Worldwide, forests are increasingly affected by nonnative insects and diseases, some of which cause substantial tree mortality. Forests in the United States have been invaded by a particularly large number (>450) of tree-feeding pest species. While information exists about the ecological impacts of certain pests, region-wide assessments of the composite ecosystem impacts of all species are limited. Here we analyze 92,978 forest plots distributed across the conterminous United States to estimate biomass loss associated with elevated mortality rates caused by the 15 most damaging nonnative forest pests. We find that these species combined caused an additional (i.e., above background levels) tree mortality rate of 5.53 TgC per year. Compensation, in the form of increased growth and recruitment of nonhost species, was not detectable when measured across entire invaded ranges but does occur several decades following pest invasions. In addition, 41.1% of the total live forest biomass in the conterminous United States is at risk of future loss from these 15 pests. These results indicate that forest pest invasions, driven primarily by globalization, represent a huge risk to US forests and have significant impacts on carbon dynamics.

Beech bark disease (BBD) is an insect–fungus complex involving the beech scale insect ( Cryptococcus fagisuga Lind.) and one of two canker fungi. Beech scale was introduced to Halifax, Nova Scotia around 1890, presumably with the fungus Neonectria coccinea var. faginata Lohm. The disease has subsequently spread through a large portion of the range of beech. We used historical maps of the extent of the advancing BBD front (defined by presence of scale insects) in North America to estimate its rate of spread as 14.7 ± 0.9 km/year. This estimate did not account for stochastic “jumps” by the scale insects to several disjunct locations; therefore, this rate is a conservative estimate. Comparison of the year of scale colonization with beech density did not suggest a relationship between the scale spread rate and beech density. Our analyses also indicated that BBD has invaded less than 30% of regions where beech is present, but it has invaded most of the regions where beech is a dominant component of stands. Despite regional increases in beech mortality following invasion, considerable amounts of live beech remain in invaded areas. Moreover, the volume of beech has increased in most areas, though generally at lower rates than that observed for associated tree species.

Several initiatives have been proposed to mitigate forest loss and climate change through tree planting as well as maintaining and restoring forest ecosystems. These initiatives have both inspired and been inspired by global assessments of tree and forest attributes and their contributions to offset carbon dioxide (CO2) emissions. Here we use data from more than 130,000 national forest inventory plots to describe the contribution of nearly 1.4 trillion trees on forestland in the conterminous United States to mitigate CO2 emissions and the potential to enhance carbon sequestration capacity on productive forestland. Forests and harvested wood products uptake the equivalent of more than 14% of economy-wide CO2 emissions in the United States annually, and there is potential to increase carbon sequestration capacity by ∼20% (−187.7 million metric tons [MMT] CO2 ±9.1 MMT CO2) per year by fully stocking all understocked productive forestland. However, there are challenges and opportunities to be considered with tree planting. We provide context and estimates from the United States to inform assessments of the potential contributions of forests in climate change mitigation associated with tree planting.

Simple population models predict that the spread of an invading species through a homogenous habitat should be equal in all directions, but geographic variation in the habitat that affects either reproduction or movement could result in variable rates of spread. We analyse records of the historical range expansion of the hemlock woolly adelgid (HWA) (Adelges tsugae Annand) in the eastern United States from 1951 to 2006 to document that this species has spread in an anisotropic fashion. Furthermore, the magnitude and direction of this anisotropy has varied through time. We explore the extent to which this spatial and temporal variation in spread can be explained by geographical variation in climate and by the abundance of hosts, eastern hemlock (Tsuga canadensis L.) and Carolina hemlock (Tsuga caroliniana Engelm.). We found that a significant component of the spatial anisotropy in HWA spread rate can be explained by the geographical distribution of host trees. January temperatures were negatively associated with spread rates but this may be an artifact of the association between hemlock and cold climates. The current distribution of the adelgid in eastern N. America may be approaching the extent of its potential range to the south and west determined by availability of host hemlock and to the north determined by lethal cold winter temperatures.

Periodically over the last century, forests of the Eastern United States have been devastated by invasive pests. We used existing data to predict the geographical extent of future damage from beech bark disease (BBD), hemlock woolly adelgid (HWA), and gypsy moth. The distributions of host species of these alien pests were mapped in 1-km 2 cells by interpolating host basal area/ha from 93,611 forest-inventory plots in 37 states. The interpolated surfaces were adjusted for forest density (percent land cover) by multiplying values by an estimate of percent forest cover derived from existing land-cover maps (30-m 2 cells). According to our estimates, BBD currently occupies only about 27 percent of its potential range in land area, but has invaded more than 54 percent in total host density. HWA occupies nearly 26 percent of its potential range in land area, and about one-quarter in total host density. Gypsy moth occupies only 23 percent of its potential range in the Eastern United States, and only 26 percent in total host density. Headquarters of the Northeastern Research Station is inNewtown Square, Pennsylvania. Field laboratories are maintained at: Amherst, Massachusetts, in cooperation with the University of Massachusetts Burlington, Vermont, in cooperation with the University of Vermont Delaware, Ohio Durham, New Hampshire, in cooperation with the University of New Hampshire Hamden, Connecticut, in cooperation with

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The density and composition of regeneration drives future forest character for forests in need of replacement. Forested ecosystems face numerous regeneration stressors including invasive plants, insects and diseases, herbivory, lack of management, and climate change. As stands that make up these systems age, it is imperative to track the viability of forest reproduction. The information required for understanding the complexity of forest dynamics during the stand establishment stage has been lacking in our Nation's forest inventory. This poses a particular problem for analysts working with the major deciduous forest systems of the Midwest and Northeast United States that require detailed information on advance reproduction. To address this need, the Forest Inventory and Analysis (FIA) program of the U.S. Forest Service, Northern Research Station (NRS) has added protocols for measuring all established tree seedlings and for assessing browse impact. This information is compiled using new NRS-FIA forest sampling and analytical methodologiesthe regeneration indicator. The regeneration indicator is described along with examples and suggestions to guide research on the difficult question of whether the region's forests are able to regenerate in the face of numerous stressors. Cover Photos

The first full annual inventory of West Virginia's forests reports 12.0 million acres of forest land or 78 percent of the State's land area. The area of forest land has changed little since 2000. Of this land, 7.2 million acres (60 percent) are held by family forest owners. The current growing-stock inventory is 25 billion cubic feet-12 percent more than in 2000-and averages 2,136 cubic feet per acre. Yellow-poplar continues to lead in volume followed by white and chestnut oaks. Since 2000, the saw log portion of growing-stock volume has increased by 23 percent to 88 billion board feet. In the latest inventory, net growth exceeded removals for all major species. Detailed information on forest inventory methods and data quality estimates is included in a DVD at the back of this report. Tables of population estimates and a glossary are also included. AcknowledgmentsThe authors would like to thank West Virginia's inventory crew members over the 2004-2008 inventory cycle: