全新世中期以来黄土高原中部生物多样性研究

根据孢粉分析、古文献记载、生物地名考证以及对现今物种群多样性等方面的研究资料，结合气候变迁，论述了全新世以来，在自然和人为因素影响下，黄土高原中部地区景观和生物多样性的演变过程及其恢复和保护措施。     

全新世以来黄土高原侵蚀环境研究述评

全新世以来黄土高原的侵蚀问题,历来是国内外学者研究的热门．黄土高原的环境演变和水土流失问题也是黄土高原研究的难点和重点．本研究从全新世以来黄土高原植被变化、降水量变化和土壤侵蚀量变化等几个方面,简要回顾了国内学者在上述领域的研究成果,针对领域内的成就和问题提出了粗浅看法和建议．文章认为,全新世以来黄土高原总体植被景观以草原为主;降水量也有显著变化,总体呈现东南高,西北低的态势,400mm等降水量线大致沿东南-西北方向移动;土壤侵蚀强度也有阶段性变化,全新世早中期主要受自然因素影响,晚期受自然因素和人为因素双重影响．     

罗霄山脉山地沼泽全新世以来的古气候记录

在中亚热带罗霄山脉东南段井冈山地区的江西坳山地沼泽钻取了150 cm的岩芯样品（JXA钻孔）,通过6个AMS 14C测年结果建立钻孔的年代框架,运用烧失量、腐殖化度、有机碳同位素和灰度值等多项古气候代用指标分析,重建了该地区约11 cal. ka B.P.以来的气候演化历史。结果表明：江西坳山地沼泽的古环境演变过程可以分为４个阶段：11―9.2 cal. ka B.P.钻孔沉积物的有机碳含量低,碳同位素偏负,显示C3植物为主,为气候凉干期;9.2―5.3 cal. ka B.P.碳同位素、有机碳和腐殖化度等指标均指示森林植被繁茂,沉积物泥炭堆积速度加快,为气候最适宜期;5.3―2.2 cal. ka B.P.碳同位素显著变化,有机质含量较高;2.2―0 cal. ka B.P.气候呈现季风再次增强的趋势,人类活动增强。与周边其他的研究结果对比发现：全新世以来罗霄山脉江西坳山地泥炭沼泽的古环境替代指标与低纬度地区其他全新世气候记录基本一致。     

敦化盆地晚全新世泥炭沉积中化学元素记录的古气候分析

在对敦化吉祥泥炭剖面的Na、K、Mg、Ca、Fe、Cr、Mn、Sr、Ba和Pb等元素进行分析的基础上,采用Morlet一维连续小波分析其时频变化,将剖面晚全新世以来的古气候过程分为6个阶段:公元前730年前的温暖降温期;公元前730年～公元前205年的温和湿润期;公元前205年～公元255年早期温暖湿润,之后变凉干;公...     

关中盆地西部黄土台塬全新世气候事件研究

通过对陕西歧山黄土剖面地层学和土壤学研究，磁化率、全铁、粒度、CaCO3和TOC测定分析,发现在全新世的全球性“大暖期”即将到来之前，黄土台塬面有洪水发生。在全新世大暖期当中，季风气候有明显的波动变化。尤其是在6000a BP前后季风气候转折，形成了6000－5000a BP显著的干旱阶段。这使得全新世大暖期分裂成为两个主要的温暖湿润阶段。各项气候代用指标显示8500－6000a BP是大暖期中最为温暖湿润的时期。在大约3100a BP季风格局发生变化，气候向着干旱化发展，全新世的成壤期为黄土堆积期所取代。这些事实对于我们客观地评价半湿润－半干旱地区的季风气候对于全球变化的响应规律具有重要的科学意义。     

黄土高原东西部全新世剖面炭屑记录的火环境变化

对黄土高原东、西部全新世3个典型黄土—土壤剖面磁化率和炭屑浓度进行分析和对比研究,探讨该区域剖面中炭屑含量变化及其所记录的火环境变化特征。马兰黄土堆积时期,气候干旱而不稳定,地方性和区域性火频繁发生,炭屑含量较高;全新世早期,气候由冷干向温湿过渡,但仍较干旱,炭屑含量相应也较高;全新世中期是全新世最为温暖湿润的时期,炭屑含量出现全新世时期的最低值,但在夏商文化时期和庙底沟文化时期炭屑含量出现峰值,则是人类活动的结果;全新世晚期,在干旱的气候条件下,人类活动加速了火的频率和强度,炭屑含量大幅度增加。在全新世不同时期,黄土高原东、西部的炭屑含量存在一定差异,黄土高原东部火活动较为微弱,而西部火活动相对频繁,这是火环境条件区域差异性的表现。     

黄土高原南部全新世土壤微结构形成机理探讨

通过对黄土高原南部不同剖面土壤微结构的研究和与相邻地区的对比 ,探讨了风化成土过程的特征 ,揭示出全新世土壤S0 是由上下两个土壤层组成的复合土壤 ,显示两个较完整的成土过程。早期成土阶段形成了具棕壤特征的古土壤S0 2 ,晚期成土阶段形成了淋溶褐土型古土壤S0 1 。土壤S0 以上的部分是风尘堆积增强时期形成的风积黄土层 ,但被人类耕作活动所扰动。     

黄土高原南部全新世古土壤的沉积序列

Optically stimulated luminescence （OSL） dating for polymlneral fine-grained loess samples, collected in Laoguantai （LGT） section on the south of the Chinese Loess Plateau, was made by application of single-aliquot regenerative-dose （SAR） protocol. A ＇Double-SAW procedure in which aliquots are subjected to both infrared （IR） and blue stimulations was used and two sets of equivalent dose （De） determinations were produced and assumed to relate predominantly to feldspathic and quartz fine grain populations respectively, The OSL ages estimated from IRSL signals are smaller than those estimated from [post-IR] OSL signals due to the anomalous fading of feldspar IR signals, based on fading experiment, The young ages of the samples near ground surface may be originated from the post-depositional disturbance by the intensifying humanity＇s cultivation since 3.0 ka BP in the Guanzhong Basin, south of the Chinese Loess Plateau. Based on OSL dating, as well as field observations and stratigraphic correlation, we determine the chronology of the LGT Ioess-paleosol sequence. In combination with climate proxy records, it is indicated that aeolian loess deposition and pedogenesis underwent polyphase changes during the Holocene, likely to have been driven by shifts in the East Asian monsoon. This suggests that aeolian loess deposition is episodic and highly variable, with contributions from non-aeolian processes such as alluvial deposition found in the area.     

中晚全新世湘西莲花洞石笋灰度变化特征 及其古气候意义

以湖南湘西莲花洞LH2石笋为研究对象,在高精度铀系定年的基础上,构建了湘西地区中晚全新世文石石笋灰度序列。中晚全新世,LH2石笋灰度值与δ18O值呈负相关同步变化,与旋回沉积速率呈正相关关系。LH2石笋的剖面灰度与文石的结晶形态有关,受降雨量和温度的控制。LH2石笋灰度显示,中晚全新世（8.6—0.03 ka B.P.）湘西地区气候变化可以划分为3个阶段：8.6—5.7 ka B.P.期间,夏季风强盛,气候暖湿,灰度值整体偏高;5.7—2.8 ka B.P.期间,灰度值逐渐降低,指示夏季风持续减弱,气候从暖湿向冷干过渡;2.8—0.03 ka B.P.期间,灰度值整体偏低,且存在较大幅度的波动,表明该时段气候整体偏冷干,但其间存在明显的温湿波动。在轨道尺度上,LH2石笋灰度值主要受北半球夏季太阳辐射量和热带辐合带（ITCZ）位置的控制。在百年尺度上LH2石笋灰度值的突变可能与北大西洋冰筏事件存在关联;年代际尺度上,LH2石笋灰度的变化受太阳活动和太平洋年代际涛动（PDO）的调控。在年际尺度上LH2石笋灰度的波动可能受厄尔尼诺—南方涛动（ENSO）活动驱动。     

An early Holocene erosion phase on the loess tablelands in the southern Loess Plateau of China

A Holocene loess profile to the west of Xi'an China was studied multi-disciplinarily to investigate the relationships between soil erosion and monsoonal climatic change. The proxy data obtained from this aeolian loess and palaeosol sequence indicate large-scale variations of climate in the southern Loess Plateau since the last glaciation. A rainwash bed, indicative of a wetter climate, excessive runoff and erosion on the loess tablelands, was identified relating to the early Holocene before the onset of the “climatic optimum”. This is synchronous with the early Holocene physiographic erosional stage identified in the valleys in North China. It means that severe erosion took place when the region was undergoing climatic amelioration during the early Holocene. The evidence presented in this paper shows that the erosion occurred as a regional response to a monsoonal climatic shift in the southern Loess Plateau. During the last glaciation, prior to the erosion phase, the land surface on the tablelands had been largely stable except for the rapid accumulation of aeolian dust and the resultant increase in its elevation. Relatively slow dust accumulation and intensive bio-pedogenesis responding to the Holocene “climatic optimum” followed the erosion phase. The loess tablelands were most vulnerable to erosion during the large-scale monsoonal climatic shift from dry-cold glacial to humid-warm post-glacial conditions in the southern Loess Plateau.     

泾河上游黄土高原全新世成壤环境演变与人类活动影响

通过对黄土高原腹地甘肃合水MJY-A全新世土壤剖面磁化率、粒度、全铁、TOC、TC、CaCO3等气候代用指标的测定分析。结果表明：在全新世早期,黄土高原中部地区气候虽比较温和干燥,风尘堆积速率降低,土壤发育表现为边沉积边成壤的自然过程;到了全新世中期,气候较为温暖湿润,地表植被发育,生物风化成壤作用强烈,土壤发育依旧表现为自然的成壤过程,形成深厚的古土壤-黑垆土(S0);到了全新世晚期,气候开始恶化,干旱少雨,植被急剧退化,沙尘暴频繁发生,形成的现代黄土层(L0)覆盖了土壤(S0)使之成为埋藏古土壤,土壤发育深受人类活动的影响。现代黄土高原土地资源的退化,并不全是由自然要素本身固有的规律所造成的,而是在自然要素本身变化的背景上叠加了人类活动影响的结果。     

宁夏长城塬全新世黄土-古土壤序列微形态特征及意义

利用偏光显微镜对宁夏长城塬全新世黄土-古土壤序列(CCY)的微形态特征进行了详细观察和分析。结果表明,S0层的粗颗粒形态参数（如C/F(10 μm)、面积、周长、等圆直径等）以及土壤形成物、孔隙、微垒结等微形态指标明显区别与黄土层L层,其中C/F(10 μm)值在全剖面中达到最小值,孔隙度达到最大值,残积黏土铁染程度最强烈,指示出古土壤S0层受到的风化作用较为强烈,成壤强度较强。同时,微形态变化能够与磁化率、CaCO3、粒度含量变化进行良好的对比;通过对比得出C/F(10 μm)值、孔隙度、土壤形成物存在形式也可作为指示气候变化的一个重要指标。     

Chronology of the Holocene loess-paleosol section and its deposition and pedogenesis on the south of Chinese Loess Plateau

Optically stimulated luminescence (OSL) dating for polymineral fine-grained loess samples, collected in Laoguantai (LGT) section on the south of the Chinese Loess Plateau, was made by application of single-aliquot regenerative-dose (SAR) protocol. A ‘Double-SAR’ procedure in which aliquots are subjected to both infrared (IR) and blue stimulations was used, and two sets of equivalent dose (De) determinations were produced and assumed to relate predominantly to feldspathic and quartz fine grain populations respectively. The OSL ages estimated from IRSL signals are smaller than those estimated from [post-IR] OSL signals due to the anomalous fading of feldspar IR signals, based on fading experiment. The young ages of the samples near ground surface may be originated from the post-depositional disturbance by the intensifying humanity’s cultivation since 3.0 ka BP in the Guanzhong Basin, south of the Chinese Loess Plateau. Based on OSL dating, as well as field observations and stratigraphic correlation, we determine the chronology of the LGT loess-paleosol sequence. In combination with climate proxy records, it is indicated that aeolian loess deposition and pedogenesis underwent polyphase changes during the Holocene, likely to have been driven by shifts in the East Asian monsoon. This suggests that aeolian loess deposition is episodic and highly variable, with contributions from non-aeolian processes such as alluvial deposition found in the area.     

黄土高原东缘晚全新世高精度高分辨率石笋古环境记录

基于山西武乡太行龙洞一支石笋5个230Th年龄和190个氧同位素数据重建4 400~150 a B.P.高分辨率δ18O序列。石笋δ18O值逐渐增加,除最近约600 a外,在千年尺度长期趋势变化上与中国南部其它洞穴记录相一致,表明晚全新世亚洲夏季风强度持续减弱响应于同一驱动机制。一次显著的气候突变事件发生在2 550~2 000 aB.P.,与史料记载的干旱期大致相对应。功率谱分析揭示出106 a周期,与树轮Δ14C太阳活动周期大体一致,说明百年尺度上太阳活动与东亚季风变化有一定关联性。     

The impacts of urbanization on soil erosion in the Loess Plateau region

1 IntroductionThe Loess Plateau region covers an area of 62.4(104 km2 and lies in the center of northern China. Urbanization and economic development have been quickened in recent decades. Both the number of towns established and scale of cities have increased. Although the pace of urbanization has been accelerated, the eco-environmental control in urban areas still lags behind relatively. Moreover, the construction and development of cities damaged the already vulnerable eco-environment to …     

黄土高原泥流灾害成因及特征

黄土泥流是戴土地区一类重要的灾害地貌过程,是泥石流的一个特殊类型,是水土流失的一种特殊形式,也是山地环境恶化、水土流失极严重的标志。本文在对黄土泥流这一黄土高原特有的严重水土流失现象的分布、成因、物质组成、动静力学性质、堆积形态等全面系统研究的基础上,对其和一般泥石流与高含沙水流做了初步对比和分析,揭示了黄土泥流灾害的形成规律、运动机制和沉积特征。     

不同植被类型的土壤水分对黄土高原的影响

Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth. The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter-annual change. Soil moisture in 0–10 m depth of six vegetation types, i.e., crop, grass, planted shrub of caragana, planted forests of arborvitae, pine and the mixture of pine and arborvitae were measured in 2001, 2005 and 2006. Soil moisture in about 0–3 m of cropland and about 0–2 m of other vegetation types varied inter-annually dependent on annual precipitation, but was stable inter-annually below these depths. In 0–2 m, soil moisture of cropland was significantly greater than those of all other vegetation types, and there were no significant differences among other vegetation types. In 2–10 m, there was no significant moisture difference between cropland and grassland, but the soil moistures under both of them were significantly higher than those of planted shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point, and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly lower than those of forests, but the absolute difference was very small. The results of this study implicated that the planted shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on present year precipitation for transpiration.