The Sustainability of Ohio’s
By Dan Balser and Richard Widmann - July 2009
This report presents an analysis based on data gathered in Ohio by the Forest
Inventory & Analysis (FIA) program.
FIA is a national program of the Forest Service, U.S Department of
Agriculture, which conducts and maintains comprehensive inventories of the
forest resources in the United
FIA data collected since 1991 indicates that net growth has been twice
that of removals with the net change amounting to an annual increase of 1.4
percent in inventory volume. This
implies that the current level of removals is sustainable and that increases in
timber volumes will continue. Forest
sustainability in Ohio
is addressed by looking at trends in growing-stock volume and measures of
annual growth, removals and mortality.
It is recognized that sustainability is a complex issue that takes in
ecological, social, and economic processes occurring over multiple geographic
and temporal scales and at times is defined more by what is not sustainable
rather than what is. "Forest
ecosystems are not sustainable if volume or biomass losses exceed growth over
large areas or long time periods” (Shifley 2007). Assessing sustainability in terms of wood
production and consumption and changes in total volume at the state level are
broad measures, but ones that should not be overlooked. "The concept of large-scale, long-term,
non-declining volume is clear, measurable, and deeply rooted in our
conservation ethic” (Shifley 2007). The
broad scale data and analysis presented in this report should not be used to draw
conclusions on how individual owners manage their particular holdings.
The FIA Program collects, analyzes, and reports information
on the status and trends of America’s
forests. The first inventory in Ohio was implemented in
1951 (Hutchison 1956). Subsequent
periodic inventories were completed in 1968, (Kingsley and Mayer 1970), 1979
(Dennis and Birch 1981), and 1991(Griffith et al 1993). Beginning in 2000, Ohio’s forests have been inventoried
annually (Widmann and others in press).
In the annualized inventory, about 20 percent of the plots in the state
are measured every year and each plot is revisited every 5 years. This annual inventory system allows for
coverage every year and a 5-year reporting cycle. FIA maintains databases and makes tools
available to access data through the Internet.
Data from Ohio’s
recent inventories may be accessed through the Forest Inventory Data Online
(FIDO) program at: http://fia.fs.fed.us/tools-data/,
or the FIA Mapmaker program at: http://www.fia.fs.fed.us/tools-data/other/default.asp. FIA statistical procedures have been
scientifically reviewed and data meet specific quality standards (Bechtold and
Patterson 2005). To learn more about the
FIA program visit: http://www.fia.fs.fed.us.
In 2006, Ohio’s
forest land area (including reserved and low-productivity land) totaled over
7.9 million acres (Fig. 1). Increases in
forest land area have occurred over the last 50 years because of afforestation
of agricultural land; although, since 1991, the forest land base has not
significantly changed. Trends in
timberland area (excludes reserved and low-productivity land) have closely
followed those for forest land.
forests are primarily occupied by hardwood species. The oak-hickory forest types comprise 54
percent of the forest land and maple-beech-birch types comprise 31
percent. These forests have been
maturing as indicated by the continued increase in area of large diameter
stands. In 2006, nearly two thirds of
the timberland was occupied with sawtimber size stands while 13 percent was in
either seedling, sapling or a non-stocked condition. The predominance of sawtimber-size stands is
not unusual for hardwood forests managed primarily with selection harvesting
methods, as is common in Ohio.
Private landowners hold approximately 88 percent of the
forest land with the remainder belonging to public agencies. Of the nearly 7 million acres of forest land
in private ownership, 84 percent is owned by families and individuals.
Figure 1: Area of
forest land and timberland, Ohio,
by inventory year. Error bars represent
67-percent confidence intervals.
Ninety-two percent of the sound
wood volume in live trees is contained in growing-stock trees. These are commercially important species with
good form and are at least 5 inches in diameter at breast height. Rough and rotten trees account for 7 and 1
percent, respectively. The total volume
of growing stock on Ohio’s
timberland has steadily increased since 1952 (Fig. 2). The 2006 estimate of 12.3 billion cubic feet
is 22 percent greater than in 1991 and averages 1603 cubic feet per acre. Most of the gains in volume were in trees
large enough to produce sawlogs (11.0-inches d.b.h. and greater for hardwood
species). The portion
of volume large enough to produce sawlogs, increased by 35 percent to 41
billion board feet (Fig. 3), and now averages 5,338 board feet per acre, more
than double the sawlog volumes recorded in 1979. Continuous increases in volume have brought Ohio’s timber resource
to record levels in both total volume and volumes per acre.
Yellow-poplar is the leading species by volume, accounting
for 12.2 percent of total board-foot volume followed by white oak and
hickory. Together the oaks represent
26.7 percent of total board-foot volume and maples 15.3 percent. Ninety-six percent of Ohio’s sawtimber volume is in hardwood
volume of crop trees 5 inches DBH and greater on timberland by inventory year, Ohio, 1952, 1968, 1979,
1991, and 2006. Error bars represent
67-percent confidence intervals.
Figure 3.--Board foot
volume of crop trees 11 inches DBH and greater
on timberland by inventory year, Ohio,
1952, 1968, 1979, 1991, and 2006. Error
bars represent 67-percent confidence intervals.
Annual Growth, Removals, and Mortality
During the last 50 years in Ohio, the growth of trees has greatly
outpaced mortality and removals. The
most recent inventory revealed that since 1991, on an annual basis, the gross
growth totaled 419 million cubic feet (Fig. 4).
Eighty-one percent of this growth was accretion (growth on trees that
were at least 5 inches in diameter at the time of the previous inventory) and
19 percent was ingrowth (trees that were less than 5 inches and grew to at
least 5-inches in diameter). Annual
mortality averaged 99 million cubic feet resulting in a net growth of 320
million cubic feet. Removals include
trees harvested from land that remains in timberland, trees on timberland that
have been reclassified to reserved forest land, and trees lost because the
forest was converted to a non-forest use.
Removals of trees due to harvesting and land use change averaged 160
million cubic feet, leaving an annual surplus or net change of 160 million
cubic feet. About two-thirds of the
removals were due to the harvesting of trees, with the remainder was due to
changes in land use. As a percentage of
the inventory, gross growth was 3.8 %, mortality was 0.9 %, net growth was 2.9 %, removals was
1.4%, and net change was 1.4 %.
The net change of 160 million cubic feet was nearly the same
as during the 1980-91 inventory period, though all the components were higher
(Fig. 5). Higher growth was offset by
higher mortality and removals.
The ratio of growth-to-removals (G/R) averaged 2.0:1 for the
period 1992-2006, but varied considerably between major ownership groups and
species. On publicly owned timberland
G/R averaged 2.6:1 while on all privately owned timberland G/R averaged
2.0:1. Of the major species growing in Ohio, red maple, sugar
maple and yellow-poplar have the highest ratios of growth to removals, 4.1,
2.8, and 2.6:1 respectively.
Figure 4.--Average annual components of change in growing-stock volume.
Figure 5.--Average annual net growth and removals of growing-stock
volume on timberland by inventory period
Today’s well-stocked forests are a result of net growth
consistently outpacing removals during the last half century and the surplus
accumulating in the forest. Increases in
volume have occurred while these same forests have supplied a steady stream of
wood to Ohio’s
forest products industry. Since 1991, net
growth has been twice that of removals with the net change amounting to an
annual increase of 1.4 percent in inventory volume. This implies that the current level of
removals is sustainable and that increases in timber volumes will
continue. This is true since nearly
two-thirds of removals are due to harvesting, and trees regenerate and thrive
after harvesting so long as the land remains in forest. The small portion of removals due to
timberland being reclassified to reserved forest land will continue to provide
benefits other than timber products.
However, the nearly one-third of removals due to conversion of
timberland to non-forest uses threatens sustainability because such changes are
usually permanent. As a result, future
timber growth from these lands is lost, as are related benefits, like the
recharge of groundwater aquifers and conservation of forest habitats.
Commercial timber harvests can be used as a tool in maintaining
ecologically sustainable conditions and retaining working forests. The economic returns from harvests provide an
incentive to private owners to maintain land in forest and practice sustainable
management. Continuous monitoring of Ohio’s forests by FIA
provides current assessments of forest conditions and will alert those
concerned to changes in the current balance between growth and removals.
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forested ecosystems to achieve multiresource benefits: proceedings of the 2007
national silviculture workshop; 2007 May 7-10; Ketchikan, AK.
Gen. Tech. Rep. PNW-733. Portland, OR: U.S.
Department of Agriculture, Forest Service, Pacific
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Widmann, Richard H.; Balser, Dan; and others. (in press) Ohio’s forests
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About the authors:
Dan Balser is a Forest Health Specialist with Ohio’s Department of Natural Resources-
Division of Forestry.
Richard H. Widmann is a Forester with the Forest Inventory and Analysis
work unit at the Northern Research Station, Forest Service, U.S. Department of
For additional information, contact:
Forest Health Specialist
Ohio Department of Natural Resources
Division of Forestry
2045 Morse Road, Bldg H-1
Columbus, OH 43229-6605
USDA Forest Service
Forest Inventory and Analysis
St. Paul, MN 55108