"Pulse of the Forest" by James P. Jackson (American Forestry Association, 1319 18th St. NW., Washington, D.C. 20036; 132 pages; illustrated in full color; $14, can be ordered direct).

The publisher is a national conservation organization -- independent and nonpolitical -- whose goals are to advance intelligent management and use of our forests, soil, water, wildlife and all other natural resources.

The author is actively involved in a number of conservation organizations in Missouri, has taught high school biology for almost 20 years, moonlighting during summers as a freelance natural history writer. His first book, "Biography of a Tree," won the Missouri Writers Guild plaque for best book published in 1980.

Deciduous forests are fascinating for their changes through four seasons, the author says. "A person may not know one tree from another but will have a good mental image of the carpet of lovely wildflowers that blossom in spring before leaves emerge on the trees.

"The variable oakleaf caterpillar and other potential defoliators of forest trees seldom have population explosions -- not necessarily because of the braconid wasp (which deposit their eggs either in eggs of moths or in newly hatched caterpillars) but likely because they are normally controlled by a whole variety of enemies.

"The founding fathers of the United States devised many checks and balances for our democratic form of government; yet many people never realize that checks and balances are also important to a forest community. A case in point is the careless, indiscriminate use of pesticides. Insect poisons can easily wipe out beneficial insects along with the target species. Destroying whole food chains is no way to maintain the health of any natural community. There are hidden dangers in all kinds of monoculture.

"The worst thing that can happen to a deciduous forest is complete removal from the landscape. This means clearing for farms, highways, and all forms of urban sprawl. It is true that much of the orignial forest covering the eastern United States is now cleared for this and other uses; very little of it will ever revert to forest. But nearly all of what remains should be preserved intact.

"Plants do not grow in the same way as animals. Most animals grow only so much and then, after reaching maturity, get no larger. There are some exceptions, such as fishes and reptiles, which never completely stop growing; but their lives are rather short. A tree, on the other hand, grows as long as it has the spark of life; even when old and diseased, it endures year after year after year while dying branch by branch.

"Another difference between plant and animal growth is on the microscopic level -- that is, in how their cells develop. Animals produce cells either for growth or repair, in all parts of their bodies. Such cells specialize immediately into skin, muscle, bone, and other tissues as they are formed by division of other cells. Plants follow a different pattern; they produce new cells in restricted areas only, and all are the same at first; they specialized later.

"The area of cell production in plants, known as meristems, are basically three in number. One is just behind root tips, the second is in growing shoots of upward and outward growth, and the third is a paper thin cambium layer between the bark and the inner parts of woody plants. Cells divide and redivide within each meristem. Later they become inflated with life's juicies, stiffen in capsules of cellulose, then specialize into leaves, stems, roots and reproductive parts.

"In trees there is a fourth dimension outside of the inner bark. It is the cork cambium and produces only one type of cell: outer bark. The main cambium, however, produces cells that develop into inner bark on one side and wood on the other. Some of the inner bark cells then specialize into phloem tubes that transport sap downward, while some of the wood cells become zylem tubes to haul sap upward in the tree.

"These details of growth, compared to those of animals, tell us that the growing part of a tree is on the outside. It is a lying glove whose fingers lengthen as roots and twigs get longer, and expands as branches and the trunk grow in diameter."