There is much discussion in conservation circles about, on the one hand, species disappearing from sight, sound and memory and, on the other, species newly rooting in places they have not always been.

As I wandered along a deer trail through a section of otherwise pristine woodland and discovered a rock wall with no apparent historical connection, I remembered an experience when I was a daily news reporter covering the machinations of a county planning board.

A residential development was under consideration and group of young conservation-minded folks appeared before the board to object. The development was at the top of a hill, they pointed out, and its roofs and streets would send tons of stormwater to inundate a wetland at the bottom of the hill, where it cleaned a tributary feeding a nearby river.

A hike was planned into the target area and on the designated day, planners, conservationists and developers visited the site to take in-person inventory.

The developers rightly pointed out that as long as people make babies, developers will make houses for them. The site under consideration ticked all the boxes: a buildable parcel of sufficient acreage to be profitable, with an excellent view of the river and at a price the current landowner was willing to accept.

The conservationists explained the forest through which we walked was unchanged since probably the beginning of time — at least since well before a man named Pierpole and the Abenaki tribe had welcomed the first European settlers to the area, the land had been protecting the wildlife and the wetland, they said.

One of the young people joyfully swept her arm across the forest, populated by a stand of mostly birch and marked mostly by deer trails, and proclaimed it pristine. It should be kept forever thus, she announced.

Suddenly there appeared through the stands of mostly birches, a rock wall created by one or a couple of those earlier settlers. The wall was all that remained, but sufficient proof that the corporation seeking approval that day was not the first developer to want to cut trees to build homes and pile rocks — a No Trespassing sign of sorts — around a garden that feeds the new families.

Ken Bailey, one of the senior members of the planning board, had stood one day in the yard outside the bedroom in which he was born and related to me his history in the area, beginning with two brothers who had received the land in payment for their services during the Revolutionary War. That original tract had become a half-dozen towns, including the county seat. The aging patriarch wondered whether his grandson, the seventh generation of Baileys to work the land, might be the last to have a farm to work.

He remarked, as he often did, about the “view stew” that had enticed thousands of “folks from away,” and would entice thousands more, to buy pieces of the pastoral promises that would be replaced by new homes.

“View stew” was all that remained when the farms fell under the builders’ hammers, Bailey noted, “and it was wicked hard to chew.”

It turns out “pristine” and “invasive” are subjective terms, their values determined by those defining them. Typically, pristine applies to the way of my existence, and invasive is what comes afterward.

We are the most invasive species on our planet and like any other invasive plant, we redesign our new home to suit ourselves. There is very little, if any, truly pristine land remaining on Earth. Unfortunately, slowly but inexorably, we are driving indigenous plants and critters to extinction.

I often wonder, as did Ken Bailey, how to define and deal with the invasives.