ABSTRACTAimLiterature and fossil records document the long‐term occurrence sites of large herbivorous mammals in China. These sites exhibit spatially uneven distribution, potentially reflecting constraints on the dispersal of large herbivorous mammals imposed by stable geomorphic factors. In this study, we examine the impact of landforms on the dispersal of four taxa of large herbivorous mammals across China.LocationChina.TaxonRhinocerotidae, Elephantidae, Equus, Camelus.MethodsWe employed the Omniscape algorithm to create a connectivity model from geomorphic data (slope, elevation and ground cover), assessing the extent to which Chinese landforms obstruct large herbivore dispersal. This model utilised historical distribution sites to delineate barrier strips.ResultsDispersal barriers show regional variation, segmenting China into four distinct regions. The Tibetan Plateau, Taklamakan Desert and Qinling Mountains constitute Region A, presenting the most significant barrier. Region B, characterised by dense, continuous mountain ranges and arid landforms in Northwest China, poses a secondary barrier. Region C, with fragmented mountain ranges in Southwest China, exhibits a diminished barrier effect. Region D features the eastern coastal plains with minimal geomorphic constraints.ConclusionsThe edge mountains of the Tibetan Plateau form a continuous barrier strip. The Qinling–Taihang–Yanshan mountain chain constitutes a discontinuous barrier strip. This is because the mountain chain belongs to two geological structural units and is eroded by rivers, creating many corridors.

优先保护区识别对受威胁物种的多样性保护具有重要价值.基于GIS空间分析、管理及预测能力,以中国受威胁陆栖哺乳动物为对象,建立受威胁物种的分布二值网格系统;利用Dobson算法对研究区3810个网格单元进行筛除,确定全国范围下受威胁物种的优先保护区域;结合中国主要的自然保护地分布数据(国家公园和自然保护区),采用保护空缺方法分析优先保护区内受威胁动物的保护现状.研究发现,29个50km×50km的网格单元就包含了全部的受威胁陆栖哺乳物种,其中位于喜马拉雅山东南区等地的10个网格区域覆盖有80％以上的物种,其所处的10组县级行政区内被主要自然保护地保护的土地面积占25.9％,物种数占83.6％,存在一定的保护空缺.本文采用Dobson排除算法,以小面积规则网格为基本单元,顾及到了实验结果的客观性,有助于提高优先保护区的识别效率.

Parabolic dunes can transform from and into other types of dunes in response to environmental changes. The sand hills, including some parabolic dunes, on the shore of Poyang Lake mainly accumulated during the Last Glaciation and are rare inland aeolian landforms in the humid monsoon climate zone in East China. However, the characteristics, distribution and formation of the parabolic dunes in this region are still not clear. Three sand hills with similar scales and wind regimes at Shaling, Jishan and Songmenshan were selected as the research targets. Integrating topographical, hydrological, vegetation and wind data, we found that the development of the parabolic dunes was effectively controlled by both the vegetation cover of the sand hills and the space available downwind of the sand hills. No parabolic dunes were found at Songmenshan and Shaling; the former has too little vegetation cover, favouring the formation of blowouts, and the latter lacks available space since Shaling is surrounded by villages and farmlands. Three types of parabolic dunes that developed sequentially in the downwind direction, namely, type A, type B and type C dunes, are observed at Jishan, and their formation is related to a narrowly unimodal and high-energy wind regime. Different from existing models, type A dunes are found to originate from the wedge-shaped depositional lobes of trough blowouts; type B dunes transform from type A dunes after migration; and type C dunes develop from very low sand drifts. Composite parabolic dunes are formed when the sand supply is plentiful, while simple parabolic dunes appear when the sand supply is limited. The formation of the parabolic dunes occurred approximately 250 years ago, which is close to the documented time when the sand hills were reactivated due to the vegetation being anthropogenically damaged. Therefore, anthropogenic destruction of vegetation is a trigger for producing parabolic dunes in this humid area. This study may shed light on the evolution of aeolian landforms in humid monsoon climate zones. (c) 2021 Published by Elsevier B.V.

下蜀黄土的物源问题对于理解亚热带东亚季风区干旱化过程至关重要.目前采用的物源示踪方法存在一定的局限性,对下蜀黄土物源的认识也存在争议.粒度端元分析可定量分解出沉积物中不同动力过程和来源的粒度组分,具有解析风尘沉积物源的较好潜力.本文应用参数化粒度端元分析方法,对镇江大港和九江马垱两个下蜀黄土剖面的物源组分进行了研究.结果发现:下蜀黄土可分离为超细粒(EM1)、细粒(EM2)、中粒(EM3)和粗粒(EM4)4个粒度端元,其中EM1(众数分别为0.7μm和0.9μm)源于粉尘沉积后风化成壤作用形成的次生组分,EM2(众数均为6μm)为长距离搬运的远源组分,EM3(众数分别为25μm和28μm)是区域近地面冬季风搬运的近源粉尘,EM4(众数分别为44μm和45μm)则来自于沉积区附近的局地源组分.相似的区域风化成壤背景导致两地的EM1含量及变化均十分相似(镇江9.88％,九江9.06％);近源加局地源组分(EM3?+?EM4)则构成了两地下蜀黄土的主要来源(镇江51.79％,九江63.35％);西北气流将干旱-半干旱地区的粉尘输送至长江下游地区形成远源组分(EM2,镇江38.33％,九江27.59％),而在区域近地面东北风的作用下,两剖面间粒度端元的变化序列存在"异元相似"的现象(即大港剖面EM3与马垱剖面的EM2变化曲线相似,大港剖面EM4与马垱剖面EM3变化曲线相似).因此,下蜀黄土是不同物源组分混合而形成的沉积物,不同区域下蜀黄土的物源既有差异,又存在一定的空间联系.

The Xiashu Loess distributed in the region from Nanjing to Zhenjiang is lack of a reliable time scale. Taking a drilling core at Zhenjiang as an example, we discuss the reliability of the reconstructed relative paleointensity of geomagnetic field in the Xiashu Loess. Rock magnetic experiments show that the Xiashu Loess approximately meets the requirements for reconstruction of the relative paleointensity in sediments. Using the low-field susceptibility (chi) to normalize the natural remanence (NRM300) after being thermally demagnetized at 300 degrees C, we obtain the record of the relative paleointensity variation in the Xiashu Loess. Comparing with the single or synthesized curves both in neighboring regions and in the world, we find that the relative paleointensity in the Xiashu Loess exhibits main characteristics of the global dipole field, which can be used to establish the time scale. The obtained time scale shows that the chronological sequence of magnetic susceptibility of the Xiashu Loess cannot be correlated to that of loess in north China, which demonstrates the change mechanism of magnetic susceptibility differs from one another. The sedimentation rate is relevant to magnetic susceptibility in the Xiashu Loess. The low sedimentation rate corresponds to the low magnetic susceptibility, which results from the increased precipitation. Both the sedimentation rate and the magnetic susceptibility reveal that the paleoclimate change can be divided into four stages. The precipitation of the East Asian monsoon was low at Stage IV (819 similar to 700 ka) which is roughly correlated to the Middle Pleistocene Transition (MPT). The precipitation increased at Stage III (700 similar to 412 ka) which is roughly correlated to the Great Interglacial. The monsoon precipitation decreased at Stage II (412 similar to 197 ka) and probably was lower than that at Stage IV. The monsoon precipitation decreased to the lowest level at Stage I (197 similar to 34 ka). In general, the precipitation of East Asian monsoon continued to decrease since the MPT and the aridification was gradually strengthened in this region.