Filling the gap: improving estimates of working tree resources in agricultural landscapes

Abstract

Agroforestry plantings and other trees intentionally established in rural and urban areas are emerging as innovative management options for addressing resource issues and achieving landscape-level goals. An understanding of the ecosystem services contributed by these and future plantings would provide critical information to policy and program developers, and a comprehensive inventory would contribute to estimating the cumulative effects of these plantings. Trees used in these practices are not explicitly inventoried by the primary national forest resource inventory of the United States: the Forest Inventory and Analysis (FIA) program of the USDA Forest Service. The FIA program currently limits its inventories to trees in forests meeting specific size and density criteria, but the draft FIA Strategic Plan suggests the addition of an “other treed land inventory” (excluding urban forests). In this study, we use FIA data to estimate the agroforestry and other tree resources of the Midwest and document some obstacles to effective inventories of agroforestry practices. We compare our estimates of forestland area in the Midwest to those derived from MODIS (MODerate Resolution Imaging Spectroradiometer) Vegetative Continuous Fields (VCF). The differences between these two estimates, particularly in sparsely forested states, support the idea that the expansion of the FIA program to an all-tree inventory would fill an important gap. We propose minor modifications to the inventory that would lead to an improved assessment of agroforestry and other tree resources and practices.