Trees prepare for their annual fashion show
Factors influencing fall leaf color
Article by Dr. Wayne Clatterbuck, UT Department of Forestry,
Wildlife and Fisheries, and Dr. Kevin Hoyt, UT Forest Resources AgResearch and Education Center
Posted by Sheldon Barker
 |
| The outstanding fall color is wonderful to behold from a bench along a trail at
the UT Arboretum. Photo by R. Evans, courtesy UTIA. |
New York, Paris and Milan all have their fashion weeks
scheduled to the minute months in advance, but the annual fashion week for
Tennessee forests can be much less predictable.
Everyone wants to know when will be the best time to view
autumn’s big show, but leaf color predictions can be quite tricky says Wayne
Clatterbuck, professor of forest management in the Department of Forestry,
Wildlife and Fisheries with the University of Tennessee Institute of
Agriculture.
“Environmental factors that influence leaf color are hard to
predict, so just when the the colors will peak is an annual mystery,”
Clatterbuck said. “Most of the factors that influence leaf color are related to
weather conditions prior to and during the leaf color change. Specific weather
conditions are difficult to forecast in advance.”
But certain fall characteristics can be counted on,
Clatterbuck admits. “Changing leaf color is triggered by the shorter days of
sunlight - called the photoperiod - which is constant from year to year, then
influenced by temperature and moisture,” he said. In general, Clatterbuck
says these weather conditions generally yield specific results:
-
Warm, dry weather with extended droughts or moisture deficits
Fall color that is not as vibrant, is short lived (a week or so) and the
timing can be delayed a week or more.
-
Cool nights and warm days
Cool nights with temperatures in the 40s and low 50s (but not freezing)
with daytime highs in the 60s and 70s tend to retain leaf color longer, and the
colors are more pronounced, especially if the days are sunny.
- Sunny days vs. overcast days
Sunny days create more vibrant leaf color. Several rainy or
overcast days in a row when leaves are turning color will cause them to be more
dull.
A little rain will yield a longer period of leaf color.
- Freezing overnight temperatures and early frost
Flashy forest fashion will quickly fade. Leaves will turn brown and die.
The color of leaves changes first at the higher elevations where it is cooler,
then progresses to the valleys at the lower elevations. Color in the mountains
of East Tennessee usually begins during the second week of October and advances
to the valleys and the Coastal Plain of West Tennessee by the end of October.
It can even last into the first two weeks of November. Thus, leaf color can
peak at various dates depending on your location in the state or region.
Are you looking for some more information on how to identify the trees
by their leaves? Check out the simple online guide provided by the UT Forest
Resources AgResearch and Education Center and Arboretum in Oak Ridge:
http://forestry.tennessee.edu/treeidleafsimple.htm
The UT Forest Resources AgResearch and Education Center is
celebrating its 50
th year of service. If you want to check out the
facility and fall color for yourself, visit UT Arboretum. There are walking
trails that can be combined for hikes of various lengths. Most are very family
friendly and interpretive signs describe points of interest along the way.
There is no admission fee. Visit the Arboretum’s website for details:
http://forestry.tennessee.edu/arboretum.htm
The UT Institute of Agriculture provides teaching, research
and outreach through the colleges of Agricultural Sciences and Natural
Resources and Veterinary Medicine; UT AgResearch, including its system of 10
research and education centers; and UT Extension with offices in every
Tennessee county.
The Sequatchie
County 4-H Forestry Judging Teams recently competed at the Central Region
contest held at the Cedars of Lebanon State Park. Three teams and two individuals competed from
Sequatchie County. The senior team of Bailey Scott, Donnie Briggs, Deston Hobbs
and Zach Scott won the regional contest and will be advancing to the State
contest to be held October 18 in Knoxville. Senior individuals competing at the
regional contest were Isaac Lloyd and Faith Merryfield. The Junior High Team of
Taylor Scott, Shelley Griffith, Josh Griffith and Eli Hale was first overall in
their division. The Junior team of Casey Scott, Gideon Lloyd and Daniel Scott
placed second overall.