Using biological criteria and indicators to address forest inventory data at the state level

The Santiago Declaration identified seven criteria and 67 indicators for assessing the conservation and sustainable management of temperate and boreal forests. Data collected by the Forest Inventory and Analysis (FIA) program of the US Department of Agriculture Forest Service can be used to directly address at least 11 biological indicators. The FIA program has conducted periodic inventories of forestland for several decades. These inventories provide statistical estimates of forest area, timber volume, growth, removals, and mortality. Recent legislation has mandated that the Forest Service inventory the forestland of the US on an annual basis measuring the entire set of national sample plots over a 5-year period. This paper identifies which criteria and indicators can be addressed by FIA data; the scale at which it may be appropriate to use these data; and how recent changes will impact the Forest Service's ability to provide information needed to address these indicators. Data from the two most recent inventories of Iowa (1974 and 1990) and Minnesota (1977 and 1990) are used to show how criteria and indicators relate to trends in forest composition and extent, timber resource utilization, and the population size of native and non-native trees. These two states have distinctly different forest resources, ranging from sparse to dense, and provide a good test of the effectiveness of using forest inventory data to provide criteria and indicator information at the state level. Analysis of the data for the last two inventories of Iowa and Minnesota reveals that the area of timberland has increased by 34 and 8%, respectively, while growing-stock volumes have increased by 47 and 23%. Volumes of most native species increased over the period, especially for pioneer species such as Juniperus virginiana L. [Little (1979). Agricultural Handbook No. 541, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Ft. Collins, CO] (eastern red cedar). A notable exception was the 52% decline of Ulmus americana L. (American elm) due to the spread of Dutch elm disease. The number of non-native species also increased. In Iowa, the estimated number of live Ulmus pumila L. (Siberian elm) trees, a non-native species, went from 0 in 1974 to 675 × 103 in 1990. During the 1990 inventory of Minnesota another non-native species, Ailanthus altissima (Mill.) Swingle (tree of heaven), was sampled for the first time.