The authors presented carbon isotope data from fossilized common millet seeds collected from archeological sites in northern China. The carbon isotope record was then used to reconstruct summer precipitation during the mid-Holocene, on the basis of the relationship between millet C isotopes and summer precipitation established in a modern process study by the same group (Yang and Li 2015). The authors then used the reconstructed summer precipitation to discuss East Asian summer monsoon dynamics.

We reconstructed paleovegetation changes on the Chinese Loess Plateau by applying concepts in palynology and pollination biology to the statistical analysis of the size of Artemisia pollen grains from 26 surface samples, four loess paleosoil profiles, and extant Artemisia species. We found that the size of Artemisia pollen grains varied in different plant communities, and was positively correlated with local habitat quality and population density of local Artemisia communities. The Mean Artemisia Pollen Size (MAPS), which has changed significantly since Marine Isotope Stage 3 (MIS3), reflects integrated ecological changes, including compositional changes and shifts in population density. During MIS3, the high MAPS values indicate that high population densities of Artemisia grassland covered the northern and southern Loess Plateau. During the Last Glacial Maximum (LGM), with much less favorable growing conditions, a low MAPS value indicates that lower-density short grass steppe covered the Loess Plateau at that time. Overall, the results demonstrate that a statistical analysis of the size of fossil pollen grains at genus level can provide useful ecological information, e.g., on changes in the composition and population density of local communities, and thus can lead to a better understanding of the evolution of terrestrial ecosystems.

Abstract. In order to produce quantitative Holocene precipitation reconstructions for particular geographical areas, explicit proxies and accurate dating controls are required. The fossilized seeds of common millet (Panicum miliaceum) are found throughout the sedimentary strata of northern China, and are highly suited to the production of accurate quantitative Holocene precipitation reconstructions: their isotopic carbon composition (δ13C) gives a measure of the precipitation required during the growing season, and allows these seeds to be dated. We therefore used a robust regression function, as part of a systematic study of the δ13C of common millet, to produce a quantitative reconstruction of Mid Holocene summer precipitation in the Guanzhong Basin. Our results showed that summer precipitation from 7.7–3.4 ka BP was 240–477 mm, with a mean of 354 mm, i.e. ~ 50 mm or 17 % higher than present levels. Maximal mean summer precipitation peaked at 414 mm, ~ 109 mm (or 36 %) higher than today, occurring during 6.4–5.5 ka BP; this is when the East Asian Summer Monsoon (EASM) was at its peak. As the δ13C-based precipitation record can reliably indicate EASM intensity during the Holocene, this work can provide a reliable proxy for further research into the detailed processes, and precise mechanisms, of the EASM.

粟、黍炭化种子遗存是研究早期人类活动的重要植物考古材料.通过不同温度条件下的室内炭化实验及野外火焙实验,研究现代粟、黍种子形态和亚显微结构特征,拟揭示粟、黍种子遗存形成的条件与原因.200℃以下种子形态变化呈缩小趋势,胚乳淀粉粒保持结晶结构;250℃粟形态呈膨胀增大趋势,黍种子形变较严重,粟和黍胚乳淀粉粒都过渡为无定形结构;300℃种子部分灰化,炭化种子出现多孔现象,亚显微结构呈蜂窝状的孔洞.北牛遗址史前窖穴中的种子遗存仍保持结晶结构,显示水分子不参与淀粉结晶,为脱水炭化作用而成.野外火焙实验结果显示火堆底部地表的炭化粟、黍种子亚显微结构呈无定形,考古文化堆积中炭化种子遗存亚显微结构也呈无定形.与250℃条件下的炭化种子结构特征相一致,判定文化层的种子遗存形成并不受明火直接烧烤,而是在250℃左右的温度条件下烘焙而形成的.

通过东灰山遗址含文化层沉积物元素地球化学分析,结合高精度AMS 14 C测年和考古资料,重建河西走廊地区3700~3400 cal BP期间人类活动特征。铜（Cu）、锌（Zn）、铅（Pb）、锶（Sr）和铷（Rb）元素以及Rb/Sr比值显示,东灰山地区3710~3690 cal BP间人类活动强度不大,农业和青铜铸造活动主要出现在3690~3500 cal BP时段,3500 cal BP以后人类活动强度减弱。Rb/Sr比值可作为早期人类活动替代指标,与人类活动强度呈反相关关系。

炭屑化石的显微结构研究是根据木材的解剖特征(组成木材的细胞与组织的形态和排列方式)确定燃烧植物的类型,重建古植被和古环境,探讨人类活动对环境的影响.火石梁和缸缸洼青铜冶炼点位于河西走廊西北部、黑河流域下游巴丹吉林南缘沙地中,散布了大量的炭屑化石遗存.通过炭屑化石3个切面(横切面、径切面和弦切面)显微结构特征研究,比对现代切片标本和木材解剖图版,识别和确定炭屑化石的木材种属,确定 2100～1860BC期间的青铜冶炼所用木材为柽柳、杨属、柳属、蓼科4种乔灌木植物,火石梁和缸缸洼地区大量乔、灌群落生长要比目前荒漠生态环境优越的多.先民的青铜冶炼活动导致乔木和灌木植物被大量砍伐,植被盖度急剧降低,对生态环境产生重大影响,是1900BC左右杨属、柳属和蓼科乔灌木植物基本消失的主要原因.

The utilization and smelting of metal is a revolutionary event during developing process of human society.The records of element geochemistry from lacustrine sediment at Lake Tiaohu in Hexi Corridor,during Holocene indicated that the high values of element such as Cu,Pb,Zn,and Ni appeared in the period of 10500-9500 and 8000-7200cal aBP,responding to the episode of glacial meltwater rising in the period of increasing temperature in early Holocene of the and the period of precipitation strength during Holocene optimum,respectively.The highest peak values of Cu,As,Pb,Zn and Ni appeared between 4200 and 3700cal aBP.Additionally,the secondary high values of Cu,Pb,Zn and Ni appeared in the period of 3000-2700cal aBP and 2100- 1900cal aBP.The element abnormality between 4200 and 3700cal aBP record the earliest bronze smelting in Northwest China and the element of arsenic was the major component in bronze alloy in this period.The element high values of Cu,Pb,Zn,Ni in Western Zhou Dynasty(3000-2700cal aBP) and Han Dynasty(2100-1900cal aBP) were probably the result of bronze smelting by ancient people.The record of element geochemistry could identify the starting-end time of bronze smelting,and it also provided the message on the component characteristic of bronze alloy in different periods.

Landuse classification is an important problem in the remote sensing field. It can be used in a wide range of applications. In this paper, we propose a hybrid method fusing edges and regions information for the landuse classification of multispectral images. It mainly includes the steps of image pre-processing, initial segmentation and region merging. Especially, a novel spatial mean shift procedure is proposed so that some information can be extracted and used in the successive steps. Aiming at the multispectral images processing, we also design a band weighting strategy that give a proper weight to each band adoptively according to the region to be processed. Experimental results on the Landsat TM and ETM+ images validate the performance of the proposed method.

The Sanjiang Plain is the largest fresh water wetland distribution area in China and the center of waterfowls breeding and habitat area in Asia, but over the past 50 years, more than 73% of its wetland had lost because of agricultural development, and as a result, the wetland biodiversity declines dramatically, and the remnant wetlands are in a very fragment state. Based on historical maps, remote sensing data and GIS techniques, this paper selected two watersheds to analyze their wetland landscape fragmentation process during 1950-2000. It was indicated that land reclamation resulted in a decrease of 98% wetland corridors in Qixing River, 90% in Naoli River, 87% in the middle reach of Bielahong River, and 94% in the lower reach of Bielahong River; The amount of isolated wetlands in watershed increased dramatically; The maximum patch areas of wetland decreased by 92.6% in Naoli River watershed and 74.6% in Bielahong River watershed, and the mean wetland patch area in the two watersheds decreased by 99%. Before 1983, the wetland landscape was in an extensive area distribution state (the index of patch density was < 0.1), but after 1983, it fragmented dramatically, with the index of patch density larger than 1.5. The shape fragmentation indices of wetland decreased from 1950 to 2000, indicating a very big change in wetland patch shapes in the watersheds. The area fragmentation indices of wetland also increased from 1950 to 2000, especially after 1983, showing that the wetlands were in a serious fragmentation state. The wetland landscape fragmentation changed from a landmass and island model to a satellite model, and finally to a completely isolated model, which indicated the great changes in spatial structure of wetland in the Sanjiang Plain.

The Small Sanjiang Plain (SSP), was formerly the largest wetland complex in China, located in the Northeastern part of Heilongjiang Province, China. Home to vast numbers of waterfowls, fish, and plants, the SSP is globally significant for biodiversity conservation. The loss and fragmentation of wetlands as a result agricultural development over 50 years has impacted wetland communities and their biodiversity. We used GIS to inventory large-scale land-use changes from 1950 to 2000, together with other statistical data. We found that 73.6% of the wetlands were lost due to agricultural development. Consequences of these land-use changes included: i) a rapid decline in waterfowl and plant species with the loss and fragmentation of natural wetlands and wetland ecosystem degradation; ii) greater variation in wetland water levels as the result of land-use changes over the years; N) disruption of the dynamic river-floodplain connection by construction of drainage ditches and levees; and iv) a decrease in floodplain area that caused increased flooding peak flows and runoff. Here we show how these changes affect wetland biodiversity and impact important wetland species.

The estimated total area of wetland in China is more than 25.9 million hectares including about 11.9 million hectares of marshes and bogs, 9.1 million hectares of lake and about 2.2 million hectares of coastal salt marshes and mudflats. The area of wetland is equivalent to 2.7% of the land surface. China also has 2.7 million hectares of shallow sea water (less 5m in depth at low tide). Marshes and bogs are equivalent 1.3% of the land surface. Only three provinces (regions)—Qinghai, Xizang (Tibet) and Heilongjiang — have a larger total area of marsh and bog. According to the structure, type and development of wetland in different river basins, wetland can be classified nine main regions. The experiments indicate that the coefficient of the marsh to regulate flood is similar to that of lakes. Wetlands occupy 17.8% of the Sanjiang Plain area, the annual carbon contribution is 0.78 × 10 4 t. Carbon released from marsh soil return into atmosphere is 3.95 × 10 6 t/a. At present there is a sharp contradiction between population growth and natural resources shortage, causing wetland to be exerted with huge pressures and serious threats.