Deforestation and Desertification(沙漠化)The Sahel zone lies between the Sahara desert and the fertile savannahs(热带大草原)of northern Nigeria and South Sudan. The word sahel comes from Arabic and means marginal or transitional ,and this is a good description of
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Deforestation and Desertification(沙漠化)
The Sahel zone lies between the Sahara desert and the fertile savannahs(热带大草原)of northern Nigeria and South Sudan. The word sahel comes from Arabic and means marginal or transitional ,and this is a good description of the semi-arid(半干旱) lands, which occupy much of the Western African countries of Mail, Mauritania, Niger ,and Chad.
Unfortunately, over the last century the Sahara desert has steadily crept southwards eating into once productive Sahel lands. United Nations surveys show that over 70 percent of the dry land in agriculture use in Africa has deteriorate dover the last 30 years. Droughts have become more severe, the most recent lasting over twenty years in parts of the Sahel region. The same process of desertification is taking place across southern Africa as the Kalahari desert advances into Botswana and parts of South Africa.
One of the major causes of this desert advance is poor agricultural land use, driven by the pressures of increasing population. Overgrazing一 keeping too many farm animals on the land一means that grasses and other plants cannot recover, and scarce water supplies are exhausted. Over cultivation一 trying to grow too many crops on poor land一 results in the soil becoming even less fertile and drier, and beginning to break up. Soil erosion (侵蚀) follows, and the land turns into desert.
Another cause of desertification is loss of tree cover. Trees are cut down for use as fuel and to clear land for agricultural use. Tree roots help to bind the soil together, to conserve moisture, and to provide a habitat for her plants and animals. When trees are cut down, the soil begins to dry and loosen, wind and rain erosion increase, other plant species die, and eventually the fertile top soil may be almost entirely lost, leaving only bare rock and dust.
The effects of loss of topsoil and increased drought are irreversible. They are, however, preventable. Careful conservation of tree cover and sustainable agricultural land use have been shown to halt deterioration of soils and lessen the effects of shortage of rainfall. One project in Kita in south-west Malifunded by UNDP has involved local communities in sustainable management offorest, while at the same time providing a viable(有活力的)agricultural economy. This may be a model for similar projects in other West African countries.
文章{1~5)
The Sahel zone is an area which _____.
The Sahel zone lies between the Sahara desert and the fertile savannahs(热带大草原)of northern Nigeria and South Sudan. The word sahel comes from Arabic and means marginal or transitional ,and this is a good description of the semi-arid(半干旱) lands, which occupy much of the Western African countries of Mail, Mauritania, Niger ,and Chad.
Unfortunately, over the last century the Sahara desert has steadily crept southwards eating into once productive Sahel lands. United Nations surveys show that over 70 percent of the dry land in agriculture use in Africa has deteriorate dover the last 30 years. Droughts have become more severe, the most recent lasting over twenty years in parts of the Sahel region. The same process of desertification is taking place across southern Africa as the Kalahari desert advances into Botswana and parts of South Africa.
One of the major causes of this desert advance is poor agricultural land use, driven by the pressures of increasing population. Overgrazing一 keeping too many farm animals on the land一means that grasses and other plants cannot recover, and scarce water supplies are exhausted. Over cultivation一 trying to grow too many crops on poor land一 results in the soil becoming even less fertile and drier, and beginning to break up. Soil erosion (侵蚀) follows, and the land turns into desert.
Another cause of desertification is loss of tree cover. Trees are cut down for use as fuel and to clear land for agricultural use. Tree roots help to bind the soil together, to conserve moisture, and to provide a habitat for her plants and animals. When trees are cut down, the soil begins to dry and loosen, wind and rain erosion increase, other plant species die, and eventually the fertile top soil may be almost entirely lost, leaving only bare rock and dust.
The effects of loss of topsoil and increased drought are irreversible. They are, however, preventable. Careful conservation of tree cover and sustainable agricultural land use have been shown to halt deterioration of soils and lessen the effects of shortage of rainfall. One project in Kita in south-west Malifunded by UNDP has involved local communities in sustainable management offorest, while at the same time providing a viable(有活力的)agricultural economy. This may be a model for similar projects in other West African countries.
文章{1~5)
The Sahel zone is an area which _____.
A.is covered with sad and grass
B.has a long history
C.occupies much of South Nigeria
D.belongs to Sudan
B.has a long history
C.occupies much of South Nigeria
D.belongs to Sudan
相似考题
更多“Deforestation and Desertification(沙漠化) ”相关问题
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第1题：
目前中国沙漠化发展迅速，我国是世界上沙漠化受害最深的国家。 （ ）
参考答案：错误
正确答案：×
我国是世界上沙漠化受害最深的国家之一。
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第2题：
In order to prevent desertification, the author proposes _____.A.making good use of international aids
B.developing a sustainable agricultural economy
C.gaining international support
D.converting agricultural land into forest答案：B解析： -
第3题：
沙漠化的概念。沙漠化的形成原因有哪些？
正确答案: 非沙漠向沙漠转化，使沙漠逐渐扩大的过程，叫沙漠化。
在地质历史上的沙漠化是由于气候的变化和地壳运动使自然地理环境发生变化所致。
现代的沙漠化，则大多与人类不注要保护环境，大量砍伐原始森林、盲目开荒破坏水土保持、过度放牧破坏植被、过量开采地表水和地下水等。 -
第4题：
沙漠化
正确答案: 是指干旱和半干旱地区，由于自然因素和人类活动的影响而引起生态系统的破坏，使原来非沙漠地区出现了类似沙漠环境的变化过程。 -
第5题：
简述沙漠化危害。
正确答案: （1）地表组成物质中细粒含量减少，粗粒含量增加，土壤机械组成粗化，土壤物理性状恶化，容重增加，孔隙度减少，透水性增加，保肥、保水性减弱。
（2）由于土壤风蚀，使得土壤中营养物质含量减少，肥力下降，而且这种下降程度随沙漠化程度加剧而加剧。
（3）原始地形破碎，利用的难度增加。
（4）植被退化，沙漠化不仅使植被盖度减少，而且使群落组成也发生变化，一般表现在利用价值高的成分减少，旱生盐生成分增加。
（5）土地生产力下降，可利用的、生产力较高的土地资源沦为难以利用或无法利用的流沙地，由于土壤侵蚀，土壤肥力减少，物理性状恶化及植被退化等，使得土地生产力减小，流沙和沙丘的出现，则使土地无法利用，沦为荒地。
（6）生态环境条件恶化，生态系统功能紊乱，平衡失调，一般随着植被的破坏，风蚀的产生和加剧，使风沙日增，空气尘埃含量增多，气候变干。 -
第6题：
简述过度农垦的沙漠化现代过程。
正确答案: 这类沙漠化土地面积占现代沙漠化土地面积23.3%，主要分布于干草原及荒漠草原地带的沙质草原或固定沙地。半干旱地区的旱作农业，受水、肥等自然条件制约，一般单位面积产量不高也不稳定，而人口增加的压力又迫使人们不自觉的通过扩大垦植面积或进行掠夺式经营来追求总产量。扩大开垦面积并未带来较大产量，反而导致环境恶化，形成了“扩大耕地面积→增加风蚀→产量下降→再度扩大耕地”的恶性循环。 -
第7题：
名词解释题土地沙漠化正确答案： 是指在干旱多风的沙质地表环境中，由于过度地人为活动破坏了脆弱的生态平衡，使原非沙漠的地区出现了以风沙活动为主要特征的类似沙漠景观，造成了土地生产力下降的环境退化过程。解析： 暂无解析 -
第8题：
问答题沙漠化的概念。沙漠化的形成原因有哪些？正确答案： 非沙漠向沙漠转化，使沙漠逐渐扩大的过程，叫沙漠化。
在地质历史上的沙漠化是由于气候的变化和地壳运动使自然地理环境发生变化所致。
现代的沙漠化，则大多与人类不注要保护环境，大量砍伐原始森林、盲目开荒破坏水土保持、过度放牧破坏植被、过量开采地表水和地下水等。解析： 暂无解析 -
第9题：
填空题Around the turn of the century, there was a vast rainforest in Rwanda reduced its original size by deforestation and refugee resettlement.____正确答案： I解析：
根据题干信息“Around the turn of the century”和“Rwanda”可以定位到I段“Once a vast rainforest, activities such as deforestation and refugee resettlement reduced it to a fraction of its original size around the turn of the century.”，故匹配段落为I段。 -
第10题：
What is the situation about the desertification in Africa?A.The deserts are replaced with grasslands
B.The deserts are expanding
C.the deserts are moving northwards
D.the deserts are being deserted答案：D解析： -
第11题：
What is the root cause of desertification?A.poor farming
B.overpopulation
C.radical climate change
D.disappearance of rare plant species答案：A解析： -
第12题：
土地沙漠化
正确答案: 是指在干旱多风的沙质地表环境中，由于过度地人为活动破坏了脆弱的生态平衡，使原非沙漠的地区出现了以风沙活动为主要特征的类似沙漠景观，造成了土地生产力下降的环境退化过程。 -
第13题：
简述沙漠化的趋势？
正确答案:移动方向向南和向东推移，受影响地区的范围越来越广，对东南农业文明构成威胁。沙尘暴甚至已影响到江南地区。 -
第14题：
简述我国沙漠化土地的分布及类型。
正确答案: 分布：我国北方沙漠化土地主要分布在：富裕、扶风、康平一线以西，康平、赤峰、张家口、绥德、固原、昆仑山一线以北
类型：根据其地理分布和发生特点划分为以下三种类型：
①发生在干草原和荒漠草原地带的沙漠化土地
1主要是由于人为过度的经济活动造成的，特别是过度的农牧业利用与樵柴等活动。2主要分布在乌鞘岭、贺兰山以东，东北平原南部以西，中蒙边境以南，长城以北的广大地区。
②发生在荒漠地带河流下游绿洲附近的沙漠化土地
1.主要是由于河流变迁，水资源利用不当造成的，此外绿洲边缘樵柴等活动造成的植
被破坏也是加速这些地区沙漠化过程的因素。
2.分布于乌鞘岭以西，昆仑山以北
③发生在半湿润地区的沙漠化土地
1.发生在河流故道沿岸，干旱季节又有大风出现的地方。是古代河流冲积物在风力作用下形成的。如河南东部及河北平原中部、南部一些河流故道沿岸地区，再如洛河下游的沙苑一带。
2.这些沙漠化土地分布面积小，一般呈斑点状零散分布在平原上，共有34个县市。 -
第15题：
我国北方地区历史时期所形成的沙漠化土地，按其发生发展的特点可以分成哪两类？通过对沙漠化历史过程的分析，应吸取哪些教训？
正确答案: 我国北方地区历史时期所形成的沙漠化土地，按其发生发展的特点可以分成两类：
①荒漠地带历史时期所形成的沙漠化土地
这类沙漠化土地广泛分布在贺兰山以西沙漠边缘的河流沿岸或深入到沙漠内部的河流下游。荒漠地带城市绿洲的废弃都与灌溉水源的断绝有关系，其原因如下：水资源利用不当、战争破坏水利设施、河流变迁（淤积改道）。
②干草原及荒漠草原地带历史时期形成的沙漠化土地
其形成原因复杂，大部分由于人类活动，破坏了沙质草地。
两者的差异：前者当沙漠土地一旦形成后很少再受人为活动的影响，沙漠化发展过程的模式呈简单的直线发展；而后者当沙漠化土地形成后沙漠受人为活动的影响，历史过程形成的沙漠化土地与现代过程所形成的沙漠化土地往往交替在一起。通过对沙漠化历史过程的分析，应吸取以下教训：
①合理利用水资源
②合理利用土地，适度开发
③保护植被 -
第16题：
问答题荒漠化与沙漠化区别正确答案： 荒漠化是一个动态发展过程，其实质是土地退化，分布在干旱、半干旱及亚湿润干旱地区，形成原因是气候因素等自然因素和人类活动的共同作用的产物，表现为土地沙漠化、石质荒漠化和次生盐碱化。沙漠化只是荒漠化的表现形式之一，它是原来非沙漠的地区出现类似沙漠的景观的过程。解析： 暂无解析 -
第17题：
问答题简述过度农垦的沙漠化现代过程。正确答案： 这类沙漠化土地面积占现代沙漠化土地面积23.3%，主要分布于干草原及荒漠草原地带的沙质草原或固定沙地。半干旱地区的旱作农业，受水、肥等自然条件制约，一般单位面积产量不高也不稳定，而人口增加的压力又迫使人们不自觉的通过扩大垦植面积或进行掠夺式经营来追求总产量。扩大开垦面积并未带来较大产量，反而导致环境恶化，形成了“扩大耕地面积→增加风蚀→产量下降→再度扩大耕地”的恶性循环。解析： 暂无解析 -
第18题：
名词解释题沙漠化正确答案： 是包括气候变异和人类活动在内的种种因素所造成的干旱、半干旱和亚湿润干旱地区的土地退化。解析： 暂无解析