首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Neotropical coastal mangrove forests are usually “zonal,” with certain mangrove species foundpredominantly in the seaward portio
Neotropical coastal mangrove forests are usually “zonal,” with certain mangrove species foundpredominantly in the seaward portio
admin
2009-04-18
33
问题
Neotropical coastal mangrove forests are usually “zonal,” with certain mangrove species foundpredominantly in the seaward portion of the habitat and other mangrove species on the morelandward portions of the coast. The earliest research on mangrove forests produced descriptions ofspecies distribution from shore to land, without exploring the causes of the distributions.
The idea that zonation is caused by plant succession was first expressed by J. H. Davis in a studyof Florida mangrove forests. According to Davis’ scheme, the shoreline is being extended in aseaward direction because of the “land-building” role of mangroves, which, by trapping sedimentsover time, extend the shore. As a habitat gradually becomes more inland as the shore extends, the“land-building” species are replaced. This continuous process of accretion and succession wouldbe interrupted only by hurricanes or storm flushings.
Recently the universal application of Davis’s succession paradigm has been challenged. It appearsthat in areas where weak currents and weak tidal energies allow the accumulation of sediments,mangroves will follow land formation and accelerate the rate of soil accretion; succession willproceed according to Davis’s scheme. But on stable coastlines, the distribution of mangrovespecies results in other patterns of zonation; “land building” does not occur.
To find a principle that explains the various distribution patterns, several researchers have lookedto salinity and its effects on mangrove. While mangroves can develop in fresh water, they can alsothrive in salinities as high as 2.5 times that of seawater. However, those mangrove species found infreshwater habitats do well only in the absence of competition, thus suggesting that salinitytolerance is a critical factor in competitive success among mangrove species. Research suggeststhat mangroves will normally dominate highly saline regions, although not because they requiresalt. Rather, they are metabolically efficient (and hence grow well) in portions of an environmentwhose high salinity excludes plants adapted to lower salinities. Tides create different degrees ofsalinity along a coastline. The characteristic mangrove species of each zone should exhibit ahigher metabolic efficiency at that salinity than will any potential invader, including other speciesof mangrove.
选项
A、refute the idea that the zonation exhibited in mangrove forests is caused by adaption to salinity
B、describe the pattern of zonation typically found in Florida mangrove forests
C、argue that Davis’ succession paradigm cannot be successfully applied to Florida mangrove forests
D、discuss hypotheses that attempt to explain the zonation of coastal mangrove forests
E、establish that plants that do well in saline forest environments requre salt to achieve maximum metabolic efficiency
答案
D
解析
This question asks you to identify the primary purpose of the passage as a whole. The best answer is D. The passage discusses two hypothesis concerning zonation of mangrove forests. Choice A can be eliminated because the passage presents as a viable hypothesis the idea that mangrove zonation may be caused by adaptation to salinity. Choice B is incorrect because the passage is concerned with the causes of zonation patterns, not simple with a description of those patterns. Both C and E contradict information that is presented in the passage.
转载请注明原文地址:https://kaotiyun.com/show/8NtO777K
本试题收录于:
GMAT VERBAL题库GMAT分类
0
GMAT VERBAL
GMAT
相关试题推荐
Nooneknowshowmanlearnedtomakewords.Perhapshebeganbymakingsoundslikethosemadebyanimals.Perhapshegruntedlik
Fiftyyearsago,wealthypeoplelikedhuntingwildanimalsforfun______sightseeing.
SHANGHAI:【T1】Eligible(符合条件的)couplesinthecityareforthefirsttimebeingencouragedtohaveasecondchild,asauthoritiesm
Concerningmoneyoranythingelse,conflictsbetweenhusbandandwifeusuallyreflectapowerstruggle.Conflictsbetweenparen
Isawacarinthedistance,butIcouldn’t______whetheritwasredornot.
A:Firstly,allowmetointroducemyself.MynameisJohnBrown,managerofthecompany.B:______.
IfyoulookcloselyatsomeoftheearlycopiesoftheDeclarationofIndependence,beyondtheflourishedsignatureofJohnHanc
Though______,manylawsofnatureexist.
Toomanypeoplethinkthatintelligenceisagiftofnatureandthatthereislittleanyonecandotoimprovetheirs.【T1】IQtest
Thankstothemeansofmoderntransportationandcommunication,theworldisgettingsmaller.Thewholeworldcommunityappears
随机试题
中国最大的国际船舶代理公司是成立于_______年的_______()
对外财务报表
关于"地球化学性疾病",错误的是
血浆凝血酶原时间(PT)延长可见于下列情况,但哪项除外
陪审员王某参加一起案件审判。被告辩护人当庭提出被告有正当防卫和自首情节,公诉人予以否定,提请合议庭不予采信,审判长没有就此进行调查。王某对审判长没有征询合议庭其他成员意见就决定不予调查,在评议时提出异议,但审判长不同意。对此,关于王某可以行使的权力,下列哪
在对象选择中,通过对每个部件与其他各部件的功能重要程度进行逐一对比打分,相对重要的得1分,不重要得0分,此方法称为()。
在我国货币层次划分中M0通常是指()。
国家的劳动安全法律规范一般属于()法律范围,以绝对肯定的形式予以规定。
对左边的立体图形进行任意切割,右边哪一项不可能是该立体图形的截面?
显示器的主要技术指标之一是()。
最新回复
(
0
)