plant of substantial height and breadth.

Trees are not only relatively large organisms but also tend to be somewhat long lived. They in addition tend to define the environments in which they live, either in terms of the immediately local ecology or by gathering together to define and .

Trees are crucial components of the 's water cycle along with essential to the continued existence of much , and also serve as key components of the global carbon cycle, in particular serving to individually for decades or even centuries.

See also ecological succession and climax species.

The following is a quote of , 1897, as reprinted in the , November, 2012, pp. 78-79:

The forests of , however slighted by man, must have been a great delight to ; for they were the best he ever planted. The whole continent was a , and from the beginning it seemed to be favored above all the other wild parks and gardens of the globe … these forests were composed of about five hundred species of trees, all of them in some way useful to man, ranging in size from twenty-five feet in height and less than one foot in diameter at the ground to four hundred feet in height and more than twenty feet in diameter— proclaiming the gospel of beauty like

With such variety, harmony, and triumphant exuberance, even , it would seem, might have rested content with the forests of , and planted no more.

So they appeared a few centuries ago when they were rejoicing in wildness. The with could do them no more harm than could gnawing and browsing . Even the fires of the Indians and the fierce shattering seemed to work together only for good in clearing spots here and there for smooth garden , and openings for seeking the light. But when the of the rang out in the startled their doom was sealed. Every tree heard the sound, and pillars of smoke gave the sign in the sky …

Many of nature's five hundred kinds of wild trees had to make way for and . In the settlement and of the country, more than or beauty was wanted; and in the blindness of hunger, the early settlers claiming as their guide, regarded God's trees as only a larger kind of pernicious , extremely hard to get rid of. Accordingly, with no eye to the future, these destroyers waged interminable forest wars …

Every other civilized in the has been compelled to care for its forests, and so must we if waste and destruction are not to go on to the bitter end … So far our has done nothing effective with its forests, though the best in the world, but is like a rich and foolish spendthrift who has inherited a magnificent estate in perfect order, and then has left his rich fields and , forests and parks, to be sold and plundered and wasted at will, depending on their inexhaustible abundance …

says that things refuse to be mismanaged long. An exception would seem to be found in the case of our forests, which have been mismanaged rather long, and now come desperately near being like smashed off and spilt hides, branching horns, or magnificent … It took more than three thousand years to make some of the trees in these Western woods—trees that are still standing in perfect strength and beauty, waving and singing in the mighty forests of the . Through all the wonderful, eventful centuries since 's time—and long before that—God has cared for these trees, saved them from , disease, , and a thousand straining, leveling tempests and ; but he cannot save them from fools—only can do that.

Video (Tree identification, "How to identify trees, What to look for")

Video (Tree identification, "How to identify trees", various examples)

Video (Tree identification, Tree ID Project")

Video (Tree identification, differentiating among trees using )

Video (Tree identification, keying out a tree)

Video (Tree identification, using a tree identification field guide)

Video (Tree identification, choosing a tree identification book)

Video ("", exploration of )

Video ("", exploration of )

See, in addition, OSU-M trees.