Friday, February 17, 2012

Life of a Hickory Tree Part 2

A yellow Hickory leaf.
Not only are hickory nuts sought out by wildlife, humans also have partook in the gathering of these nuts.  Though hickories were less common than oaks in Midwestern and Eastern wooded areas they still were an important food source for Native Americans.  Being oaks and hickories often grow right alongside each other I am sure hickory nuts were often gathered with acorns in the fall.  Both fall from trees at approximately the same time.  Even today hickory nuts are one of the most popular types of tree nuts eaten.  The pecan comes from a hickory tree closely related to the shagbark.  While many people claim that shagbarks produce a nut that tastes superior to the pecan, the shagbark unfortunately is an inconsistent producer.  Pecans are produced consistently year after year while shagbark nuts are produced in an abundance only every few years or so.  Being farmers don’t like to wait a few years to obtain a harvest, the pecan quickly dominated agriculturally.  So the next time you eat pecan pie or pralines remember the hickory they grew on.  Other hickory trees also produce nuts however, none of them taste anywhere near as good as the pecan or shagbark.  The pignut and bitternut hickories produce nuts that taste about as good as their names sound.  I have tasted some before and couldn’t tolerate the taste for more than a few seconds. 
Hickory nuts.
Ideally, the lost hickory nut will find itself in a disturbed location such as along a forest edge, a recently burned area or in a forest clearing where larger canopy trees have recently fallen or been logged.  While hickories do tolerate some shade, they prefer lots of sun, so recently disturbed areas are preferred.  Typically, oaks will invade an area before hickories do but, if an area has a lower level of disturbance, frequently hickories will closely follow the oaks in becoming established.  The Shagbark Hickory is the most common type of hickory of the oak-hickory forest.  While this hickory is tolerant of most soil types it does not do well in wet soils and prefers the drier soils.  So ideally the nut will be cached in mesic to dry soil.  Once here, the seed must be exposed to cold winter temperatures before it will germinate.  After exposure to winter cold however, soil moistened by melting snow and warmer temperatures cause the seed to rapidly germinate.  Immediately at germination, the seed puts all of its energy into developing a thick strong taproot.  This taproot can be several inches long before any green shoots sprout above ground.  But once green sprouts do appear, light harvested through photosynthesis is rapidly converted into energy to grow this taproot.  Over the lifespan of this tree, this taproot will be the primary root from which smaller roots venturing outward.  As a result, hickories are considered one of the sturdiest trees of the forest.  The hickories, life philosophy, at least for the first several years, is root before shoot; this is similar to the oak.  This results in an extremely slow growing tree and often other trees out-compete hickories by shading them out.  Amazingly, even slow growing oak trees outpace the hickory.  But slow growth emphasizing a strong taproot builds a well established, durable tree with high quality wood.  Within the prairie to forest transition, wind and drought are common problems that must be overcome for survival.  The great strength hickories gain from deep root to high limbs allows them to survive strong winds with firm anchoring, strong stature, and deep probing in search of hidden soil moisture.
Even though hickories are not well adapted to brush or grass fires like this one, young hickories still can sprout back after the fire.
Establishing a strong taproot not only overcomes drought and wind, it overcomes another factor common to the prairie to forest transition: fire.  Fires are most common in fall and spring.  In the fall, low intensity ground fires can disturb an area, clearing competing vegetation, and making it an ideal location for a hickory seedling to establish itself.  In spring, fire can be much more dangerous to hickory sprouts by killing them.  Hickory seedlings are also targets for grazing animals such as the white tail deer.  However, if a hickory sprout or seedling is killed by fire or eaten, the well established root can rapidly resprout.  Once resprouted after fire, competing vegetation has been burned away, and the young hickory can rapidly grow without competition.  This ability to resprout maintains itself until the tree is 20 or so years old.  At this point, fire will more likely kill the tree and the root will not be able to resprout.  Hickories do not have the thick fire-resistant bark upland oaks do.  Their bark is rather thin and is easily damaged by fire, so hickories can only establish themselves in woodland areas that are burned less frequently.  While oaks can survive ground fires about every two to ten years, hickory forests can only survive low intensity fires every twenty or more years.  For this reason, hickories are commonly found in slightly moister areas that have lower fire frequencies. 

No comments:

Post a Comment