Forest Inventory and Analysis

Highlights of Wisconsin's 1996 Forest Inventory

All Species || Economic Impact || Jack Pine || Oak-Hickory || Aspen
Paper Birch || Maple-Basswood || Cherry and Walnut

All Species

• Wisconsin forestland increased by 640,000 acres between 1983 and 1996.
  • 1983 - 15.32 million acres; 1996 - 15.96 million acres.
  • Forestland made up 46% of total Wisconsin land area.
  • Timberland area increased by 940,000 acres. 1983 - 14.76 million acres; 1996 - 15.70 million acres.
  • Forestland definition - Land area that is at least 16.7% covered by forest trees (or was in the past) and is not currently developed for nonforest use.

• Private individuals own 57% of the timberland area in Wisconsin.
  • 30% government-owned
  • 7% - forest industry
  • 4% - private corporations
  • 2% - tribal lands

• Hardwood succession is very evident. Acreage of aspen-birch forest type declined, while maple-basswood and soft maple-ash types increased. Maple-basswood was the most common forest type.
  • Aspen-birch forest type: 1983 - 3.8 million acres; 1996 - 3.4 million acres.
  • Maple-basswood forest type: 1983 - 4.1 million acres; 1996 - 5.3 million acres.
  • Elm-ash-soft maple forest type: 1.3 million acres; 1996 - 1.5 million acres.

• Number of live trees over 10-feet tall on Wisconsin forestland increased by 1.4 billion between 1983 and 1996.
  • 1983 - 8.4 billion trees; 1996 - 9.8 billion trees.
  • 1,700 live trees per Wisconsin resident.

• Growing stock volume increased by 2.0 billion cubic feet between 1983 and 1996.
  • 1983 - 16.5 billion cubic feet
  • 1996 - 18.5 billion cubic feet
  • Conifers increased from 3.8 to 4.4.
  • Hardwoods increased from 12.7 to 14.1.

• Growing stock volume of larger trees increased between 1983 and 1996.
  • Volumes of 5-9 inch diameter conifers and 5-11 inch hardwoods decreased from 8.7 to 8.3 billion cubic feet between 1983 and 1996.
  • Volumes of 9-15 inch diameter conifers and 11-15 inch hardwoods increased from 4.6 to 5.8 billion cubic feet between 1983 and 1996.
  • Volume of 15+ inch diameter trees increased from 3.2 to 4.4 billion cubic feet between 1983 and 1996.

• Quality of sawtimber appears to have improved between 1983 and 1996.
  • Percentage of sawtimber volume in highest quality classifications (grades 1 and 2) increased from 28% in 1983 to 40% in 1996.
  • Much of the in-grade percent increase is due to the overall diameter increase in sawtimber. Grade 1 trees must be at least 16-inch dbh and grade 2 trees at least 13-inch dbh.

• Growing stock average net annual growth exceeded average annual removals by 158 million cubic feet between 1983 and 1996.
  • 1983-96: Net growth - 490 million cubic feet; Removals - 332 million cubic feet. Removals were 68% of net growth.
  • 1968-83: Net growth - 491 million cubic feet; Removals - 221 million cubic feet. Removals were 45% of net growth.
  • Average net annual growth definition: Average annual gross growth minus death due to natural causes.

• Sawtimber average net annual growth (1,681 million board feet) exceeded average annual removals (986 million board feet) between 1983 and 1996. Removals were 59% of net growth.
  • 1968-83: Growth - 1,443 million cubic feet; Removals - 609 million cubic feet. Removals 42% of growth.

• Most common conifer species groups by volume are:
  • Red pine - 988 million cubic feet (22% of conifers and 5% of total)
  • White pine - 929 million cubic feet (21% of conifers and 5% of total)
  • Northern white-cedar - 569 million cubic feet (13% of conifers and 3% of total)
  • Balsam fir - 471 million cubic feet (11% of conifers and 3% of total)
  • Hemlock - 401 million cubic feet (9% of conifers and 2% of total)
  • Jack pine - 382 million cubic feet (9% of conifers and 2% of total)

• Most common hardwood species groups by volume are:
  • Aspen (quaking and bigtooth aspen) - 2,482 million cubic feet (18% of hardwoods and 13% of total)
  • Red oak (red, black and pin oak) - 2,389 million cubic feet (17% of hardwoods and 13% of total)
  • Hard maple (sugar and black maple) - 2,155 million cubic feet (15% of hardwoods and 12% of total)
  • Soft maple (red and silver maple) - 1,906 million cubic feet (14% of hardwoods and 10% of total)
  • Basswood - 1,092 million cubic feet (8% of hardwoods and 6% of total)
  • White oak - 927 million cubic feet (7% of hardwoods and 5% of total)
  • Paper birch - 832 million cubic feet (6% of hardwoods and 4% of total)

• 269 million tree seedlings have been distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

• 1.3 billion tree seedlings have been distributed for field planting in Wisconsin by DNR nurseries since the program began in 1911.

Economic Importance of Forest Industry in Wisconsin - 1996

• Economic data is supplied by Department of Commerce. Information available for various years back to 1982.

• 1982 value of shipments was $8.4 billion.

• Total stumpage value estimate in 1996 - $209 million (Marcouiller). Based on 4th quarter, 1996 Timber Mart North.

Jack Pine

• Jack pine forest type acreage declined by 148,000 acres between 1983 and 1996.
  • 1983 - 535,000 acres; 1996 - 387,000 acres.
  • 57% of jack pine volume is on the jack pine forest type, down from 67% in 1983.
  • Jack pine appears to be more dispersed among forest types than in 1983, affecting resource availability and operability.

• Jack pine growing stock volume decreased by 146 million cubic feet between 1983 and 1996.
  • 1983 - 528 million cubic feet; 1996 - 382 million cubic feet.

• Average annual removals of jack pine exceeded average net annual growth by 7.9 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 10.1 million cubic feet; Removals - 18.0 million cubic feet. Removals were 179% of net growth.
  • 1968-83 : Net growth - 23.1 million cubic feet; Removals - 18.2 million cubic feet. Removals were 79% of net growth.

• The decrease in jack pine acreage and volume is the result of increasing harvest levels and aging, coupled with pest infestations, particularly bud worm, in the jack pine forest.
  • Higher levels of bud worm infestation in older stands (over 45 years old) is a natural occurrence.
  • Older jack pine produce more male cones which are the preferred bud worm food source.
  • Older and stressed jack pine are more susceptible to bark beetle and Armillaria.
  • Jack pine is a fire-dependent, pioneer species which historically became established in northern Wisconsin after clearcutting and extensive wildfires in the late 19th and early 20th centuries.
  • Wisconsin is on the southern edge of the jack pine range resulting in less vigorous trees here than farther north.

• Reversal of the downward trend in jack pine does not look promising for the future.
  • Jack pine forest type acreage between 1 and 20 years old is down from 117,000 acres in 1983 to 60,000 acres in 1996.
  • Numbers of 1-3 inch jack pine saplings are down from 105 million in 1983 to 57 million in 1996.
  • Jack pine acreage is being replaced by red pine acreage. Red pine is less susceptible to forest pests and is longer-lived.

• 16 million jack pine seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

• 154 million red pine seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

Oak-Hickory

• Oak-hickory forest type increased by 33,000 acres between 1983 and 1996.
  • 1983 - 2,853,000 acres; 1996 - 2,886,000 acres.
  • 59% of select red oak, 71% of select white oak, and 82% of other red oak growing stock volumes are on the oak-hickory forest type. The 1983 inventory showed 65%, 76% and 82%, respectively, for the species groups.
  • Select red and white oaks are becoming more dispersed among forest types, while the percentage of other red oaks remained about the same.

• Select red oak (Northern red oak) growing stock volume increased by 226 million cubic feet between 1983 and 1996.
  • 1983 - 1,504 million cubic feet; 1996 - 1,730 million cubic feet.

• Select white oak (white, swamp white and bur) growing stock volume increased by 168 million cubic feet between 1983 and 1996.
  • 1983 - 759 million cubic feet; 1996 - 927 million cubic feet.

• Other red oak (black and pin) growing stock volume decreased slightly by 2 million cubic feet between 1983 and 1996.
  • 1983 - 662 million cubic feet; 1996 - 660 million cubic feet.

• Select red oak average annual removals exceeded average net annual growth by 9.4 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 43.9 million cubic feet; Removals - 53.3 million cubic feet. Removals were 121% of net growth.
  • 1968-83 : Net growth - 34.5 million cubic feet; Removals - 21.0 million cubic feet. Removals were 61% of net growth.

• Select white oak average annual removals exceeded average net annual growth by 2.0 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 16.7 million cubic feet; Removals - 18.7 million cubic feet. Removals were 112% of net growth.
  • 1968-83 : Net growth - 11.5 million cubic feet; Removals - 5.4 million cubic feet. Removals were 47% of net growth.

• Other red oak average net annual growth exceeded removals by 2.0 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 12.4 million cubic feet; Removals - 10.4 million cubic feet. Removals were 84% of net growth.
  • 1968-83 : Net growth - 15.9 million cubic feet; Removals - 5.9 million cubic feet. Removals were 37% of net growth.

• Small oak-hickory forest type increased due to tree planting and natural reforestation of marginal cropland.
  • Heavier harvests of valuable red and white oak, particularly in southwestern Wisconsin, have taken their toll on the resource.
  • The droughts of 1988-89 caused higher natural mortality in the oaks especially in the central sands area of the state. Infestations of two-lined chestnut borer and forest tent caterpillar have also resulted in increased mortality.
  • Oak was originally established by periodic wildfires in pre-settlement times which reduced competition from less fire resistant species. With the coming of the pioneers, frequency of burning was greatly reduced allowing more shade tolerant species to become established in the oak-hickory understory.
  • The oaks will remain a component of more diverse mixed hardwood forests into the future. Oak is a mid-successional species on mesic sites. Due to the oak's inability to regenerate without disturbance in moderate to heavy shade on mesic sites and acorn predation by animals and birds, the oak-hickory type usually succeeds to central and northern hardwoods in southern Wisconsin and northern hardwoods in the north.
  • On lighter soils, especially in the central sands, oaks are able to regenerate since there is less competition from other species such as maple.
  • Acreage of oak-hickory forest type between 1 and 20 years old is down from 451,000 acres in 1983 to 212,000 acres in 1996. However, numbers of 1-3 inch oak saplings are up from 171 million in 1983 to 266 million in 1996. This apparent incongruity is probably explained by the increasing species diversity in Wisconsin forests.

• 11 million red oak seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

• 1.2 million white oak seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

Aspen

• Aspen forest type acreage declined by 265,000 acres between 1983 and 1996.
  • 1983 - 3,151,000 acres; 1996 - 2,886,000 acres.
  • 54% of aspen volume is on the aspen forest type, down from 64% in 1983.
  • 23% of aspen volume is on the maple-basswood forest type, up from 14% in 1983.
  • Aspen is becoming more dispersed among forest types, affecting resource availability and operability.

• Aspen growing stock volume decreased by 344 million cubic feet between 1983 and 1996.
  • 1983 - 2,826 million cubic feet; 1996 - 2,482 million cubic feet.

• Aspen average annual removals exceeded average net annual growth by 8.3 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 74.2 million cubic feet; Removals - 82.5 million cubic feet. Removals were 111% of net growth.
  • 1968-83 : Net growth - 79.9 million cubic feet; Removals - 63.7 million cubic feet. Removals were 80% of net growth.

• The decrease in aspen acreage and volume is the result of increasing harvest levels and aging of the aspen forest.
  • Aspen is a short-lived species (60-70 years) that has come under increasing harvest pressure from the paper and chip board products industries.
  • Average annual mortality rate did not change significantly between 1983 and 1996.
  • Aspen is a pioneer species which historically became established on a massive scale in northern Wisconsin after clearcutting and extensive wildfires in the late 19th and early 20th centuries.
  • Aspen regenerates primarily through stump sprouting and cloning from the root system.
  • The seedlings must have full sunlight to survive.
  • Clearcutting is the best method for regenerating these sun-loving species. Very often harvests have not completely clearcut stands, typically leaving a residual stand of more shade tolerant species.
  • Acreage of aspen forest type between 1 and 20 years old is down from 1,084,000 acres in 1983 to 997,000 acres in 1996. However, numbers of 1-3 inch aspen saplings are up from 843 million in 1983 to 1,334 million in 1996.
  • This apparent incongruity is probably explained by the increasing species diversity in Wisconsin forests, increasing density of the forests and conversion of old farm fields to aspen.
  • The aspen forest type is being replaced through natural succession by the expanding maple-basswood forest type.

• 134,000 aspen seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

Paper Birch

• Acreage of the paper birch forest type declined by 265,000 acres between 1983 and 1996.
  • 1983 - 661,000 acres; 1996 - 494,000 acres.
  • 33% of paper birch volume is on the paper birch forest type, down from 34% in 1983.
  • 31% of paper birch volume is on the maple-basswood forest type, up from 19% in 1983.
  • Paper birch is becoming more dispersed among forest types, affecting resource availability and operability.

• Paper birch growing stock volume decreased by 258 million cubic feet between 1983 and 1996.
  • 1983 - 1,090 million cubic feet; 1996 - 832 million cubic feet.

• Paper birch average annual removals exceeded average net annual growth by 13.7 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 7.5 million cubic feet; Removals - 21.2 million cubic feet. Removals were 283% of net growth.
  • 1968-83 : Net growth - 34.9 million cubic feet; Removals - 12.5 million cubic feet. Removals were 36% of net growth.

• The decrease in paper birch acreage and volume is the result of aging of the paper birch forest, drought in 1988-89 and associated bronze birch borer infestations, birch leaf miner infestations and increasing harvest levels.
  • Paper birch, like aspen, is a short-lived species (70-80 years) that has come under increasing harvest pressure.
  • Average annual mortality increased significantly between 1983 and 1996.
  • The drought years of 1988-89 had a severe impact on the paper birch resource.
  • Drought-induced stress resulted in increased infestations by the bronze birch borer.
  • Birch leaf miner infestations have increased, though this is unrelated to drought-induced stress.
  • Paper birch has history and life requirements similar to aspen. Paper birch is a pioneer species which became established on a large scale in northern Wisconsin along with aspen.
  • Natural regeneration of paper birch is very difficult on sites where shade tolerant understory species have become established.
  • The seedlings must have full sunlight to survive.
  • Acreage of paper birch forest type between 1 and 20 years old is down from 115,000 acres in 1983 to 67,000 acres in 1996. However, numbers of 1-3 inch paper birch saplings are up from 156 million in 1983 to 161 million in 1996.
  • This apparent incongruity is probably explained by the increasing species diversity in Wisconsin forests, increasing density of the forests and conversion of old farm fields to aspen and paper birch to a lesser extent.
  • The paper birch forest type is being replaced through natural succession by the expanding maple-basswood forest type.

Maple-Basswood

• Maple-basswood forest type acreage increased by 1.2 million acres between 1983 and 1996.
  • 1983 - 4,097,000 acres; 1996 - 5,300,000 acres.
  • 94% of hard maple and 59% of soft maple growing stock volumes are on the maple-basswood forest type. The 1983 inventory showed 91% and 46%, respectively for the species groups.
  • Hard and soft maples are becoming more concentrated on the maple-basswood forest type.

• Hard maple growing stock volume increased by 540 million cubic feet between 1983 and 1996.
  • 1983 - 1,615 million cubic feet; 1996 - 2,155 million cubic feet.

• Soft maple growing stock volume increased by 685 million cubic feet between 1983 and 1996.
  • 1983 - 1,221 million cubic feet; 1996 - 1,906 million cubic feet.

• Hard maple average net annual growth exceeded average annual removals by 35.6 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 60.4 million cubic feet; Removals - 24.8 million cubic feet. Removals were 41% of net growth.
  • 1968-83 : Net growth - 46.8 million cubic feet; Removals - 14.5 million cubic feet. Removals were 31% of net growth.

• Soft maple average net annual growth exceeded removals by 42.3 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 65.0 million cubic feet; Removals - 22.7 million cubic feet. Removals were 35% of net growth.
  • 1968-83 : Net growth - 51.6 million cubic feet; Removals - 10.0 million cubic feet. Removals were 19% of net growth.

• Maple-basswood forest type has increased due to natural succession primarily from aspen and paper birch types.
  • Aspen and paper birch aging and associated mortality, as well as heavier harvests, are accelerating natural succession to maple-basswood.
  • There are no major forest pest problems in the maple species at the present time.
  • Acreage of maple-basswood forest type between 1 and 20 years old is down from 633,000 acres in 1983 to 506,000 acres in 1996.
  • However, numbers of 1-3 inch hard maple saplings are up from 420 million in 1983 to 459 million in 1996, and soft maples are up from 538 million to 582 million over the same time period.
  • This apparent incongruity is probably explained by the increasing tree size between inventories and maple shade tolerance, resulting in maple stands larger than 1-3 inches when dominant non-maples die or are harvested.

• 2.3 million hard maple seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

• 834,000 soft maple (silver) seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.

Cherry and Walnut

• Black cherry growing stock volume increased by 26 million cubic feet between 1983 and 1996.
  • 1983 - 174 million cubic feet; 1996 - 200 million cubic feet.

• Black walnut growing stock volume increased by 22 million cubic feet between 1983 and 1996.
  • 1983 - 26 million cubic feet; 1996 - 48 million cubic feet.

• Black cherry average net annual exceeded average annual removals by 2.6 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 5.9 million cubic feet; Removals - 3.3 million cubic feet. Removals were 56% of net growth.
  • 1968-83 : Net growth - 6.3 million cubic feet; Removals - 0.7 million cubic feet. Removals were 11% of net growth.

• Black walnut average net annual growth exceeded average annual removals by 1.4 million cubic feet between 1983 and 1996.
  • 1983-96 : Net growth - 1,581,000 cubic feet; Removals - 186,000 cubic feet. Removals were 12% of net growth.
  • 1968-83 : Net growth - 611,000 cubic feet; Removals - 71,000 cubic feet. Removals were 12% of net growth.

• Black cherry and black walnut account for only 1.1% and 0.3%, respectively, of the total volume of trees over 5-inches in diameter in Wisconsin.
  • Black cherry and black walnut are on the northwestern edges of their natural ranges in North America, forming only a minor part of the Wisconsin forest.
  • Higher quality black cherry and black walnut are valuable and desirable timber species; however, they are not being over harvested (growth exceeds removals) at the present time.
  • There are no major black cherry or black walnut forest pest problems at the present time.
  • Numbers of 1-3 inch black cherry saplings are up from 114 million in 1983 to 204 million in 1996 and black walnuts are up from 1.5 million to 4.1 million over the same time period.

• 4.1 million black walnut seedlings were distributed for field planting in Wisconsin by DNR nurseries between 1983 and 1996.