山西沁河上游河岸植被缓冲带评价与恢复重建研究

在对河岸带特性进行调查的基础上,针对我国北方河岸带的特点.提出了从植被结构完整性和河岸结构稳定性两方面的14个指标组成的河岸带植被结构和功能评价体系、对山西省沁河的一级支流赤石桥河和紫红河的河岸带植被进行了评价;同时进行河岸缓冲带恢复重建试验,研究了不同恢复措施下纯草、乱石滩、纯灌三种沁河上游河岸带典型地块的植被恢复效...     

Evidence for Glacial Control of Rapid Sea Level Changes in the Early Cretaceous

Lower Cretaceous bulk carbonate from deep sea sediments records sudden inputs of strontium resulting from the exposure of continental shelves. Strontium data from an interval spanning 7 million years in the Berriasian-Valanginian imply that global sea level fluctuated about 50 meters over time scales of 200,000 to 500,000 years, which is in agreement with the Exxon sea level curve. Oxygen isotope measurements indicate that the growth of continental ice sheets caused these rapid sea level changes. If glaciation caused all the rapid sea level changes in the Cretaceous that are indicated by the Exxon curve, then an Antarctic ice sheet may have existed despite overall climatic warmth.