By establishment, is meant the planting of new forests and the cutting of mature forests, in such a way as to encourage a natural growth of new trees without artificial planting or seeding.  The planting may consist of sowing seed, or of setting out young trees.  The establishment of a forest by cutting may consist of the removal of all mature trees and dependence upon the remaining stumps to reproduce the forest from sprouts, or it may consist of the removal of only a portion of the mature trees, thus giving the young seedlings on the ground room in which to grow.

By protection, is meant the safeguarding of the forest from fire, wind, insects, disease and injury for which man is directly responsible.  Here, the forester also prevents injury to the trees from the grazing and browsing of sheep and goats, and keeps his forest so well stocked that no wind can uproot the trees nor can the sun dry up the moist forest soil.

[Illustration:  FIG. 122.—­A Forest of Bull Pine Cut on Forestry Principles. (Photograph taken on the Black Hills National Forest, South Dakota.)]

By utilization, is meant the conservative and intelligent harvesting of the forest, with the aim of obtaining the greatest amount of product from a given area, with the least waste, in the quickest time, and without the slightest deterioration of the forest as a whole.  The forester cuts his mature trees, only, and generally leaves a sufficient number on the ground to preserve the forest soil and to cast seed for the production of a new crop.  In this way, he secures an annual output without hurting the forest itself.  He studies the properties and values of the different woods and places them where they will be most useful.  He lays down principles for so harvesting the timber and the by-products of the forest that there will be the least waste and injury to the trees which remain standing.  He utilizes the forest, but does not cut enough to interfere with the neighboring water-sheds, which the forests protect.

[Illustration:  123.—­A White Pine Plantation, in Rhode Island, Where the Crowns of the Trees Have Met.  The trees are fifteen years old and in many cases every other tree had to be removed.]

Forestry, therefore, deals with a vast and varied mass of information, comprising all the known facts relating to the life of a forest.  It does not deal with the individual tree and its planting and care,—­that would be arboriculture.  Nor does it consider the grouping of trees for aesthetic effect,—­that would be landscape gardening.  It concerns itself with the forest as a community of trees and with the utilization of the forest on an economic basis.

Each one of these activities in Forestry is a study in itself and involves considerable detail, of which the reader may obtain a general knowledge in the following pages.  For a more complete discussion, the reader is referred to any of the standard books on Forestry.