Common Definitions Used by the FIA
Idle farmland: Former cropland or pasture
that has not been tended for within the last 2 years and has less
than 10 percent stocking with live trees (established seedlings
or larger trees), regardless of species.
Improved/maintained pasture: Land that
is currently used and maintained for grazing (not including grazed
- Lands held in trust by the United States or States, for Indian
tribes or individual Indians.
- Lands owned in fee by Indian tribes whether subject to Federal
or State restrictions against alienation or not.
Industrial and commercial land: Supply
yards, parking lots, factories, etc.
Ingrowth: The estimated net volume
of growing-stock trees that became 5.0 inches d.b.h. or larger during
the period between inventories . Also, the estimated net volume
of growing-stock trees 5.0 inches d.b.h. and larger that are growing
on land that was reclassified from noncommercial forest land or
nonforest land to timberland.
International 1/4-inch rule: A log
rule or formula for estimating the board-foot volume of logs. The
mathematical formula is: (0.22D2 - 0.71D)(0.904762) for 4-foot sections,
where D=diameter inside bark at the small end of the log section.
This rule is used as the USDA Forest Service standard log rule in
the Eastern United States.
- Bureau of Census: The area of dry land and land temporarily
or partly covered by water, such as marshes, swamps, and river
flood plains; streams, sloughs, estuaries, and canals less than
200 feet wide; and lakes, reservoirs, and ponds less than 4.5
acres in area.
- Forest Inventory and Analysis: same as Bureau of Census except
that the minimum width of streams, etc. is 120 feet, and the minimum
size of lakes, etc. is 1 acre.
Merchantable stem: The main stem of
the tree between a 1-foot stump height and a 4-inch top diameter
(outside the bark), including the wood and bark.
Mining and waste land: Surface mining,
gravel pits, dumps.
Miscellaneous private lands: Privately
owned lands other than forest industry and farmer-owned lands.
Mortality: The estimated net volume
of growing-stock trees at the previous inventory that died from
natural causes before the current inventory (divided by the number
of growing seasons between surveys to produce average annual mortality)
National Forest lands: Federal lands
legally designated as National Forests or purchase units and other
lands administered as part of the National Forest System by the
USDA Forest Service.
Net change: The difference between
the current and previous inventory estimates of growing-stock volume
(divided by the number of growing seasons between surveys to produce
average annual net change). Components of net change are ingrowth
plus accretion, minus mortality, minus cull increment, plus cull
decrement, minus removals.
Net growth: The change, resulting from
natural causes, in growing-stock volume during the period between
surveys (divided by the number of growing seasons to produce average
annual net growth). Components of net growth are ingrowth plus accretion,
minus mortality, minus cull increment, plus cull decrement.
Noncensus water: Streams/rivers between
120 feet and 200 feet in width, and bodies of water between 1 and
4.5 acres in size. The Bureau of the Census classifies such water
Noncommercial forest land: Reserved
productive forest land, Christmas tree plantations, other forest
land, and other reserved forest land (see definitions).
Noncommercial species: Tree species
of typically small size, poor form, or inferior quality that normally
do not develop into trees suitable for industrial wood products.
Nonforest land: Land that has never
supported forests, or land formerly forested but now in nonforest
use such as cropland, pasture, residential areas, or highways.
Nonsalvable dead tree: A dead tree
with most or all of its bark missing that is at least 5.0 inches
d.b.h. and is at least 4.5 feet tall.
Nonstocked area: A stand-size class
of forest land that is stocked with less than 10 percent of minimum
full stocking with live trees.
Other cropland: Includes cropland used
for cover crops and soil improvement (legumes).
Other farmland: All nonforest land
on a farm excluding cropland, pasture, and idle farmland; includes
farm lanes, stock pens, and farmsteads.
Other forest land: Forest land that
is incapable of producing 20 cubic feet per acre per year of industrial
wood under natural conditions, because of adverse site conditions
(formerly known as unproductive forest land).
Other reserved forest land: Forest
land that is incapable of producing 20 cubic feet per acre per year
of industrial wood under natural conditions, because of adverse
site conditions, and is protected through statute or administrative
Ownership class: A classification of
forest land based on ownership and nature of business or control
of decision making for the land. It encompasses all types of legal
entities having ownership interest in the land, whether public or
Pasture land: Includes any pasture
land other than cropland and woodland pasture. It can include lands
that have had lime fertilizer or seed applied, or that had been
improved by irrigation, drainage, or control of weeds and brush.
Pastured cropland: Includes rotation
pasture and grazing land that would have been used for crops without
Pastured timberland: Land that is partially
developed, maintained, or managed for pasture and grazing, but which
continues to meet the definition of timberland.
Poletimber stand: A stand-size class
of forest land that is stocked with at least 10 percent of minimum
full stocking with live trees with half or more of such stocking
in poletimber or sawtimber trees or both, and in which the stocking
of poletimber exceeds that of sawtimber.
Poletimber tree: A live tree of commercial
species meeting regional specifications of soundness and form and
at least 5.0 inches in d.b.h., but smaller than a sawtimber tree.
Preferred tree: A high-quality tree,
from a lumber viewpoint, that would be favored in cultural operations.
General characteristics include grade 1 butt log (if sawtimber size),
good form, good vigor, and freedom from serious damage.