首页
登录
职称英语
In an intact plant community, undisturbed by human intervention, the compositi
In an intact plant community, undisturbed by human intervention, the compositi
游客
2023-12-16
28
管理
问题
In an intact plant community, undisturbed by human intervention, the composition of a community is mainly a function of the climate and the type of soil. Today, such original communities are very rare—they are practically limited to national parks and reservations.
Civilization has progressively transformed the conditions determining the composition of plant communities. For several thousand years vast areas of arable land have been hoed, ploughed, harrowed and grassland has been cut or grazed. During the last decades the use of chemical substances, such as fertilizers and most recently of weed killers (herbicides) has greatly influenced the composition of weed communities in farm land.
All selective herbicides have specific ranges of activity. They control the most important weeds but not all the plants of a community. The latter profit from the new free space and from the fertilizer as much as the crop does; hence they often spread rapidly and become weeds unless another herbicide for their eradication is found.
The soil contains enormous quantities of seeds of numerous specie—up to half a million per square meters according to scientific literature—that retain their ability to germinate for decades. Thus it may occur that weeds that were hardly noticed before emerge in masses after the elimination of their competitors. Hence, the knowledge of the composition of weed communities before selective weed killers are applied is not only of scientific interest since the plant species present in the soil in the form of seeds must be considered as potential weeds. For efficient control the identification of weeds at the seedling stage, i.e. at a time when they can still be controlled, is particularly necessary; for the choice of the appropriate herbicide depends on the composition of the weed community. [br] The composition of a plant community______.
选项
A、depends on climate and soil type in a virgin environment undamaged by human beings
B、was greatly affected by human beings before they started using chemical substances on the soil
C、was radically transformed by uncivilized human beings
D、refers to plants, trees, climate, type of soil and the ecological environment
答案
A
解析
本题为细节判断题。原文的第一段的第一句话就告诉了我们:植物种群,尤其是未被人类破坏的植物种群,它的构成主要取决于气候和土壤的类型。A与原文描述的内容相符。B,C,D的描述与原文不相符合。
转载请注明原文地址:https://tihaiku.com/zcyy/3278164.html
相关试题推荐
HowmanyyearsdostudentshavetostudyatcommunitycollegeintheUnitedStat
HowmanyyearsdostudentshavetostudyatcommunitycollegeintheUnitedStat
TotheTunxisCommunityCollegeClassof2002,Ioffermycongratulations.
TotheTunxisCommunityCollegeClassof2002,Ioffermycongratulations.
Inanintactplantcommunity,undisturbedbyhumanintervention,thecompositi
SincejoiningtheEuropeanEconomicCommunityin______,Britainhasadoptedthe
Thecommunitycollegeisakindof______collegespopularin______tosatisfyth
CommunitycourtsandcommunityjusticeprevailedinEnglandatthetimeoft
CommunitycourtsandcommunityjusticeprevailedinEnglandatthetimeoft
Naturalhealersandevensegmentsoftheconventionalmedicalcommunityreco
随机试题
Time-SavingTech1.Theweb-Turnthepage-【T1】__
WhatdoweknowaboutCoursera?[originaltext]CourseraisaMOOCplatformthath
TheBritishtookoverthecontinentofAustraliaanddeclaredit"terranullius"
Highstreetshopsuseavarietyofmeanstoattractshoppers,suchasstriki
Whatdoestheclubtrytohelpchildrenwith?[br][originaltext]W:Hello,Chil
Thethreeforeignerswaspushedoutofthewaybecause______.[br]Thethreefo
肿瘤实质由两种以上细胞所构成的有()A.绒毛膜癌 B.多形性横纹肌肉瘤
某危险化学品罐区位于人口相对稀少的空旷地带,罐区500m范围内有一村庄,现常住人
在设备安装过程中,常见的零部件装配有( )。A.齿轮装配 B.键、销、胀套装
项目负责人的安全生产管理能力考核要点包括()。A.执行安全生产的法律法规情况
最新回复
(
0
)