New Jersey cannot spare more land for forests. She now has upwards of two million acres, and if we apply the rule that a state with 30 per cent of her area in forests is well off, we shall reduce the total to about a million and a half acres. But this will adjust itself; our present concern is to stop the waste of our forest resources and bring them to serve one of the most highly organized communities in the nation.
With respect to trees, as distinguished from forests, this intensive life and concentrated population make it imperative that cities and towns be provided with parks and as much street shade as possible. Thus there are two ample fields for study and work, the one dealing with trees and their social bearings, the other with forests and their economic relations.
The art of caring for _trees_ is called arboriculture, and one who devotes himself to it an arborist. The art of producing and developing tree communities, or _forests_, is silviculture or forestry.
The intimate study of trees is full of interest. The sap, consisting of raw food material gathered by the root hairs from the soil, courses upward, through the newer wood cells of trunk and branch, to the leaves; there, under the action of sunlight, it is assimilated with carbon dioxide, and, so prepared as tree food, passes downward through the newer bark. Thus, the process never entirely suspended, even in winter, but varying in vigor with the seasons, the tree grows in stature by producing new shoots each year. No part of a tree that has concluded a season's growth is ever elongated, but remains fixed, and length is added to its terminal by the development of new buds. This is why a branch always remains at the height at which it started. On account of this fact the age of a tree or branch may be determined by counting back from the terminal one year for each section of development. On most deciduous trees this is hard to follow for more than a few years, but on the evergreens, which produce their branches in whorls, it is easy. On the other hand, diameter growth may continue indefinitely and is exhibited on any cross-section in a series of annual rings. A count of these rings will give the age of the tree at that point.