Germinating Acorn — Plants as an Important Link
Plants serve as one of the essential links in nearly all ecosystems. Plants provide food, shelter, and breathable air that link all living things by being the “root” of nearly all food chains.
Although very few (around 1%) of the acorns produced by a single oak actually grow to become mature trees, acorns serve more than one singular purpose. Relatively high in carbohydrates, fallen acorns are abundant on the ground in autumn and winter when other plant food sources are not available or easily accessible. Mammals that feed on acorns include white-tailed deer, gray squirrels, fox squirrels, flying squirrels, mice, voles, rabbits, raccoons, opossums, gray foxes, red foxes, bears, wild hogs, and more. Birds, including endangered scrub jays, blue jays, wild turkey, bobwhite quail, wood ducks, mallard ducks, woodpeckers, and crows also feast upon acorns. Fallen oak leaves shelter the many small mammals, reptiles, and amphibians that live in the leaf litter that accumulate beneath oaks. Raking and removing oak leaves can even diminish this habitat because it breaks up the cycle where decomposed leaves fortify the soil and re-nourish the tree.
Many birds conceal their nests from predators in the dense foliage of oak trees and even use oak foliage in nest construction. The jay (Garrulus glandarius) is particularly important as a dispersal agent for acorns, as it will transport them up to a kilometer away from the tree and bury them in the ground. The jay doesn't recover all the acorns it stores this way, so some survive to germinate and grow into new trees.
Birds also depend on insects for nourishment, and take advantage of the large numbers of invertebrates found in oaks. Many organisms have evolved with the oak to produce the abnormal growths that are known as galls. Over 40 species, including midges, mites and wasps, are responsible for stimulating the oak, by means which are not fully understood, to produce unusual growth forms on its leaves or twigs, within which the larva of the insect lives and feeds. Some galls, such as the oak apple, which is caused by a wasp (Biorhiza pallida), support complex communities of insects that consist of parasites, predators and inquilines (insects which exhibit cuckoo-like behavior).
Large numbers of insects feed on oak leaves, and several species of moth larvae feed only upon oak leaves. Moth cocoons disappear easily among decomposing leaf litter, and the caterpillars are quite well camouflaged in shades of green to reduce the risk of predation by birds as they crawl into the tree and feast on living leaves. Moth species common to oaks include the oak hook-tip moth (Drepana binaria), the winter moth (Operophtera brunata) and micro-moths such as Phyllonorycter quercifoliella, whose larvae produce mines in the leaves.
Many species of butterflies are found in oak woods, including the speckled wood (Pararge aegeria) and the pearl-bordered fritillary (Boloria euphrosyne). The purple hairstreak (Quercusia quercus) is the only butterfly whose larvae feed exclusively on the oak.
Numerous beetles are also associated with oak trees, including the oak bark beetle (Scolytus intricatus), whose larvae create a distinctive pattern in the tree's wood. Several nut weevils lay their eggs in acorns during early summer, and the larvae feed inside the acorns, pupating after they have fallen to the ground.
Given the abundance of insects that live on oaks, it is not unusual to find a number of spiders on the trees as well. Some species spin webs amongst the leaves, while others, like the crab spider, rely on camouflage to ambush their prey.
For an introductory video on how to germinate an acorn, visit: http://www.ehow.com/video_2329375_grow-germinating-oak-acorns.html
For information about planting oak trees, go to: http://www.wildbirds.org/oaks/oaks.htm
