiltration rate. Light stocking (4 SSU ha?1) influenced all soil parameters most favourably. From a hydrologic point of view, grazing levels and rotation schemes need to be tailored for sustainable utilization of arid subshrub/grass vegetation by livestock. 相似文献
11.
陕西咸阳人工林地土壤干层研究 总被引：20，自引：4，他引：16
根据咸阳庞西村苹果林地、梧桐林地和草地土壤含水量测定,研究了0~6m土壤含水量的变化和土壤干层特点与分布。结果显示, 咸阳人工林地从表层向下含水量呈现由高到低再到低的变化;10龄苹果林地2~4m深处土壤含水量平均为8.3%,12龄梧桐林2~4m深处土壤含水量平均为8.6%,均发育了明显的土壤干层;4龄苹果林下土层有干化显示,但无干层发育;草地土层含水量明显较苹果林地高,无土壤干化的显示。研究表明,土壤干层形成的具体原因一是降水量少决定的薄膜水带埋藏深度小,二是薄膜水的运移速度缓慢和含水量低。为保持人工林基本正常的生长和土壤水的正常运移,应避免严重的土壤干层出现。咸阳附近土壤干层的出现表明土壤干层在黄土高原广泛分布,该区的植被恢复首先应以疏林或森林草原为主,待土壤水分改善后再考虑恢复森林植被。 相似文献
12.
13.
Antonio Ceballos Jos Mart&#x;&#x;nez-Fernndez Fernando Santos Pilar Alonso 《Journal of Arid Environments》2002,51(4):501
This paper examines the soil-water behaviour of sandy soils representative of a broad area in the Duero river basin (Spain), with semi-arid bioclimatic characteristics. Soil-moisture measurements of the first 25 cm of soil profile were taken using time domain reflectometry (TDR) methodology. The infiltration process was studied by means of field experiments combining rainfall simulations and TDR techniques. Finally, a set of hydrodynamic variables was calculated in the laboratory (i.e. available soil-water content, soil-water-retention curves and hydraulic conductivity).The average available soil-water content is 0·07 cm3 cm−3, in accordance with the predominance of the sandy textural fraction (85%). The rainfall simulation experiments show that infiltration prevails over overland flow, with a steady-state infiltration rate higher than rainfall application (40mmh−1) in most cases; a low water-retention capacity was also observed. The evolution of soil-moisture over time indicates a close dependence on intra-annual rainfall variability due to the low water-retention capacity of sandy soils. With a maximum water-storage capacity of around 0·18 cm3 cm−3, the soils studied show high sensitivity to dry spells and may remain with <50% of the available soil-water content for several months during the year. 相似文献
14.
西双版纳热带山地利用过程中的土壤退化 总被引：3，自引：1，他引：3
土壤养分和土壤微生物生长代谢水平的衰退是热带山地退化的重要表现形式。二者的变化基本是一致的。即从热带雨林→33a次生林→6a轮歇地→4a轮歇地→旱谷地→橡胶林→荒草坡呈降低趋势；相对于热带雨林而言，不同利用方式土壤微生物和土壤养分状况均有不同程度的下降，且随退化程度增高减幅增大，土壤微生物衰减的速率比土壤养分的衰减更快。说明山地的退化严重影响着土壤微生物的生长代谢水平以及它们之间的协同作用，从而影响土壤碳氮循环代谢途径。降低土壤肥力水平。 相似文献
15.
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
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
16.
Effect of apple production base on regional water cycle in Weibei upland of the Loess Plateau 总被引：2，自引：0，他引：2
Weibei upland of the Loess Plateau containing Xianyang city, northern part of Weinan city, southern part of Yan'an city and a part of Tongchuan city covers a total area of 30,000 km2 with an elevation of 900 to 1500 m above sea level and annual average precipitation is from 550 to 600 mm. The Luochuan and Changwu uplands are two of those large uplands in Weibei region. These uplands have been identified as a commercial apple production base for its special features of topography and climate… 相似文献
17.
通过对青海湖北刚察县沙流河附近厚度15 cm、20 cm、30 cm、40 cm薄土层的土壤含水量的测定,研究了此区土壤水分含量和水循环等问题.研究结果表明,沙柳河附近40 cm以上土层以粗粉砂为主.薄土层含水量从表层向下呈现出低-高-低的变化趋势,这是表层水分易于蒸发、中部蒸发较少和下部水分易于入渗流失的结果.虽然该区土壤在0.40m以上含水量较高,没有土壤干层发育,但如按1 m厚度土壤和1.5m厚度土壤计算,该区薄土层水分不足,并由中度干层和严重于层发育,±壤水分为负平衡.与厚土层相比,该区薄土层分布区土壤水分存在形式多为薄膜水,含水量较低,蓄水量少,土壤水库调节能力差,易于发生荒漠化,这样的地区应该是青海湖流域生态环境保护的重点地区. 相似文献
18.
Weibei upland, located in southern part of the Loess Plateau, is a commercial apple production base in China. The enlargement of apple-planting area has a great impact on the regional water cycle. The effects of different land use on hydrological parameters are compared and studied in this paper. The main results are as follows: (1) The initial and steady infiltration rates in apple orchard are higher than those in other land use types such as grassland, idle land and farmland. Their initial rates of infiltration are 0.823 cm/min, 0.215 cm/min, 0.534 cm/min and 0.586 cm/min in apple orchard, grassland, idle land and farmland respectively. Their steady infiltration rates are 0.45 cm/min, 0.038 cm/min, 0.191 cm/min and 0.155 cm/min respectively. (2) There is no runoff generated in plot of apple orchard in all 8 storm events in observed natural rainfalls, while runoff is generated in winter wheat plot, corn plot and alfalfa plot with runoff coefficients of 2.39%, 1.58% and 0.31% respectively. (3) The transpiration of apple trees is strong and thus soil moisture is gradually depleted. The average soil water contents in 3-9 m soil profile in Changwu plots with apple trees of 14 and 32 years in age are 11.77% and 11.59% and in Luochuan plots with those of 15 and 28 years in age are 11.7% and 11.59% respectively, which are nearly 9.0% of wilting moisture of Changwu soil and 8.6% of wilting moisture of Luochuan soil. The pathway of rainfall percolating to groundwater is hindered by dry soil profile. 相似文献
19.
The interception and evaporation of fog, dew and water vapour by soils and lichens in a coastal desert were measured with automated lysimeters at hourly intervals spanning a 12 month period. Fog water and lichen thalli were chemically analysed at monthly intervals. The chemical composition of the lichens did not correspond with the elemental concentration sequence in collected fog water of oceanic origin. However, elemental concentrations were generally greater in Teloschistes capensis, whose canopy area to dry mass ratio was higher than that of Ramalina sp., indicative of a more efficient mineral absorbing thinner thallus. Non-rainfall atmospheric moisture intercepted by the bare gypsum soil was 10 times greater and that solely by the lichens up to 3 times greater than the measured rainfall amount. Water vapour contributed the highest percentage of the non-rainfall atmospheric moisture absorbed by the lichens and bare soil, followed by fog, with dew contributing the smallest percentage. T. capensis displayed two-fold greater interception and two-thirds less evaporation of non-rainfall atmospheric moisture than Ramalina sp. which may explain T. capensis 3 times greater canopy cover. Our results substantiate the crucial role of atmospheric water vapour and fog in driving lichen photosynthesis and distribution in a coastal desert. 相似文献
20.
In-situ rainwater harvesting and gravel mulch combination for corn production in the dry semi-arid region of China 总被引：7，自引：0，他引：7
A field study was conducted to determine the effect of a combination of ridge and furrow method of in-situ rainwater harvesting with gravel mulch on corn production, soil moisture storage, and water-use efficiency in the dry semi-arid region of China. Results showed that plastic-covered ridges had an average runoff efficiency (runoff/rainfall) of 87% as compared to 7% for bare ridges, and could generate runoff at a threshold value of 0·8±0·2 mm rainfall. Bare ridges produced runoff only under high intensity rainfall events, and was ineffective for harvesting rainfall in the study area. The plastic-covered ridge and gravel-mulched furrow method of rainwater harvesting was effective in conserving moisture and increasing yield and water-use efficiency. The grain yield in this treatment was 1·9 times that of the conventional flat soil cultivation (control), and the water-use efficiency was 1·8 times that of the control. The good performance of the film-covered surface ridges and gravel-mulched furrows is attributed to the better utilization of light rains, improvement of infiltration in the root zone, and suppression of evaporation losses. 相似文献