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Green Landscaping: Greenacres


Wild Ones Handbook


"When we garden with native and naturalized wildflowers, we garden not only with Nature but also with history." -

Brooklyn Botanic Garden

Forest Cathedrals
by Pat Armstrong

Forests are old and wise; they evoke feelings of reverence. Their air hangs heavy with the misty incense of ancient conifers. Their spires filter light through lacy leaves, radiating celestial beams as through cathedral stained glass windows.

At the end of the Cretaceous period, some 75 million years ago, the cycads, conifers, ferns and other Jurassic plants and giant reptiles began to decline as mammals and Angiosperms (true flowering plants) began to rise. South America and Africa had begun separating from the supercontinent Pangea in the Cretaceous, but the tertiary forest still continued across North America and Euro-Asia as the Atlantic Ocean widened between them.

About 15,000 years ago all the trees in eastern North America were hunched-together refugees, pushed to the mountaintops of the southern Appalachians by glaciers. As the ice retreated, the huddled species began to spread. As they migrated back into the landscape, they sorted according to the soils and climates encountered.

Only a handful of Spruces, Firs, Larches, Aspens and Birches reached the arctic tundra in the boreal forest of Canada. Similarly, a few species of Junipers, Pines and Oaks moved southwest and west to the savannas, barrens and forest glades at the edge of the prairie. Even the richest deciduous forests of the Midwest contain only a few species of Beech, Maple, Tulip, Ash, Elm and Basswood instead of the over 600 species that made up the ancestral tertiary forest.

Trees and rainfall go together. We have tropical rain forests and temperate rain forests, cloud forests and fog forests, flood plain, flatwoods and swamp forests, mesic and mesophytic forests. These are our richest forests, and when the rainfall drops below 30 inches a year, the forests began to peter out into savannas and prairies.

Trees need water, save water, hold water. They protect and supply the watershed. They evaporate water to cool and humidify the air around them. Their leaves and branches intercept rain, making it last longer and fall more lightly upon the soil. Their size and clustering restrict the wind and its ability to desiccate. It is cool, dark, shady, humid, quiet, calm and fertile in a forest. Humus, leaf litter and duff pile up and are sifted, sorted, decomposed and recycled by fungi and invertebrates in their mysterious unseen ways.

Plants are arranged in horizontal layers. The tallest trees making the canopy top, younger trees and shorter species compose the understory below the canopy. Still younger trees, saplings and tall shrubs make up the next layer. Then there are small shrubs, seedling trees and the herbaceous plants on the forest floor, and finally the humus and duff layer on top of the soil with all its roots, microrhizae and organisms.

Light is the controlling factor. Plants must adapt to its transient supply. Blooming and leafing out in spring progresses from the ground up. Flowers bloom first, using stored energy in their bulbs, before the shrubs, understory and canopy leaf out and eclipse the sun. Shrubs and trees often bloom before their leaves emerge and owe their survival to wind-pollinated flowers that produce seeds with wings that act like propellers for dispersing through the relatively open branches.

In the summer, deep shade envelops the forest floor and only the largest of leaves, held horizontally to catch as much light as possible, can survive. Spring ephemerals disappear until next year. The many sizes, shapes, textures and shades of green of the leaves become a pleasing tapestry in groundcover layers. Bloodroot, Mayapple, Sarsaparilla, Wild Ginger, Bedstraw, Trillium, Solomon's Seal and Plume, with ferns and mosses, enchant all summer.

By the end of August leaves are tattered and shriveled. Their colors flame in October as they die and fall to the forest floor to be recycled. More light encourages asters, goldenrods and other flowers to burst into bloom. Fleshy fruits and berries, acorns, nuts, and seeds with forks, prongs, stickers and burs entice birds, mammals, and insects to eat them, store them or carry them away to propagate somewhere else.

In winter, the forest rests, lifting bare limbs to the sky or sloughing off snow mounds from bouncy evergreen branches. Nests, galls, footprints disclose the identities of its inhabitants. There is some evidence that the fall of great civilizations like Greece and Rome is linked to the destruction of their forests. When the trees are cut and the water is gone, we, too, perish. 



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