Earth Journal

by Gary Pendleton

Succession in the Forest

Scrub pines prepare poor soil for what’s later to come

Pinus virginiana is a humble tree. The weak and brittle wood has no commercial value. Aesthetically, it lacks the grandeur of other coniferous cousins. It has a spindly trunk, and the needles are short and twisted. The poor scrub pine is as humble as its name implies.

It can be so dark inside a healthy stand of scrub pines that practically nothing can grow; the forbidding space is cramped with a tangle of dead limbs. On the other hand, when you step into a forest dominated by the tall and stately loblolly pine, it seems a cathedral. The filtered light is soft; the atmosphere is airy and welcoming.

Naturalist and popular author Donald Cullross Peattie showed a knack for finding the virtues of even unlovable trees. In his two-volume The Natural History of Trees, he said of the scrub pine:

“It swiftly takes over abandoned lands and holds them for 75 years or so, until better types of forest can, in the cycle of succession, assume control. No other tree in its range does this more effectively.”

What Peattie said about succession is worth a note. Abandoned farm fields typically lack the conditions to support growth of a healthy and diverse forest of native hardwoods, the type of forest that can make a home for a host of wildlife. Pines can tolerate poor soil and dry conditions.

Scientific name: Pinus virginiana

What to look for: Medium-sized pine tree. Short twisted needles in bundles of two. Cones are abundant, 11⁄2 to 2 inches long, often bent back on the twig.

Where to look: Abandoned farm fields and second-growth woods, mainly in upland areas with good drainage.

Places to visit: Jug Bay Wetlands Sanctuary; Calvert Cliffs State Park.

Over time, the topsoil is restored as the short-lived pines die out. Since pine seeds won’t germinate in the dark conditions that prevail underneath the young pinewoods, scrub pine is slowly replaced by a diverse array of oaks, hickories and maples. The young hardwoods do well in the cool, dappled shade provided by the pines as they die and create gaps in the canopy, allowing just enough light for hardwood seedlings to grow.

It takes about five years for scrub pine to take over from the orange-tinged broom sedge that first takes hold of the field, Peattie explained. After about two decades, redbuds and dogwoods will have gained a foothold. After three-quarters of a century, the scrub pines will have begun to die out and be replaced by the great, long-lived hardwoods.

Along the miles of winding trails at the Jug Bay Wetlands Sanctuary and other natural areas in our region, alert hikers can find places where the process of succession is playing out. There are mixed stands of young hardwoods growing among decrepit pines. In other places, tight pockets of younger scrub pines create densely shadowed, pine-scented chambers.

The story of the land is told, in part, by what grows or doesn’t grow in a particular place. Pinus virginiana plays an important part of the story. It smells good, too.