Stream Corner

High up in the mountains, trees and dwarf pine hold back build-ups of snow, thus preventing the formation of the avalanches, that are a common occurrence on treeless slopes when there is a thaw, leaving devastation in their wake and often taking their toll in human lives as well.

At night, conversely, they reduce the hnliation of warmth into the atmosphere. Tree belts and expanses of turf enable better penetration of water into the soil, I lie water then being returned again by them to the atmosphere in the form of vapour during the process of transpiration and evaporation. That is why the lower and the relative humidity higher in parks and tree-lined streets.

Trees with a large leaf surface are similarly efficient filters of polluted city air. Their leaves, especially if they are tomentose and covered with fine hairs, entrap large quantities of dust particles, which arc then washed off onto the ground by rain. The fact that trees and shrubs lower the speed of wind in city streets also promotes the settling of dust and the clearing of the air. Rows of trees and shrubs between traffic lanes or between street and sidewalk lower the noise of traffic by as much as 10 to 15 per, cent.

The isolated veterans scattered throughout the countryside, hicfly on hills or at crossroads, are an indication of the role they played in the lives of our ancestors and the instinct these morn had for their appropriate location.

Today, we realize that, besides being a source of raw materials, trees are of even greater importance for their role in the regulation of climate, water management, hygiene, health, recreation; ttid, last but not least, in beautifying the environment. The past century has witnessed a rapid increase in world population, and the progress of science and technology has greatly changed man's way of life. The result has been the emergence of vast industrial and suburban areas, with the majority of people living in cities, which have a specific climate and air polluted with dust, gases and other noxious substances. Industrial centres lind cities are plagued by increasing noise that goes beyond bearable limits, the work pace is accelerating and man's tirrvous system is being exposed to ever greater stresses.

The outlook for the future is one of further increase of puimlation, further mechanization of life, higher consumption ol water, increasing noise and greater loads on man's nervous ystem. With such prospects in view, the role of trees, shrubs rind other plants in cities will be of increasing importance, orests will have an increasingly significant role in water management, and people will seek respite from the stress of their daily lives in the country amidst the green of grass, shrubs lid trees.