Natural Notes: How Trees Built America

This blog post consists of notes from a lecture on the cultural significance of certain trees in the early stages of the United States.  The slideshow lecture took place at Sand Ridge Nature Center in South Holland, Illinois on 13 January 2016.  The speaker was Michael Panygnot, a resource technician with the Forest Preserves of Cook County.  

Ship and Housing Construction

When pioneers established cities in the "New World", they often developed areas that were former Native American settlements.  Many early settlers were sponsored by companies to log and clear forests.  Pioneers were not generally good with axes and did not know how to properly nor safely fell trees.  It generally took pioneer families one year to clear land, built houses, and plant crops.  

Certain tree species served an important economic and cultural purpose to pioneers.  An important task for early colonial Americans was to build a fleet of navy ships to defend themselves against enemies.  American Chestnuts (Castanea dentata) and various oaks (Quercus spp.) were often used in the construction of hulls and decks.  Pitch Pine (Pinus rigida) were used to provide waterproofing materials for ships (turpentine).  Eastern White Pine (P. strobus) was also used to build ship masts, as pines were large trees during colonial times, with some measuring up to 230 feet in height.  The wood from white pine was also used heavily for building other structures like buildings, and this valuable wood was often used in place of currency.  

There were significant battle events in America's colonial history related to trees.  The Mast Tree Riot of 1734 was a revolt against the British claiming trees for use exclusively in their ship masts.  A similar revolt took place during the Pine Tree Riot of 1772 when a sheriff in charge of a mill and with interests in protecting the Royal Navy's trees was kidnapped.  

In summary, trees were important to early American colonists for ships, walls to build forts, and for construction of houses.  

Apples

Apples were introduced to American around 1620 by William Baxton.  There are currently about 2.500 varieties of apples in the United States.  Apples have high heterozygosity meaning each individual is very different from one another.  Therefore, they are easy to cultivate.  Apples are originally native to Western and Central China.  Apple cider used to refer to what we now call "hard cider" and "cider" today is really apple juice.  

Apples were important considerations for land acquisition.  George Washington required his tenants at Mount Vernon to plant 100 apple trees and 100 peach trees within three years.  The Ohio Company required the planting of 50 apple trees and 20 peach trees per 100 acres of land.  

Railroads and Costs of Colonial Expansion

Early rails were called strap rails.  They were made of pine timbers and some iron.  Strap rails were inexpensive to built but dangerous for passengers.  By 1850, 3-4 million cords of wood per year were used for fuel alone.  It peaked to 7 million cords per year by 1870.  Cords used for rail construction were harmful to passengers as forest fires often followed trains along their flammable tracks.

Later, cross ties were often made of white oaks or chestnuts.  They were routinely replaced every 10 years.  Around 60 million treed per year were felled to make these more modern cross ties, and often much of the wood went to waste.  Chestnuts were preferred since their wood was high in tannins and as such was fairly rot resistant.  Chestnut trees would attain of height of 115 feet with a diameter up to four feet.  The wood was also easy to split.  

Chestnut Blight and Attempts to Save American Chestnuts

In 1904, withering of Chestnut leaves were noted at the Bronx Zoo.  In 1906, the cause was determined to be a blight from a fungus.  In 1913, it was discovered that the Chestnut Blight fungus originated in China.  

Efforts to save the chestnut have been underway for some time.  The use of a hypervirus was been attempted, which was developed to utilize the blight fungus as a host.  To date this method has been unsuccessful.  Back-cross breeding has been performed using the blight-resistant Chinese Chestnut, C. mollissima.  Selective breeding of resistant American individuals discovered in many locations is also being attempted.  It should be noted that none of the aforementioned methods eliminate the blight but rather they ideally make the trees better handle the fungus infection.  

There are some American Chestnut Trees that have survived the blight until recent times.  The largest surviving stand was planted in the 1800s in West Salem, Wisconsin - well outside of the native range (which is primarily in the eastern United States) until 1987 when infection was detected.  Recently a large tree was discovered still standing in Vermont.  

Colonial Deforestation

The East Cost was mostly deforested by settlers by 1860.  The Great Lakes  prime forests met their fate between 1860 - 1870.  Less than 2.5% of prime growth forest per state in the Great Lakes remains.  Prime forests of the south were logged out by the 1920s, especially pine forests.  

Forest Recovery

The timber industry did not find reforestation to be economical until the 1940s.  Forest cover increased and then stabilized until the 1970s.  This was due to increased urbanization of America's human population as well as a shift from wood to coal and oil as energy sources.  Fire suppression and more efficient agricultural practices allowed many areas to recover forests.  

The Citrus Industry & Citrus Greening

In 1493 Columbus introduced oranges to North America.  Franciscan missionaries later brought them over to California.  Orange juice was marketed in 1910.  A major boom to the citrus industry occurred during the flue epidemic of 1918-20 when high amounts of Vitamin c were discovered in citrus fruits.   

Unforutently, citrus greening is becoming a problem in the United States.  Citrus Greening is a vector borne disease transmitted by the Asian citrus psyllid.  This insect transmits Candidatus Liberbacter bacteria, which causes the disease.  Citrus greening inhibits fruit development and cause leaf chlorosis, eventually killing the tree.  

Currently, there is no cure for citrus greening, but there are some treatment methods that might have potential.  These include pesticides, foliar fertilizers, reflective mulching, and antibiotics.  

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A canopy of oaks trees dominates the overstory of this recovering woodland area in Northern Illinois.