南水北调东线工程运行3年后东平湖浮游植物群落特征及环境驱动因子     

董贯仓  冷春梅  丛旭日  刘超  朱士文  孙鲁峰  高云芳  客涵  李秀启 《湖泊科学》2022,34(1):61-73

为掌握东平湖浮游植物在南水北调东线工程运行后的群落结构变化特征及探究其环境驱动因子,于通水运行3周年后的2017年分4个季节对东平湖的18个样点进行采样调查,同步开展水环境调查.结果 显示:共检出浮游植物191种属(包括变种),其中硅藻门、绿藻门、裸藻门、蓝藻门、金藻门、黄藻门、甲藻门和隐藻门分别为64、57、28、2...  相似文献   

Prospectivity Mapping for Tungsten Polymetallic Mineral Resources,Nanling Metallogenic Belt,South China: Use of Random Forest Algorithm from a Perspective of Data Imbalance     

Li  Tongfei  Xia  Qinglin  Zhao  Mengyang  Gui  Zhou  Leng  Shuai 《Natural Resources Research》2020,29(1):203-227

Natural Resources Research - Mineral systems are composed of many interacting components that lead to complex, singular and rare properties of geo-data. In mineral prospectivity mapping (MPM),...  相似文献   

Molecular characterisation of the complete nuclear ribosomal DNA sequence of the blacklip abalone Haliotis rubra     

Zhansheng Guo  Leng Han  Yi Ding 《新西兰海洋与淡水研究杂志》2018,52(3):430-443

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Long-term dynamics of cultivated land resources and their driving forces of Guyuan City in upper reaches of Jinghe River     

CHEN Caocao XIE Gaodi ZHEN Lin LENG Yunfa 《中国地理科学(英文版)》2008,18(1):33-40

The land use patterns in Guyuan City, Ningxia Hui Autonomous Region of China, have changed greatly over the years, due to population growth and farming and stock raising development. This study, using 50-year statistical data of cultivated land and 14-year spatial data of land use pattern, analyzed the developmental stages, the character, and the spatial variance of farmland in the city, and discussed the driving forces of cultivated land changes based on empirical and conceptual statistical models. First, the change of cultivated land area went through different stages of rapid increase, fluctuating change, decrease and rapid decrease from 1949 to 2004, additionally, social and economic policies in different stages had an important impact on farmland variance. Second, from 1986 to 2000, the quantity of cultivated land increased, but its quality decreased. Third, social and economic factors are determinant factors in cultivated land transition. Five constructed paths explain cultivated land transition. Factors that have direct or indirect effects on farmland include the economy （Xeco）, the population （Xpop）, agricultural output （Xagr）, and scientific input （Xsci）. The sequence of impact was Xeco〉Xpop〉Xsci〉Xagr. Among all these impacts, Xeco was the major positive one, and Xpop was the major negative one. It is urgent to take measures or adopt a policy to stop the vicious cycle in eco-environment and agriculture production. Otherwise, negative patterns of farmland use will increase, and high-quality cultivated land will continue to decline.  相似文献