This late-date (circa 2000) map was created from a pre-existing classification, the IFMAP (Integrated Forest Monitoring, Assessment, and Prescription) classification, created by Space Imaging under contract to the Michigan Department of Natural Resources, beginning in 1999.
Field data were collected by MiDNR foresters and biologists in the summers of 1999-2001, drawn upon 1:15840 aerial photos. Quantitative information was collected with the photos relating to species composition in the understory, overstory, and ground cover. Training data collection was stratified over the entire state with regard to ecoregion, sub-ecoregion, and TM path/row. Within each "eco-scene", we attempted to collect examples of each of the land cover classes present. The information collected was sufficient to classify the sites, both natural and constructed, to an Anderson Level IV class, though the IFMAP classification was designed to classify land cover to level III.
During this time, the Landsat scenes selected for the classification were georeferenced to the MIRIS (Michigan Resource Inventory System) base roads and balanced and mosaicked. Three mosaics were produced: spring, summer, and fall, for the Upper and Lower Peninsulas. There were several areas of clouds, both in the Lower and Upper Peninsulas, that needed to be patched by imagery acquired much earlier, as early as 1992. These areas are small. Once the mosaics were completed, the training sites were digitized and checked for consistency on each of the dates. The signature data were then extracted to form the training site database for each date. The summer mosaics were classified to Anderson level 1 using statistical cluster analysis with ERDAS Imagine and S-plus statistical software. Once the result was satisfactory, the seven level 1 classes were separately classified to Anderson level 2 using the same techniques. Some modeling with ancillary data was necessary, primarily to isolate lowland types from upland types. The ancillary data used consisted of a weighted combination of NWI, a presettlement vegetation layer, and the MIRIS hydrology layer.
Once the level 2 map was complete, the map was divided by TM scene area and level 2 class. To achieve the level 3 classes, different imagery dates were used depending upon the class. For instance, fall, or senescence, imagery was used to differentiate the level 3 broadleaf species, since the turning of the leaves aids in separation of broadleaf types. Differences between spring and summer images were used to classify some wetland types using differences in water levels. Differentiation of urban types (high-intensity/low-intensity) was often made using a thresholding technique in Landsat band 1 (blue).
Upon completion of the level 3 product, the map was disseminated among DNR foresters and biologists for field verification and checked for consistency against an older DNR forest database. The former step was very instructive in pointing out regions and sites in which the map accuracy was good and where additional work was needed. Using this data in conjunction with forest predictive models guided further supervised reclassification of natural areas.
From the IFMAP classification, a level 2 preliminary classification was made from a crosswalk developed between the IFMAP and C-CAP classification schemes. The IFMAP training sites were also recalculated under the C-CAP scheme. On average, 11% of the training sites did not directly crosswalk due to different land cover component thresholds. These training sites were traced to the pixels that they labeled, and those pixels were given the new C-CAP classification. This step produced a preliminary C-CAP basemap.
Since the Southern Lower Peninsula of Michigan was completed for the IFMAP project prior to the Michigan C-CAP project coming up for bid, the required 3-mile buffer into Indiana and Ohio was not made. The buffer had to be classified, and, in anticipation of the edgematching award, the decision was made to extend the buffer to 10 miles.
To accomplish this, the triple-date TM imagery used to classify Southern Michigan originally was subset to cover an area at least 50 miles into Michigan and 10 miles into Indiana and Ohio. These subsets were then classified using an unsupervised routine (ISODATA), and, beginning with the summer date, were summarized with the C-CAP base map. The summaries were then used to label the clusters when there was a clear majority cover type. When a clear majority did not exist, another date was chosen to re-cluster unlabeled pixels. After the three dates were used few pixels remained unclassified, and those were clustered with Southern Michigan training sites, or manually edited. Manual editing was used as well to edgematch the extension to Southern Michigan. At this point, NOAA CSC staff visited the Ann Arbor office, and performed an accuracy assessment by gathering points throughout the state, as discussed in the accuracy portion of the metadata.
Once the first assessment of the draft map was complete, comments generated from drop points collected with AA points were incorporated into the map, and the map was sent for another assessment. The Upper Peninsula was assessed separately from the Lower Peninsula, and iterations of comments and modifications continued for several rounds, until the target accuracy of 85% overall and 80% minimum class accuracy was achieved. Several classes, such as Palustrine Aquatic Bed and Unconsolidated Shore, did not have enough points for statistical significance. Scrub Shrub in the Upper Peninsula had not enough points for significance. There was a fair amount of confusion between pasture grassland and cultivated land, especially in the Upper Peninsula. This required a number of iterations to create a satisfactory representation. Much of the confusion is believed to arise from phenological variation and crop rotation.
Large urban areas from the IFMAP classification had a different appearance than those in other C-CAP products. The decision was made to filter the Michigan C-CAP urban areas to bring them into line with the products already completed. The model operated on contiguous areas of urban land cover greater than 2000 pixels.
After the classification was accepted by NOAA CSC, it was edgematched to classifications of the surrounding states. Edgematching involved using the overlaps between the state classifications and locating a path in that zone that would not produce a localized seam line. Subsequently, the overlap zone, including a zone up to 10 miles or more from the state border was edited as with the Ohio extension to equalize the classifications.
Includes areas dominated by single stemmed, woody vegetation unbranched 0.6 to 1 meter (2 to 3 feet) above the ground and having a height greater than 6 meters (20 feet).
Includes areas in which more than 67 percent of the trees remain green throughout the year. Both coniferous and broad-leaved evergreens are included in this category.
Areas dominated by woody vegetation less than 6 meters in height. This class includes true shrubs, young trees, and trees or shrubs that are small or stunted because of environmental conditions.
Includes all nontidal wetlands dominated by woody vegetation greater than or equal to 6 meters in height, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is below 0.5 parts per thousand (ppt).
Includes all nontidal wetlands dominated by woody vegetation less than or equal to 6 meters in height, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is below 0.5 ppt.
Includes all nontidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens, and all such wetlands that occur in tidal areas in which salinity due to ocean- derived salts is below 0.5 ppt.
Includes all tidal wetlands dominated by woody vegetation less than or equal to 6 meters in height, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is above 0.5 ppt.
Characterized by erect, rooted, herbaceous hydrophytes (excluding mosses and lichens) that are present for most of the growing season in most years. Perennial plants usually dominate these wetlands. All water regimes are included except those that are subtidal and irregularly exposed.
Characterized by substrates lacking vegetation except for pioneering plants that become established during brief periods when growing conditions are favorable. Erosion and deposition by waves and currents produce a number of landforms, such as beaches, bars, and flats, all of which are included in this class.
Includes persistent snow and ice persist for greater portions of the year.