For nature lovers, superb trees and birds

The Audubon Society Book of Trees, by Les Line and Ann and Myron Sutton. New York: Harry N. Abrams. 264 pp. $50. John Gould's Birds, by John Gould. New York: A&W Publishers Inc. 239 pp. $39.95 until Dec. 31, $50 thereafter.

Both of these lush, substantial volumes are superbly produced examples of the printer's and, in one case, the photographer's art.

''The Audubon Society Book of Trees'' has a worldwide scope, fine photographs , and (obviously) a conservation ethic. It is the fifth volume in the Abrams Audubon series, all written by Audubon magazine editor Les Line in cooperation with various specialists (in this case Ann and Myron Sutton, a geologist and botanist, respectively). It has an environmental and evolutionary framework, celebrating not just the variety and beauty of the world's forests, but their capacity to adapt to and exploit virtually all of the earth's terrestrial and many of its aquatic habitats.

Each of the book's 10 sections focuses on a climatic or geographical habitat - rain forests, coastal areas, arid regions, etc. - and explores the ways in which various tree species have adapted in similar habitats over the globe. (In one instance, Line even speculates on how the prickly pear cactus may have developed into a tree to escape the Galapagos turtle!)

Most of the photographs are visually striking, but they have been chosen and arranged within a meaningful context as well. The short essays that precede each group of tree and forest portraits are interesting and informative.

There is also a sense of a real voice in the text. Line creates an ''I was there'' feeling through his ability to project his own puzzlement, curiosity, and a genuine sense of wonder. His environmental sensitivity is impressive because it is quietly cognizant of the complexity of the issues involved and the losses ''we stand to lose if a truce is not declared in our war on trees.''

''John Gould's Birds'' was originally published as ''Birds of Great Britain.'' Its 367 lithographed color plates are generally regarded as the high watermark in Victorian ornithological art. The original edition appeared from 1862 to 1873 in five folio volumes weighing 20 pounds each, and the present edition is the first designed for the general public's purse and bookshelf. At once a historical document and an artwork, it carries an enduring appeal for the modern audience that makes its republication welcome.

Gould was not strictly speaking a painter, or even an artist. Born in 1804, the son of a royal gardener, he was successively a taxidermist, curator of the London Zoological Museum, competent sketcher, inexhaustible collector of bird skins and specimens around the world, enthusiastic entrepreneur, and skilled publisher of the most important and inclusive series of illustrated ornithological works in Europe in the 19th century.

Inspired by the work of Audubon (whom he met in England and who also routinely hired others to complete his paintings), Gould employed a succession of highly talented illustrators, beginning with his wife, which included the limerickist Edward Lear, H. C. Richter, and the moody German artist Joseph Wolf. Often Gould provided the rough sketch for the plates, but frequently (and always in Wolf's case) he simply oversaw the final production. Still, the entire work bears his stamp and a certain English sensibility, and while Gould's birds lack the untamed wildness of Audubon's conceptions, they are vastly more sophisticated and ''finished'' works of art.

Beautifully reproduced in Italy for this edition, Gould's plates contain a subtle depth, a wealth of botanical as well as ornithological information, and that characteristic warmth and detail of the 19th-century palette. An engaging and informative biographical essay by his great-great-granddaughter, Maureen Lambourine, introduces us to that peculiarly 19th-century figure, ''John Gould: the Bird Man.''