Background Materials for DTW Reports


Dirt to Trees to Wildlife (DTW) is an online tool consisting of DTW Mapper and this companion website housing information used by DTW Mapper to create reports about an area of interest.

DTW identifies potential forest types based on characteristics of the underlying soils. Over 1,400 distinct soils are grouped based on common characteristics that determine what vegetation grows on them. These soil groups are related to 18 forest types and three non-forest types. For ease of conversation, we refer to all 21 types as “forest types.” Since each forest type provides specific habitat needs, wildlife species that prefer a given forest type for breeding have been determined. Breeding habitats of 330 wildlife species are included.

Through DTW Mapper, you will receive a report allowing for a comparison of an existing forest type with potential forest types based on soils. Recommended forest management practices are provided for each forest type along with a list of wildlife species that uses each forest type for breeding. Species of Greatest Conservation Need (SGCN) as identified in at least one New England state Wildlife Action Plan are identified by forest type and recommended practices for each are available. The authors intend that land managers use this tool to make informed decisions affecting wildlife habitat specific to a subject property.

While this is a powerful tool combining research from three disciplines, you may find inconsistencies between this product and on-the-ground experience. Please email feedback to With help from users like you, this product will become even more powerful through time.

Following is a discussion about the three components of DTW (i.e., soils, silviculture and habitats).

  • DIRT: Soil Data and Relationships
  • TREES: Silviculture
  • WILDLIFE: Wildlife and Habitats

Dirt: Soil Data and Relationships

by Joe Homer, Soil Scientist

In New Hampshire, there are approximately 190 soil series and 1,400 soil map units. One hundred ninety soil series combined into 20 or so Leak Forest Habitat Groups. Common physical properties were used, primarily parent material, dominant soil texture, drainage class and depth to bedrock. These concepts are traditionally used to group soils to develop interpretations for a wide variety of uses. Some correlations from soil series to Forest Habitat Groups were straightforward while others required professional judgment. 

Original versions of the correlation between soil series and Forest Habitat Groups were done to promote soil mapping in the White Mountain National Forest and based on work in the Bartlett Experimental Forest. With further modification, the groupings and concepts were expanded to all of New Hampshire using common physical properties, parent material, dominant soil texture, drainage class and depth to bedrock.

The close relationship between soil properties and vegetation in a natural, undisturbed (unmanaged) setting is well-established. From the Massachusetts to the Canadian border in New Hampshire, we see distinct changes in tree species and vegetation. The species we see growing on wet or moist compact glacial till (Forest Habitat Group 4) in Rockingham County along the Massachusetts border will often be different than those in Coös County along the Canadian border. As we move forward with field-testing and refinements, forestry professionals input is needed to further fine-tune forest types-to-soil groupings. Further collaborations between soil scientists, foresters and wildlife biologists using this information will produce refined interpretations for the management of forests and wildlife.

Soil Map Unit Concepts

During the mapping of soils on a county-wide basis by the NRCS, map unit concepts that include slope, surface texture and stoniness are developed based on soil series. Soil map units are not pure and do not contain 100 percent of the soil named in the map unit. In most New Hampshire soil map units, approximately 85% of the soil within any given delineation or polygon is the named soil or soils in the map unit name. A map unit description is written for each soil map unit, which describes inclusions within the map unit, names the inclusions, and identifies the properties and percentages of each inclusion. A specific site on the landscape, may be on an inclusion within a map unit.

Kinds of Soil Map Units

On the landscape, soil areas differ in size and shape, in degree of contrast with adjacent soils, and in geographic relationships. Four kinds of map units are used in New Hampshire county-wide soil surveys to show these relationships: consociations, complexes, associations, and undifferentiated groups.

  • Consociations—Delineated areas are dominantly a single soil series. Generally, about 85% of the delineation is the soil series named for the map unit. Most of the remainder of the delineation consists of soil components so similar to the named soil that major interpretations are not affected significantly.
  • Complexes and associations—Consist of two or more dissimilar components occurring in a regularly repeating pattern. Complexes and associations are used in areas where the individual soil components cannot be mapped separately at a scale of mapping for the county. In both complexes and associations, the major components are sufficiently different in morphology or behavior that the map unit cannot be called a consociation. In each delineation of either a complex or an association, each major component is normally present, though their proportions may vary appreciably from one delineation to another. The total amount of inclusions in a map unit that are dissimilar to any of the major components does not exceed about 15 percent if limiting and 25 percent if non-limiting, and a single kind of dissimilar limiting inclusion generally does not exceed 10 percent if very contrasting.
  • Undifferentiated groups—Consist of two or more soil components that are not consistently associated geographically and, therefore, do not always occur together in the same map delineation. These soils are included as the same named map unit because use and management are the same or very similar for common uses. Generally, they are included together because some common feature such as steepness, stoniness, or flooding determines use and management. Every delineation has at least one of the major components and some may have all of them. The same principles regarding proportion of inclusions apply to undifferentiated groups as to consociations.

Soil Map Orders

In New Hampshire county-wide NRCS soil surveys, two mapping Orders are used. Most of New Hampshire is mapped at the Order II level of intensity. Order II mapping is designed for general land use planning and includes a variety of interpretations for urban and agricultural uses (house lots, septic systems, roads, corn, hay, row crops, etc.) as well as forestry, recreation and wildlife. Some areas in Coös, Grafton, Carroll and limited areas in Cheshire counties are mapped at the Order III level of intensity because forestry, recreation and wildlife were the primary land uses and it was anticipated at the time of mapping that interpretations for urban and agricultural uses were not required. The introductory section of each NRCS county soil survey report provides information about mapping intensities within the county.

Soil Map Units – Minimum Delineation Size

At the start of an NRCS county-wide soil survey, the project leader makes a decision on the minimum size delineation applied throughout the county. In New Hampshire, this varies from county to county. The decision is based largely on intended uses for the mapping and interpretations, and the scale of imagery used during the mapping process. In Coös and Grafton counties, in areas mapped at the Order II level of intensity, the minimum size delineations are approximately 3 acres. Order III minimum delineations are approximately 40 acres in Coös County and 10 acres in Grafton. Throughout the rest of the state, minimum size delineations are generally 5 to 6 acres at the Order II level of mapping intensity.

Trees: Silviculture

by Brendan Prusik, Forester

Dirt to Trees to Widlife includes 21 vegetation types, including three non-forest types—Speckled Alder, Palustrine (associated with wetlands) and Upland (associated with non-wetland soils). For ease of conversation, we refer to all 21 types as “forest types.” Basic recommendations are included for each forest type to maximize diversity of breeding habitats appropriate for that forest type. To enhance select species, links to strategies for managing Species of Greatest Conservation Need are included.



Paper Birch

Northern Hardwoods

Sugar Maple, American Beech, Yellow Birch


Yellow Birch

Sugar Maple

Southern Hardwoods

Red Maple

Silver Maple


Balsam Fir


Red Spruce

Balsam Fir (high elevation)

Red Spruce (high elevation)

Spruce-Fir (high elevation)




Northern Red Oak


Eastern White Pine

Speckled Alder

Speckled Alder




Wildlife: Wildlife and Habitats

by John Lanier, Wildlife Biologist

The Atlantic Coast Joint Venture (ACJV) set common goals for bird conservation in the Atlantic Flyway. ACJV has grouped much of the North American Atlantic Coast into Bird Conservation Regions (BCR). These BCRs are considered by most biologists a standard foundation for wildlife conservation work. The DTW tool covers Bird Conservation Region 14 (BCR14), which includes lands from northwestern Connecticut to the Gulf of St Lawrence. The only portion of New Hampshire that does not fall within BCR14 is its coastal area.

The Technical Guide to Forest Wildlife Habitat Management in New England (DeGraaf, 2007) lists 330 wildlife species applicable to BCR14. This list varies from salamanders to moose and everything in between. Over 90 of these have been identified as Species of Greatest Conservation Need (SGCN) in one or more of the Wildlife Action Plans in the New England states. Each of these species show breeding preference for one or more of 21 forest types that are incorporated in this tool. Each wildlife species is assigned to the forest type(s) it prefers for breeding. It is recognized that some wildlife species may use other types for breeding but this tool intends to identify the most important ones.

Recommendations are provided for each of the 90 plus SGCN. In some cases, such as woodcock, golden-winged warbler, bald eagle and New England cottontail, the recommendations were developed by working groups. However, for most of these species, recommendations were developed based on the best available knowledge by individuals working on DTW. These recommended practices are basic and the expectation is to improve them as knowledge of the special habitat requirements for each SGCN species changes.

Before implementing any project consider bats: Forest managment could impact non-migratory bats

Six out of the nine species of bats in BCR14 are non-migratory and their populations are being severely impacted by a disease known as White Nose Syndrome (WNS). BCR 14 is in the middle of the WNS Zone as delineated by the U.S. Fish and Wildlife Service. Two of these non-migratory species have Federal status under the Endangered Species Act. The Indiana bat is listed as endangered, and the northern long-eared bat is listed as threatened. The other four could possibly become listed federally and are listed in several states within BCR 14. The Indiana bat is, at present, confined to the Champlain Valley in Vermont. The northern long-eared bat, however, is present all through BCR 14. The other species are also present across BCR14, with migratory bats hibernating outside of BCR 14. Bats feed on insects captured over forested canopies, wetlands, water bodies and non-forested openings such as fields. Most roost in hollow trees under shaggy bark by hanging off tree branches, or in buildings. They are not fussy about which forest type they hunt over or through, and do not seem to be very selective about where they roost although some like it warmer than others.

Bats can be all over the place and can be impacted by forest management activities unless they are hibernating. Even then, the forested conditions around where they hibernate can be adversely modified by forest management activities. The forested conditions around their hibernacula are where they gather just prior to hibernation (known as swarming) to breed and just following hibernation in the spring (known as staging).

Before implementing any project, contact your state wildlife agency to learn if there are known hibernacula or recorded roost trees or other habitat concerns in or near the project. There are federal regulations governing the Indiana and northern long-eared bats and there may be other state regulations as well.

If either the Indiana or northern-long-eared bat may be affected by the project, and there are federal funds supporting the project, follow rule 4d under the Endangered Species Act (January 13, 2016) and we recommend that the 4d rule process be followed for every project, federally funded or not.