登陆注册
7652700000084

第84章 环境对地球生命的影响(5)

In recent years the demand for lumber and wood pulp and the careless and wasteful way in which the forests have been handled by the lumbermen has greatly reduced the forests of the United States. It has been authoritativelystated that if the present waste of our forest land con tin ues, the timber supply of the country will be exhausted before 1940. Not only are the forests being recklessly cut down,but forest fires are each

year destroying millions

BAD FORESTRY.

The forest was razed, leaving no small trees for future growth.

of dollars worth of timber. When the importance of lumber to all kinds of industries is considered, the rapid exhausting of our forest supplies becomes almost appalling.

But not only is the destruction of the forests a menace to the industries in which lumber is necessary, but the effects are far reaching in many other directions. Slopes from which the forests have beenBAD FORESTRY.

The hillside was stripped, leaving it a prey to erosion.

removed become an easy prey to the forces of erosion, and the soil which for thousands of years has been accumulating may be swept away by the rainfall of a few seasons, leaving the slopes bare of soil and devoid of vegetable life. Thus the sites of valuable forests, which by proper care might have been continual wealth producers, are rendered nearly profitless deserts.

The harmfulness, however, does not stop here. The rain that falls upon these slopes, and which was formerly retained by the roots and vegetation, so that it slowly crept downward into the valleys and streams, now runs off quickly, flooding the rivers and doing damage to regions at a distance. Streams which formerly varied but little in their volume during the entire year, now become subject to great extremes of high and low water. This renders them less useful for manufacturing, commerce and water supply to say nothing of the frightful damage done each year by floods.

GOOD FORESTRY.

Notice how carefully the underbrush has been

removed to guard against fire.

The destruction of the forests tends also to exterminate the wild animals and deprives man of a chance to get away from his artificial surroundings and obtain a knowledge and an enjoyment of life and nature which has been unaffected by his own dominant influence.

In many European countries the forests have become a national care and not only is the cutting of trees, except under certain restrictions, prohibited, but the greatest care is maintained to guard against fires. In our own country the government hasrecently established a number of forest preserves which are carefully patrolled, and here the destruction from forest fires is rigidly guarded against. Great care of all forests should be taken by hunters, campersGOOD FORESTRY.

Notice how the underbrush and small limbs have been cleaned up.

and all others who visit them, and also by the railways passing through them. Loggers and lumbermen should see that it is to their interest to maintain growing forests and not wantonly to destroy them.

When the native forests are destroyed, trees of other kinds may in time replace those removed, but frequently these are of less commercial value. Thus, when the conifer forests of the northern states are cut off, birches and poplars replace them. If only the larger trees had been cut, leaving the smaller and younger trees to hold the ground, the more valuable forests might have been retained.

122.Flora of the United States. -The United States has such agreat range of climate, soil, elevation and other geographical condi- tions that it possesses a large variety of plants. About five hundred dif- ferent kinds of native treeshave been listed, and there are many different kinds of shrubs and smaller plants. To these native plants must be added many useful as well as ornamental plants and not a few noxious weeds, which have been imported from other countries and havefound an agreeable home here.

A CALIFORNIA BIG TREE.

Notice the size at the base.

The largest and perhaps most remarkable trees in the United States are the Big Trees of California, a species of redwood. Trees of this species have been measured which were 325 ft. high, more than 100 ft. higher than Bunker Hill Monument, and others which were more than 90 ft. in circumference. A plant which has probably appropriated more territory than any other plant in the world is the "sage brush" of the arid western plains. These low grayish shrubs cover hundreds of thousands of square miles. They are useless except for fuel. In the well- watered part of the country, plants are abundant and varied, rangingfrom the subtropical palms of the Gulf coast to the semi-arctic types of the northern border.

123.Fauna of the United States. -As the wide treeless plainsand prairies of the central part of the country contained few coverts for skulking animals of prey, they were admirably adapted to the wants of gregarious grazing animals. Here were found the countless herds of antelopes and buffaloes which in the early days of transcontinental travel swarmed over the territory crossed by the railroads and not in- frequently forced the trains to stop and wait until they had crossed the track. To-day they are almost exterminated.

The forests of the northern regions with their grassy glades and meadows, once the home of great herds of caribou and great numbers of moose, have too frequently resounded to the sound of ax and gun still to contain many of these noble creatures.

Among the mountains with their rough surfaces and rugged fastnesses the black, brown, and grizzly bear onceroamed supreme, but now they find

COYOTE.

The prairie wolf of the western plains.

security only in the most inaccessible

places. Wolves once skulked in bands far and wide over almost the entire country, ready to pull down and devour weaker animals, but now both they and their prey have almost vanished.

同类推荐
  • 英国学生文学读本(套装共6册)

    英国学生文学读本(套装共6册)

    《英国学生文学读本(套装共6册)》以英文原版形式出版,图文并茂。编写体例统一严谨,包括生词、课文、语音、拼读练习、词汇解释等,同时还附加了单词拓展练习。可以伴随学生从小学直至高中或大学阶段。同时也适合成人英语学习者提高英语阅读水平使用,让众多国内读者在了解西方文学的同时,也感受英语语言的魅力。
  • 人生处处充满选择

    人生处处充满选择

    精选名人经典演讲:本书精选奥巴马、乔布斯、马克伯格、J.K.罗琳等现当代名人演讲,他们现身说法,通俗易懂地讲述了他们在人生中的选择与处世之道,给人以极大的启示和借鉴意义。过去的选择造就了你现在的一切,现在的选择就是你未来的命运。如果你知道去哪儿,全世界都会为你让路。
  • 加拿大学生文学读本(第5册)

    加拿大学生文学读本(第5册)

    《西方家庭学校原版教材与经典读本?加拿大学生文学读本(第5册)》由加拿大教育部门编写的教材,分级编写,全套共五本。全书通过趣味而有教育意义的故事,引发孩子们学习语言的兴趣;并向规范、美丽的文学作品过渡,让孩子们掌握语言的艺术,并感受本国的人文历史,带读者步入优美的英语文学世界。书中所选故事不仅有助于提升学生的读写能力,让国内学生依托教材,全面系统地训练英语,同时,通过书中的道德故事、寓言、诗歌、文学作品等,感受加拿大的历史文化,培养良好的阅读兴趣。
  • 英国学生文学读本4册

    英国学生文学读本4册

    《西方家庭学校原版教材与经典读本?英国学生文学读本(第4册)》以英文原版形式出版,图文并茂。编写体例统一严谨,包括生词、课文、语音、拼读练习、词汇解释等,同时还附加了单词拓展练习,《西方家庭学校原版教材与经典读本?英国学生文学读本(第4册)》是一套完整的英语学习教材。这些选文,体现了英国丰富的历史文化知识和西方国家的道德价值观念。
热门推荐
  • 快穿之主神暗恋我

    快穿之主神暗恋我

    不明不白地死了。又失去了生前的记忆。还绑定了一枚既不萌也不暖,实为未知生物的系统,云裳感觉心好累。好吧,既然你说完成任务就能重生,那就不要大意地开始快穿吧。可是各种绿茶婊、黑莲花、负心汉……还有非人生物乱入是什么鬼!主神:山有木兮木有枝,心悦君兮君不知。云裳:呵呵呵……我原是天界陨落的战神?高冷的主神大人暗恋我?开什么玩笑!主神不多废话,扑倒之。结局he,1V1。
  • 燕落江湖

    燕落江湖

    岁时亲生父母把我抛弃,原因:是因为我异于常人。当我凭着自己的努力当是最年轻的时他们又出现在我的面前我以为他们终于想起我这个亲生女儿可是没有想到的是居然为了“钱”对“亲情”绝望时想去散散心时一不小心来到了古代。
  • 末世高手在都市

    末世高手在都市

    末世顶级高手血狱魔尊穿越到安静平和的现代都市……末世中,令人闻风丧胆的魔刀再次出鞘!
  • 龙珠战士修真行

    龙珠战士修真行

    地球青年看龙珠时,电脑发生爆炸,穿越异界,不过穿越自然有福利,和沙鲁融合,竟而拥有了沙鲁体内所有的龙珠战士血脉。召悍弟,抢美女,修真世界逍遥游战强敌,败猛士,龙珠战士修真行
  • tfboys之浅夏离秋

    tfboys之浅夏离秋

    那一年,他遇见了她,看见别的男生和她在一起,他会难过,看见她受欺负,他会心疼,他开始珍惜与她在一起的时光,见到她会忍不住叫声小笨蛋。最后,终于走过坎坷曲折的路,幸福的生活在了一起
  • 超级邪少闯都市

    超级邪少闯都市

    不要以为喝矿泉水的都是没钱的,不要以为不写作业的都是坏学生,不要以为拿着打火机就是要吸烟,不要以为整天都笑的人就是心情好,不要有太多的以为,你看到的或许是别人选择让你看到的。热血青春一道疤。青春一去似流沙。历经沧桑几人伴。阅尽浮华一声叹。
  • 原来你给我的是守护

    原来你给我的是守护

    我相信,我的明天一定会有你。我可以等你,到地老天荒。
  • TFBOYS之十年时年

    TFBOYS之十年时年

    当我再次遇见你,已是十年后,你下台,走进后台,我跟上去“你是我的心上人,也会是我枕边人,将来会是我同棺人”你终于,回抱我,原来,只是梦,三年前,七年后,我们对不起你们…
  • 梦空

    梦空

    梦醒了,梦真的醒了吗?真相又在哪里?穿梭在重重交织的世界之中,行走在荒凉的大地之上,苦苦的追寻着
  • 重生神算少夫人:霸宠99次

    重生神算少夫人:霸宠99次

    一朝重生,她身赋异秉,一道生辰八字,算尽一生!却唯独算不出自己和他的命运。前生他避爱不谈,最终为她挡枪而死,今世他对她一见钟情,每天狂示爱!“沈从宴,你答应过我们一周两次的!”他强势霸宠,“昨晚你缠着我要两次的时候可不是这么做的。”