Treesearch

Total nitrogen (N) and sulfur (S) deposition in forest systems can have either positive or negative impacts on tree growth. The growth of many forests in North America is limited by N availability. Therefore, N fertilization is often a key component of forest management, and in areas of N deposition, tree growth may be stimulated. However, N additions can sometimes be greater than what trees require and can negatively impact tree health and growth. Systems where atmospheric deposition of N and S is greater than the critical load may be examples of such forest conditions. When critical...

The Forest and Analysis Program of the Northern Research Station (NRS-FIA) has re-designed Phase 3 measurements and intensified the sample intensity following a study to balance costs, utility, and sample size. The sampling scheme consists of estimating canopy-cover percent for six vegetation growth habits on 24-foot-radius subplots in four height classes and as an aerial view, and measuring tree saplings and seedlings on 6.8-foot-radius microplots. In the past two years, all of the basic submodels in SORTIE, an individual-tree distance-dependent model, were parameterized for the 50 most...

The LANDFIRE program is developing 2010 maps of vegetation and wildland fuel attributes for the United States at 30-meter resolution. Currently available vegetation layers include ca. 2001 and 2008 forest canopy cover and canopy height derived from Landsat and Forest Inventory and Analysis (FIA) plot measurements. The LANDFIRE canopy cover layer for the conterminous United States is the first of its kind developed with FIA tree measurements as the source of ground reference data. The mapping process is based on regression tree models with FIA plot values as the dependent variables (canopy...

We investigate how vegetation in the Tanana Valley of interior Alaska (120,000 km2) has responded to a changing climate over the preceding three decades (1982-2012). Expected impacts include: 1) drying of wetlands and subsequent encroachment of woody vegetation into areas previously dominated by herbaceous and bryoid vegetation types, 2) changes in forest composition resulting from succession processes within burned areas, 3) mortality and defoliation from increased insect activity attributable to a warming climate, 4) effects on tree growth attributable to drought stress and/or reduced...

Forest Health and Monitoring (FHM) and Palmer's Drought Severity Index (PDSI) data were obtained for 11 states in the southeastern United States to assess the relationship between drought and crown dieback. Correlation analyses were performed at the species group and ecoregion levels within the study area. The results indicate a negative correlation between drought and crown dieback within 3 to 5 years of the onset of drought conditions.

Forest Inventory and Analysis (FIA) and PRISM climate data from 1991-2000 were obtained for 10 states in the southeastern United States. Mortality was calculated for each plot, and annual values for precipitation and maximum and minimum temperature were extracted from the PRISM data. Data were then stratified by upland/bottomland for red oak species, and classification and regression tree (CART) analysis was used to determine the influence of climate variables on mortality at ecoregion province and section levels. The results presented here will provide a basis for future research on the...

The annual forest inventory of New Mexico began as an accelerated inventory, and 8 of the 10 Phase 2 panels were sampled between 2008 and 2011. The inventory includes a large proportion of nonresponse. FIA's estimation process uses post-stratification and assumes that nonresponse occurs at random within each stratum. We construct an estimator for the New Mexico inventory and derive an estimated variance based on the missing-at-random assumption.

Tree diameter growth models are widely used in many forestry applications, often to predict tree size at a future point in time. Also, there are instances where projections of past diameters are needed. An individual tree model has been developed to estimate diameter growth of multi-stem woodland tree species where the diameter is measured at root collar. The model was built from radial growth data on trees sampled from plots measured in Utah, Arizona, and Nevada. Individual tree growth can be predicted from the ratio of live woodland stems to all stems and from mean past 10-year radial...

In most forest inventory data, it is not feasible to estimate the canopy coverage of trees having certain characteristics due to the lack of information on crown size. In this study, data from the Forest Inventory and Analysis (FIA) program was used to assign crown sizes to individual trees using published crown width models. This process effectively links trees to area such that canopy cover area estimates can be made using domains that include tree-level attributes (e.g., canopy cover of red maple having total height ≥80 feet). Advantages of implementing this approach are 1) estimation...

Wildlife species-habitat matrices are used to relate lists of species with abundance of their habitats. The Forest Inventory and Analysis Program provides data on forest composition and structure, but these attributes may not correspond directly with definitions of wildlife habitats. We used FIA tree data and tree crown diameter models to estimate canopy cover, from which we assigned FIA conditions to NatureServe forest and woodland habitat domains and National Land Cover Dataset (NLCD) forest classes within the 20-state northern FIA region. Hardwood and softwood types were most abundant...