种植香根草是防治水土流失和绿化护坡重要措施

香根草是一种独特的禾本科草本植物,具有极强的生态适应性和抗逆(旱、湿、寒、热、酸、碱)能力.生长迅速,根系发达.栽种技术不复杂,成本投资不大,见效快.利用它来防治水土流失、绿化护坡、恢复植被、改良土壤、改善环境小气候、净化污水和营养化水体.还可作畜牧业饲料、农业肥料与覆盖物等.     

Late pleistocene faunal extinctions in southern patagonia

Major environmental changes recorded in pollen records from various sites in southern Patagonia and Tierra del Fuego are also reflected in pollen and cuticle data from dung of the late Pleistocene groundsloth. The most prominent change was the large-scale reduction of steppe environment about 10,000 years ago, which coincides with the latest dates for extinctions of many large grazers such as the giant groundsloth. Stress on food resources for all the large grazers may well have hastened their extinction. Hunting pressure by paleoindians may have been the final blow.     

Mass extinctions in the marine fossil record

A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background extinction rates appear to have declined since Cambrian time, which is consistent with the prediction that optimization of fitness should increase through evolutionary time.