9] VITAL IMPORTANCE TO MANKIND 277 



a particular place depends to a considerable extent on whether the 

 plant from which it comes can be cultivated locally — especially if it 

 is bulky and needed in large quantities or in a fresh state, as so many 

 foods, etc., are. And quite apart from this direct dependence of 

 mankind on the crop and other plant productivity of different areas, 

 we get very different environments created by different types of 

 vegetation — as was already pointed out in the second paragraph of 

 this chapter. Among many other things, trees give shade and 

 shelter, and when they are widely aggregated into forests, these 

 may regulate climate to a considerable extent, ' damping down ' 

 temperature and humidity fluctuations in their shade. In some 

 ways, in spite of their transpiration, trees may also help to conserve 

 water, for example by preventing run-off and floods, meanwhile 

 checking erosion. Forests moreover afford shelter and range for 

 livestock and wild animals, and recreation for human beings. 



The widespread use of such ecological devices as sand-binding 

 Grasses or other plants and wind-breaking trees and shrubs, is further 

 testimony to the value of plant life to mankind. Particularly are 

 various surface-binding plants of importance in combating erosion, 

 which is one of the world's worst scourges, as is further indicated 

 in our concluding two chapters. 



Finally it should be noted here as well as in the next section that, 

 in the local environments which Man makes for himself, the import- 

 ance of gardens of one sort or another is enormous practically the 

 world over. And the supply and use of agricultural, forestral, and 

 horticultural implements such as harvesters, saws, and lawnmowers, 

 and the general tending of plants, involves vast industries almost 

 everywhere. 



Aesthetic and Ornamental 



In most landscape views, plants form the chief embellishment, 

 and landscapes would suffer greatly without them. Apart from the 

 vital needs they satisfy and the material benefits they bestow, plants 

 greatly enhance Man's aesthetic appreciation of the world in which 

 he lives — both in their natural growth as vegetation, whether 

 arborescent or otherwise, and through their cultivation for orna- 

 mental purposes. Almost everywhere Man lives, gardens are 

 cultivated fdr recreational and other reasons, and the dustiest city 

 streets and drabbest homes are enlivened by greenery and pot or 

 cut flowers. 



