PENNYSTONE  •  RESOURCES  •  NOTEBOOK

When the forest reclaims its turf

Unhappy with the prospects of a perpetual blanket of leaves skirting a Kalmia latifolia, the moss turned its attention elsewhere. In the opposite direction, slightly downslope, lay a fertile field of opportunity.

And so it began creeping outward, lofting an occasional spore, seeking a foothold. For Polystichum commune and its smaller colleague, Thuidium delicatulum, the advantage was clear. The soil is a weak mix of sand, silt and clay, laced with bits of sandstone and shale just under the surface, suitable space for any respectable bryophyte.

All that stood in its path was a conventional suburban-style lawn.

Wary but determined, the moss chose first the ground the lawn liked least: here a patch of gloomy shade, there the tips of rocks gradually rising to the surface with each winter's frosts. With outposts established at last, it was time for the main assault.

The lawn, quite likely, stands no chance against this energetic and determined force. Out of their natural element, the combination of grasses that comprise a popular sun-shade mix cannot sustain itself, if only because it is regularly mowed and never allowed to flower and seed. The mosses have occupied this field for millions of years, can roll with all the passing environmental punches, and will advance rapidly when other species, such as the elements of the lawn, are dormant. Without support of lime, fertilizer and chemical herbicides, the lawn will slowly succumb to the inevitable.

This drama, being played out on a small patch of roadside lawn is a microcosm of a larger dynamic we recently investigated concerning the destiny of land once cleared by early settlers, eager to make use of the vast resources of timber and the open land for agricultural purposes. Testament to the efforts of agrarians are long rows of piled up stone, plucked from the open ground and used to form borders that defined what were mostly little more than pastures.

Much of it would test the will of the farmer, for the forest soils are notoriously poor in nutrients, laced with glacial till, the slopes in many places steep and the productivity dismal. And always lurking nearby were the forests, prepared to reclaim the land for themselves, just like the moss that methodically assaults the lawn.

Nature, it seems, wastes little time in cleaning up messes. A forest system is a formidable juggernaut with a full arsenal of resources to attack wounds on its sense of order. There are always a variety of tree species working collaboratively to form a sheltering canopy, a field of correct nutrients, a means for conserving water and even affecting the climate itself. With it are a supporting cast of shrubs, graminoids, ferns and fern allies, vines, lichens, even cactus and of course an array of bryophytes. Each of these earns its keep by making a contribution to the larger whole, and this ecosystem in turn supports a myriad of animal, insect, bacterial and fungal life which completes the balance and puts the wheels of sustainability in motion.

So, like the pioneers, we step into an arena with our motorized equipment, our seed and chemicals and commercial mulches, sometimes even soil, prepared to conquer the land that we believe we own simply because we paid money to get a piece of paper. The forest neither sighs disappointment, weeps in sadness, or growls with annoyance. It can afford to sacrifice a few trees, shrubs, herbaceous species - all the way down to a single tuft of moss - to our attempts to "beautify" the land by disrupting the soil chemistry.

Our landcaping activities are little more than what a forest experiences in great natural calamities, ranging from massive ice sheets to passing fire. It has time and experience on its side and simply waits for the opportunity to clean up the mess.

The patch of lawn along the road becomes a product of manor mentality, to make the estate all the more impressive by devoting vast spaces to turf, whose only functions are decoration, mowing and fertilizing. It is among the worst possible land uses for stormwater retention and among the most expensive ways to use land (not to mention among the most polluting, both air and water).

So it begged the question: what would occur if it were mowed but not otherwise maintained? For a time, the turf guarded its territory, but by autumn Thuidium delicatulum , along with some rogue Mnium began to appear and the Polystichum commune had organized a few tentative positions. The main assault appears to have begun in earnest in the following spring, with sentinals appearing in many locations.

Is it a better alternative? As far as the forest is concerned, yes. Moss protects bare ground without intruding on the root systems of trees and shrubs below, insulates the soil below, and holds substantial quantities of water - a living mulch. It remains to be seen how energetic the moss will be when it reaches that line defined by more sun than it might prefer and when it begins to compete with native graminoids - especially the sturdy carexes and clump grasses that lounge in full sun.

In terms of human taste, the reviews of moss are mixed. Turf grasses are easier to maintain in many ways. Periodic feeding, weed suppressants, lime supplements, reseeding, constant watering and regular mowing reward us with a sleek carpet that pleases the eye.

Moss fields can be mixed species and result in a patchy look, and debris must be removed. This begins with the autumnal blanket of leaves, but also the small bits of residual litter shed by an active tree canopy. It can't really be raked; the more delicate mosses just can't handle the tearing (which precludes them for being a carpet for children to enjoy).

To make it "perfect," one can expect to do a considerable amount of hand cleaning. In a natural setting, the occasional arrival of duff represents only a brief obstacle; in time it will rot and the moss will overwhelm it and tuck it into the growing organic layer that feeds the system.

The difference, of course, is that forests are not neat and tidy places, at least in the human perspective of landscaping. That raises the final question: is the goal to dwell within the ecosystem or to try to control it?