火干扰对森林土壤斥水性的影响研究进展

土壤斥水性是指水分不能或很难湿润土壤颗粒表面的现象,很多植被类型及气候带森林存在土壤斥水性。土壤斥水性受水分、温度、干湿交替、土壤质地、植被类型等生物和非生物因子的影响。而火干扰是森林生态系统土壤斥水性的重要影响因子,使森林土壤斥水性增强,渗透率降低,地表截留体减少,从而增加地表径流和土壤侵蚀。就火干扰对土壤斥水性的发生机理及其对水文过程的影响进行了较为全面的总结和讨论,并指出目前存在的问题和未来的研究重点。森林火灾后火烧迹地地表径流和土壤侵蚀显著增加,定量预测火灾后土壤斥水性对径流与侵蚀的影响比较困难,因此,基于不同尺度和自然降雨的火灾后斥水性对地表径流和土壤侵蚀的实验及长期定位观测是今后的研究方向与重点。     

喀斯特坡面生物结皮发育特征及其对土壤水分入渗的影响

作为地表植被恢复的先锋种群和景观的重要组成部分,生物土壤结皮(BSCs)对地表过程具有重要影响.为探明喀斯特地区BSCs发育特征及其对土壤水分入渗的影响,本研究选取喀斯特代表性坡面开展了BSCs实地调查和人工模拟降雨试验,探究了BSCs覆盖土壤的水分入渗过程,试验设计了5个BSCs盖度水平(0、28％、40％、70％、...     

Field measurement of soil water repellency and its impact on water flow under different vegetation

Numerous recent laboratory studies have shown that vegetation can influence soil water flow by inducing very low levels of water repellency. In this study we extended on this previous research by developing a field-based test using a miniature infiltrometer to assess low levels of water repellency from physically based measurements of liquid flow in soil. The field-based test was verified through a simple laboratory experiment and then applied to determine the impact of vegetation and antecedent soil water content. The soil hydraulic properties determined were hydraulic conductivity, sorptivity, as well as the persistence and index of water repellency. Tests were conducted following a dry spell and wet spell on (1) forest soil (0 cm depth), (2) glade soil (0 cm depth) and (3) glade soil (50 cm depth). It was found that both the persistence and index of water repellency, R, decreased in the order as follows: forest soil > glade soil (0 cm) > glade soil (50 cm) for both dry and wet spell. The range of values of R was 0.28 (wettable) to 360 (highly water repellent), which affected hydraulic conductivity k _r(−2 cm). R increased and hence k _r(−2 cm) decreased in the order: forest soil < glade soil (0 cm) < glade soil (50 cm) for both the dry and wet spell. There were clear interactions between vegetation and changes to water flow caused by presence of repellency. Presented at the International Conference on Biohydrology, Prague, Czech Republic, 20–22 September 2006.     

不同初始含水率下粘质土壤的入渗过程

土壤入渗是降雨渗入土体形成土壤水的基本水文过程,土壤渗透能力影响着地表径流和土壤侵蚀强度。土壤初始含水量决定了入渗初期的土水势,是影响土壤入渗过程的重要因素。利用环刀法,观测了三峡库区林地和草地的土壤入渗过程,对比分析了不同初始含水率下土壤入渗率和常用入渗模型的适宜性。结果表明,随土壤初始含水率的增大,林地和草地下土壤初始入渗率减小,入渗趋于稳定所需时间缩短,累积入渗量和稳定入渗率增大。土壤含水率为12%的林地初始入渗率为8.95 mm/min,是含水率40%林地初始入渗率的4倍,但1h累积入渗量仅是含水率40%林地的2/3。有机质含量丰富的草地土壤入渗过程对初始含水率的敏感性较弱,干湿草地相比较入渗参数的差异不如林地明显。随时间的延长,土壤入渗率逐渐降低,入渗曲线渐趋平缓,最小二乘法拟合结果显示Horton模型对林地和草地下土壤入渗过程的拟合效果较好,且模型参数具有物理意义,是分析和预测三峡库区林草覆盖下土壤入渗过程的适宜模型。     

Water repellency of post-boggy soils with a various content of organic matter

The objective of this study was to estimate the water repellency of post-boggy soils in north-eastern Poland. Potential water repellency was determined based on the water drop penetration time (WDPT) test and the molarity of an ethanol droplet (MED) test. A total of 276 soil samples with a varied organic carbon (OC) content, ranging from trace amounts in sandy subsoils to 44.4% in organic soils, were analyzed. The investigated material represents peat-muck soils (Eutri-Sapric Histsols) and muck-like soils (Arenic Gleysols, Areni-Humic Gleysols, Gleyic Arenosols). The mineral matter of the analyzed soils comprised loose sand. The obtained results indicate that peat soil formations are marked by higher potential water repellency than muck soil formations. The highest WDPT values (16 390 s) were reported in respect of an alder peat sample with 41.9% OC content, collected at a depth of 55–60 cm. In the group of muck soils, a sample with 36.7% OC content, collected at a depth of 15–20 cm, was marked by the highest water repellency (WDPT 10 492 s). The water repellency of the studied soils is dependent on organic matter content, and it is manifested only when organic matter content is higher than 20%. Soils with OC content of up to 12% show low water repellency or are hydrophilic. Organic soil formations (>12% OC) are characterized by a varied degree of water repellency, but WDPT values in excess of 2000 s are reported only in respect of soils containing more than 35% OC. A significant positive correlation between the content of organic matter, organic carbon, total nitrogen and water repellency was observed in the entire studied population (n = 276). A significant positive correlation was also found between WDPT values and the C:N ratio, while a significant negative correlation was reported in respect of .     

物理结皮和生物结皮的斥水特征及其对水分入渗的影响

土壤结皮是一种常见的自然现象,但由于结皮形成机制的不同,会产生不同的亲水性和斥水性,从而影响土壤的水力学特征与水文循环。本研究利用水滴穿透时间法测定了野外不同植被下物理结皮和生物结皮的斥水特征,利用扫描电镜观测了结皮的表面形态,并用微型入渗装置测定了结皮及其对照土壤的入渗特征。结果表明: 1)物理结皮的平均水滴穿透时间(WDPT)为3.3 s,对照为0.9 s,表现为亲水性;生物结皮的平均WDPT介于20.9～140.9 s,是无结皮的2.8～19倍,其中君迁子和刺槐林下的生物结皮平均WDPT分别为134.5和140.9 s。2)与对照相比,物理结皮累积入渗量、平均入渗速率和吸湿力分别降低了0～4.3%、3.5%～5.1%和27.2%～90.1%,生物结皮分别降低了0～25%、1.4%～28.2%和36.0%～84.9%。3)无论是否存在结皮,利用Philip模型拟合处理入渗数据均存在“曲棍球状”曲线;曲线上斥水性停止时间(WRCT)之前,点源微入渗以水平方向上的扩散为主,WRCT点以后以垂直方向上的入渗为主,土壤结皮的形成延长了该转折点的形成时间。综上,物理结皮是无机矿质颗粒堵塞了表层土壤,不影响斥水性的变化;生物结皮表现为斥水性有机物对土壤结构的影响,增强了其斥水性。物理结皮和生物结皮均会降低土壤的累积入渗量和平均入渗速率,但物理结皮主要影响土壤的吸湿力,对稳定入渗速率影响不大;生物结皮不仅降低了土壤吸湿力,还增加了稳定入渗速率。     

Effect of maize canopy and water repellency on moisture patterns in a Dutch black plaggen soil

Man-made raised sandy soils in the Netherlands are classified as brown or black plaggen soils. When dry, the brown soils are wettable, but the black soils are water repellent. For one growing season, transects were sampled in a maize cropped black plaggen soil at the Heino experimental farm. Due to interception and stemflow, water was concentrated near the roots of the maize. Between the maize rows, higher soil water contents were found in microdepressions, due to rainwater dripping to the ground from overhanging leaves. Redistribution of soil water from wet to dry areas was restricted by the water repellency of the dry sand. As a consequence, there was a distinct variation in soil moisture content. These irregular wetting patterns did not induce preferential downward flow, but widened over time; because the dry, water repellent subsoil impeded and resisted infiltration into the deeper subsoil.     

Burrowing by translocated boodie (Bettongia lesueur) populations alters soils but has limited effects on vegetation

Digging and burrowing mammals modify soil resources, creating shelter for other animals and influencing vegetation and soil biota. The use of conservation translocations to reinstate the ecosystem functions of digging and burrowing mammals is becoming more common. However, in an increasingly altered world, the roles of translocated populations, and their importance for other species, may be different. Boodies (Bettongia lesueur), a commonly translocated species in Australia, construct extensive warrens, but how their warrens affect soil properties and vegetation communities is unknown. We investigated soil properties, vegetation communities, and novel ecosystem elements (specifically non‐native flora and fauna) on boodie warrens at three translocation sites widely distributed across the species’ former range. We found that soil moisture and most soil nutrients were higher, and soil compaction was lower, on warrens in all sites and habitat types. In contrast, there were few substantial changes to vegetation species richness, cover, composition, or productivity. In one habitat type, the cover of shrubs less than 1 m tall was greater on warrens than control plots. At the two sites where non‐native plants were present, their cover was greater, and they were more commonly found on boodie warrens compared to control plots. Fourteen species of native mammals and reptiles were recorded using the warrens, but, where they occurred, the scat of the non‐native rabbit (Oryctolagus cuniculus) was also more abundant on the warrens. Together, our results suggest that translocated boodie populations may be benefiting both native and non‐native flora and fauna. Translocated boodies, through the construction of their warrens, substantially alter the sites where they are released, but this does not always reflect their historic ecosystem roles.     

Postfire soil water repellency in piñon–juniper woodlands: Extent,severity, and thickness relative to ecological site characteristics and climate

Wildfires can create or intensify water repellency in soil, limiting the soil's capacity to wet and retain water. The objective of this research was to quantify soil water repellency characteristics within burned piñon–juniper woodlands and relate this information to ecological site characteristics. We sampled soil water repellency across forty‐one 1,000 m² study plots within three major wildfires that burned in piñon–juniper woodlands. Water repellency was found to be extensive—present at 37% of the total points sampled—and strongly related to piñon–juniper canopy cover. Models developed for predicting SWR extent and severity had R²_adj values of 0.67 and 0.61, respectively; both models included piñon–juniper canopy cover and relative humidity the month before the fire as coefficient terms. These results are important as they suggest that postfire water repellency will increase in the coming years as infilling processes enhance piñon–juniper canopy cover. Furthermore, reductions in relative humidity brought about by a changing climate have the potential to link additively with infilling processes to increase the frequency and intensity of wildfires and produce stronger water repellency over a greater spatial extent. In working through these challenges, land managers can apply the predictive models developed in this study to prioritize fuel control and postfire restoration treatments.     

三峡库区苔藓生物结皮对土壤水分入渗的影响

在三峡库区王家桥小流域选取以苔藓为优势种的生物结皮样地,以附近无结皮发育的裸地为对照,设计5个盖度水平(1%～20%、20%～40%、40%～60%、60%～80%和80%～100%),采用环刀法测定土壤入渗过程,研究生物结皮盖度对入渗过程的影响。结果表明: 与裸地相比,生物结皮发育可显著提高表层土壤粘结力、孔隙度、黏粒含量、水稳性团聚体和有机碳含量,显著降低土壤容重和砂粒含量。生物结皮促进了土壤水分入渗,初始入渗率、稳定入渗率、平均入渗率和累积入渗量可达裸地的2.0倍及以上,土壤入渗性能随结皮盖度的增大呈先增加后减小的变化规律,在40%～60%盖度下最大。通径分析显示,土壤初始入渗率主要受结皮盖度、土壤容重和有机碳含量的影响,稳定入渗率主要受结皮盖度和土壤容重的影响。Horton模型对三峡库区生物结皮覆盖土壤的水分入渗过程拟合效果最佳。     

荒漠结皮层藓类植物死亡对表层土壤水分蒸发和入渗的影响

水分是荒漠植物生长最主要的限制因子,藓类结皮作为荒漠土壤表层重要覆被物,对土壤水分蒸发入渗具有重要影响。研究表明,在全球气候变化背景下,不确定的降水格局变化导致结皮层藓类植物出现集群死亡现象,但这一过程对荒漠地表土壤水分蒸发与入渗过程的影响及其机理尚不清楚。以古尔班通古特沙漠齿肋赤藓结皮为研究对象,利用便携式渗透计和蒸发仪,研究了结皮层藓类植物死亡对土壤水分蒸发与入渗的影响。结果表明,与裸沙相比,藓类结皮的存在显著抑制了水分入渗,而藓类植物死亡的结皮层抑制作用最大,其初渗速率、稳渗速率和累积入渗量分别是活藓类结皮的39.89%、85.91%及64.48%,仅为裸沙的5.96%、13.13%及20.42%。在水分蒸发初期,裸沙的水分蒸发速率明显高于活藓类结皮和藓类植物死亡的结皮层,但藓类植物死亡的结皮层维持相对稳定的蒸发速率的时间长于裸沙和活藓类结皮,这也导致最终累计蒸发量以藓类植物死亡的结皮层最高、裸沙最低。可见,荒漠生物土壤结皮中藓类植物死亡会明显减少土壤水分入渗、增大水分蒸发,进一步影响荒漠表层土壤水分格局,从而影响生物土壤结皮与维管植物的水分利用关系。     

煤矿复垦区土壤水动力学特性对下渗过程的影响

煤矿复垦区土壤水对植物生长、溶质运移以及土壤环境的变化起着至关重要的作用。定量揭示煤矿复垦区土壤水下渗过程是亟待诠释的关键科学问题。本研究通过测定典型矿区不同深度土壤非饱和导水率、容重、总孔隙度和粒径等水动力学参数,结合染色示踪试验,刻画矿区非饱和带土壤水运移过程。染色示踪结果显示30、60 L和90 L这3种实验下渗水量条件下,水流沿X方向侧向扩散的最大距离分别为10、30 cm和35 cm,沿Y方向侧向扩散的最大距离分别为10、25 cm和30 cm。互相关函数显示随着下渗水量增大,水流扩散作用也在加强,但过多水量并没有明显增加下渗深度和扩散距离。吸力大于300 hpa时,0.01—0.05 mm土壤粒径含量和非饱和导水率呈负相关关系;吸力和非饱和导水率采用指数函数拟合效果较好(r~20.9),对拟合参数a、b和土壤容重(x)进行回归分析:a=0.0015x~2-0.00499x+0.0004,b=0.0583x~2+0.1234x-0.072。同一吸力下土壤容重大的土样非饱和导水率较小;吸力值为300 hpa是非饱和导水率的转折点;非饱和导水率和土壤容重呈现负相关关系,和总孔隙度呈现正相关关系,且二者的相关性随吸力的增加而降低。     

Rise in CO<Subscript>2</Subscript> affects soil water transport through repellency

Several studies have shown improved soil stability under elevated atmospheric CO₂ caused by increased plant and microbial biomass. These studies have not quantified the mechanisms responsible for soil stabilisation or the effect on water relations. The objective of this study was to assess changes in water repellency under elevated CO₂. We hypothesised that increased plant biomass will drive an increase in water repellency, either directly or through secondary microbial processes. Barley plants were grown at ambient (360 ppm) and elevated (720 ppm) CO₂ concentrations in controlled chambers. Each plant was grown in a separate tube of 1.2 m length constructed from 22 mm depth × 47 mm width plastic conduit trunk and packed with sieved arable soil to 55% porosity. After 10 weeks growth the soil was dried at 40°C before measuring water sorptivity, ethanol sorptivity and repellency at many depths with a 0.14 mm radius microinfiltrometer. This provided a microscale measure of the capacity of soil to rewet after severe drying. At testing roots extended throughout the depth of the soil in the tube. The depth of the measurement had no effect on sorptivity or repellency. A rise in CO₂ resulted in a decrease in water sorptivity from 1.13 ± 0.06 (s.e) mm s^−1/2 to 1.00 ± 0.05 mm s^−1/2 (P < 0.05) and an increase in water repellency from 1.80 ± 0.09 to 2.07 ± 0.08 (P < 0.05). Ethanol sorptivity was not affected by CO₂ concentration, suggesting a similar pore structure. Repellency was therefore the primary cause of decreased water sorptivity. The implications will be both positive and negative, with repellency potentially increasing soil stability but also causing patchier wetting of the root-zone.     

原油污染对黄绵土和风沙土水分入渗的影响

原油进入土壤后会堵塞土壤孔隙,影响土壤斥水性,改变土壤水分运动状况.本研究利用土柱模拟的方法,研究了不同原油污染程度(0、0.5％、1％、2％、4％)对黄绵土和风沙土水分入渗过程的影响.结果 表明:随着原油含量的增加,两种土壤湿润锋的推进速度和入渗速率均减小,土壤原油污染程度为4％时湿润锋运移到土柱底部的所需时间最长,...     

植被格局对土壤入渗和水沙过程影响的模拟试验研究

合理的植被格局能够提高土壤入渗性能和抗冲性,有效阻蚀减沙,平衡土壤保持与土壤水分保蓄二者关系,进而促进生态环境的改善。基于径流小区人工模拟降雨,研究了多种植被格局生物量密度（0、50%、100%）和分布方式（坡上分布、坡下分布、均匀分布）的土壤入渗、产流、产沙特征以及土壤储水量变化。结果表明：使用Philip模型、Kostiakov模型、Horton模型模拟坡面入渗过程,Horton模型的拟合结果最优。不同植被格局产流率的变化趋势基本一致,大体可分为两个阶段：初期阶段迅速增长,中后期阶段增长变缓并逐渐趋于稳定状态。产沙率的变化趋势随植被格局的不同而略有差异。相较于产流过程,产沙过程变化剧烈、规律性差。总体而言,降低生物量密度能够增加降雨期间的径流量（从19.21 mm到25.44-38.09 mm再到51.79 mm）和侵蚀量（从118.97 g/m²到237.57-597.90 g/m²再到1400.29 g/m²）,土壤水分得到更好的保蓄。从植被分布方式的角度来看,均匀分布的植被格局有利于更好地控制土壤侵蚀和径流,却促进了土壤水分的消耗。坡下分布的植被格局,例如植被过滤带的形式,能够最好地同时控制水土流失和土壤耗水。权衡考虑水土流失防治与土壤水分消耗,建议采用适宜密度（本研究为110 g/m²）且集中分布在出口附近的植被格局。     

渝北水源区水源涵养林构建模式对土壤渗透性的影响

土壤渗透性是评价土壤水源涵养作用重要指标之一,其受制于许多外在和内在因素的影响,与植被类型、土壤结构、土壤种类和降雨强度等关系密切。为探讨不同构建模式水源涵养林对土壤渗透性能的影响,以裸地为对照,以土壤初渗速率,稳渗速率,平均渗透速率和渗透总量表征土壤渗透性,对重庆北部水源区8种不同构建模式的水源涵养林地的土壤渗透性及其与理化性质的关系进行研究。结果表明:不同模式水源林地和同一模式林地不同层次土壤渗透性能存在较大差异,各林地土壤渗透性随土壤深度的增加而降低,母质层土壤渗透性受林分类型和林分结构等外界条件的干扰较小,差异不显著;8种林地土壤渗透性均好于裸地,各林地土壤渗透性能大小依次为:广东山胡椒×杉木混交林马尾松×柳杉混交林(火烧迹地)四川大头茶×四川山矾混交林毛竹×四川山矾×马尾松混交林马尾松×广东山胡椒混交林马尾松×四川大头茶混交林广东山胡椒×四川杨桐混交林毛竹纯林裸地,根据土壤渗透能力可将8种模式林分类型分为4类:第1类,广东山胡椒×杉木混交林和马尾松×柳杉混交林,土壤渗透性最好;第2类,四川大头茶×四川山矾混交林,土壤渗透能力较好;第3类,毛竹×四川山矾×马尾松混交林、马尾松×广东山胡椒混交林、广东山胡椒×四川杨桐混交林、马尾松×四川大头茶混交林,土壤渗透性好;第4类,毛竹林和裸露地,土壤渗透性最差。以广东山胡椒和杉木混交的林分模式的土壤渗透性最好,毛竹纯林地最差,毛竹纯林对提高土壤渗透性作用较差,营林时适当增加毛竹林中其他树种的混交比例可增强林地土壤渗透性能。通用经验方程对各林分土壤入渗过程的拟合效果最好,比较适用于描述本研究区域水源涵养林地土壤入渗特征的模型,Kostiakov方程拟合效果次之,Horton方程最差;结合相关分析,筛选出9个极显著或显著影响土壤渗透性能的土壤理化性质因子,通过主成分分析法,得到土壤渗透性能综合参数α及与其极显著相关因子的综合参数β,并构建土壤渗透性各指标及其综合参数α与β的线性回归模型,为重庆北部的水源涵养林建设和防治水土流失提供理论依据。     

宁夏河东沙地生物土壤结皮对土壤性质及入渗过程的影响

为了揭示沙漠化治理过程中生物土壤结皮覆盖对土壤入渗过程的影响规律,以宁夏河东沙地人工沙漠治理区4种典型地表覆盖类型：裸沙(BS)、藻类结皮(AC)、藓类结皮(MC)、草本-藓类结皮(H-MC)为研究对象,基于野外双环入渗试验与室内模拟,分析了3种生物土壤结皮覆盖下土壤性质的变化与土壤入渗特征。结果表明：(1)与BS相比,3种结皮覆盖下表层土壤砂粒含量减少2.0%—5.1%,粉粒含量增加3.6%—5.8%,有机质含量增加了5—6倍,AC和MC覆盖下土壤总孔隙度与饱和含水量降低,而H-MC与之相反;(2)平均入渗速率表现为BS>H-MC>AC>MC,1h累计入渗量表现为H-MC>BS>AC>MC,与BS相比,AC、MC和H-MC的初渗速率依次减少了14.3%、37.2%、11.8%,AC、MC的稳渗速率分别降低了14.4%和18.3%,H-MC的稳渗速率增加了4.5%;(3)三种模型中,Kostiakov模型最适用于模拟生物土壤结皮覆盖下土壤水分入渗过程。综上,研究区内不同发育程度生物土壤结皮改变了下层土壤的性质以及土壤的入渗特征,MC与AC阻碍水分入渗...     

南京市城市土壤水分入渗特征

采用双环法测定了南京市代表性的土地利用类型下土壤的水分入渗率,研究了不同压实程度下土壤的入渗特征.结果表明：南京市不同压实程度土壤的入渗能力差异较大;土壤压实越严重,其容重越大、孔隙度越小,土壤入渗率越小;严重压实的土壤中存在水分入渗的限制层,致使稳定入渗率明显降低;土壤初始入渗率与稳定入渗率的差异较大,两者之间存在显著的线性相关关系.研究区土壤稳定入渗率的分布范围非常广（1～679 mm·h^-1）,这与城市土壤的压实、结构状况以及粗骨性砾石的存在密切相关.城市土壤入渗率的减小导致地表径流系数以及发生洪涝的几率和强度增大.     

栽培番茄的塿土和黄绵土水分和温度变化规律

用土柱试验,研究了栽培樱桃番茄(Lycopersicon esculentum var.cerasiforme Alef.)的塿土和黄绵土水分运移和温度变化规律,水分运移模型选用土壤中水分分布的动力学模型,土壤温度、空气温湿度变化选用正弦曲线模型。结果表明:塿土在各个不同深度的平均含水量均高于黄绵土,塿土的入渗速率高于黄绵土,同一深度塿土温度高于黄绵土,土壤温度随着深度的增加具有明显的滞后性;黄绵土中樱桃番茄的水分利用效率大于塿土,空气温湿度、土壤温度和土壤含水量相互影响。水分运移模型在土壤浅层处可以得到很好的拟合效果,在拟合方程的变量范围内,根据时间可以较准确的确定樱桃番茄盛果期土壤浅层含水量,对于进一步提高农业干旱防御能力、有效制定节水灌溉计划、提高水分利用效率提供了理论依据。     

不同护坡草本植物的根系特征及对土壤渗透性的影响

为明确三峡库区植被边坡植物物种根系特征与土壤渗透性之间的关系,以裸地为对照,应用WinRHIZO(Pro.2004c)根系分析系统对香根草(Vetiveria zizanioides(Lin.) Nash)、百喜草(Paspalum notatum Flugge)、狗牙根(Cynodon dactylon (L) Pers.)和紫花苜蓿(Medicago sativa L.)等4种护坡草本的根系特征进行定量分析.结果表明:(1)紫花苜蓿和香根草的根长密度和根表面积密度显著大于狗牙根和百喜草;(2)不同草本类型和同一草本不同土层之间土壤渗透性存在较大差异,且各草本土壤渗透性随土层深度的增加而降低;相对于裸地而言,4种草本均能显著增强土壤渗透性,其土壤渗透性优劣表现为:香根草＞紫花苜蓿＞百喜草＞狗牙根;(3)土壤的初始入渗率、稳渗率、平均渗透率和渗透总量等各参数均随根长密度和根表面积密度增大而增强,且与直径介于0.5-5 mm不同径级的根系特征之间存在明显的相关性,故根系对土壤渗透性的增强作用主要归功于0.5-5 mm径级的根长密度和根表面积密度;(4)根长密度、根表面积密度对考斯加科夫入渗模型参数K和a有较大影响,随着根长密度和根表面积密度的增加,表征土壤初始入渗率的K值逐渐增大,而表征入渗能力衰减的参数a逐渐减小.