Recently, at Barnes and Noble’s café in Augusta, Katelyn, my 23-year-old daughter, listened to me expounding on the 1995 wolf reintroduction in Yellowstone National Park.

Habitat destruction, livestock owners, trappers, hunters and poison-laced bait had extirpated wolves from YNP by the 1920s, but 17 years ago amid controversy, government officials began returning wolves to the park.

One point about an ecological effect of the YNP wolf program popped Katelyn’s eyes wide open, and in an incredulous tone, she blurted, “Really!”

Here’s the story: After wolves established a population in YPN, aspens (called poplars in Maine), cottonwood and willows began spreading into grasslands, creating more woods than folks ever remember in modern history. The aspen species proved particularly awe-inspiring, because these trees are iconic in large regions of the West. (More on poplar later.)

At first, the correlation between wolves and forests mystified Katelyn, but after listening to a quick explanation, she immediately understood the symbiotic relationship between wolves and common western hardwoods.

Before the wolf reintroduction, elk ate browse most everywhere in the park, but by the late 1990s, wolves had reduced elk, leading to two results.

First, fewer elk meant less foraging on hardwood browse, increasing the acreage of forests and decreasing grasslands, a pig-simple concept easy for anyone to predict.

Second, the growing wolf population showed a complex side of Mother Nature much more difficult to forecast. Elk modified their behavior to survive wolves, and part of the elk strategy included avoiding browsing in certain habitat, leading to increased hardwoods there.

For example, wolves could more easily trap elk on steep slopes, in thickets and around flooded areas that had abundant food but limited escape routes. Elk steering clear of vulnerable spot allowed poplars, willows and cottonwood to thrive because these tree species suddenly had “sanctuaries.”

(No one ever told me this, but soon after wolves arrived on the scene, it seems reasonable that elk instinctively knew enough to stay away from certain habitat — a gene thing like first-year, migratory songbirds returning to an exact acre in a breeding spot without having been there before.)

Even when elk chose flat foraging spots with escape routes, they learned to browse with their heads held high to spot approaching wolves. This altered behavior increased forage at lower levels for shorter critters such as beaver and deer. Larger ground-cover carpets also helped ground-nesting birds, and on and on it goes.

I must mention one last point about elk. Through millennia, elk evolved as huge animals to survive wolf predation better. In short, wolves may reduce elk populations, but that decrease led to elk becoming large, magnificent creatures rather than being the size of a whitetail.

North American whitetails and mule deer didn’t evolve as giant ungulates, because part of the survival strategy begins with producing prolific numbers when habitat suits a dense population.

Observers can also see this population principle with African plains animals that rely on huge herds for continued survival — whether they grow small — or large-sized species, say Thompson gazelle or wildebeest.

Small changes in nature often start a chain reaction with unforeseen consequences. Since 1970, clear-cuts in northern Maine have created wonderful moose habitat, greatly increasing the herd, but the change proved abysmal for deer.

Maine wildlife biologists are now saying that much of the North Country has on average one deer per square mile, so in this vast region, it’s a tradeoff between moose and deer. Coyotes complicate the northern Maine issue, but the real problem for whitetails is declining winter habitat.

I suppose humans can manipulate nature for the better if they plan well, but it’s difficult to see every consequence from our tampering.

Also, to complicate matters even more, user groups desire different results from the land — say Maine hunters in central Maine want more deer but farmers worry about crop destruction. Any manipulation has social forces to consider.

And these forces change through the decades and by region. For instance, when I mentioned in the beginning of this column that poplar were coming back in Yellowstone, I knew many readers would think, “So what?”

It might interest folks to know that in Maine in 1908, poplar was the most harvested hardwood, often used for floors where livestock stood in barns, wagon floors and molding. It once ruled as a desired product.

Also, in nearby Rhode Island, builders often choose poplar for molding, and in fact, a Rhode Island friend in the molding business gives me scrap poplar, which has become a favorite choice for my picture-frame making. It cuts beautifully and takes a great paint or polyurethane finish.

I don’t pretend to know the definitive answer in environmental debates but do know habitat conflicts need civil discussion. Programs such as the YNP wolf program offer us a blueprint that allow clears thinkers to reach more accurate conclusions about fauna — and flora-management plans — say in Maine.