贵州雷公山秃杉种群统计分析

运用相邻格子法，对雷公山秃杉种群进行生态学调查，采用“空间推时间，横向导纵向”，分析大小级鲒构，编制静态生命表，结果表明：(1)雷公山秃杉种群大小级鲒构为明显的金字塔型是增长型种群．(2)秃杉种群静态生命表的生存分析表明，在种群的生活史中，幼年阶段存在明显的自疏和他疏现象．(3)秃杉种群存活曲线表明秃杉种群存活曲线为第Ⅲ型。     

信宜天马山优势种群的静态生命表及存活曲线

根据天马山各优势种的大小结构图、静态生命表及存活曲线,对存活曲线进行线性回归.结果表明:鸭脚木存活曲线仍代表增长型种群,属于基部宽而顶部窄的金字塔结构,中间也没有缺失现象.马尾松、杉木、枫香和罗浮柿的存活曲线代表衰退型种群,基本上无幼树,属于严重的倒金字塔结构,中间也有严重的缺失现象.     

雷公山秃杉群落β多样性分析

β多样性反映了环境被物种分隔的程度。对国家Ⅱ级保护物种秃杉(Taiwania flousiana Gaussen)群落的物种多样性研究相对缺乏,作者以雷公山5个样地的调查数据为基础,选用β多样性测度方法的whittaker(βw)、cody(βc)、Morisita-Horn(Cmh)指数,分析秃杉群落的β多样性,结果表明:(1)秃杉群落β多样性指数随物种个体数的增减而发生变化。(2)秃杉群落β多样性受秃杉种群结构的影响,当种群径级结构相似时其群落间的多样性具有很大的相似性。     

石门台山顶矮林的静态生命表及存活曲线

根据山顶矮林各优势种的大小结构图、静态生命表及存活曲线，并对存活曲线进行线性回归，红锥属于稳定的种群，疏齿木荷、五列木、密花树扣木荷的存活曲线仍代表增长型种群，并且都属于基部宽而顶部窄的金字塔结构，中间也没有缺失现象。     

异质环境条件下秃杉种群的更新

对贵州雷公山秃杉（Taiwania flousiana Gaussen）种群,采用常规的群落学野外调查方法,结合秃杉种群径级结构,用二元属性数据的β多样性指数,分析了秃杉种群更新与环境条件的关系.结果表明：①β多样性指数较好的反映光因子是形成秃杉群落环境异质性的主要因子.②秃杉群落的更新受群落内部光因子的影响.③秃杉种群的更新是林窗更新.     

英山吴家山森林公园榉树种群结构

对英山吴家山森林公园榉树(ZelkovaschneiderianaHand.-Mazz.)种群大小级结构、存活曲线、高度级结构进行研究,探讨了该地区榉树种群的结构.结果表明:榉树种群幼树、幼苗严重不足,中成树成高频分布,整个种群表现为一不稳定的成熟类型.     

元宝山冷杉种群结构和动态的初步研究

对元宝山冷杉种群的大小结构,存活曲线和水平分布格局及动态的研究表明:元宝山冷杉种群在森林群落中具有增长型的繁殖潜力而表现了衰退型的演替趋势;种群分布格局由集群分布演变为均匀分布.元宝山冷杉种群动态受环境影响相当明显.种群生态学研究对人为调节种群发展具有重要意义.     

贵州雷公山秃杉种群分布格局的研究

采用相邻格子样方法取样数据,应用方差/均值比的t检验法、负二项参数、格林指数、Cassie指标、扩散指数、聚集度指标、平均拥挤度、聚块性指数等方法,研究了贵州雷公山秃杉种群的空间分布格局及其动态.结果表明:秃杉种群空间格局为聚集分布;从幼苗到大树,其聚集程度和规模逐渐减小,大树呈均匀分布.     

雷公山自然保护区的保护植物

雷公山国家级自然保护区保护植物有28种.其中,一级有红豆杉、南方红豆杉、金佛兰等6种;二级有柔毛油杉、秃杉、翠柏、福建柏等22种.对保护植物的利用价值进行了初步的评述.     

存活曲线到底能说明什么?

题目:下图为种群的3种存活曲线:(1 )如果第Ⅰ类为养牛场的牛群,则表示牧场经营很正常,这属于　　　　型种群,其特点是　　　　的个体很多,而　　　　的个体很少,则种群的　　　　会越来越大。(2 )如果第Ⅲ类是养鸡场的鸡群,则表示这个养鸡场已陷入危机,经营者采取的措施是:①留     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…