 So, you owned some woods, and you got to wondering which trees to cut and which to leave in. That's the way it begins. Only in my case, my grandson Kevin asked the question. I was putting in these poles a few years back, and he was at that curious age. Well, a question. I was pulling some weeds, told him it'd give the desirable plants more room to grow. He asked me if you could do that in the woods with trees. That got me to thinking, and poking around for the answer. Always loved the woods, loved to hunt and hike, watched the animals and the birds. Enjoyed the peace and the beauty, but I never paid much attention to how the forest grows, and it never occurred to me that I could work it like my garden and make it grow the way I want until I started reading and talking to folks and watching nature at work. Did you ever wonder how a forest gets started? Well, there's lots of ways. One way is for trees to take over abandoned fields. This was farmland a couple of years ago. Then when the owner quit farming, nature took over. Weeds grew up in briars and woody plants, and trees began seeding in. Some of the seeds were carried in by rodents and small animals. Acorns, for instance, brought in and buried by squirrels. Other seeds, like cherry, were carried in by birds. And some, like the maples, were blown in by the wind. Now, here's another way to get a new forest started. This was forest land cut over just a few years back. Nature's competition went to work here, too. Seeds were carried in by birds and animals and the wind. And there were seeds already here in the forest floor. Thousands of them, sprouts popping up from roots and stumps that are full of life. This land was also clear cut, but some of the trees were left standing. That has a lot to do with what grows and what doesn't. Because the seeds and sprouts of some kind of trees need more sunlight to grow than those of others. You know, the sun's important for plants and that includes trees, too. Some trees need clear fields or large forest openings to grow. Foresters call them intolerant because they need the sun and can't tolerate the shade. And because some of our most valuable hardwoods are more or less intolerant, like black cherry and red oak, they grow well only where there's lots of sunlight down on the forest floor. So when this happens, you have an even-aged stand of mostly intolerant trees. Some trees don't need sunlight. Sugar maple, red maple, and red spruce are tolerant species that grow right in the shade of other trees. As the forest gets older, the tops of the trees fill out and become a canopy, shutting out the sunlight. Then only the shade tolerant trees can grow down under the other trees. This land was cut over, too, but only the big trees were taken. The loss of occasional trees won't change the pattern. With only small openings in the canopy, the forest will eventually be taken over by shade tolerant trees of all ages. But what happens after the new forest becomes established? This area was clear-cut five years ago, and now the place looks like a lot of brush. Thousands of seedlings and sprouts trying to reach up and grab the sunlight, like yellow poplar, black cherry, and red oak. These trees will be beauty someday if they just keep their hold on the sunlight. Some folks think they need to thin out a stand like this, but it's not necessary. Nature will do the job. And by the time the stand is 12 years old, the dominant trees are established, and lots of others, probably 3,000, have died. There's not much now for animals to eat. But it's a lot easier for you and me to get around, and we can begin to think about which trees to leave and which to cut out. But you need to know something about how trees grow, because not all of them grow the same. Not all the same trees grow the same in different places. You take this northern red oak, for instance. Doing fine, but it's got a lot going for it. Did you ever wonder why some trees grow taller than others, and why some trees are so big around, while others never mount too much, has a lot to do with the land itself? Some places are just better than others for growing trees. This hollow, for instance, where the top soil has piled up for years. How well a tree will grow depends on lots of things. The depth of the soil and how much moisture it can hold. The presence of rich nutrients. Where it grows on the slope. The direction that the slope faces, north, south, east, or west. And drainage. It's just like growing anything else. You want a good tree, you need good land. Another thing that affects growth is the number of trees trying to live on the land. Stands to reason that the more there are, the less chance any of them has of growing big around. It's like that garden of yours. If you don't thin it out, nothing does well. The trees that have the biggest trunks also have the biggest tops, or crowns, as the foresters call them. And if there's room for the crown to expand, the trees can grow bigger around. Trees need light and root space to produce food for growth. And when the forest is young, there's room for strong trees to spread out and up, and roots to go down and out. And as the forest begins to cover over, the location of a tree's crown has lots to do with the way it'll grow. The biggest trees get sun on their crowns, and even down their sides. They're called dominant trees. Those trees getting sun on their top, but less on their sides, are called co-dominant trees. Others, though, have to struggle to get any sun at all. They are intermediate, while some just limp along in the shade and are suppressed. But usually, there are only a few dominant trees. The stronger co-dominance will emerge as crop trees. The weaker co-dominance and intermediates will be lost. Trees that die and fall to the forest floor decay and are used again as nutrients by those that survive, ensuring that the biggest trees continue to grow. Of course, not all trees grow at the same rate. These are the same age. But look at this yellow poplar. Its leaves are taken in the light, and its roots are pulling in food and moisture from the soil. And nearby, this sugar maple, same age as the poplar. But it's growing slower, because it's underneath the bigger trees. Did you ever wonder how a tree grows? It's interesting. It grows in a long, thin cone, adding a new layer each year, growing out and up at the same time its roots are spreading and getting stronger. If it's a fast growing species in a good location with room to grow, its layers will be thicker than other trees. When you cut through a tree, you can see the year by year growth or tree rings. They show how old the tree is. And the wider rings tell you that growing conditions were good that year. Narrow rings tell you that a nearby tree was competing for sunlight and moisture, or there was little rainfall during the growing season, or insects ate off the leaves. So foresters use tree rings to see how well a tree has grown. This is the cross section of an oak tree showing the growth of the rings. And this is another oak, larger than the first. Both were the same age. But this one grew faster because of better growing conditions. Of course, you don't want to go around cutting down all your trees to see how well they're growing. But you might want to use an increment borer to get a core sample to look at growth or get a forester to look at your woods with you. Speaking of growth, these trees are beginning to crowd each other. So their growth will be slowed down. This tree is doing well, had plenty of light and good soil. Probably at an early age, it became dominant and reached a co-dominant position as the stand grew. It measures nearly 21 inches across on this special tape that reads the diameter. This tree is not as large. Its growth has slowed down and will probably get worse because it's in an intermediate position. The smaller tree will eventually die. And the larger tree will spread to take over its space. You know, a forest keeps changing as it grows. And thousands of little sprouts and seedlings which were there in the beginning are not around years later. Say you start with a stand of oak. Maybe 7,000 stems per acre. 10 years later, a little over half are left. 20 years later, a little over a fourth. But now they're three to six inches in diameter and about 30 feet tall. When our oak stand is 40 years old, only 600 trees remain. But over 100 of them are 7 inches thick, some 10 inches. And they're about 50 feet high. Something else is happening too. Our 40-year-old woodlot is starting to produce soft timber, more than 3,200 board feet of low-quality lumber per acre. When our oaks are 100 years old, about 250 trees are left. But a third of them are 11 inches or more in diameter. And the soft timber volume has jumped way up to 21,000 feet. So in 100 years, our 7,000 oaks have been reduced to 250. Less than four in 100 survived. But they stand almost 80 feet. They average about 10 inches in diameter and contain six and a half times as much lumber as they did at age 40. I love the woods when it gets old like this. And the animals come and go. And the birds. There's something peaceful about these big trees. This one must be more than 100 years old. And most folks don't realize they can have a say in what kind of birds and animals come into their wood. Take this hole, for instance. It serves as home to a squirrel family. Real turkey little fellas. As the forest changes, so does the wildlife. In the early years, when it's a jungle, it's home to deer and grouse and young turkeys and lots of creatures. Then when strong trees take over and the undergrowth thins out, there's not much lives there except rabbits and rodents. Later in middle age, it's deserted until the trees produce acorns, beech nuts and hickory nuts. Then when the forest grows old and some of the trees die in cavities form, different animals come in to live. Coons and squirrels and owls and hawks to help control rodents and wild turkey and bear. Grape vines will bring wildlife too, but they also choke out trees. And once they develop a canopy, they block out the light and nothing will grow beneath them. So you need to look at each situation. Figure out what you want and make some decisions. And you need to remember how a forest grows. It can take over an abandoned field or a place that's been cut over. And the kind of tree that grows depends on whether the conditions are favorable for tolerant or intolerant species. And remember, how well it grows depends on lots of things. The quality of the land, the depth of the soil, the amount of moisture, the number of trees in competition, and the position of each tree on the land. The forest keeps changing too. From a newly reforested place with thousands of sprouts and seedlings, to a stand of healthy trees of significant height and diameter providing valuable lumber, the wildlife changes too. From deer and grouse and birds that nest and feed in the young forest, to cavity nesting species, owls, hawks, squirrels, raccoons, even bear that use the mature woods. So once you understand how a forest grows, then you can decide what you want to do to manage it. And figure out how you want to work with your own woods to get the kind of trees and wildlife you want. You might need to clear cut some patches so you can grow trees that don't like the shade. You might want to cut out some scrubby hardwoods in places where they don't do well and put in pines instead. You might decide to seed some old pastures or hillsides or cut timber in an older stand to encourage the kind of trees you want or remove trees from a young stand to give others more room to grow. Complicated, you say? Well, I suppose it is a bit, but there's lots of good folks who'll help you. There's lots of foresters. There's federal and state and company foresters and consulting foresters too. And the county agent can help you with educational and reference materials, workshops and tours. And you know, it's lots of fun. Deciding which trees to take out and which to leave in. Making a home for the birds. Sending out invitations to the deer and the squirrels. And making a little profit too without hurting this beautiful place.