草原恢复时土壤有机矿质复合体中结合态腐殖质变化

从退化草原恢复前后的土壤样品中,提取各粒级土壤有机矿质复合体,用不同浸提剂提取表征不同结合状态的腐殖质,对其含量,分布和组成在草原恢复过程中的变经进行了分析,得出了土壤各粒级复合体中腐殖主要以松、紧结合形式存在;它大部分分 粘粒和组、细粉粒级复合体中;     

高寒草甸不同类型草地土壤机械组成及肥力比较

研究了青藏高原高寒草甸不同类型草地土壤机械组成和土壤养分变化特征,并用相关分析探讨了土壤理化特征、土壤机械组成对不同草地类型群落物种组成、生物量变化的响应。结果表明:不同草地类型土壤机械组成分布大致是矮嵩草草甸:粉粒>细砂粒>粘粒>粗砂粒;高山嵩草草甸:细砂粒>粉粒>粘粒>粗砂粒;藏嵩草沼泽化草甸:细砂粒>粉粒>粘粒>粗砂粒;金露梅灌丛:粉粒>粘粒≥细砂粒>粗砂粒。矮嵩草草甸、高山嵩草草甸为粉砂质粘壤土,藏嵩草沼泽化草甸为壤土,金露梅灌丛为壤质粘土。矮嵩草草甸、高山嵩草草甸和金露梅灌丛土壤颗粒分布相对比较均匀(除藏嵩草沼泽化草甸外),主要集中在<0.5mm的范围内,土壤粘粒含量普遍大于20%。土壤全量养分和速效养分以及土壤物理特征均影响着高寒草甸不同草地类型土壤质量和土壤结构。土壤结构和养分状况是判断高寒草甸生态系统生态功能维持的关键指标之一。     

川西北草地沙化对土壤颗粒组成和土壤磷钾养分的影响

为揭示川西北若尔盖草原在草地沙化过程中土壤颗粒组成和矿质养分的变化特征,文中通过野外调查和室内分析化验,研究了川西北沙化过程中草地的土壤颗粒组成及磷、钾的变化特征。结果表明:草地沙化过程中0-100cm土层土壤结构受到了严重破坏,呈现出明显的粗化特征,土壤砂粒含量显著增加,粉粒、粘粒、土壤速效磷和速效钾含量显著减少。其中,0-20cm土层变化最为明显,极重度沙化草地土壤完全沙化,沙粒含量高达95.83%,相对未沙化草地增加了28.15%,速效磷、速效钾含量非常缺乏,分别仅为3.64mg·kg-1、24.66mg·kg-1,相对于未沙化草地分别降低了52.79%和74.29%。说明在沙化草地治理过程中,需及时补充适量的磷钾矿质养分。不同草地退化阶段研究表明,未沙化草地至中度沙化草地演变过程中,沙粒含量显著升高,粉粒、粘粒、速效磷、速效钾均有极显著降低,说明沙化草地的治理应将轻中度沙化阶段作为关键时期。     

黄土高原不同林龄土壤质地和矿质元素差异研究

对黄土高原不同林龄和不同树种条件下土壤的机械组成和矿质元素含量进行了分析研究,结果表明:①成林土壤砂粒、粉粒含量低于中幼林土壤,粘粒含量高于中幼林土壤,且呈显著性差异;②成林土壤Al2O3、Fe2O3、TiO2、MnO2、K2O含量相对于中幼林土壤有不同程度的增加,除MnO2外,差异均为极显著;成林土壤中Al2O3、Fe2O3、TiO2、MnO2在土壤中下层有不同程度的富集,SiO2、CaO含量降低;③矿质元素含量与土壤质地密切相关。     

不同草地类型土壤有效态微量元素含量特征

以贺兰山西坡不同草地类型土壤为对象,研究了土壤中微量元素Fe,Mn,Zn,Cu有效态含量特征及土壤有机碳、pH值、黏粉粒含量与气候因素之间的相互关系。结果表明:土壤有效态Fe,Mn,Zn的含量随着海拔的降低而逐渐降低,有效态Cu含量的积累顺序为:山地草原>荒漠化草原>高山草甸>草原化荒漠。4种元素在各种草地类型的积累量变化为:高山草甸Fe>Mn>Zn和Cu;山地草原和荒漠化草原Fe>Mn>Cu>Zn,草原化荒漠土壤中Fe和Mn含量差异不大,并大于Zn和Cu。土壤有效态Fe,Mn,Zn的含量与年均降水量、土壤有机碳、<0.05 mm黏粉粒含量都呈显著正相关,而与年均温度和土壤pH值呈显著负相关。土壤有效态Cu含量与年降水量、年均温度、土壤有机碳含量和<0.05 mm黏粉粒含量基本呈二次多项式,而与土壤pH相关性不显著。影响土壤有效态Fe和Mn含量的关键因素,0~20 cm土层为有机碳、年降水量和年均温,而20~40 cm土层土壤有机碳是其最重要的影响因素。0~20 cm土层土壤有效态Zn主要受土壤pH、黏粉粒含量和年降水量的影响。     

三江源区土地利用方式对土壤氮素特征的影响

以三江源区曲麻莱县高寒草甸草原、退化高寒草甸草原、退化高寒草原和人工草地4种土地利用方式为研究对象,研究了不同土地利用方式的土壤全氮、有效氮、铵态氮、硝态氮、无机氮总量及比例,结果表明:4种利用方式土壤的氮素含量均处于较低水平,在0~10 cm土层,土壤全氮与有效氮含量表现出相似的规律性,人工草地最高,退化高寒草甸草原最低。与高寒草甸草原相比,退化高寒草甸草原0~10 cm土层全氮和有效氮含量分别降低了52.4%和76.2%,而10~40 cm土层的全氮和有效氮含量却明显增加。对土壤铵态氮和硝态氮含量的研究结果进一步表明,研究区域土壤中无机氮以硝态氮为主,退化导致0~10 cm土层的铵态氮和硝态氮含量降低,退化和人工种植均导致0~10 cm土层硝态氮含量明显降低,而10~20 cm和20~40 cm土层的硝态氮含量明显升高,且这两个土层之间差异不显著,40~60 cm土层又明显降低。因此,退化和人工种植均导致土壤硝态氮沿土壤剖面淋溶下移,并且淋溶主要发生在0~40 cm深度的土壤中。土壤无机氮总量与硝态氮表现出相似的规律性,对土壤无机氮总量和比例的研究也表明退化加剧了土壤氮素的矿化过程。     

草原开垦对草原土壤及植被的扰动生态学作用

研究草原开垦对草原土壤及植被的扰动作用，选择不同开垦年限的农田，测其土壤理化性质，调查农田杂草种类状况，结果发现随开垦年限的增加，草原发生了一系列演变,＜0.001mm的土壤粘粒含量逐渐降低，1－0.25mm之间的粗砂粒含量逐渐升高。土壤有机质含量逐渐减少，pH值、电导率及含盐量均比工昌原对照地土壤低。农田杂草由开垦初期以多年生草本植物占优势到开垦多年以后以一年生草本植物占优势，开垦草原对草原土壤及植被均有不同程度的扰动作用，因此，开垦草原应以生态系统学观点作为指导思想，在不具备建立农田生态系统条件的草原区，应弃耕还牧，否则，将引起草原的退化。     

围栏禁牧对毛乌素沙地土壤理化特征的影响

过度放牧导致干旱半干旱区毛乌素沙地草地严重退化。通过禁牧措施排除放牧干扰,使草地自然恢复,作为一种低投入的措施在世界各国退化草地生态系统恢复中得到广泛采用。文中对毛乌素沙地三种不同管理类型(持续放牧、围栏5年和围栏16年)土壤理化性状进行了研究,研究结果显示:围栏禁牧5年对0～30cm土壤颗粒组成和容重没有显著影响;围栏禁牧16年0～10cm土壤容重显著小于持续放牧区,而极细沙、粉粒和粘粒含量显著高于持续放牧区;围栏5年显著增加了0～5cm土壤有机碳,而0～30cm的全氮均没有显著增加。围栏16年土壤有机碳较放牧区在0～5cm、5～10cm、10～30cm分别显著增加了231%、81%、55%;全氮含量的变化趋势与之相同。结果表明,围栏5年对土壤粘粉粒、全氮含量的恢复基本没有效果;围栏16年能显著增加表层土壤粘粉粒含量和有机碳、全氮,但土壤碳、氮水平还是在比较低的水平(有机碳:4.30g.kg-1;全氮:0.74g.kg-1),即长期禁牧可以逐渐改善土壤质地和提高土壤肥力。研究结果为半干旱退化沙质草地生态系统的恢复、重建及管理提供科学依据。     

臭柏群落演替过程中土壤环境的变化

在臭柏群落演替过程中土壤含水量总的趋势为先上升后下降。在进展演替阶段呈上升趋势,逆行演替阶段逐渐下降。0~5 cm表层土壤的含水量变化不明显,上层5~30 cm的土壤含水量有明显的先上升后下降的趋势,而深层的土壤含水量变化不大。从土壤剖面来讲,随着土层的加深土壤含水量在逐渐的下降。随着进展演替土壤颗粒组成发生变化,砂粒含量趋于减少、粉粒和粘粒增多、有机质含量逐渐增加、C/N下降,逆行演替阶段与其相反;臭柏群落的演替对有机质积累的影响主要集中在土壤表层0~50cm土层内;物种丰富度、盖度与土壤粘粒、C、N、K、P呈正相关。由此可见,臭柏群落进展演替的系统内容与基质的改造和土壤发育密切联系,它们之间彼此影响,相互配合。     

草原土壤胀缩运动的发生机制研究

着重调查草原地裂缝的空间静态分布及时间动态分布,并调查土壤及植被状况,研究草原土壤胀缩运动的发生机制,结果表明:土壤的开裂主要与土壤粘粒(<0.001mm)含量有关,土壤粘粒含量越高,土壤胀缩程度越大。认为土壤胀缩运动主要决定于土壤粘粒的含量,同时季节性冻融作用与干湿交替作用是导致土壤胀缩运动的直接因素。     

30 a耕作对高寒草地土壤碳氮与颗粒组成的影响

根据青海湖流域1987—2010年5期遥感图像解译,在青海湖北部区域存在毗邻的30 a未曾变动草地和耕地。以这两类土壤为研究对象,对其0~60 cm土层的土壤总碳、土壤全氮、土壤粒度组分进行对比研究。结果表明:草地和耕地土壤总碳和全氮含量以30 cm为界,分异明显,界上草地总碳和全氮含量大于耕地,而界下两者之间差异较小。另外,草地总碳和全氮含量最大值出现在0~10 cm,耕地总碳和全氮含量最大值出现在10~20 cm。草地和耕地粒度组成上都属于砂黏壤级,其中草地粉砂和黏粒大于耕地,而砂含量小于耕地。30 cm以上,草地和耕地间土壤粒度组分差异大,30 cm以下差异小。草地土壤黏粒和粉砂组分与总碳(P0.05)、全氮(P0.01)呈显著相关,而土壤砂粒组分与其相关性不显著;耕地总碳和全氮与各土壤粒级组分之间均无显著相关性。     

Bodenfauna als Ökologischer Dienstleister – Collembolen und Nematoden fördern den Abbau von Deoxynivalenol in Fusarium-infiziertem Weizenstroh

A minicontainer-study under laboratory conditions was conducted with the following fungivorous members of soil fauna: Aphelenchoides saprophilus, Nematoda and Folsomia candida, Collembola. The objective was to investigate, if the introduced soil fauna is able to reduce the concentration of Fusarium-biomass and the mycotoxin deoxynivalenol (DON) in wheat straw. Furthermore, the study aimed wether the degradation efficiency is affected by different soil texture (sandy loam, silt loam, clay loam). Therefore, minicontainer were filled with soil and wheat straw. Soil fauna was introduced in different combination into the minicontainer (single collembolan, single nematode, faunal interaction and a non-faunal treatment). The minicontainer were divided into 2 sets: one set received artificially Fusarium-infected and DON-contaminated wheat straw, the second set received non-infected straw. After 2 and 4 weeks, soil and straw were sampled for analysing Fusarium-biomass and DON content by using ELISA-technique. After 4 weeks Fusarium-biomass was reduced notably and DON-concentration was degraded significantly throughout all treatments. The highest reduction of DON-concentration was found in the faunal interaction treatment. The DON-concentration in the sandy- and silt loam treatments were reduced more efficiently compared to the clay loam treatment. We conclude that nematodes and collembolans contribute to the degradation of Fusarium-biomass and the mycotoxin DON in wheat straw as ecosystem services.     

玛曲高寒草地沙化对土壤理化特性的影响

以玛曲高寒草地处于不同沙化发展阶段的潜在沙化地、轻度沙化地、中度沙化地和重度沙化地为研究对象,阶地作为对照,对0～60 cm土壤剖面的机械组成和土壤有机碳、全氮、全磷以及速效钾含量进行了测定,分析结果表明:1)随草地沙化程度的加剧,不同类型沙化草地的黏粒和粉粒含量迅速下降,细砂粒含量逐渐下降而粗砂粒含量逐渐上升。2)随草地沙化程度的加剧,不同程度沙化草地的有机碳和全N含量呈逐渐下降趋势。3)从不同程度沙化草地各层土壤的养分含量来看,阶地和潜在沙化地各土层有机碳和全N含量随土层深度加深逐渐下降,中度沙化地、重度沙化地各土层有机碳和全N含量呈现基本稳定的状态。     

Changes in soil properties and erodibility of gully heads induced by vegetation restoration on the Loess Plateau,China

Soil erosion on the Loess Plateau of China is effectively controlled due to the implementation of several ecological restoration projects that improve soil properties and reduce soil erodibility. However, few studies have examined the effects of vegetation restoration on soil properties and erodibility of gully head in the gully regions of the Loess Plateau. The objectives of this study were to quantify the effects of vegetation restoration on soil properties and erodibility in this region. Specifically, a control site in a slope cropland and 9 sites in 3 restored land-use types(5 sites in grassland, 3 in woodland and 1 in shrubland) in the Nanxiaohegou watershed of a typical gully region on the Loess Plateau were selected, and soil and root samples were collected to assess soil properties and root characteristics. Soil erodibility factor was calculated by the Erosion Productivity Impact Calculator method. Our results revealed that vegetation restoration increased soil sand content, soil saturated hydraulic conductivity, organic matter content and mean weight diameter of water-stable aggregate but decreased soil silt and clay contents and soil disintegration rate. A significant difference in soil erodibility was observed among different vegetation restoration patterns or land-use types. Compared with cropland, soil erodibility decreased in the restored lands by 3.99% to 21.43%. The restoration patterns of Cleistogenes caespitosa K. and Artemisia sacrorum L. in the grassland showed the lowest soil erodibility and can be considered as the optimal vegetation restoration pattern for improving soil anti-erodibility of the gully heads. Additionally, the negative linear change in soil erodibility for grassland with restoration time was faster than those of woodland and shrubland. Soil erodibility was significantly correlated with soil particle size distribution, soil disintegration rate, soil saturated hydraulic conductivity, water-stable aggregate stability, organic matter content and root characteristics(including root average diameter, root length density, root surface density and root biomass density), but it showed no association with soil bulk density and soil total porosity. These findings indicate that although vegetation destruction is a short-term process, returning the soil erodibility of cropland to the level of grassland, woodland and shrubland is a long-term process(8–50 years).     

Spatial variability of soil water content and related factors across the Hexi Corridor of China

Soil water content(SWC) is a key factor limiting ecosystem sustainability in arid and semi-arid areas of the Hexi Corridor of China, which is characterized by an ecological environment that is vulnerable to climate change. However, there is a knowledge gap regarding the large-scale spatial distribution of SWC in this region. The specific objectives of this study were to determine the spatial distribution patterns of SWC across the Hexi Corridor and identify the factors responsible for spatial variation of SWC at a regional scale. This study collected and analyzed SWC in the 0–100 cm soil profile from 109 field sampling sites(farmland, grassland and forestland) across the Hexi Corridor in 2017. We selected 17 factors, including land use, topography(latitude, longitude, elevation, slope gradient, and slope aspect), soil properties(soil clay content, soil silt content, soil bulk density, saturated hydraulic conductivity, field capacity, and soil organic carbon content), climate factors(mean annual precipitation, potential evaporation, and aridity index), plant characteristic(vegetation coverage) and planting pattern(irrigation or rain-fed), as possible environmental variables to analyze their effects on SWC. The results showed that SWC was 0.083(±0.067) g/g in the 0–100 cm soil profile and decreased in the order of farmland, grassland and forestland. The SWC in the upper soil layers(0–20, 20–40 and 40–60 cm) had obvious difference when the mean annual precipitation differed by 200 mm. The SWC decreased from southeast to northwest following the same pattern as precipitation, and had a moderate to strong spatial dependence in a large effective range(75–378 km). The SWC showed a similar distribution and had no significant difference between soil layers in the 0–100 cm soil profile. The principal component analysis showed that the mean annual precipitation, geographical position(longitude and latitude) and soil properties(soil bulk density and soil clay content) were the main factors dominating the variance of environmental variables. A stepwise linear regression equation showed that plant characteristic(vegetation coverage) and soil properties(soil organic carbon content, field capacity and soil clay content) were the optimal factors to predict the variation of SWC. Soil clay content could be better to explain the SWC variation in the deeper soil layers compared with the other factors.     

土壤退化与草地退化关系的研究

内蒙古草原在畜牧业生产及环境生态上均占有重要的地位 ,但草地退化比较严重 ,土壤是草地生态系统的基础环境 ,土壤退化与草地退化关系十分密切 ,都受到自然因素与生产活动的影响 ,但土壤退化比草地上植被的退化缓慢 ,土壤具有较强的抗拒退化的能力 ,它是土壤性质的综合表现 ,可以称之为土壤稳定性 ,土壤的稳定性是支撑草地生产稳定和恢复的重要因素 ,在评价与改良退化草地时 ,要充分了解土壤的退化程度 ,引起退化的主导因子 ,因地制宜地采取措施才能收到良好的效果     

Land cover changes and the effects of cultivation on soil properties in Shelihu wetland,Horqin Sandy Land,Northern China

Land cover change plays an essential role in the alternation of soils properties.By field investigation and applying satellite images,land cover information in the Shelihu wetland was carried out in an area of 2,819 hm 2 in 1985,1995,2000,2005,2010 and 2011,respectively,in Horqin Sandy Land.A total of 57 soil sampling sites across Shelihu were chosen in wet meadow(CL0),cropland(CL) and sandy land(SL) according to the spatial characteristics of water body change.Soil texture,organic carbon(SOC),total nitrogen(TN) and total phosphorus(TP) contents,electrical conductivity(EC) and pH were measured at the soil depths of 0-10,10-20 and 20-40 cm to examine the influence of agricultural conversion and continuous cultivation on soil properties.The results showed that the study area was covered by water body in 1985,which gradually declined afterwards and then reclaimed rapidly at a mean annual rate of 132.1 hm 2 /a from wet meadow to cropland since 1995.In 2011,water body was drained and the area was occupied by 10.8% of CL0,76.9% of CL and 12.3% of SL.Large amounts of SOC,TN and TP were accumulated in the above depths in CL0.Soil in CL0 also had higher EC and silt and clay fractions,lower pH than in SL and CL.Soil in SL was seriously degraded with lower contents of SOC,TN and TP than in CL and CL0.SOC,TN content and EC in CL decreased with the increase of cultivation age,while pH showed a reverse trend with significance at plough horizon.The agricultural conversion in Shelihu was driven by the comprehensive factors of precipitation reduction,economic development and intense competitions for irrigation water.Continuous cultivation in this process is not sustainable because of SOC degradation and nutrient content reduction.The key point is that conventional tillage and removal of residuals induced further land degradation.Wetland reclamation for immediate economic interests led to greater costs in the long-term environmental restoration in Horqin Sandy Land.     

科尔沁沙地不同植物群落土壤呼吸及环境因素分析

对科尔沁沙地固定、半固定和流动沙丘土壤呼吸的日进程、季节变化及其环境因素进行了测定分析.结果表明:1)土壤呼吸速率与植物群落生物量、土壤有机碳、全氮及粘粉粒含量之间存在显著的正相关关系;固定沙丘日平均土壤呼吸速率分别是半固定和流动沙丘的1.18和2.02倍.2)从固定、半固定到流动沙丘,土壤温度及近地表空气温度呈现增加...