新疆吐鲁番洋海墓地出土的粮食作物及其古环境意义

首次对吐鲁番洋海墓地出土的植物遗存进行了系统研究,并鉴定出3种粮食作物：黍（Panicum miliaceum）、青稞（Hordeum vulgare var. nudum）和普通小麦（Triticum aestivum）。吐鲁番地区降水稀少、环境干燥,因此考古遗址中的植物遗存大都保存完好。这些粮食作物均为当地生产。其中,黍可能是古代洋海人的主要粮食作物。通过植物遗存分析,2800年前的洋海古气候应该比较适合农业生产。古环境分析表明,古洋海人的部落位于一片绿洲中,绿洲内有一定面积的湿地,内生喜湿杂草。另外,河旁或高地上还有胡杨（Populus euphratica）、柳（Salix sp.）及云杉属（Picea sp.）等乔木分布。     

Dating the introduction of cereal cultivation to the British Isles: early palaeoecological evidence from the Isle of Man

The adoption of cereal cultivation is a key benchmark in the transition from Mesolithic hunter–gatherer foraging to Neolithic farming economies, but the nature, timing and ecological–cultural context of the earliest cereal use in the British Isles and northwest Europe is still uncertain. We present AMS radiocarbon dating and fine‐resolution pollen evidence from the Isle of Man for cereal growing in the latter stages of a distinct episode of forest disturbance at almost 6000 yr BP (uncalibrated). The coherent ecological structure of this phase at the fine resolution level suggests that it records cereal cultivation well before the Ulmus decline, rather than wild grass pollen grains. This example is one of a cluster of early dates for cereal‐type pollen near the start of the sixth millenium BP, including several around the Irish Sea, which indicate that the introduction of cereal agriculture probably occurred as early in the central British Isles as in the northern European plain. This early cereal phase is followed later by a probable phase of pre‐Ulmus decline pastoral activity. We also report Mesolithic age woodland disturbance around 7000 yr BP (uncalibrated) and the first radiocarbon dates for mid‐Holocene forest history of the Isle of Man. Copyright © 2003 John Wiley & Sons, Ltd.     

“一带一路”国家粮食贸易网络空间格局及其演化机制

农产品贸易是“一带一路”沿线国家间经贸合作的重要内容,但现有贸易理论无法很好地解释“一带一路”国家间粮食贸易网络的格局演化。该文构建了一个四维菱形分析框架,并将社会网络分析与空间计量分析相结合,基于1993—2016年联合国商品贸易数据,分析了“一带一路”国家间粮食贸易网络的空间结构特征及其演化机制。结果表明：① “一带一路”国家间的粮食贸易网络密度不断提高,贸易关系和贸易强度不断加深,在全球粮食贸易网络中的地位呈波动上升态势,并出现明显的贸易俱乐部现象;② 该粮食贸易网络呈现由无核到多核再到重塑的演化历程;③ 中国与其他“一带一路”国家间的粮食贸易经历了从出口导向到进口导向的演化历程,“一带一路”倡议提高了中国在全球粮食贸易网络中的地位;④ “一带一路”国家间粮食贸易网络的演化是受资源禀赋、经济环境、文化认同和政治博弈4个因素共同作用的结果,各因素在不同阶段所起的作用不同;粮食贸易较其他贸易而言特色鲜明,其稳定性更强。研究结果对促进“一带一路”国家农业贸易的健康繁荣,建设开放包容的经济环境具有指导意义。     

1993-2017年气候变化对西藏谷物单产的定量影响

Climate change is a global environmental crisis, but there have been few studies of the effects of climate change on cereal yields on the Tibetan Plateau. We used data from meteorological stations and statistical yearbooks to assess the impacts of climate change on cereal yields in Tibet. Three types of statistical models were selected: fixed-effects model, first-difference models, and linear detrending models. We analyzed the impacts of climate change(including the minimum temperature, precipitation, growing degree days and solar radiation) on cereal yields in Tibet from 1993 to 2017 at the county, prefecture-level city, and autonomous region scales. The results showed that the sensitivity of cereal yields in Tibet to temperature(minimum temperature and growing degree days) was greater than their sensitivity to precipitation and solar radiation. The joint impacts of climate variables were positive, but the sensitivity and significance varied in different regions. The impacts of minimum temperature, precipitation, and solar radiation were positive in all cities, apart from the negative impacts of growing degree days on cereal yields in Lhasa. The impacts of climate trends on cereal yields in Tibet were positive and the results were in the range of 1.5%–4.8%. Among the three types of model, the fixed-effects model was the most robust and the linear detrending model performed better than the first-difference model. The robustness of the first-difference model decreased after adding the interaction terms between different climate variables. Our findings will help in implementing more spatially targeted agricultural adaptations to cope with the impacts of climate change on the agro-ecosystem of the Tibetan Plateau.