Map Descriptions

Map Descriptions

This section provides a brief description of each map included in this report. It follows the sequence of maps that were developed and used to prioritize field sites. Each map provided crucial preliminary information that guided our summer 1999 fieldwork. The sites chosen for fieldwork, as well as additional sites within the town that have important landscape features, are described briefly in the section on site descriptions.

Hanover Base Map

Other maps in this report follow the same general format as this Base Map. Surface features that help people familiar with the town to find specific locations are presented, including major roads and trails, surface waters, and the town boundary. The Conservation Lands layer was mapped by the Society of Protection of New Hampshire Forests, and was last updated by Complex Systems Research Center (University of New Hampshire) in 1998. It includes all lands under some form of protection, ranging from active Developed Public Land to Permanent Conservation Lands. Also on the base map are the locations of 1999 Observation Points.

Hanover Tax Map

Provided by the Hanover Planning Office, this map shows the current ownership patterns. This map is projected differently than other state data layers depicted in this report, and could not be overlain with other data layers.

Topographic Relief

The top map is the National Elevation Database digital elevation model shaded relief map from the U.S. Geologic Survey. The bottom map depicts meter elevation topography lines, from a statewide hypsography (elevation) data layer, distributed by Complex Systems Research Center (UNH).

The highest elevations in Hanover, along the Moose Mountain ridgeline, contain several of the town's least common natural community types. Rocky ridgelines with spruce and fir occur there, with other plant species, though not rare statewide, are found nowhere else in Hanover (e.g. pink corydalis, Corydalis sempervirens). Moose Mountain is also the only place in Hanover with significant evidence of the January 1998 ice storm. Trees in both the heavy and light damage areas are still broken, bent, and difficult to hike through. While this storm event substantially changed the character of the forest, trees and other vegetation are already recovering. Salvage timber operations since the ice storm will also have an effect on recovering forests and wildlife patterns. It may be years until the full effect of this region-wide storm is understood.

Hydrologic Features

This composite map shows the distribution of important hydrological features in and around Hanover. It combines both surface and groundwater features, hydric soils, ponded waters, and hydric soils. Of particular note is the diversity of hydrologic features at Pressey, Mink, and Scales/Lovejoy Brooks.

Composite Field Map

This composite map combines the features that we used to prioritize field sites. These include:

  • Topography
  • Aquifers
  • Wetlands
  • Hydric soils
  • Surface waters
  • Current conservation lands

Hydrologic diversity (e.g. multiple features within one wetland complex) was important in selecting sites around Mink, Pressey, Scales and Lovejoy Brooks as targets for fieldwork. We visited Bottomless Pit due to its uniqueness in the town. Greensboro Road Wetland, and Three Mile Wetland provided good examples of the more common beaver flowage wetlands in the town.

We chose high-elevation sites, occasionally with steep slopes, because they also have a tendency to support unusual natural communities and plants. The Moose Mountain ridgeline was the obvious choice, but we also visited sites with relatively high elevation and steep slopes west of Moose Mountain, including Lord's Hill, Oak Hill, and hills north of Greensboro Road.

Conservation lands that have already protected unique areas or important town land management areas also provided important field sites. The Hanover Waterworks land is managed for timber, but provides a large, unbroken swath of forest land important for wildlife, forest buffer, and maintenance of high water quality. The Appalachian Trail lands traverse some of the most beautiful and intact forest land in the town, and harbor several known locations of rare plants and exemplary natural communities. Huntington Hill, Mink Brook lands (including the Dana Property), and Bottomless Pit, although already under current protection, could serve as core areas around which more conservation lands could be added.

Forest Blocks

Large tracts of contiguous forest blocks are a current focus for protecting common, large forests that harbor both common and rare species, habitats and natural communities. These help maintain ecological processes (such as nutrient cycling and water filtration) within these common forest types that are essential for the long-term protection of biodiversity. This map uses roads to break forest tracts into large blocks that are color-coded by size of the specific block. This Hanover map is a portion of a statewide forest block map produced by the University of Vermont's Spatial Analysis Laboratory (1998). While many forest blocks in Hanover are larger than 1,000 acres, none are larger than 10,000 acres, although a nearby forest block larger than 25,000 acres extends to the northeast from Hanover's extreme northeastern corner. Conservation planning at a regional level has recognized these large landscapes, and multi-town efforts to protect large forest blocks may be an effective means of conserving such extensive contiguous blocks.

Forest Cover

While producing a complete habitat map for the entire town of Hanover is beyond the scope of this project, this forest cover type map may provide a useful framework for such an effort. This is a portion of a statewide forest cover map produced by the UVM Spatial Analysis Laboratory using Landsat TM satellite imagery from 1992-1993. It is currently fairly coarse, but it depicts deciduous, coniferous, and mixed forest cover types, and several non-forested cover types as well. These kinds of maps are growing increasingly accurate and should soon be excellent tools for habitat mapping in towns.

The information on this map combined with aerial photographs and 1999 field data (Appendix 3 and 4) would provide a good baseline for additional field inventories and timber stand information.

Regional Forest Blocks

At a broader landscape scale than the town, forest blocks reflect patterns in historical population trends, which have been strongly influenced by topography. East and north of Hanover the foothills of the White Mountains provide vast tracts of forested wilderness. The southwestern corner of the White Mountain National Forest, in Rumney and Wentworth, represents a tiny corner of New Hampshire's larger central forests. South of Hanover, forests are more fragmented by higher population density and agricultural land-use patterns.

Hanover Forest Blocks with Road Buffer

It is useful to identify forest blocks at the town level, as well as the regional level, in order to provide guidance for town planning. The constraints of political boundaries are artificial with respect to natural communities and species distribution. Of course, Hanover must focus on its own lands, but it is important to keep neighboring communities in mind.

In order to assess Hanover's forest blocks, TNC used ArcView (a geographic information system - GIS - software package) to create a one-hundred-meter (approximately 300 feet) buffer around current roads to define contiguous blocks of land left within the roaded perimeters. (Although the scientific literature varies in its conclusions about buffer width, 100 meters is often a standard distance from roads necessary to ensure natural conditions.) While a road may encroach into a block, it actually defines a block only if the land is completely surrounded (for example, Moose Mountain Road climbs the mountain from the west, but does not bisect the entire mountain to divide it into two forest blocks).

There are 19 forest blocks greater than 250 acres, and fourteen of these serve as the basis for the following site descriptions. Due to limited information and the limitations of current field data, we felt we could not comment on five of the nineteen blocks at this time. Parcel size can help focus land management decisions on the important landscapes for recreation, timber management, protection of biodiversity, and other values.

However, size is not the only consideration. For example, rare plants near the mouth of Mink Brook do not occur in a large forest block, but their protection is desirable at the local scale in which they grow. The Mink Brook Nature Preserve and Mink Brook Wetlands Area should protect these plants. On the other hand, the Connecticut River Block may be large, but because of its linear shape, extensive edge, and narrow buffer areas it does not qualify as a high-priority large forest block.