A Spatial-Temporal Model of Rhinoceros Extinction in China

IntroductionThreethousandyearsago,wildrhinoceros(RhinocerosuniCOFniS,R.sondsiCusandDiCeFOfhiRussumatI6nsiS)livedinthevastareaofChina,thenortherndiStributionboundarywasmorethan1800kmalongYellowRiver.Withtheincreaseofhumanpopulationpressure,thehabitatsofrhinocerosshrankcontinuouslyandextinCtionoccurredinYunnaninearly20thcenturyli].'Thelong-termhiStoricaldocumentsonthechangesofrhinocerosdiStributioninChinaareuniqueintheworld.Itis3400-3200yearssgo(about1400-1200BC,ShangDynaSty)thatrhin…     

pH和有机质对三种不同土壤镁吸附特性的影响

选取黄壤、紫色土和石灰性土3种土壤为研究对象,采用一次平衡吸附法,研究了pH、有机质对镁吸附的影响.结果表明,不同pH和有机质条件下,土壤对镁的最大吸附量有较大差异,黄壤和紫色土受pH影响较明显,在pH3.5～7.5这个范围,黄壤对镁的最大吸附量变化在1 336.25g～2 054.77 mg/kg,紫色土在1 417.04～2 025.38 mg/kg,石灰性土变化不大.去有机质后,黄壤、紫色土和石灰性土对镁的吸附能力下降,最大吸附量分别减少363.31,148.72,120.00 mg/kg.Langmuir方程能很好的拟合土壤对镁的吸附过程.

Abstract：

The effects of pH and organic matter on adsorption of magnesium in yellow soil, purple soil and calcareous soil were studied in a batch adsorption experiment. Considerable differences were observed among the three soils in their maximum Mg adsorption under different pH and organic matter conditions.The adsorption of magnesium was mainly related to the changes in pH in yellow soil and purple soil. In the pH range of 3.5-7.5, the maximum magnesium adsorption varied from 1 336.25 to 2 054.77 mg · kg-1 in the yellow soil and from 1 417.04 to 2 025.38 mg · kg-1 in the purple soil, while little change was detected in the calcareous soil. The ability of Mg adsorption decreased after the removal of organic matter in the above three soils and the maximum Mg adsorption decreased by 363.31 mg· kg-1 , 148.72 mg · kg-1 and 120.00 mg · kg-1, respectively. Magnesium adsorption in soils was well fitted with the Langmuir equation.     

Winter foraging plants of domestic sheep in Hulunbeir grassland

IntroductionAtpresent,thcrearel11anyl11etl1odstodccidefbodco11-stiintion8fherbivores,sucI1asstol11acl1a11al}'sis,fcccsanalysisanddirectobservation.Sol11co11calsouscdesoPl1agusfistulal11etl1odtoanalyzc.Sincel97(),fecesanalysiswaswildlyusedbecauseofitseasiersampIinganditslittledisturba11cetoanimal(Vavractal,l98(),Norburg,l988,GaoZl1o11gxinctal,l99l).Tllisnlctllodt`asalsouscdintI1isstud}'.Tllccxpcri-lllclltaln1aterialcamcfron1XinbarI1uyou,HuIUI1bcir,tvllicllI4'bctWccnlol1gitudcll5"-ll7"48'…     

呼伦贝尔草原放牧绵羊食性的初步研究

采用粪便显微组织学分析技术，分析了呼伦贝尔草原放牧绵羊冬季采食植物的种类组成，对不同牧草的喜食程度，并探讨了当地牧草资源的质量状况及改良草场，合理放牧等问题，研究表明，放牧绵羊冬季食物以禾本科植物为主，占７３．３％，豆科植物次之，占１１．６％菊科植物占第３位，为７．４％，其它科植物所占比例较小。     

自贡市现代农业发展水平评价

发展现代农业是未来农业发展的主题,是农业农村发展的主要任务。文章以自贡市现代农业为研究对象,借鉴相关研究成果,构建自贡市现代农业评价指标体系,基于层次分析法建立评价模型,利用2012年统计数据,测评自贡市现代农业发展水平,结果表明自贡市现代农业发展水平评价得分为49.22,处于现代农业发展起步阶段。     

濒危野生动物保护的理论与策略

论述了濒危野生动物的概念与特征、易于濒危和灭绝的类型、濒危原因等问题,并提出6点保护措施。     

丘陵地区农业基础设施建设模式探讨

丘陵地区的农业生产是提高我国粮食生产能力的重要补充。基于此,分析了丘陵地区的农业基础设施发展现状及问题,并提出农田整理、水利设施和道路设施等方面建设模式,以提升其农业基础设施水平。