American Sycamore

Plantanus Occidentalis

                                                        

By:  Timothy Pritchard

 

The Eastern half of the North American continent is blessed with the gift of ancient fertile soils.  Before European settlement, the majority of this land was covered with lush forest bearing a wealth of biodiversity and impressively aged trees.  Much of this area has been disturbed over the development of today’s American society, although between the cities, sprawl, and industrial zones there are still hills and mountains adorned with the deep roots of temperate broadleaf and mixed forest.   Such joy and peace can be found roaming through these hills and walking their streams while taking refuge under the shade of the trees that have taken root upon them.  One of the most identifiable species that decorates paths as these is the American Sycamore, Platanus occidentalis. 

 

  

 

Figure 1:  The mottled trunk of a mature American Sycamore (Platanus occidentalis).

http://www.britannica.com/eb/art/print?id=7657

 

            This water loving tree is one of the many common species of large Angiosperms that grace the eastern half of the United States where it native.  They can be found along lakesides, flood plains, river banks, and smaller streams.  These trees are readily identified by their bark which is distinctly light colored and mottled in tone.  That of mature individuals begins to peel off of the trunk, and acquires a tattered look making the trees appear increasingly defined.  The deciduous Sycamore leaves are alternate, simple, and palmately 3-7 lobed; residing upon the lateral buds of zigzag twigs.  Flowers appear with leaves as minute separate heads, and are either staminate or pistillate with 3-8 sepals and petals (Harlow 1979).   While these flowers may be difficult to identify, the fruit of this tree is much more conspicuous, growing as one inch spherical structures hanging from an elongated stalk.  The fruit matures in early autumn, and is composed of many nutlets and tufts of brown hair (Little 2000). 

 

Figure 2:  A nearly matured fruit of the American Sycamore with brown hair structures visible http://www.dof.virginia.gov/trees/images/sycamore-fruit.jpg

 

 

 

After maturation, the fruits fall from the tree and are dispersed by means of a nearby waterway, weather, small birds or animals to distribute them.  The seeds germinate once favorable conditions are met by direct sunlight, relatively loose soil, and plentiful water. Seedlings may grow at a rapid pace once they have been established, and sprouts may reach up to 25 feet of growth within the first year of development.  The American Sycamore is known for its rapid growth rate among hardwoods, and for its exceptional expansion in diameter relative to vertical growth.  Flowering generally begins to occur at six to seven years, and optimum numbers of seeds are produced between the ages of 50 and 200 (Nesom 2002).  Though this age range may represent the species’ most productive time, some individuals have life spans between 500 and 600 years, and may attain a height of over 100 feet.  Diameter is most often between three and eight feet, but measurements have been recorded up to 14 feet (Harlow 1979).

 

 

 

 

 

Figure 3:  The simple, lobed structure of the American Sycamore leaf. http://www.aces.edu/forestry/images/dendrology/american_sycamore.jpg

 

For backpackers of the forest and wanderers of the woodland, the presence of Sycamore almost always indicates a nearby water source, and makes for easy navigation along a stream.  The habitat of the American Sycamore is not limited to waterways, however these trees generally only flourish in areas where soil is saturated an average of 2-4 months out of each year.  They have a remarkable ability to withstand flooding for weeks at a time.  In the instance of a young sapling taken by flooding during the prime weeks of the growing season, intact roots will almost always give rise to resilient growth once conditions are favorable (Nesom 2002).   

 

As with many species of vascular plants, the American Sycamore has a close association with mycorrhizal fungi, which explains their ability to grow quickly and develop into massive individuals.  Above ground, they interact with their ecosystems by providing habitat for small forest animals, and significantly contributing to the canopies of their respective forests.  The trunks of older trees often rot and become hollow making ideal nesting structures for squirrels, chimney swifts, and many other species.  Humans utilize the hardwood of Sycamores in production of furniture parts, paneling, paper, and especially in the manufacturing of butchers block (Samuelson 2003).  These common giants of the eastern forests are staples of the landscape, and an intricate part of what makes the Midwest and coastal areas of the country an important place to enjoy life and sustain natural beauty.

                  

 Figure 4:  Nativity of American Sycamore

www.plants.usda.gov

 

 

 

 

 

 

Figure 5: American Sycamore Distribution

www.plants.usda.gov

 

 

Eastern Broadleaf and Mixed Temperate Forest

 

            The forests of the eastern half of the United States have a wonderful ability to create new imagery for every season.  Life in this expansive area appears drastically different throughout the year and provides a constant spectacle.  Summers are a time when the lush canopies display their foliage in full form.  Hills and mountains become gigantic heads of broccoli that hold a wealth of bustling life within.  Fall comes and everything is afire until the leaves are snuffed by winter’s approaching chill, leaving the landscape naked and at rest.  Spring reveals new growth upon the branches, and the understory can be seen bearing fresh flowers to host the stirring wildlife in its first glorious bask in the sun.  These events are shared worldwide within the temperate zones of Earth.  While each region has its own unique set of native flora, a common mythology of the land abides.

The American Sycamore (Platanus occidentalis), is one of the many large broad leaf tree species that inhabit the Eastern North American broadleaf and mixed temperate forests.  These forests occupy a very substantial part of the continent’s natural or reserved area, and harbor enormous biodiversity.  In broadleaf dominated areas, forests are mostly deciduous, but coniferous and deciduous stands are often intermingled yielding mixed temperate forest.  Sycamore stands may be nearly exclusive, especially along stream banks where they thrive, but are often found to be associated with various other broad-leaved species.  Maple, Oak, Ash, and Beech are among the taxa commonly found in mixed forests alongside Sycamore (Allaby 1999). 

 

In a technical sense, a forest is defined as an area that is at least 60 percent covered by the tree canopy.  If the forest is over 80 percent deciduous, then it is considered to be a deciduous forest, although there may be a small percentage of coniferous trees or other species.  In a mixed forest, though there is generally a dominant tree type, the lesser must comprise at least 20 percent.  Broad-leaved trees generally require at least 120 days per year of temperatures exceeding 50º F, but coniferous trees need only around 30 days a year above this temperature mark (Allaby 1999).  Given this, the northern most forests of the world are typically dominated by conifers, and broadleaf dominated forests usually lie in the lower latitudes of the temperate zone.   In either case, large amounts of water and soil nutrient are required to sustain forests of massive trees.  The eastern half of the United States is ideal land for this type of flora because of the existing geological features, including the Appalachian mountain belt.  These mountains are incredibly old, and have undergone the processes of weathering for millions of years.  Many parts of this region were also glaciated during the last ice age and river valleys are etched into the landscape.  The occurrence of weathering and erosion have created remarkably fertile land throughout this part of the country, and given rise to abundant forests.

 

These forests are habitat to a vast number of mammals, amphibians, reptiles, birds, and insects.  The broadleaf trees in particular are essential for bird nesting, and shelter for squirrels and other small creatures that inhabit their structures.  Migratory birds depend on such forests during their continental journeys, and large mammals such as deer, raccoons and wild boar reside in them.  The understory and forest floor also contain a rich array flora.  Spring yields a multitude of wildflowers, mosses and ferns flourishing beneath the canopy, and various shrubs and shade plants are resident as well.

 

Natural disturbance is relatively rare in the Eastern temperate forests.  The climate is moist enough that lightning induced fires are extremely scarce.  Flooding is an issue in river valleys or upon areas of dense clay soil, but most floods do not have the capacity to inflict permanent damage beyond the rotting of older trees.  Severe weather conditions such as tornadoes can cause considerable damage, especially in flattened areas throughout the Midwest.  Snow and ice accumulation may build up excessive weight and bring down limbs or damage the crowns of even the most colossal trees.  Drought is perhaps the most overall threatening force, and influence can be seen in extreme cases where entire forests begin to lose their foliage, and certain species fail to grow.  Despite the occasional natural disturbance factors, areas of older growth tend to remain very vital and develop reach seed banks and nutrient rich soils.  This is perhaps indicative of the most pervasive threat facing these forests today.

 

The fertile soils of the eastern deciduous forest have produced several commodities that are in high societal demand.  Large scale farming has created a necessity for large areas of fertile land, and the Eastern temperate forests have provided this in a geographically convenient location relative to trade.  Paper and wood products have also been over-harvested, first from the ideally flat farming areas, and since throughout the hills.  The ubiquitous coal mines of Appalachia were discovered after European settlement, and tapped of their most accessible resources.  More recent technologies have allowed miners to strip substantial areas of land and rock in order to reach the more elusive coal beds.  Not only does the utilization of coal begin with mass destruction to natural forest ecosystems and geologic features, but then results in acid precipitation which serves to further degrade the existing habitat.  The consumptive behavior of human beings has truly rendered these forests into a state of vulnerability. 

 

Global climate change is an issue with a direct correlation to the destruction of temperate forests.  Forests serve as a means to recycle carbon.  A certain amount of atmospheric carbon is taken in at considerable quantities by trees, and replaced with oxygen.  Carbon is stored in the soil, but is released with disruption, so deforestation increases atmospheric carbon levels by exponential numbers (Brown 1999).  Climate change has been attributed to the disruption of the carbon cycle, and is likely accredited with the certain natural disasters that these forests are faced with.

 

It is quite clear that the natural state of these forests must be restored.  Old growth forests are loosely defined as those existing with little to no disturbance by Euro-American settlers.  While it is estimated that these Eastern old growth forests originally covered somewhere near 950 million acres, they only exist in small patches across the landscape of which they once covered (Davis 1996).  Restoring these ecosystems requires much more than the reestablishment of tree growth.  When such forests are removed, they take with them thousands of years worth of seed banking, a multitude of conspicuous and inconspicuous wildlife, and their relationship to the lesser flora of with which the trees coexisted.

 

Fortunately, in the wake of environment awareness rising, the absolute value of forests is gaining recognition.  The 1997 Kyoto protocol recognized the presence of well established forests as a key component of reducing atmospheric carbon.  Efforts are being made regionally to restore areas of old growth and retain those that remain undisturbed.  It will take these measures, along the education of the masses in regards to sustainable, less consumptive living, to reaffirm the temperate broadleaf and mixed forests as the defining attributes of the eastern United States.              

 

 

 

 

 

 

 

 

Works Cited:

Allaby M. 1999. Ecosystem:  Temperate Forests. Facts on File, Inc. New York, New York.

 

 

Little E.L. 2000. National Audubon Society Field Guide to Trees: Eastern Region. Alfred A. Knopf Inc.  New York, New York.

 

Nesom, G. 2002.  USDA NRCS Plant Guide: American Sycamore Platanus occidentalis L.http://plants.usda.gov/plantguide/pdf/cs_ploc.pdf

 

Samuelson L.J., Hogan M.E. 2003. Forest Trees:  A Guide to the Southeastern and Mid-Atlantic Regions of the United States. Prentice Hall.  Upper Saddle River, New Jersey. 

 

Brown S.L., Shroeder P., Kern J.S., 1999. Spatial distribution of biomass in forests of the eastern USA. Forest Ecology Management 123, pp 81-90.

Davis M.B. 1996. Eastern Old-Growth Forests:  Prospects for Rediscovery and Recovery.  Island Press, Washington, DC.

 

Harlow W.M., Harrar E.S., White F.M. 1979. Textbook of Dendrology:  Covering the Important Trees of the United States and Canada. Sixth Ed.  McGraw-Hill New York, New York.