科尔沁沙地人工小叶锦鸡儿植被水分入渗动态研究

通过对科尔沁沙地不同年龄人工小叶锦鸡儿固沙植被降雨入渗的研究 ,阐明植被对沙地水分入渗的影响。结果表明 ,在降雨量 4 3 4mm ,降雨强度 3 9mm·h-1时 ,降雨后 12 0h内流动沙丘和 5年生人工小叶锦鸡儿植被的水分入渗深度分别为 180cm和 15 0cm ,15年生人工小叶锦鸡儿植被降雨入渗深度为 10 0cm。流动沙丘降雨后土壤水分变化剧烈 ;有植被沙地降雨后土壤水分变化平缓 ,水分下渗浅 .随着植被年龄的增加 ,浅层土壤截留降雨能力不断加强 ,最终形成不透水土层。降雨后短期内流动沙丘浅层土壤中含水量高 ,后期有植被沙丘深层土壤含水量高     

黄土丘陵区不同土地利用模式对深层土壤含水量的影响

对陕北米脂人工经济林、神木退耕还林和榆林榆阳区防风固沙林具有代表性植被类型0～20 m土壤剖面水分特征的差异进行了研究,分析黄土丘陵区不同土地利用模式对深层土壤剖面水分分布和储存特征的影响及生态环境效应.结果表明: 在0～20 m土层,不同位点具有代表性土地利用方式均影响土壤含水量的垂直分布;在整个剖面中,人工经济林土壤储水量有显著差异,为矮化枣树 ＞ 未矮化枣树,储水量相差587.9 mm;神木退耕还林和榆林榆阳区防风固沙林土壤剖面中土壤储水量无较大差异,在神木整个剖面中土壤储水量的大小为退化人工草地 ＞ 柠条林,储水量相差98.8 mm;在榆阳为荒草地 ＞ 樟子松,储水量相差7.5 mm.与未矮化枣树相比,人工经济林矮化枣树减少了对土壤水分的消耗,矮化枣树冠幅较小,降低了蒸腾作用,从而更加有利于土壤水分的可持续利用;人工柠条林和退化人工草地土壤水分含量无明显差异,这是因为退化人工草地过去为苜蓿地,根系分布深以及生物量大,对土壤深层水分利用较大所致;防风固沙林樟子松与荒草地整个剖面中的平均土壤含水量较低,土壤砂粒含量较高,土壤持水性差,土壤含水量随土壤深度的增加而增加,平均土壤含水量分别为3.4%和3.6%,且该地植物对深层土壤水分影响有限.综上,土壤剖面中土壤水分除了受土壤质地的控制,不同土地利用模式由于植物根系不同,对土壤水分也产生较大的影响.为此,选择合适的植物对于土壤深层水的保护和持续利用非常重要.     

人工小叶锦鸡儿(Caragana microphylla)灌丛土壤水分动态研究

采用由植被空间序列断时间系列的方法。分析了1984,1987,1995和1999年建立的人工小叶锦鸡儿固沙植被土壤水分的时空变化特征,结果表明,受沙地土壤机械组成的影响,沙地土壤组成以物理性沙粒为主,＞0.01mm沙粒占97％以上,凋萎湿度为1．55％,田间持水量5．5%,大有效水为3．95％,随着固沙植被优势度的增加,小叶锦鸡儿灌丛下土壤含水量持续下降,1984年建立的植被区土壤含水量明显低于1999年建立的植被区;在年内土壤水分季节变化中,4个阶段植被区土壤水分状况在4－6月不断降低,到6月达到最低值,7－10月逐渐回升;对于建立较早的植被区（1984和1987年）,土壤水分垂直变化表现出随着土层深度的增加,土壤含水量逐递减的趋势,特别是70cm下土层中,土壤含水下降明显,含水量低于凋萎湿度,由于对根际区域土壤水分的利用,加剧了固沙植被区深层土壤（70cm下）水分的亏缺,进而影响植被物种的组成,随着小叶锦鸡儿灌丛年龄的增加,浅根性植物所占比重增加。     

荒漠草原两种类型土壤的水分动态对比

基于2017—2018年的定位监测数据,分析了宁夏东部的盐池荒漠草原2种不同类型土壤(灰钙土和风沙土)的水分时空动态特征。结果表明: 2017和2018年生长季(5—10月),研究区降雨量分别为208.2和274.8 mm,降雨在各月份的分配差异较大。2018年除5月存在极端降雨事件(129.6 mm)外,其余各月降雨量均低于2017年。土壤水分变化的季节动态规律大致可以分为两个阶段:土壤水分补偿期(5月初至6月初)和土壤水分波动期(6月中旬至9月底)。0～20 cm土层土壤含水量在降雨后呈骤增骤减的脉冲式特点,深层土壤含水量较稳定。灰钙土土壤含水量随土层加深表现为“升-降-升”的变化,风沙土土壤含水量在0～60 cm土层出现井喷式增加,而后增加缓慢,但随着土层深度的增加土壤含水量逐渐增大。2017年,灰钙土全剖面(0～100 cm)土壤水分表现为积累型,风沙土表现为消耗型;2018年,两种类型的土壤水分在全剖面均表现为消耗型。两种土壤类型土壤水分的时间稳定性随土壤深度的增加而增强,灰钙土和风沙土全剖面的平均土壤含水量代表性土层分别为80～100和40～60 cm。2种类型土壤的土壤水分时空分布不同,风沙土受降水的影响高于灰钙土。降水会降低土壤水分的变异性,改变土壤水分的时间稳定性。     

嘉峪关草湖湿地土壤水分含量与植被盖度的空间格局

土壤水分含量是植被格局形成和演变的主要因素。探讨干旱区盐沼湿地土壤水分含量的空间异质性,有助于揭示湿地植物的环境适应机理和土壤水分与湿地植物的相互关系。本研究利用地统计学方法建立了嘉峪关草湖湿地3个不同长势(植被盖度高、中、低)假苇拂子茅(Calamagrostis pseudophragmites)单优种群斑块土壤(0～90 cm)水分含量与植被盖度的变异函数理论模型,以Kriging插值法绘制了土壤水分含量与植被盖度的空间格局分布图,采用Moran I系数确定了湿地土壤水分含量和植被盖度的空间自相关关系,分析了湿地土壤水分含量与植被盖度的空间异质性及其相互作用关系。结果表明:草湖湿地样地土壤的平均含水量为湖边干湖沙丘间平地;盐分平均含量为干湖湖边沙丘间平地;在斑块尺度上,土壤水分含量和植被盖度均符合正态分布;各层土壤水分含量和假苇拂子茅盖度的空间结构均具有明显的斑块状分布特点,且均存在高度的空间异质性; 3个样地各层土壤的水分含量和植被盖度均具有空间正相关性和空间集聚特征,60～90 cm土壤水分含量的空间集聚强度较0～30和30～60 cm土层更大,湖边样地植被盖度空间集聚特征更明显。假苇拂子茅最大限度利用土壤水分资源,提高了其对干旱生境的适应力,且在一定程度上影响小尺度土壤水分的空间分布格局。     

荒漠区包气带土壤物理特征及其对地下水毛管上升影响的模拟

以巴丹吉林沙漠边缘荒漠区域为研究对象,选取两种典型的沙丘土壤剖面(沙壤土和砂土混合,均一砂土)进行土壤物理特征分析,并在此基础上模拟了不同土壤因素对毛管水上升过程的影响,探讨毛管水上升变化与土壤物理性质的关系,试图揭示地下水-毛管水-土壤水之间的相互作用过程.结果表明:研究区地下水毛管上升主要受土壤容重和土壤黏粒含量的影响,并且毛管水上升高度在地下潜水层以上为沙壤土的剖面中能够达到152 cm;地下潜水层以上为砂土的剖面中为120 cm.砂土中毛管水补给区域各土层水分分布更为均匀,并且从潜水面至地面方向土壤含水量呈递减趋势,沙壤土中毛管水补给区域土壤水分变异较大.借助Hydrus-3D模型能够较好模拟多因子影响下的土壤毛管水运动过程.潜水面以上土壤结构变化显著影响毛管水上升和剖面水分分布状况,但毛管水上升是否受季节性蒸发变化的影响以及毛管水与植物需水的关系有待进一步探究.     

内蒙古希拉穆仁草原春季土壤水与水分平衡研究

为了揭示希拉穆仁草原土壤含水量, 水分存在形式, 水分有效性, 水循环和土壤干层等问题, 对该区不同地形草地进行了打钻取样, 对含水量及粒度进行测定与分析。结果显示: 研究区多数土壤剖面中含水量变化在2%-10%之间, 平均含水量多在3%-6%之间。高地采样区土壤水分垂向变化波动较大, 变化趋势不明显; 平地采样区土壤上中部含水量多于下部。研究区土壤水分大部分处于难效水状态, 土壤水分对植被生长具有明显的抑制作用, 但平地采样区在剖面上部0-0.5 m的平均含水量较高地采样区略多, 表明平地采样区植被生长受到土壤水分的胁迫性相对较小。研究区普遍有干层发育且等级较高, 干层分布接近地表。其中, 高地采样区剖面0-0.5 m全部为重度干层, 下部有轻度干层和中度干层发育; 平地采样区几乎全部为重度干层。该区春季5月份土壤水分几乎都以含量很低的薄膜水形式存在, 大气降水被蒸发与蒸腾等全部消耗, 没有剩余水分补给地下水。综上指示该区土壤水分为明显的负平衡, 水循环呈现土壤-植物-大气的水分循环模式, 属于不完整的水分循环类型。     

黄土丘陵沟壑区不同植被类型土壤有效水和持水能力

以黄土丘陵沟壑区坊塌流域不同植被类型为研究对象,在野外调查的基础上,利用离心机法测定不同植被类型0—10、10—20 cm土层不同吸力下的土壤含水率,并利用Van Gennuchten模型对土壤水分特征曲线进行拟合,对比分析了不同植被类型不同土层土壤水分特征曲线、土壤水分有效性和持水性。结果表明:随着植被恢复的进行,不同植被类型土壤水分特征曲线出现了明显的差异,但是其斜率基本不变且不同植被类型0—10、10—20 cm土层土壤水分特征曲线都呈近似的"S"型;不同植被类型0—10、10—20 cm土层土壤有效水范围分别为22.65%—26.80%、23.97%—28.13%,除白羊草群落和刺槐林外呈现出多年生蒿禾类群落低于灌木群落而高于一年生草本群落的变化趋势;不同植被类型土壤持水能力在0—10 cm土层没有显著性差异,在10—20 cm呈现出多年生蒿禾类群落低于灌木群落而高于一年生草本群落,其中白羊草群落最大,刺槐林最低。刺槐林有效水分和土壤持水能力都较低,建议适当采取间伐并促进其近自然化恢复来实现土壤水分的可持续利用,尽量避免在阳坡缺水地区种植刺槐。对于研究地区土壤水分的可持续利用、植被恢复和科学合理的进行植被配置具有重要意义。     

干旱荒漠区煤矸石山覆土区土壤水分物理性质的空间异质性

基于网格取样(20 m×20 m),采用经典统计学和地统计学相结合的方法,研究了干旱荒漠区煤矸石山表层(0~5 cm)土壤水分物理性质的空间异质性和分布格局。结果表明:研究区土壤容重、毛管孔隙度、毛管最大持水量、总孔隙度、饱和含水量表现为弱变异,土壤含水率表现为中等变异。除土壤容重的最佳拟合模型为高斯模型外,其余指标的最佳拟合模型均为指数模型;土壤容重和含水率的块基比[C₀/(C₀+C)]较小,空间自相关性强烈;土壤毛管孔隙度、毛管最大持水量、总孔隙度和土壤饱和含水量则表现为中等的空间自相关性;土壤容重与毛管孔隙度、毛管最大持水量、总孔隙度、饱和含水量呈极显著负相关,土壤含水率与其余指标没有显著的相关关系;土壤毛管孔隙度、毛管最大持水量、总孔隙度及饱和含水量两两之间呈极显著正相关关系;Kringing等值线图表明,土壤毛管孔隙度、毛管最大持水量、总孔隙度和饱和含水量分布类似,高值集中在坡中部及下部左侧,土壤容重则与之相反,土壤含水率的大小主要受坡位的影响,由坡上向坡下增大。建议干旱荒漠区煤矸石山覆土区在人工植被恢复时应采取整地措施,疏松根区土壤;在植被恢复初期,应适当提高坡上部的灌水量,以改善煤矸石山覆土区土壤水分状况,为植被恢复营造均一、良好的土壤水分物理条件。     

三峡山地不同类型植被和坡位对土壤水文功能的影响

土壤层下渗和贮蓄水分的水文功能是森林保持水土、涵养水源的基础。以三峡山地大老岭林区为研究区,采集常绿林、落叶林和草地覆盖下不同坡位的原状土样,测定其饱和导水率和水分特征曲线,分析植被类型和坡位对土壤水分参数和库容的影响。结果表明:常绿林地的入渗性能最好,饱和导水率为7.80—322.81 cm/d,大于落叶林地(0.33—137.03 cm/d)和草地(0.84—115.80 cm/d);坡位间差异表现为上坡高于下坡。不同样地的饱和含水量差异较小,但毛管持水量和田间持水量差异明显,草地最大,为20.77%—50.39%;不同坡位比较表现为下坡高于上坡。不同样地土壤水库容量差异较大,由田间持水量得到的库容量占总库容量的百分比以草地最大(63.25%),其次是落叶林地,常绿林地最小;坡位上表现为下坡的田间持水库容大于上坡。饱和导水率与土壤总孔隙度、有机质含量呈显著正相关,与容重呈显著负相关;饱和含水量、毛管持水量、田间持水量均与土壤总孔隙度、有机质含量和粉粒含量呈显著正相关,与容重、砂粒含量呈显著负相关。综合以上,草地持水性能最强,利于保蓄水分,常绿林地最弱,更利于水分入渗,补给地下水,下坡位的持水性能强于上坡位。     

不同质地土壤对花生根系生长、分布和产量的影响

为了探究土壤类型与花生(Arachis hypogaea)根系生长及产量之间的关系, 采用箱栽的方法, 研究了不同质地土壤(砂土、壤土、黏土)对花生根系生长、分布和产量的影响。砂土和壤土中花生根系干物质重各时期均显著高于黏土中, 但生育后期黏土中花生根系干物质重比壤土和砂土下降相对较慢。从不同类型土壤质地根系分布及根系活力来看, 黏土根系主要分布在上层土壤, 但上层土壤根系活力后期下降慢; 砂土有利于花生根系向深层土壤生长, 但上层土壤根系活力后期下降快; 而壤土对花生根系生长和活力时空分布的影响介于黏土和砂土之间。砂土有利于花生荚果的膨大, 且花生荚果干物质积累早而快, 但后期荚果干物质重积累少; 壤土的花生荚果干物质积累中后期多, 黏土则在整个生育期均不利于花生荚果干物质积累。最终荚果产量、籽仁产量和有效果数均表现为壤土最大、砂土次之、黏土最小。研究表明通气性和保肥保水能力居中的壤土更适合花生的根系生长发育及产量的形成。     

Soil water dynamics and vegetation patterns in a semiarid grassland

Long-term (1985–1992) dynamics and spatial variations in soil water below the evaporative zone were evaluated for a shortgrass steppe with a low and variable precipitation regime. Each of a sandy loam, clay loam, and two sandy clay loam sites comprised a toposequence with upland, midslope and lowland positions. Soil water was monitored at 15 cm intervals providing estimates covering 22.5 to 97.5 cm depths.Soil water throughout the profile was highest in the clay loam site and lowest in the sandy loam site. However, stored soil water did not vary systematically among slope positions. Total vegetation cover was highest on the lowland in two sites, but was greatest on the midslope position in the other two. Total vegetation cover was greatest on the CL site, which was the wettest in terms of soil water. Soil water depletion was related to the depth-distribution of roots. There was an inverse relationship between aboveground production and soil water content of the 30, 45 and 60 cm layers during the growth period. Root distributions through the profile did not, however, vary with soil texture or with different soil water profiles controlled by texture. The less variable water content of deeper soil layers is a resource which potentially buffers the impact of pronounced variability in precipitation and thus contributes to vegetation stability of the shortgrass community.     

科尔沁沙地不同地形小叶锦鸡儿灌丛土壤水分动态

根据科尔沁沙地广泛分布的小叶锦鸡儿灌丛的植被调查和土壤水分监测数据,分析了沙地人工固沙灌丛的土壤水分时空动态和土壤储水量变化,并应用水量平衡法测定了灌丛蒸散发.结果表明:丘间地的土壤水分条件最好,丘中次之,丘上最低;灌丛区的土壤水分含量随深度增加而增加,在生长季内不会发生水分胁迫.灌丛区土壤水分与降雨过程高度相关,深层(50～180 cm)土壤水分同降雨的相关性高于表层(0～50 cm)土壤,并且深层土壤水分的变异也大于表层.整个生长期内,小叶锦鸡儿灌丛土壤储水量增加,土壤水分处于积累中,估算蒸散量占同期降雨量的64%以上.     

Feeding inhibition and mortality in Reticulitermes flavipes (Isoptera: Rhinotermitidae) after exposure to imidacloprid-treated soils

Feeding inhibition and mortality of Reticulitermes flavipes (Kollar) exposed to sand, sandy loam, loam, and silty clay loam soils treated with several concentrations of imidacloprid were studied using bioassay techniques under laboratory conditions. Termite workers stopped feeding after exposure to treated soils. Differences in feeding reduction varied among the soil types. Based on the magnitude of the F-statistics, the effect of imidacloprid on the reduction of termite feeding was greatest in sand followed by sandy loam, loam, and silty clay loam soils. Soil properties such as organic matter content, silt and clay proportions, pH, and cation exchange capacity were suggested to affect the bioavailability of imidacloprid. Similar soil effects on mortality were observed in termites continuously exposed to treated soil for 21 d. In three of four soils tested, susceptibility to imidacloprid was not affected by the source of the termites tested.     

The influence of soil texture on the soil water dynamics and vegetation structure of a shortgrass steppe ecosystem

We analyzed soil water data from three sites with different soil textures in the shortgrass steppe of northeastern Colorado, USA. Our objective was to evaluate the relationship between the occurrence of plant functional types and the effect of soil texture on soil water availability. Soil water availability was greatest in the upper soil layers at all three sites, but the loamy sand site had significantly greater soil water availability than the sandy clay loam and sandy clay sites in wetter years at depths below 60 cm. Calculations of proportional water availability by layer using both field data and fifty-year soil water model simulations, showed that the sandy clay loam and sandy clay soils on average had greater water availability in layers 30 cm and above, but that the loamy sand had the greatest water availability in layers beneath this, particularly at 105 cm. This observation can be linked to the occurrence of a fine textured subsoil at this site. The textural pattern in the loamy sand profile effectively creates two water resources: a shallow pool accessible to all plants; and a deep pool accessible only to deep-rooted plants. This is offered as an explanation for the co-dominance of the two main plant functional types at the loamy sand site. At the other two sites, shallow-rooted shortgrass vegetation dominated, being more consistent with the general pattern for the area. Thus the patterns of vegetation structure at the three sites were consistent with the hypothesis. Aboveground net primary production data for the three sites, along with transpiration estimates from the model simulations, indicated that the additional water availability in the coarse textured soil was associated with higher overall plant productivity.Nomenclature: Taxonomic nomenclature follows R. L. McGregor & T. M. Barkley (1986) Flora of the Great Plains. Great Plains Flora Association. University Press of Kansas, Lawrence.     

温度对不同粘粒含量稻田土壤有机碳矿化的影响

模拟了亚热带地区3种不同粘粒含量的水稻土(砂壤土、壤粘土、粉粘土)在5种温度(10、15、20、25和30℃)下的有机碳(SOC)矿化特征,分析SOC矿化对温度变化的响应.结果表明:在160d的培养期内,温度对3种水稻土SOC矿化量的影响有一定差异,30℃时砂壤土、壤粘土和粉粘土SOC矿化量分别是10℃时的3.5、5.2和4.7倍.在较低温度(≤20℃)下,SOC矿化速度较低且相对稳定;在较高温度(≥25℃)下,前期SOC矿化速度较高,随着培养时间的延长逐渐降低,并趋于稳定.3种水稻土SOC矿化的温度系数(Q10)随培养时间出现波动,砂壤土的Q10平均值最低,为1.92,壤粘土和粉粘土的Q10平均值较接近,分别为2.37和2.32;3种土壤矿化速率常数(k)与温度呈极显著的指数相关(P<0.01).3种水稻土有机碳矿化对温度变化的响应敏感度依次为壤粘土>粉粘土>砂壤土.     

Quantification and correlation of vesicular-arbuscular mycorrhizal propagules with soil properties of some mollisols of northern India

The populations of vesicular-arbuscular mycorrhizae (VAM) propagules by the most probable number method in some mollisols and their correlations with some important soil properties were determined. On average, the six soils, Phoolbagh clay loam, Beni silty clay loam, Haldi loam, Nagla loam, Khamia sandy loam and Patherchatta sandy loam contained 4.9, 4.0, 7.9, 7.9, 3.3 and 13.0 propagules/g soil, respectively, i.e. none of the soils was found to be high in VAM. The size of the VAM population was compared to soil properties such as pH, organic carbon, sand content, available phosphorus and available potassium, cation-exchange capacity, silt and clay contents. A significant positive correlation (r=0.586) was only found with available soil phosphorus (P<0.05) and a significant negative correlation (r=-0.555) with soil clay content (P<0.05).Directorate research paper series No. 7862     

稻草易地还土对丘陵红壤有机质和主要物理性质的影响

选取新垦坡地和熟化旱地2种典型土地利用类型,研究了稻草易地还土对丘陵红壤有机质含量和主要物理性质的影响,并探讨了土壤有机质、田间持水量、容重、孔隙度间的相关性.结果表明稻草易地还土可提高丘陵红壤有机质含量,改良土壤物理性质,增强土壤蓄水性能.与不施肥或化肥处理相比,稻草易地还土提高了耕层(0～20 cm)土壤有机质含量5.8%～28.9%和＞0.25 mm水稳性大团聚体含量;降低了亚表层(10～15 cm)土壤容重,降低幅度为4.5%～7.5%,提高了亚表层土壤的田间持水量和孔隙度,提高幅度分别为6.8%～16.2%和4.8%～7.7%(P＜0.05).相关分析表明,土壤有机质含量(0～20 cm)与亚表层土壤容重(r=-0.799)、孔隙度(r=0.803)、田间持水量(r=0.844)呈极显著相关(P＜0.01);表层、亚表层土壤田间持水量与土壤容重(r=-0.638)、孔隙度(r=0.664)呈显著相关(P＜0.05).     

Effect of Soil Texture on the Distribution and Infectivity of Neoaplectana carpocapsae (Nematoda: Steinernematidae)

The vertical migration of N. carpocapsae infective juveniles applied to the soil surface or introduced 14 cm below the soil surface was studied in four different soil types (pure silica sand, coarse sandy loam, silty clay loam, and clay). The percentage of juveniles able to migrate and infect wax moth pupae placed in the soil decreased as the percentage of clay and silt increased. Most nematodes placed on the soil surface remained within 2 cm of the surface, but some penetrated to a depth of 10 cm in pure silica sand and coarse sandy loam to infect pupae. Some pupae at the same depth were also infected with nematodes in silty clay loam soil. In pure silica sand and coarse sandy loam, nematodes introduced 14 cm below the soil surface were able to infect wax moth pupae located between 4 and 24 cm. Movement was least in clay soil and limited in silty clay loam. Nematodes showed a tendency to disperse upwards from the point of application. In all cases the number of migrating nematodes was greatest when wax moth pupae were present.     

Effect of Soil Texture on the Distribution and Infectivity of Neoaplectana glaseri (Nematoda: Steinernematidae)

The vertical migration of infective juveniles of Neoaplectana glaseri applied to the soil surface or introduced 16 cm below the soil surface was studied in pure silica sand, coarse sandy loam, silty clay loam, and clay. The number of juveniles that migrated and infected wax moth pupae placed in the soil decreased as the proportion of clay and silt increased. The majority of nematodes moved downwards 2-6 cm from the surface, but some penetrated to a depth of 14 cm in pure silica sand and coarse sandy loam. In pure silica sand and coarse sandy loam, nematodes introduced 16 cm below the soil surface were able to infect wax moth pupae located at depths of 0-4 cm and 28-32 cm. Nematodes showed a greater tendency to disperse downwards from the point of application. Movement of the nematode was least in clay soil and limited in silty clay loam soil. The number of migrating nematodes was greatest when wax moth pupae were present.