220 SCIENCE OF THF. STUDY OF TUEF.S. PAHT H. 



relation in which trees and sliriibs stand to man. It is not our intention to 

 enter fartiier into those subjects here, than may be necessary to show to what 

 circumstances, in the economical history of trees, we ought chiefly to direct 

 our attention, in composing the history of each particular species. The 

 subject may be divided into two sections. 



Sect. I. Trees and Shrubs considered toith Reference to uncultivated 



Nature. 



It appears highly probable, that the greater part of the surface of our globe 

 has been, at one time, covered with wood ; because, among other reasons, coal 

 is found in almost all countries ; at all events, it is certain that this has been 

 the case with the greater part of the temperate regions of the world at no very 

 distant period. North America was, till lately, almost entirely covered with 

 trees and shrubs, and presented few naked surfaces, except those of the allu- 

 vial deposits on the banks of its larger rivers ; and what was so recently the 

 state of America must, we may reasonably suppose, have once, at least, been 

 that of every other part of the world. 



The influence which a predominance of forest must have in a country 

 iminhabited by man must have extended to the animals, the herbaceous 

 vegetables, the soil, the waters, and the climate. To wild animals of every 

 kind, especially to those of the more ferocious description, forests have, in all 

 countries, furnished shelter, and, in a great measure, food : birds, insects, and 

 reptiles are the more common inhabitants of forest scenery. Herbaceous 

 plants are, for tho most part, destroyed by dense forests ; but some kinds, such 

 as epiphytal lichens, mosses, and, in some cases, Orchidese, are encouraged by 

 the thickness of the shade, and the moist heat which prevails among the trunks 

 and branches of the trees. But the great influence of forest scenery in a wild 

 state is on the soil; and, in tliis point of view, natural forests may be regarded 

 as a provision of nature for preparing the earth's surface for the cultivation of 

 corn, and of the other plants which constitute the food of man, and of domestic 

 animals. It is unnecessary to show how the soil is furnished with that organised 

 matter, on which alone "perfect plants can live, by the decay of leaves, and, 

 ultimately, by the decay of trunks and branches. The waters of a country, 

 the rivers and lakes, are necessarily aftected by the state of the woods of that 

 country. These woods must, in ail cases, act more or less as a sponge in 

 retaining the water which falls on them ; and water must thus be sui)plied 

 more gradually to the rivers, in countries covered with wood, than in countries 

 which are cleared, and regularly drained. The influence of forest scenery in 

 increasing the moisture of the atmosphere, and in preventing a climate from 

 being so hot in summer, and so cold in winter, as it would otherwise be, is 

 well understood, and, in such a slight outline as the present, requires only to 

 be mentioned. 



The use of studying the influence of trees in an uncultivated country is, to 

 afford useful hints with reference to the planting or thinning of them in 

 countries which are civilised. That which takes effect on a grand scale, where 

 forests cover many thousand acres, must operate more or less in the saine 

 manner where they extend only to hundreds, or even tens, of acres; and, con- 

 sc(|uently, this infl"uence must be kept in view in the formation of plantations, 

 both useVul and ornamental. If the forests and plantations of Britain are no 

 longer of such an extent as to afford a shelter for wolves and hyenas, they 

 stiU harbour foxes, polecats, snakes, and other noxious animals, and seve- 

 ral kinils of carnivorous birds, such as the hawk. The forests in France 

 and (rermany still contain wolves and wild boars ; and, on most parts of 

 the Continent, the forest is the place of refuge to which man flies for con- 

 ceahncnt after the commission of crime, (bee Gautieri Dcllo Itifiuso dci 

 liosr/ii, &c.) If forests in a wild state supply food to birds and insects, in a 

 civilised country birds and insects may be expected to abound more or less 

 wherever there are trees and shrubs to supply them with food and shelter. 



