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document Historic, archived Do not assume content reflects current scientific knowledge, policies, or practices. 40 Ull /93$ United States Forest Statistics Department of i Agriculture 990 Forest for Iowa, 1 Service North Central Forest Experiment Station Resource Bulletin NC-136 Gary J. Brand and John T. Walkowiak <S3 North Central Forest Experiment Station — Forest Service U.S. Department ofAgriculture 1992 Folwell Avenue St. Paul, Minnesota 55108 Manuscript approved for publication December 16, 1991 1991 This report includes the most commonly used Forest Inventory andAnaly- sis statistics. Additional forest resource data can be provided to interested users. Persons requesting additional information that can be provided from the raw inventory data are expected to paythe retrieval costs. These costs range from less than $100 for a simple request to $2,000 for a com- plex retrieval involving the services ofa Forest Inventory and Analysis computer programmer. Requests will be filled to minimize the impact on the Forest Inventory and Analysis Work Unit. Requests for unpublished information may be directed to: Project Leader Forest Inventory and Analysis North Central Forest Experiment Station 1992 FolwellAvenue St. Paul, Minnesota 55108 Phone: (612) 649-5140 or State Forester Iowa Department ofNatural Resources Wallace State Office Building East 9th & Grand Avenue Des Moines, Iowa 50319 Area served: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Mis- souri, Nebraska, North Dakota, South Dakota, Wisconsin We thank Caren Robey ofDes Moines, Iowa, forthe drawing on the front cover. FOREWORD Forest Inventory andAnalysis is a continuing endeavor mandated by the Renewable Forest and Rangeland Resources PlanningAct of 1974. Prior inventories were mandated by the McSweeney-McNary Forest Research Act of 1928. The objective ofForest Inventory andAnalysis is to periodically inventory the Nation's forest land to determine its extent, condition, volume oftimber, growth, and removals. Up-to-date resource information is essen- tial to frame forest policies and programs. USDAForest Service regional experiment stations are responsible for conducting these inventories and publishing summary reports for individual States. The North Central Forest Experiment Station is responsible for Forest Inventory and Analysis in Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Ne- braska, North Dakota, South Dakota, and Wisconsin. Field work for the Iowa forest inventory began in May 1989 and ended in February 1990. Reports ofthe two previous inventories ofIowa's timber resource are dated 1954 and 1974. The USDAAgricultural Stabilization and Conservation Service provided aerial photos used in the Iowa Forest Inventory. Contents Page Highlights 1 General 1 ForestArea 1 Number ofTrees 3 Volume 4 Timber Growth, Mortality, and Removals 5 Biomass 6 Appendix 6 Accuracy ofthe Survey 6 Survey Procedures 7 Comparing Iowa's Third Inventory With The Second Inventory 12 Tree/Log Grade 12 Metric Equivalents ofUnits Used in This Report 18 Tree Species Groups in Iowa 18 Shrub Species in Iowa 19 Definition ofTerms 19 Table Titles 26 Forest Statistics For Iowa, 1990 Gary J. Brand and John T. Walkowiak HIGHLIGHTS General NOTE: Comparisons ofdatafrom newforest Although known today primarily as an agricul- inventories with datafrom earlier inventories tural State, Iowa had about 7 million acres of indicate trends inforest resources. Comparisons forest before European settlement. Agricultural are only valid iftheprocedures used in the two clearing has dramatically reduced the area of inventories are similar. Because ofourongoing forested land. In this report, the status of efforts to improve the efficiency and reliability of Iowa's forests and the changes since the last the inventory, several changes inprocedures and inventory are presented. definitions have occurred since 1974. Some of these changes make it inappropriate to directly Iowa is divided along county boundaries into compare the 1990 data with thosepublishedfor three geographical areas called the Northeastern 1974. Therefore, datafrom the 1974 inventory Unit, Southeastern Unit, and Western Unit (fig. have been reprocessed using the 1990proce- 1). White oak-red oak-hickory and maple- dures andpublished inpart in this report. basswood are the most common forest types in Please refer to the section labeled "Comparing the Northeastern Unit; white oak-red oak- Iowa's ThirdInventory WithThe Second hickory forests predominate in the Southeastern Inventory"formore details. Unit; and elm-ash-soft maple forests coverthe most area in the less densely forested Western Gary J. Brand, Research Forester, received a Unit. bachelors degree in Chemical Engineering in 1971 and a masters offorestry degree in 1976 Forest Area from the University ofMinnesota. Hejoined the Modeling Unit at the North Central Forest • Iowa had 2.1 million acres offorested land, Experiment Station in 1977. A detail to the or 5.7 percent ofthe State's total land area in Forest Inventory and Analysis Unit gave him the 1990. The two eastern Survey Units had opportunity to work on the Iowa report. most ofthe forest land and had more oftheir landbase in forests than the Western Unit John T. Walkowiak, Urban Forestry Coordina- did. The Northeastern, Southeastern, and tor, received a bachelors degree from State Uni- Western Units were 8.1, 8.9, and 2.0 percent versity ofNew York, College ofEnvironmental forested, respectively. Sciences and Forestry in 1978 and a masters degree in Forest Resources from the University • In 1974 forests covered only 4.3 percent (1.6 ofNew Hampshire in 1984. After receiving for- million acres) ofIowa. Although forest land estry experience in New England, Nebraska, and increased in all Units, the lar—gest increase Montana, hejoined the Iowa Department of was in the Southeastern Unit 41.7 percent Natural Resources in 1989. from 1974 to 1990 (fig. 2). —— NORTHEASTERN UNIT X Lyon Osceola Dickinson Emm* Winnebago Wortn Howard Kossuth J Sioux O'Brien Clay APlatloo CGeorrrdoo Floyd Chickasaw Buena Franklin ' Plymouth Cherokee Vista Pocahontas Humboldt Wright Bremer Black Woodbury Hamilton Grundy Hawk Crawford Carroll Boone Story Marshall Benton Sheby Audubon Dallas Jasper ^ Pottawattamie Cass Adair Madison Warren Marion Mahaska Keokuk Milk Montgomery Adams Clarke Monroe Wapello Jefferson Van Page Taylor Ringgold Decatur Wayne Appanoose Davis Buren WESTERN UNIT SOUTHEASTERN UNIT Figure 1. Forest Survey Units inIowa. 1.2' • Timberland in Iowa was estimated at 1.9 million acres in 1990, up from 1.5 million 1.0- 1974 acres in 1974. The 1974 to 1990 increase in 1990 timberland area reversed the sharp decline .8- observed from 1954 to 1974. Most ofthe w new timberland came from land formerly o classified as pasture (improved pasture, .6- c wooded pasture, and improved pasture with o trees), but now no longer grazed. .4- • Farmers owned 1.2 million acres (nearly 64 - .2 percent) ofthe timberland in Iowa in 1990 (fig. 3). Landowners classified as o-- ,„..„,„; miscellaneous private owned an additional Northeastern Southeastern Western 546,000 acres (about 28 percent) of Survey Unit timberland. Public agencies administered only 8 percent ofthe timberland in Iowa. Figure 2. Area offorest land by ForestSurvey ' Una, Iowa, 1974 and 1990. • As in 1974, the white oak-red oak-hickory forest type in 1990 covered more area than any other forest type (37 percent). It 2