I was walking down the deserted sidewalk between my US highway and some woods last year when I realized, all we see is edge. Outer impression of forest, unless we’ve visited a national forest or park, it as this dark forbidding thing. This, like dark night made darker by the lights in your houses, is a matter of the bright open spaces outside the forest, not the forest itself.
The first thing you’ll encounter when you try to poke into a forest on the edge of a road or parking lot is a lot of vines, weeds, and thorny shrubs blocking your way. These plants are all adapted to avoid herbivory, grow quickly, and spread their seeds far and wide. Thorns, spines, and allergic reactions will you for as much as 200 feet into the forest if you ever decide to go adventuring into your local woodlot.
These plants evolved to take advantage of .periodic, sunny clearings in forests, usually caused by large trees falling. To do this, they have plenty of small, dispersible, and durable seeds and quick flowering. Because they are easier to see and therefore eat, they also evolved woody stems and plenty of defensive mechanisms. The crowding is because of the rich seed banks and sun. Open space and sunlight was rare in the forest interior, and an entire complex of briars, ivies and hedges evolved to take care of these ephemeral habitats.
Until we started building roads..
1,000 years ago, no roads in the forest were wide enough to count as a clearing. Think of the Appalachian trail. Wide enough for two walkers to pass. As Europeans reintroduced the horse and introduced wheels to the continent they started to widen these roads and make new ones 4-5 times as wide as the footpaths that served as America’s highways in 1400.
Now that we have 2.5 million miles of roads between 12-200 feet wide, the forest is mostly edge and most of the forest we see is edge., Those genera that eked out a weedy existence since the dinosaurs were tromping all over everything now are doing even better than livestock.
The real beneficiaries of civilization have been these sorts of weedy species, along with the pigeons and the rats.
I can’t solve the weedy species thing, but I can suggest a remedy for the edge we see.
Trails. Particularly near streams.
Going back to the bucolic virtues of people who just wished they had steel axes and chainsaws, the footpath allows entry to the forest interior. The other benefit of riparian (streamside) trails is they provide eyes on the stream. If people have a favorite daily hike next to a stream, they are more likely to know when something goes wrong with it than if they were on the stairmaster at the gym. Somebody has to drink that water downstream, after all.
(All the land in the US more than 1/4 mile from a road, in gray. Equivalent area in green.)
The US is 50% within a 1/4 mile of a road, and 50% beyond, if you include Alaska.
Upon request by a friend, here is the above area blown up for my native Georgia area.
Right off I can see that I made a mistake in my colors for the area away from the roads. I should have used a medium gray or even a black, not a dark green. It gets too confused with the bright green of the state areas. I’ll rework these for publication.
Finally, the picture I really wanted to use, a carpenter ant colony I discovered in 15″ dbh tree in the woods near my home. I would stand in front of this entrance for minutes on my walk home and watch songle ants bring single pieces of sawdust out of the hole in the tree. If I wanted to see more ants, I would just breathe on the hole. Id get about a dozen briefly showing their black faces before going back into the colony to continue taking apart the trunk of the tree one piece of sawdust at a time.