Some Successional Trees

     Certain kinds of trees in eastern Pennsylvania, including staghorn sumacs, sassafras, red junipers, large-toothed aspens and gray birches, pioneer denuded land after burning, timbering, farming or mining and then abandoned.  All native to North America, these interesting, successional trees help hold down soil against erosion, benefit wildlife and have certain beauties the year around, while building up nutrients in the abused soil from their decaying fallen leaves, bark and wood over several years.  Eventually, successional trees will be replaced by more demanding ones that will permanently inhabit land that was degraded, but enriched by successional trees.
     Successional trees need much sunlight, which they get on denuded soil.  But these trees can't tolerate being shaded, so they gradually die out when shade-tolerant trees replace them and live permanently on what-had-been bare ground.      
     Sumac limbs are forked like antlers on buck deer.  This small tree has compound leaves, each leaf having several leaflets that turn red in autumn and flutter like banners in the wind, adding beauty to degraded landscapes.  Female sumacs grow cone-shaped clusters of red, fuzzy berries that help beautify abused landscapes.  Many of those striking berries are eaten by rodents and berry-eating birds, including starlings, American robins, cedar waxwings and other species. 
     Sassafras trees have three leaf shapes on each tree.  One leaf shape is a simple oval.  Another one is shaped like a mitten and the third has three chubby prongs, like a fork.  In fall, sassafras foliage turns to red, orange or yellow. 
     Sassafras trees also have deep-purple berries in autumn that are eaten by a variety of seed-eating birds, rodents, raccoons and other kinds of mammals.  The birds digest the pulp of the berries, but pass sassafras seeds in their droppings wherever they happen to perch.  Sassafras grows abundantly along rural roadsides because of birds perched on electric lines along those roads.  
     Spicebush swallowtail butterfly caterpillars consume the foliage of spicebushes and sassafras trees.  Each larvae spins webbing to wrap a leaf around itself so it can eat in relative safety.  These caterpillars are green to blend into the leaves' color if those leaves are opened by birds or other predators.  Furthermore, each larva has two black spots on its forward "back" that resemble eyes, which frighten away would-be predators.    
     Red junipers are a kind of conifer, with green needles on them the year around.  This pillar-shaped tree is mistakenly called red cedar, but it is in the juniper genus.
     Red junipers produce tiny, fleshy cones that are pale-blue.  Multitudes of those berry-like cones are decorative on the green junipers in winter.  And they are eaten by deer, rodents and berry-eating birds through fall and winter.  Cedar waxwings get their name, in part, from eating juniper cones.
     Saw-whet owls roost during winter days in red junipers.  And dark-eyed juncos, mourning doves and other kinds of birds roost overnight in them during winter.
     House finches, American goldfinches, chipping sparrows and field sparrows nest in junipers in summer.  Obviously, the attractive junipers are valuable to wildlife.  
     Large-toothed aspens have leaves that quiver noticeably in the wind, and have toothed margins.  That foliage turns yellow in autumn.  But aspens' long, hanging catkins, swaying in the spring wind, are the trees' most beautiful features. 
     Beavers commonly chew down these trees to eat their leaves, twigs and bark, and use the woody trunks and branches to build their dams and lodges.  Deer, hares and mice consume aspen buds, twigs and bark on still-standing trees in winter.  
     Gray birches are particularly noted for pioneering deserted strip mines and slag piles in coal regions in eastern Pennsylvania.  This birch has "dirty-white" bark and dark triangles below where the limbs emerge from the trunks.  And like aspens, this birch species has yellow foliage in fall, attractive catkins in spring, and buds, twigs and bark that are consumed by beavers, mice and deer.  Beavers also use birch branches and trunks to build dams and lodges.  And the tiny, winged seeds of birches are ingested by small, seed-eating birds through fall and winter.
     Look for these successional trees in successional landscapes any time of year.  They build up soil, feed and shelter wildlife and provide us with beauty where, otherwise, it may not be.