If I had a house in the country, I would try to respect the land. I would have an organic garden, put in a pond and maybe even get some geese. They could help “mow” a few acres around the house, which would open up the view a bit. If I got as many as 40 acres, I might even have some forest to walk through. My land would provide habitat for all sorts of native creatures. Salamanders would live in my stream and ovenbirds would raise their young in my woods. Or would they? Some species, it turns out, are more particular than others about changes to the neighborhood.
Forty acres looks like a lot of land. More than enough, one might think, to support a wide selection of choice critters. But what lives in a forest isn’t just a function of the number of trees. Many animals need significant blocks of continuous undeveloped land to grow, reproduce and thrive. 40 acres is on the small side to provide a safe and supportive habitat for animals such as hare, porcupines, beavers and many types of small birds such as warblers.
As the size of a forest parcel becomes smaller, more of the land area changes from being true forest habitat into something known as “edge habitat.” Edge occurs anywhere two habitats come together. The intersection of field and forest, and the roadsides bordering a highway running through a wilderness area, are two examples of edge habitat. Animals that favor edge habitat such as raccoons, crows and blue jays prey on forest animals that are forced to use edge habitat because of changes in their forest home.
On forested land, edge regions that penetrate as little as 200 feet into the woods become significant factors to these species survival as lot sizes decrease. A square, four-acre parcel of completely forested land, if isolated by field, or subdivision from other forest, is made up entirely of edge habitat and unsuitable for use by true forest dwellers.
Last year I took a wonderful class on land use with Professor Evan Richert, former head of the Maine State Planning Office. At the end of the semester, a student presented a startling analysis of the impact on wildlife habitat that occurs when a medium-sized house is built in the middle of an isolated forested 40-acre parcel. Once she subtracted the footprint of the house, the driveway, and the 200-foot edge zones around each of these, the seemingly large piece of apparently undisturbed forest, with only one modest house in its center, sheltered only 2 acres of what is defined as undisturbed interior forest habitat! Not much room for ovenbirds here.
Analyses like this one make it clear just how important it is that we think broadly about our goals as we decide how to use our lands. If one of our goals is preservation of wildlife habitat for species that require true forest, we cannot sub-divide our forest lands into five-acre lots. Small lots and the edge they can create provide excellent habitat for squirrels and blue jays – wonderful creatures, to be sure – but hardly in need of preservation efforts. It is also true that our village and town centers cannot be home to moose and beaver. But, if we don’t plan carefully how we wish to use our remaining undisturbed forest lands, animals that cannot live on the edge may find themselves with nowhere to call home. This would diminish our own lives as well.
Sarah Wolpow can be contacted at [email protected]
Note: This may be the last of many columns written by FootPrint’s wonderful student manager, Sarah Wolpow. She has steered clear of further sub-division of Maine’s forest to a new urban home and has recently begun a challenging new job with Friends of Merrymeeting Bay protecting one of our own favorite habitats. If you enjoyed her columns, I am sure she would enjoy hearing so.