塔克拉玛干沙漠河湖相沉积平原风蚀地貌发育的外营力作用机制

 河湖相沉积是一种非固结沉积物,是风蚀地貌发育的一种重要地质基础。在塔克拉玛干沙漠中发育在这种沉积物上的风蚀地貌分布非常普遍,但相关研究较少,尚缺乏风蚀地貌发育过程方面的研究。基于野外调查信息和理论分析,结合相关文献,分析了塔克拉玛干沙漠河湖相平原风蚀地貌发育的外营力作用机制。研究结果表明：（1）风蚀地貌发育的外营力作用主要有：风化作用、流水作用、风蚀作用以及重力作用;（2）风蚀作用是风蚀地貌发育的主要外营力,但是风化作用、流水作用和重力作用也发挥着重要的作用,它们的关键作用是形成风蚀突破口,而重力作用和风化作用是促进风蚀地貌后期快速发展的重要作用;（3）各种外营力协同作用和互为条件,它们在风蚀地貌发育的各阶段的重要性不同;（4）沉积层特殊沉积构造和外营力作用共同造成了风蚀地貌形态特征。     

树轮记录的腾格里沙漠东缘1775-2005年降水变化

 利用采自腾格里沙漠东缘的贺兰山油松树轮样本,建立树轮宽度年表。通过相关普查发现,贺兰山油松树轮宽度差值年表与腾格里沙漠东缘当年5月至7月的降水存在显著的正相关,相关系数为0.606（P<0.001）。利用贺兰山北部的树轮宽度差值年表,可较好地重建腾格里沙漠东缘近231 a来当年5月至7月的降水变化,交叉检验表明,降水重建结果稳定可靠。通过与腾格里沙漠南缘地区树轮降水重建序列对比分析,发现腾格里沙漠边缘区的树轮重建降水的干湿阶段变化具有良好的同步性,并对西北地区极端干旱历史事件有良好响应。     

Characteristics of soil water repellency after sand dune stabilization in the Tengger Desert

Soil water repellency (SWR) is one of the most important physical properties of soils found all over the world, and it may have significant effects on the eco-hydrological processes of land ecosystems. In this study, the Capillary Rise Method was used to measure the SWR in the artificial vegetation area in Shapotou, located in the southeast area of the Tengger Desert, Ningxia Province of western China. The variation of the soil water repellency among different minor topographies, different depths and different particle sizes was analyzed. The results of the study indicate that the SWR shows distinct changes with vegetation restoration, and it increases with an increase in the period of dune stabilization. In the same vegetation area, the SWR of soils in inter-dune depressions or windward slopes is slightly greater than that in crest or leeward slopes. The SWR of 0–3 cm topsoil is significantly greater than that in the 3–6 cm soil layer. The SWR decreases with an increase in grain size and the differences among the SWRs of different sieved soil fractions are found to be significant. There is also a significantly positive correlation between the SWR and the proportion of soils with grain sizes of 0–0.05, 0.05–0.01 and 0.01–0.15 mm, and a significantly negative correlation between the SWR and the propotion of soils with grain sizes exceeding 0.15 mm. The increase of SWR in revegetation areas may depend on the continuous depositing of atmospheric dust on the stabilized dune surface as well as the formation of biological soil crusts, especially on the formation of algal and lichen crusts. Enhanced SWR influences the effectiveness of water use of sand plants inhabiting the sand dunes.     

Late Quaternary hydrological dynamics in the Middle Kalahari: Forcing and feedbacks

The Kalahari region has become a major source of Quaternary palaeoenvironmental data derived primarily from the analysis of geomorphological proxies of environmental change. One suite of data, from palaeolacustrine landforms, has recently provided a new record of major hydrological changes in the last 150 ka [Burrough, S. L., Thomas, D. S. G., Bailey, R. M., 2009. Mega-Lake in the Kalahari: A Late Pleistocene record of the Palaeolake Makgadikgadi system. Quaternary Science Reviews, in press.]. Here we present an improved analysis of the drivers and feedbacks of lake level change, utilising information from three main sources: data from the lake system itself, from analyses of other late Quaternary records within the region and from climate modelling. Simulations using the Hadley Centre coupled climate model, HadCM3, suggest that once triggered, the lake body was large enough to potentially affect both local and regional climates. Surface waters and their interactions with the climate are therefore an important component of environmental dynamics during the late Quaternary. Through its capacity to couple Middle Kalahari environments to distant forcing mechanisms and to itself force environmental change, we demonstrate that the existence or absence of megalake Makgadikgadi adds a new level of complexity to the interpretations of environmental proxy records in southern Africa's summer rainfall zone.     

腾格里沙漠南缘土门剖面末次间冰阶层段的粒度特征及其反映的气候-沉积环境

腾格里沙漠南缘土门剖面末次间冰阶层段（TMS 3）由风成砂、黄土状亚砂土、砂黄土、古土壤、湖相沉积物和冲积黄土等6种沉积相相互叠覆构成。粒度分析结果显示,该层段以砂质沉积物为主,粉砂次之,黏土最少,平均值分别为65.45%、26.72%和8.83%;在砂粒级中,以细砂含量最高,其次为极细砂,其余为中砂-粗砂颗粒。粉砂含量、黏土含量、M_z和σ在风成砂中呈现谷值,在其他沉积相为峰值,中砂-粗砂和细砂则相反。粒度指标指示腾格里沙漠南缘土门剖面末次间冰阶至少经历了13次暖湿和12次冷干的气候波动,且可划分为TMS 3e（54 200~59 750 a BP）、TMS 3d （54 200~40 800 a BP）、TMS 3c （40 800~32 800 a BP）、TMS 3b （32 800~25 400 a BP）和TMS 3a （25 400~22 940 a BP）等5个亚段, 25次冷暖波动与格陵兰冰芯和中国南方石笋记录的D/O事件以及北大西洋深海沉积物记录的H事件具有很高的同步性。     

禁牧政策对库布齐沙漠农户土地利用行为的影响

作为草原地区涉及面最广、农牧民参与程度最高的一项生态政策,禁牧政策对农户的土地利用行为产生了重大的影响。基于参与式农户评估法及累积Logit回归模型等对禁牧政策作用下库布齐沙漠的农户土地利用行为变化进行了研究。结果表明：（1）禁牧后农户的耕地和草地利用行为发生了显著变化。耕地总面积平均增加0.83 hm²,饲草种植面积平均增加0.25 hm²,羊只数量平均减少39.44只,舍饲程度得到提高;（2）政策因子、户主特征因子、家庭特征因子、农户土地利用行为意识因子是影响农户土地利用行为转变的主要因素,各个因子对不同土地利用行为的影响程度不同;（3）季节休牧对农户耕地利用行为的影响程度较大,全年禁牧对农户草地利用行为的影响程度较大。结合研究结果对禁牧政策的改进提出了相关建议。     

腾格里沙漠东南缘不同生境油蒿种群的数量动态

对腾格里沙漠东南缘不同的生境条件（包括始建于1964年的人工植被区和天然植被区）下油蒿（Artemisia ordosica）种群调查取样,按照植株的体积大小分为7个龄级（Ⅰ,0~2 cm³;Ⅱ,2~5 cm³;Ⅲ,5~10 cm³;Ⅳ,10~15 cm³;Ⅴ,15~20 cm³;Ⅵ,20~30 cm³;Ⅶ,>30 cm³）,分析了种群的组成、静态生命表和存活曲线。结果表明：人工植被区油蒿种群的总体规模大于天然植被区,幼龄个体占有很高的比例;天然植被区油蒿的死亡率低于人工植被区,天然植被区Ⅰ和Ⅱ龄级油蒿种群的死亡率最高,人工植被区Ⅴ~Ⅶ龄级的油蒿种群死亡率最高;天然植被区油蒿种群的稳定性维持主要通过幼苗的更新,而人工植被区可通过幼苗的自我更新和大龄植株的自疏作用;Ⅴ龄级的油蒿个体是种群中的生存质量最佳的个体;两种生境下油蒿种群均符合Deevey Ⅱ型存活曲线。     

On the existence of characteristic shapes for desert dunes

The existence of an angle of repose for sand implies that, in any given wind regime, there is at least one configuration of sand dunes which will not be altered by that wind regime. The existence of implies that the land forms constitute a convex compact subset of a Banach space, and the result then follows from Shauder's theorem.     

河西走廊沙漠沿线春小麦品种籽粒灌浆特性的研究

利用４个分别适应沙漠地区和阴冷地区的小麦品种，研究了河西走廊沙漠沿线小麦品种的灌浆特点。春小麦籽粒灌浆的强度较大，参试品种的平均灌浆强度为１．１３５ｇ／（ｄ·１０００粒）～１．３４３ｇ／（ｄ·１０００粒）；而灌浆的持续时间较短，参试品种的乳熟期为１５ｄ～１８ｄ，灌浆持续期２７ｄ～３０ｄ。灌浆速率随着日均温和日最高气温的升降有明显波动性。小麦品种之间在灌浆性上有显著差异，甘春１１号和甘春１６号适宜在沙漠沿线种植，与临农１４号和陇春８号相比，在乳熟后期干热风天气过程中受害轻，灌浆持续时间长３ｄ～７ｄ。甘春１６号还具有灌浆强度大的特点。     

沙漠边缘地区苹果“两高一优”栽培管理技术规范

通过对沙漠边缘地区影响苹果高产高效和优质的生态因子的综合评估，在多项生产试验的基础上，提出了该区苹果幼树期、结果期两个阶段“两高一优”栽培管理技术规范。