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
The concept of biodiversity encompasses several different levels of biological organization, from the very specific to the most
The concept of biodiversity encompasses several different levels of biological organization, from the very specific to the most
admin
2013-01-12
60
问题
The concept of biodiversity encompasses several different levels of biological organization, from the very specific to the most general. It has been clear for some time that at all of these levels of organization the rich biodiversity that has always characterized the natural world is today declining. The extinctions or threatened extinctions of many species are but the most visible and well-known manifestation of a deeper and more far-reaching trend.
Changes in how the land is used are probably the principal contributor to the current decline in biodiversity. The pressures on terrestrial resources and land depend very much on population growth and the demands of early stages of economic development Moreover, land acquisition, especially for agriculture and forestry, focuses initially on those areas with the most fertile soils and equable climates, which are often the areas of greatest biological diversity. Deforestation in the humid tropics is probably the best-known current example of rapid land-use change.
During the decade of the 1970s, vast areas of tropical forest in South America, Africa, and South-east Asia were cleared and converted to agriculture and other uses. In the middle-to-late 1980s, the rates of deforestation in South America slowed dramatically, largely due to economic and tax policy changes in Brazil, but the pace of cutting in Africa and Southeast Asia, though poorly quantified, remains high.
Globally, the rate of loss of tropical forests for the 1980s has been estimated at about 1 percent per year, but there is still considerable uncertainty. The rates of extinction of local species that accompany these rapid changes in land cover may soon be far in excess of what is found today, reaching as high as 10, 000 times the natural background rate. Analyses of potential impacts on biodiversity that are based on simple measures of deforested area can provide little more than very general conclusions. Heavy applications of fertilizers and pesticides have the potential of creating additional environmental problems as well as affecting the abundance and viability of the other plants and animals and micro-organisms in the same or adjoining areas.
In addition, because of the understandable tendency to put the best land into production first, the expansion of agriculture into less fertile areas typically requires heavier applications of chemicals, more extensive site preparation, and other forms of more intensive management The typical result is increased chemical runoff to the landscape, and with ensuing degradation, additional pressure for expansion, and the like. It is such a cycle that has led to widespread desertification in some parts of the world, primarily through overgrazing that can be compounded by naturally occurring droughts.
It can be inferred from Paragraph 4 that______
选项
A、deforestation should usually precede large-scale forestry.
B、the rates of tropical forest loss are established by analyses.
C、fertilizers and pesticides resulted in the extinctions of species.
D、the rates of species extinctions are too complicated to determine.
答案
D
解析
题干问:“从第4自然段可以得到的推断是……”。此题可以定位于第4自然段,很明显作者反复说明尽管我们现在有估计,但估计往往是不准确的,从这点推出选项D“物种灭绝的速度往往太过于复杂而不可能确定”为正确选项。而选项A“毁林应该往往在前,之后再大规模的植树”,选项B“热带雨林损失的速度已经得到了科学分析的确认”和选项C“肥料以及杀虫剂往往导致了物种的灭绝”这都不可能从第4自然段的信息得出推导。
转载请注明原文地址:https://kaotiyun.com/show/6c9O777K
0
考博英语
相关试题推荐
ThedayswhentheonlyfenderabusinessmanneededtostaveoffamidlifecrisiswasontheendofaFerrariaregone.Thisyear
ThedayswhentheonlyfenderabusinessmanneededtostaveoffamidlifecrisiswasontheendofaFerrariaregone.Thisyear
ThedayswhentheonlyfenderabusinessmanneededtostaveoffamidlifecrisiswasontheendofaFerrariaregone.Thisyear
Groomingandpersonalhygienehavebeenaroundforages.It’shardtoimagineatimewhenpeopleweren’tconcernedwithtakingc
He______betweenlifeanddeathforafewdaysbutthenhepulledthrough.
Time,asweknowit,isaveryrecentinvention.Themoderntime-senseishardlyolderthantheUnitedStates.Itisaby-produc
Peoplewhobegintogodeafinadultlifehavedifferentproblemsfromthosewhoareborndeaf.Theyhavetolearndifferentway
Duringacivildefenseexercise,thepolice______thestreetsineaseanyonetriedtoleavesheltertoosoon.
【66】Astateuniversitypresidentwasarrestedtodayandchargedwithimpersonateapoliceofficerbecame,theauthoritiessay,h
AmitaiEtzioniisnotsurprisedbythelatestheadingsaboutschemingcorporatecrooks(骗子).AsavisitingprofessorattheHarva
随机试题
A.ATPB.CTPC.GTPD.UTPE.TTP参与肽链延长的是
A.肠息肉B.结肠癌C.肠套叠D.粘连性肠梗阻45岁以上妇女便血可能为
四逆散治疗肝脾不和,若心悸可加四逆散治疗肝脾不和,若腹中痛可加
可能产生阴燃火或者如发生火灾不及早报警将造成重大损失的场所,不宜选用感温探测器。()
背景资料:某高速公路施工合同段在建设单位、设计单位、施工单位、监理单位的共同努力下,施工单位精心组织施工,按质按量如期完成工程合同,符合交工验收条件后,经监理工程师同意,施工单位向项目法人提出了交工验收申请。问题:公路工程交工验收应
公路监控系统主要是实时收集道路状况、(),监视道路交通状况以及交通疏导等以保证行车安全。
与个人投资者相比,机构投资者的特点包括()。Ⅰ.投资形式灵活化Ⅱ.投资管理专业化Ⅲ.投资结构组合化Ⅳ.投资行为规范化
某居民企业2015年自行计算的应纳税所得额为70万元,销售收入为500万元。经税务机关审核,发现以下事项未进行纳税调整:(1)已计入成本费用中实际支付的合理工资为72万元,计提工会经费1.44万元并上缴0.72万元,计提职工福利费15.16万元,计提1.
某VCD生产厂商甲公司为增值税一般纳税人。2009年10月共发生下列经济业务:(1)在本市各家电商场销售6000台VCD,每台不含税销售价1000元。由于市场价格下降,公司在销售货物开具专用发票以后,另外给予家电商场2%的销售折扣,并另开了红字发
Theysaidtheywould____________(草拟一份合同)withinthisweek.
最新回复
(
0
)