矿山复垦区土壤水分时空分布对植被恢复的影响

以阜新煤矿区矸石山和排土场为研究对象,采用变异系数和有效水分参数相结合的方法,研究土壤水分时空分布对植被恢复的影响。结果表明:受土壤物质组成及形成方式的影响,矿区3个典型样地土壤水分的变异系数和有效水分参数均存在较大差异,并直接影响地上植被的生长。现有植被根系的分布对各层土壤水分尚未达到最佳利用效果。在生态重建时,排土场覆土平台应以草本和浅根灌木相结合为主,慎栽深根植物;排土场自然风化平台应以野草自然生长为主,并兼顾不同根深乔灌木混植方式;矸石山土壤水分因多处在迟效水或无效水范围,不利于植物生长,应以节水工程措施为主,以植被措施为辅加以治理。人工覆土措施可明显改善矿山复垦区土壤水分的分布状况。     

半干旱黄土丘陵区土壤水分生长季动态分析

土壤水分是半干旱地区植被生长的重要水分来源,尤其是深层土壤水分对黄土高原人工植被恢复起着至关重要的作用,阐明深层土壤水分的季节动态对揭示人类活动影响下的植被与水分的相互作用关系、维持黄土高原植被恢复的可持续性有重要的科学意义。文中基于半干旱黄土丘陵区8种典型植被0-1.8m土壤水分动态监测和0-5m深度土壤水分季节比较,研究发现:1)植被类型对土壤水分及其剖面分布具有显著影响,且不同植被土壤水分季节变化均随深度增加而减弱;2)生长季中不同植被土壤水分都呈现出先减少再增加的变化,不同植被在不同生长阶段中降雨对土壤水分的补充有所不同;3)人工植被深层土壤水分没有显著的季节变化,表明人工植被深层土壤水分已难以受到当季降水补充,维持植被生长的功能可能在逐渐减弱,黄土高原现阶段植被恢复需要平衡维持植被生长与土壤水分可持续利用。     

科尔沁沙地典型人工植被区土壤水分动态研究

半干旱沙区土壤水分对植物的成活与持续生长具有重要作用.通过对不同植物种类区土壤水分的动态监测分析表明,不同植物种类对土壤水分的影响存在显著差别;不同地下水位埋深对植被区的土壤水分状况产生重要影响,地下水埋深浅的区土壤水分长期维持较高的状态,能够满足植物生长的需求;沙丘区地下水位深,土壤水分主要依靠降水的补充,固沙植物的生长明显降低了有效土壤水分供给量,多数植物受到水分胁迫的影响.在半干旱沙丘区建立人工植被过程中,应该依照土壤水分状况配置植物种类和栽植密度,以土壤水分状况决定植物分布.地下水位较高区可栽植密度大的乔木或草本植物,而在沙丘区则一定依照降水量栽植适宜的植物和合理的栽植密度,以保证植物的长期稳定生存生长.     

基于水资源的坝上植被生态恢复建设

在半干旱地区水资源是植被生态建设的主要限制因子,也是农牧交错区生态恢复与重建的根本。本文根据坝上各县水资源调查资料,分析了水资源在坝上的时空分布特征、与光温资源的耦合程度;探讨了水资源的分布规律对植被生长与分布的影响。研究认为坝上应以自然恢复为主,林草植被恢复建设则应以地带性植被分布规律为依据,以水定草、定林,实现土壤水分的持续利用。     

民勤荒漠绿洲过渡带粘土夹层水力性质及其生态水文意义探讨

土壤水力性质是土壤水文功能的重要组成部分及影响因子，其对土壤水分分布状态、土壤水分循环的强度与速率具有重要影响。粘土夹层虽在干旱区呈不连续分布的状态，但其植被覆盖率却远高于相同水热条件下的非夹粘土壤。文中以民勤荒漠绿洲过渡带粘土夹层为研究对象，对其土壤物理性质、土壤持水性和导水性质进行测量，同时利用壕沟法对该地15年林龄的深根系乡土物种多枝柽柳根系进行了调查，分析了夹粘土壤剖面的水力性质变化特征及其影响因素，探讨了粘土夹层对干旱区植被恢复和重建的生态水文意义。结果表明：1)土壤颗粒组成和有机质含量是影响土壤持水性和导水性的重要因子。2)15年林龄多枝柽柳根系生物量(d<2mm)在粘土夹层上下界面处呈现明显增加的趋势。3)粘土夹层具有较高的持水性，其可通过毛管作用补给其他土层，同时，粘土夹层阻滞了土壤水分的运移，二者的共同作用改善了粘土夹层上下界面处的土壤水分条件。粘土夹层可以改变土壤水分入渗和存储的环境，在含有粘土夹层的土壤上进行植被建设，有助于干旱区固沙植被的恢复和建设。文中研究为了解荒漠绿洲过渡带土壤水文过程、生态恢复和重建提供了一定的数据支持。     

张掖市土壤状况与植被恢复关系评价

运用层次分析法数学模型和欧式距离公式,对张掖市境内不同植被和立地条件样地的土壤、生境状况进行了研究,并对土壤、生境状况和植被恢复关系进行了评价。评价显示：植被恢复难度划分为4个等级,分别是易（0~0.424）、中等困难（0.425~0.56）、较难（0.57~0.774）、极难（0.775~1）;张掖市植被重建与恢复过程中的主要限制因子为土壤水分、土壤砂粒含量;张掖市植被重建与恢复的难度与植被类型、土壤状况、生境状况有较好的对应关系。最后在植被恢复难度评价的基础上,针对不同难度地区提出了相应的植被恢复建议。     

植物根系水力提升作用研究进展综述

植物根系水力提升作用是植物深层根系吸收深层土壤水分,再通过浅层根系释放到较干燥浅层土壤中的过程。水力提升作用所释放的水分可缓解干燥土层水分匮乏,对改善自身及邻近植物的水分亏缺、促进植物养分吸收、促进土壤养分分解和矿化过程具有重要意义。随着对植物生态系统水分平衡问题的关注和研究手段的发展,水力提升作用日益成为干旱、半干旱区植物生态学与水文学共同关注的重要研究内容之一。通过回顾和分析水力提升作用的研究历史、影响因素、提升数量、研究方法、生态作用等,特别阐述了水力提升作用在半干旱区人工固沙植被恢复中的潜在应用价值,改善人工固沙植被区土壤水分条件,提高固沙植物群落的稳定性。     

绿洲与荒漠交错带植被恢复区土壤水分变化研究

对绿洲与荒漠交错带的不同类型防护林和不同荒漠植被恢复区土壤水分动态特征作了系统研究,研究结果表明:不同配置的类型防护林含水量整体上远低于对照;说明在无灌溉补充水分的条件下,林木的蒸腾作用耗水量大,土壤含水量低,为了林木的正常生长,应该在夏季及时补水;不同荒漠植被恢复区的土壤水分远高于空旷的沙地,说明不同荒漠植被恢复区,...     

几种工程措施对黄土区陡峭边坡植被盖度的影响及其机理

陡削以兰州新区的一段陡峭边坡作为试验地点,通过分析在植被重建初期经人工整地后形成的4种微地形(大圆形坑、小圆形坑、条形坑和原状坡面)的植被盖度特征及环境因子(土壤硬度和水分、地表和空气温度、坡位、无纺布)对植被盖度的影响,探寻能有效提高植被盖度的几种工程改造措施。研究表明:①铺设了无纺布坡面的植被盖度显著大于对照坡面;陡峭边坡不同坡位的植被盖度:下坡位>中坡位>上坡位(P<0.05),这与自然坡面植被盖度分布规律一致。②3种微地形的植被盖度均显著大于陡峭坡面,其中条形坑的土壤水分和植被盖度最大,最大盖度维持的时间最长。③微地形和坡面的植被盖度均与土壤水分呈显著正相关,与空气温度、地表温度均呈显著负相关;微地形的土壤硬度(3kg·cm^-2)适宜植物生长,大于该值会对植被生长产生抑制作用;铺设无纺布有利于促进上坡位的植被生长,使坡面植被分布更均匀。研究结果表明,在陡峭边坡坡度、坡位和温度等无法改变的情况下,选择对压实的坡面进行整地翻耕处理,增加长条坑的数量并铺设无纺布等有效的工程改造措施,能显著增加植被盖度,促进植被恢复。     

半湿润地区植被影响下的沙地水分动态

半湿润地区沙地在植被作用下土壤水分动态随季节变化，可以划分为春，夏，秋，冬四个阶段。随土层深度而增加可划分出几个明显层次：浅耕层，根系作用下水分极活跃变化层，地下水持续影响层。由于不同植物生长季不同，植物发育状况不同，生长所处位置不同而呈现出特写的土壤水分变化形势。降水，土壤性质，地下水强烈地影响着本沙地土壤水分的动态变化。植物根系对土不分动态变化影响明显，植被覆盖下的半湿润沙地表层干沙层发育最大     

黄土高原土壤水分与植被生产力的关系

土壤水分生态条件的恶化愈来愈成为黄土高原植被建设和生态环境建设的限制因素，我们在对黄土高原土壤水分生态因素分析的基础上，探讨了黄土高原土壤水分的季节性变化、土壤剖面水分变化、区域水分变异规律，分析了土壤水分与植被生产力间的相互关系，并提出了改善黄土高原土壤水分生态环境、提高植被生产力的调控技术。     

Flow regime changes in three catchments with different landforms following ecological restoration in the Chinese Loess Plateau

The Chinese Loess Plateau is known as one of the most severe soil erosion regions in the world.Two ecological restoration projects,i.e.,the integrated soil conservation project since the 1970s and the'Grain for Green'project since 1999,have been progressively implemented to control the soil erosion in this area.Ecological restoration has greatly changed flow regime over the past five decades.However,the mechanism of how flow regime responds to ecological restoration among landforms remains poorly understood.In this study,we investigated the temporal dynamics of flow regime in three catchments,i.e.,Wuqi,Honghe and Huangling hydrological stations,respectively representing the loess hilly-gully,loess table-gully and rocky mountain(covered by secondary forest)areas in the Chinese Loess Plateau,using daily hydrological data during the 1960s–2010s.The nonparametric Mann-Kendall test,Pettitt's test and daily flow series were used to investigate the changes of flow regime.Significantly negative trends of annual streamflow were detected at the Wuqi and Honghe stations,except for the Huangling station.The annual baseflow at the Wuqi station showed a significantly positive trend whereas a significantly negative trend was observed at the Honghe station,and there was no significant trend at the Huangling station.It was interesting that baseflow index significantly increased during the whole period in all catchments.However,the trends and change points of daily flow series derived by different percentages of exceedance and extreme series in different consecutive days varied among individuals.Based on the change points analysis of annual streamflow,we divided data series into three periods,i.e.,the baseline period(from 1959 and 1963 to 1979,PI),the integrated soil conservation period(1980–1999,PII)and the'Grain for Green'period(2000–2011,PIII).We found that streamflow decreased due to the reduction of high streamflow(exceeding 5%of time within a year)and median streamflow(50%)in PII and PIII at the Wuqi and Honghe stations.However,low flow(95%)increased in PII and PIII at the Wuqi station while decreased at the Honghe station.Streamflow change at the Huangling station was more stable,thus potentially resulting in much less soil erosion in the forestry area than in the other areas.The great improvement in ecological environment on the Chinese Loess Plateau revealed the advantages of ecological restoration in reducing flood amount and compensating streamflow at a regional scale.     

黄土高原乡村生态建设模式及效应分析--以延川县刘马家圪塔村为例

在实际调研的基础上,评价了陕北黄土高原延川县刘马家圪塔村现行生态建设模式,并利用对比分析法、相关分析法及趋势线分析法,分析该模式带来的经济效应,特别运用土地利用结构特征指数、土地利用动态变化模型及垦殖指数等分析了土地利用结构变化过程,对建设进程中出现的问题提出调控对策。     

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).     

Changes in diversity,composition and assembly processes of soil microbial communities during Robinia pseudoacacia L. restoration on the Loess Plateau,China

Robinia pseudoacacia L. (RP) restoration has increased vegetation cover in semi-arid regions on the Loess Plateau of China, but ecological problems have also occurred due to RP restoration, such as reduced soil moisture. Further, it is still uncertain how microbial diversity, composition and assembly processes change with RP restoration in semi-arid regions. Therefore, amplicon sequencing of small subunit ribosomal ribonucleic acid (16S rRNA) and internal transcribed spacer (ITS) genes was performed to study soil bacterial and fungal diversity, composition and assembly processes at four study sites with different stand ages of RP plantations (Y10, RP plantation with stand ages less than 10 a; Y15, RP plantation with stand ages approximately 15 a; Y25, RP plantation with stand ages approximately 25 a; and Y40, RP plantation with stand ages approximately 40 a) along a 40-a chronosequence on the Loess Plateau. The diversity of soil bacteria and fungi increased significantly during the restoration period from 10 to 15 a (P<0.05). However, compared with Y15, bacterial diversity was lower at Y25 and Y40, and fungal diversity remained stable during the restoration period between 25 and 40 a. The relative abundances of Proteobacteria and Ascomycota increased during the restoration period from 10 to 15 a. Conversely, after 15 a of restoration, they both decreased, whereas the relative abundances of Actinomycetes, Acidobacteria and Basidiomycota gradually increased. The variations in soil bacterial communities were mainly related to changes in soil total nitrogen, nitrate nitrogen and moisture contents, while soil fungal communities were mainly shaped by soil organic carbon and nitrate nitrogen contents. Bacterial communities were structured by the heterogeneous selection and stochastic process, while fungal communities were structured primarily by the stochastic process. The RP restoration induced an increase in the relative importance of heterogeneous selection on bacterial communities. Overall, this study reveals the changes in microbial diversity, community composition and assembly processes with RP restoration on the Loess Plateau and provides a new perspective on the effects of vegetation restoration on soil microbial communities in semi-arid regions.     

Attribution analysis based on Budyko hypothesis for land evapotranspiration change in the Loess Plateau,China

Land evapotranspiration (ET) is an important process connecting soil, vegetation and the atmosphere, especially in regions that experience shortage in precipitation. Since 1999, the implementation of a large-scale vegetation restoration project has significantly improved the ecological environment of the Loess Plateau in China. However, the quantitative assessment of the contribution of vegetation restoration projects to long-term ET is still in its infancy. In this study, we investigated changes in land ET and associated driving factors from 1982to 2014 in the Loess Plateau using Budyko-based partial differential methods. Overall, annual ET slightly increased by 0.28 mm/a and there were no large fluctuations after project implementation. An attribution analysis showed that precipitation was the driving factor of inter-annual variability of land ET throughout the study period; the average impacts of precipitation, potential evapotranspiration, and vegetation restoration on ET change were 61.5%, 11.5% and 26.9%, respectively. These results provide an improved understanding of the relationship between vegetation condition change and climate variation on terrestrial ET in the study area and can support future decision-making regarding water resource availability.     

Effects of artificially cultivated biological soil crusts on soil nutrients and biological activities in the Loess Plateau

Biological soil crusts （BSCs） play an important role in the early succession of vegetation restoration in the Loess Plateau, China. To evaluate the effects of artificially cultivated BSCs on the soil surface micro-envir- onment, we obtained natural moss crusts and moss-lichen crusts from the Loess Plateau of Shaanxi province, and subsequently inoculated and cultivated on horizontal and sloping surfaces of loess soil in a greenhouse. The chemical and biological properties of the subsoil under cultivated BSCs were determined after 10 weeks of cul- tivation. The results indicated that BSCs coverage was more than 65% after 10 weeks of cultivation. Moss crust coverage reached 40% after 5 weeks of cultivation. Compared with the control, soil organic matter and available nitrogen contents in moss crust with the horizontal treatments increased by 100.87% and 48.23%, respectively; increased by 67.56% and 52.17% with the sloping treatments, respectively; they also increased in moss-lichen crust with horizontal and sloping treatments, but there was no significant difference. Available phosphorus in cultivated BSCs was reduced, soil pH was lower and cationic exchange capacity was higher in cultivated BSCs than in the control. Alkaline phosphatase, urease and invertase activities were increased in artificially cultivated BSCs, and alkaline phosphatase activity in all cultivated BSCs was obviously higher than that in the control. Numbers of soil bacteria, fungi and actinomycetes were increased in the formation process of cultivated BSCs. These results indicate that BSCs could be formed rapidly in short-term cultivation and improve the mi- cro-environment of soil surface, which provides a scientific reference for vegetation restoration and ecological reconstruction in the Loess Plateau. China.     

中国西北干旱半干旱区阿拉善沙漠和黄土高原的物源分析

中国北方沙漠、黄土高原和青藏高原是亚洲粉尘释放的关键区域,元素示踪研究表明中国西部沙漠和北部沙漠是亚洲粉尘和黄土高原黄土的主要源区.通过收集总结大量的大气观测、地球化学、地形数据,对比当前研究已得到粉尘的成果和释放模式,初步认为中国黄土物质来源于阿拉善高原的巴丹吉林沙漠与腾格里沙漠.这两个沙漠(包括阿拉善高原的戈壁)的...     

黄土高原不同土壤类型有机碳密度与储量特征

土壤有机质的理化特性是黄土高原地区水土保持及生态修复的重要物质基础,充分了解黄土高原区不同土壤类型的有机碳密度与储量,对生态建设具有重要的实际意义。利用第二次全国土壤普查数据,对黄土高原不同土壤类型0～20 cm表层土体有机碳密度及储量进行估算,并分析两者的空间特征。结果表明：黄土高原区土壤有机碳密度加权平均值为2.00 kg·m-2,棕壤碳密度值最高,为15.56 kg·m-2,风沙土最低,仅为0.24 kg· m-2,空间上呈中间低四周高的分布格局。黄土高原地区总碳储量为1 239.85 Tg（1 Tg=1012 g）,灰褐土及黄绵土碳储量较高,两者占总体的46.86%,灰漠土、冻漠土、碱土较低,总量仅占0.17%,空间上呈由西北向东南递增的分布规律。黄绵土、风沙土在黄土高原区分布较广,但两者碳密度较低。因此,在今后的生态修复措施中,提高两者有机碳含量十分关键。     

陇东黄土塬区土壤包气带水分水势特征研究

选取陇东黄土包气带为研究对象,综合运用数理统计与对比分析相结合的方法,研究黄土地区包气带土壤水分、水势变化特征和土水势构成结构,结果发现,在陇东黄土塬区,坡头荒地等较干旱、沙质土壤中,包气带水分变化呈对数分布特征,而耕作土壤其水分含量特征则不满足这种类型.在土水势构成方面,溶质势所占比例平均约为20%,其中坡头荒地约占...