Greg C. Liknes

A strategic assessment of forest biomass and fuel reduction treatments in Western States

In the 15 western states there are at least 28 million acres of forest that could benefit from some type of mechanical treatment to reduce hazardous fuel loading. It is estimated that about 60 percent of this area could be operationally accessible for treatment with a total biomass treatment volume of 345 million bone dry tons (bdt). Two-thirds of this forest area is on public lands. Most of the volume is in trees 6 inches diameter and greater that have conventional utilization opportunities. Transportation cost and distance to markets, however, may preclude actual recovery. Treatment costs are increased by the need to treat large numbers of low-volume stems less than 4 inches in diameter. Gross costs can range from

Climatic regions as an indicator of forest coarse and fine woody debris carbon stocks in the United States

35 to over

Mapping trees outside forests using high-resolution aerial imagery: a comparison of pixel- and object-based classification approaches

1000 per acre depending on type of operation, terrain, and number of trees to be treated. Some areas will likely be prohibitively expensive to treat, although cost estimates presented here may be high because they are based on the use of conventional timber harvesting systems applied to small diameter treatments. Implementation of any significant fuel reduction effort will generate large volumes of biomass and require the development of additional workforce and operations capacity in western forests.

Wisconsin's forests, 2004

BackgroundCoarse and fine woody debris are substantial forest ecosystem carbon stocks; however, there is a lack of understanding how these detrital carbon stocks vary across forested landscapes. Because forest woody detritus production and decay rates may partially depend on climatic conditions, the accumulation of coarse and fine woody debris carbon stocks in forests may be correlated with climate. This study used a nationwide inventory of coarse and fine woody debris in the United States to examine how these carbon stocks vary by climatic regions and variables.ResultsMean coarse and fine woody debris forest carbon stocks vary by Köppens climatic regions across the United States. The highest carbon stocks were found in regions with cool summers while the lowest carbon stocks were found in arid desert/steppes or temperate humid regions. Coarse and fine woody debris carbon stocks were found to be positively correlated with available moisture and negatively correlated with maximum temperature.ConclusionIt was concluded with only medium confidence that coarse and fine woody debris carbon stocks may be at risk of becoming net emitter of carbon under a global climate warming scenario as increases in coarse or fine woody debris production (sinks) may be more than offset by increases in forest woody detritus decay rates (emission). Given the preliminary results of this study and the rather tenuous status of coarse and fine woody debris carbon stocks as either a source or sink of CO2, further research is suggested in the areas of forest detritus decay and production.

Map of distribution of six forest ownership types in the conterminous United States

Discrete trees and small groups of trees in nonforest settings are considered an essential resource around the world and are collectively referred to as trees outside forests (ToF). ToF provide important functions across the landscape, such as protecting soil and water resources, providing wildlife habitat, and improving farmstead energy efficiency and aesthetics. Despite the significance of ToF, forest and other natural resource inventory programs and geospatial land cover datasets that are available at a national scale do not include comprehensive information regarding ToF in the United States. Additional ground-based data collection and acquisition of specialized imagery to inventory these resources are expensive alternatives. As a potential solution, we identified two remote sensing-based approaches that use free high-resolution aerial imagery from the National Agriculture Imagery Program (NAIP) to map all tree cover in an agriculturally dominant landscape. We compared the results obtained using an unsupervised per-pixel classifier (independent component analysis—[ICA]) and an object-based image analysis (OBIA) procedure in Steele County, Minnesota, USA. Three types of accuracy assessments were used to evaluate how each method performed in terms of: (1) producing a county-level estimate of total tree-covered area, (2) correctly locating tree cover on the ground, and (3) how tree cover patch metrics computed from the classified outputs compared to those delineated by a human photo interpreter. Both approaches were found to be viable for mapping tree cover over a broad spatial extent and could serve to supplement ground-based inventory data. The ICA approach produced an estimate of total tree cover more similar to the photo-interpreted result, but the output from the OBIA method was more realistic in terms of describing the actual observed spatial pattern of tree cover.

Map of forest ownership in the conterminous United States. [Scale 1:7,500,000].

The first full, annualized inventory of Wisconsins forests was completed in 2004 after 6,478 forested plots were visited. There are more than 16.0 million acres of forest land in the Wisconsin, nearly half of the States land area; 15.8 million acres meet the definition of timberland. The total area of both forest land and timberland continues an upward trend that began in the 1960s. Red maple, sugar maple, and quaking aspen are the most common trees with diameters at breast height greater than 5 inches; there are 298, 250, and 244 million trees of these species, respectively. Aspen is the most common forest type, followed by sugar maple/beech/yellow birch, and white oak/red oak/hickory. This report includes detailed information on forest attributes and health and on agents of change such as the introduction of nonnative plants, insects, and diseases and changing land-use patterns.

Comparative assessment of methods for estimating tree canopy cover across a rural-to-urban gradient in the mid-Atlantic region of the USA

This map depicts the spatial distribution of ownership types across forest land in the conterminous United States circa 2009. The distribution is derived, in part, from Forest Inventory and Analysis (FIA) data that are collected at a sample intensity of approximately one plot per 2400 ha across the United States (U.S. Forest Service 2012). Ownership categories were mapped to the landscape using Thiessen polygons, and a forest/nonforest mask was applied to limit ownership portrayal to forested areas (Butler et al. 2014). Inset maps depict states by the percentage of forest land held by owner type indicated. States that appear darker do not necessarily have more forested land of a particular type than other states, but rather have a greater percentage of their forested land in a given ownership type.

Islands on the edge: housing development and other threats to America's Pacific and Caribbean Island forests: a Forests on the Edge report

This map depicts the spatial distribution of forest land across the conterminous United States, in 2007, differentiated into public vs. private forest land, and the percentage of corporate ownership of private forest land. Notable differences between eastern and western United States are evident on the map. Over two-thirds of western forest land is publicly owned, the majority of which is administered by the U.S. Forest Service as National Forests. In the east, more than 80 percent of forest land is privately owned.

Net change in forest density, 1873-2001. Using historical maps to monitor long-term forest trends.

Tree canopy cover significantly affects human and wildlife habitats, local hydrology, carbon cycles, fire behavior, and ecosystem services of all types. In addition, changes in tree canopy cover are both indicators and consequences of a wide variety of disturbances from urban development to climate change. There is growing demand for this information nationwide and across all land uses. The extensive inventory plot system managed by the USDA Forest Service Forest Inventory and Analysis (FIA) offers a unique opportunity for acquiring unbiased tree canopy cover information across broad areas. However, the estimates it produces had not yet been examined for comparative accuracy with other sources. In this study, we compared four different methods readily available and with significant potential for application over broad areas. The first two, field-collected and photointerpreted, are currently acquired by FIA on approximately 44,000 plots annually nationwide. The third method is a stem-mapping approach that models tree canopy cover from variables regularly measured on forested plots and is efficient enough to calculate nationwide. The fourth is a Geographic-Object-Based Image Analysis (GEOBIA) approach that uses both high-resolution imagery and leaf-off LiDAR data and has reported very high accuracies and spatial detail at state-wide levels of application. Differences in the spatial and temporal resolution and coverage of these four datasets suggest that they could provide complementary information if their relationships could be better understood. Plot- and county-level estimates of tree canopy cover derived from each of the four data sources were compared for 11 counties in Maryland, Pennsylvania, and West Virginia across a range of urbanization levels. We found high levels of systematic agreement between field and photointerpreted, stem-mapped and field, photointerpreted and GEOBIA estimates. In several cases, the relationship changed with the level of tree canopy cover. GEOBIA produced the highest tree cover estimates of all the methods compared. Results are discussed with respect to known differences between the methods and ground conditions found in both forest and nonforest areas.

Shape indexes for semi-automated detection of windbreaks in thematic tree cover maps from the central United States

This report provides an overview of expected housing density changes and related impacts to private forests on Americas islands in the Pacific and Caribbean, specifically Hawaii, Guam, American Samoa, the Commonwealth of the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands. We discuss the vulnerability of island forests to conversion for housing development, introduction and spread of invasive species, and risk of uncharacteristic wildfire, among other concerns. Our maps and projections suggest that in localized areas from 3 to 25 percent of private forest land is likely to experience a substantial increase in housing density from 2000 to 2030. Resource managers, developers, community leaders, and landowners should consider the impacts of housing development and invasive species on ecosystem services in coming decades.