Discrete trees and small groups of trees in nonforest settings are considered an essential resource around the world and are collectively referred to as trees outside forests (ToF). ToF provide important functions across the landscape, such as protecting soil and water resources, providing wildlife habitat, and improving farmstead energy efficiency and aesthetics. Despite the significance of ToF, forest and other natural resource inventory programs and geospatial land cover datasets that are available at a national scale do not include comprehensive information regarding ToF in the United States. Additional ground-based data collection and acquisition of specialized imagery to inventory these resources are expensive alternatives. As a potential solution, we identified two remote sensing-based approaches that use free high-resolution aerial imagery from the National Agriculture Imagery Program (NAIP) to map all tree cover in an agriculturally dominant landscape. We compared the results obtained using an unsupervised per-pixel classifier (independent component analysis-[ICA]) and an object-based image analysis (OBIA) procedure in Steele County, Minnesota, USA. Three types of accuracy assessments were used to evaluate how each method performed in terms of: (1) producing a county-level estimate of total tree-covered area, (2) correctly locating tree cover on the ground, and (3) how tree cover patch metrics computed from the classified outputs compared to those delineated by a human photo interpreter. Both approaches were found to be viable for mapping tree cover over a broad spatial extent and could serve to supplement ground-based inventory data. The ICA approach produced an estimate of total tree cover more similar to the photo-interpreted result, but the output from the OBIA method was more realistic in terms of describing the actual observed spatial pattern of tree cover.

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The second full annual inventory of Minnesota's forests reports 17 million acres of forest land with an average volume of more than 1,000 cubic feet per acre. Forest land is dominated by the aspen forest type, which occupies nearly 30 percent of the total forest land area. Twenty-eight percent of forest land consists of sawtimber, 35 percent poletimber, 35 percent sapling/seedlings, and 2 percent is nonstocked. The average annual net growth of live trees on forest land from 2004 to 2008 is approximately 435 million cubic feet year while average annual removals is only 288 million cubic feet per year. Removals exceeds growth for some commercial species. Additional forest attribute and forest health information is presented along with information on agents of change including changing land use patterns and the introduction of nonnative plants, insects, and disease. Detailed information on forest inventory methods, data quality estimates, and important resource statistics can be found on the Statistics and Quality Assurance DVD on the inside back cover of this report.

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The second full annual inventory of Indiana's forests reports more than 4.75 million acres of forest land with an average volume of more than 2,000 cubic feet per acre. Forest land is dominated by the white oak/red oak/hickory forest type, which occupies nearly a third of the total forest land area. Seventy-six percent of forest land consists of sawtimber, 16 percent contains poletimber, and 8 percent contains sapling/seedlings. The volume of growing stock on timberland has been rising since the 1980s and currently totals more than 8.5 billion cubic feet. The average annual net growth of growing stock on forest land from 2004 to 2008 is approximately 312 million cubic feet per year. This report includes additional information on forest attributes, land use change, carbon, timber products, forest health, and statistics and quality assurance of data collection. AcknowledgmentsThe authors would like to thank the many individuals who contributed both to the inventory and analysis of Indiana's forest resources. Primary field crew and QA staff over the [2004][2005][2006][2007][2008] field inventory cycle included Gary Stachowicz, Dan Johnson, Mark Webb, Jason Stephens, Joey Gallion, Greg Yapp, Aaron Hawkins, Matt Goeke, Kasey Krouse, Lance Dye, Dominic Lewer, Will Smith, and Pete Koehler. Data management personnel included Gary Brand, Mark Hatfield, Jay Solomakos, and James Blehm. Report reviewers included Joey Gallion and Carl Hauser of Indiana's DNR.Cover: Autumn in the deciduous forest. Photo used with permission of Indiana Dept. of Natural Resources.

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The second full annual inventory of Iowa's forests (2004-2008) reports more than 3 million acres of forest land, almost all of which is timberland (98 percent), with an average volume of more than 1,000 cubic feet of growing stock per acre. American elm and eastern hophornbeam are the most numerous tree species, but silver maple and bur oak predominate in terms of live tree volume. Iowa's forest land is comprised of 65 percent sawtimber, 19 percent poletimber, and 16 percent sapling/seedling or nonstocked size classes. Average annual net growth of growing-stock trees on Iowa's timberland increased during the past decade to the current estimate of nearly 105 million cubic feet. This report includes additional information on forest attributes, land use change, carbon, timber products, and forest health. A DVD included in this report includes 1) descriptive information on methods, statistics, and quality assurance of data collection, 2) a glossary of terms, 3) tables that summarize quality assurance, 4) a core set of tabular estimates for a variety of forest resources, and 5) a Microsoft Access database that represents an archive of data used in this report, with tools that allow users to produce customized estimates.