Results & Discussion
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Landscape & Human Population Context
The following is a list of statistics that describes Hanover's changing conservation status in New Hampshire. These were compiled for every town in New Hampshire's Changing Landscape; Population Growth, Land Use Conversion, and Resource Fragmentation in the Granite State (1999).
- 50 square miles, 32,087 acres
- 638 acres of wetlands
- 117 acres of Environmental Protection Agency (EPA) high-value wetlands (26.5 acres of which are under protection)
- 1998 population: 9,636
- 54% increase since 1950
- projected population in 2020: 10,303 (6.9% increase)
- 184 people per square mile (1998); 209 per square mile projected in 2020
- 3.3 acres per person (1998); 3.1 acres per person projected in 2020
- 6,154 acres protected in 1998 (19.6% of town, with 0.65 acres protected per person)
- 467.2 acres of water supply lands in Hanover
- 26,412 acres of forest (84% of Hanover)
- 13,755 acres deciduous forests (43% of town)
- 8,073 acres coniferous forests (25% of town)
- 4,247 acres mixed deciduous/coniferous forests (13% of town)
- The remainder is small or fragmented blocks of forest (3% of town)
- 16 contiguous forests blocks in town are greater than 500 acres
- Average forest block size is 606.5 acres
- Predicted loss of forest land by 2020 is 425.7 acres
The thirteen neighboring towns in New Hampshire show two distinct trends in the amount of land and the amount of protected acreage per person (Table 1). Both are influenced by the landscape. The first trend is in population. In general, more people live in the southern and western towns around Hanover. Lebanon, Hanover, Enfield, and Canaan have the fewest acres per person, (i.e. the greatest population density). These towns have smaller forest blocks, have more developed land, and more fragmented landscapes. Towns to the east and north have many more acres per person, larger tracts of unbroken forest, and generally higher, more rugged topography.
The second trend is in protected lands. Six of the 14 towns have less than 10% of their lands under some form of protection (Table 1). All but two towns (Rumney and Orange) have between 10 and 20% protected lands. While Hanover has one of the lowest number of acres per person (meaning high population density), it has nearly 20% of its land base under some form of conservation protection. Hanover stands out in this regard. While Enfield has a similar pattern of population and protected land, much of their land protection is at one site, the Fish and Game Enfield Wildlife Management Area. Overall, towns in this area have low population density and a relatively low percent of protected land, compared to Hanover.
Although the protected area per person in Hanover (0.65 acres) is relatively small (ranking 12th of the 14 towns), Hanover's land conservation record is strengthened by the multiple management strategies and ownerships that make up their conservation lands. The Appalachian Trail (about 2,252 acres) and the Hanover Water Works (about 1,472 acres) are the largest protected lands, but Goodwin Forest (about 505 acres), Huntington Hill (about 471 acres), Oak Hill (about 254 acres), and the Dana Property (about 248 acres), and a variety of other conservation easements add to the diversity and extent of protected land.
Table 1. Conservation lands, acreage, protected acreage and total acreage per person for fourteen towns surrounding Hanover (Sundquist and Stevens 1999).
|Town||Total Acres||Conservation Land Acreage||Protected Acres per Person||Acres per Person, 1998 / 2020 Projected|
3.3 / 3.1
29.4 / 26.2
22.8 / 20.6
40.6 / 36.2
75.0 / 62.9
11,820 (44.0) (see note 1)
18.9 / 16.5
76.5 / 67.5
10.7 / 9.5
4,813 (32.6%) (see note 2)
57.6 / 51.2
2.1 / 1.9
6.5 / 5.8
27.9 / 24.9
15.4 / 13.4
12.8 / 10.9
Note 1: Most of protected land in Rumney is White Mountain National Forest land
Note 2: Most of protected land in Orange is Cardigan Mountain State Forest land
Rare Plants & Exemplary Natural Communities
Rare plants are defined by the New Hampshire Natural Heritage Inventory (NHNHI, see Appendix 1) as imperiled, either within New Hampshire, regionally, or globally. Exemplary natural communities are those ecosystem types that are either (1) rare (such as a silver maple floodplain forest), or (2) are common natural communities, but are represented in Hanover by the best examples of its type in the state (such as an old-growth spruce-fir forest). These determinations are based on years of data analysis and compiled records within the largest database of such information in the state (at NHNHI). State rarity ranks (e.g. S1, S2, etc.) are assigned based on current information on distribution and rarity of a given species or natural community. These records are kept at NHNHI (see Appendix 1).
In the Town of Hanover, there are currently fifty-two known locations of rare species and exemplary natural communities (collectively known as "element occurrences") in NHNHI's database (Appendix 1). However, of these fifty-two, only eight are currently considered viable, that is, recorded within the last 20 years. Each element occurrence is also ranked on whether its location is well documented or not, and of the eight current records, the location of only six can be considered well documented. Of these, we visited four to confirm their location and status. These included the natural communities at Bottomless Pit and Velvet Rocks, and northern waterleaf (Hydrophyllum virginianum, S2) a plant that is rare statewide (Rank S2; see Appendix 2 for rank explanations), which was present at Velvet Rocks (Appendix 1).
We also confirmed two additional rare plant occurrences that had been recorded previously; barren strawberry (Waldsteinia fragarioides, S1), last recorded near the mouth of Mink Brook in 1965; and Goldie's Fern (Dryopteris goldiana, S2), last seen at Velvet Rocks in 1939 (Appendix 1).
We re-visited currently known exemplary natural communities in Hanover as well. Bottomless Pit has exemplary occurrences of two natural communities: an acidic seepage swamp (S3), and a level bog (S2). The rich mesic forest (S1) at Velvet Rocks, along the Appalachian Trail, is also considered one of the best forests of its type in the state (Appendix 1).
During a recent field inventory of the new Mink Brook Nature Preserve, recently acquired by the Hanover Conservation Council, populations of rare northern waterleaf (Hydrophyllum virginianum, S2), and rare meadow horsetail (Equisetum pratense, S2) were also found (Alice Schori, personal communication).
During the 1999 late-summer growing season (August 11 and October 18, 1999), TNC ecologists visited eighteen specific sites in Hanover, at which sixty-three observation points were recorded (Figure 1, Appendix 6). We recorded twenty-nine different natural community types, seventeen from uplands, twelve from wetlands. Copies of original field forms are in Appendix 4.
We found no new examples of exemplary natural communities, nor new populations of statewide rare plants during our 1999 fieldwork. This may be due to the timing of field inventories and the spatially focused nature of our searches. More fieldwork needs to be done over the growing seasons of rare species to confirm their presence or absence.
Forests & Wetlands
The forest trees and other plant species in Hanover are influenced by a number of ecological, climatic, and physical factors. Much of the Connecticut River Valley is underlain by a bedrock type-Ammonusuc Volcanics-which contributes a relatively high concentration of nutrients to the soil (Appendix 6). Soils in the Connecticut River Valley are also slightly "enriched" due their unique glacial history. As the glaciers receded to the north, large sections of the river became lakes, which allowed fine sediments (clays and silts) to drop out of suspension and provide a slightly richer soil than in other parts of New Hampshire. The high quality of the valley soils, enhanced by past flooding and siltation, is evident in the highly productive agricultural fields in the Connecticut River Valley.
This unique combination of factors that "sweetened" the soil results in a higher diversity of trees and plant species than in many other parts of the state. While most of the forest trees and herbs in Hanover are similar to forests throughout central New Hampshire, trees needing higher concentrations of nutrients (e.g. butternut, white ash, and bitternut hickory) also thrive. Common forest floor wildflowers share the ground with less common maidenhair fern, wild ginger, the rare Goldie's fern and northern waterleaf. Common spring ephemeral wildflowers such as trilliums and spring beauties are joined by the rare squirrel corn. Other rare wildflower species may still exist in Hanover, although their presence has not been recorded, in some cases, since the late 1800s. These include golden corydalis, calypso orchid, ram's-head lady's-slippers and large yellow lady's-slippers. Appendix 1 provides a full list of the current and historical records of rare plants, animals, and natural communities in Hanover.
Forests in Hanover are mixed hardwood (e.g. oak, maple, birches) and softwood (e.g. white pine, hemlock), with ample evidence of post-colonial clearing for agriculture. In other words, most or all the forests in the town are second-growth. We did not record any old-growth stands, but this does not preclude the possibility that pockets with older trees and old-growth conditions exist in Hanover. For this study, we could only visit a small fraction of the total forested area in Hanover. Many of the natural communities in Hanover appear to be in good condition, with surrounding buffers.
The various types of wetlands in Hanover are generally in good condition. Mink Brook's watershed is lined with riverside forests, swamps, and shrub thickets. Pressey Brook and Scales Brook on the eastern edge of town are highly diverse wetland systems with high-quality streamside swamps and marshes. These are surrounded by forestland that provides varying amounts of intact buffer and ample wildlife habitat. Bottomless Pit is an impressive level bog, and has provided a long-term research area for Dartmouth College ecologists. While many Hanover wetlands are in good condition, surrounding lands and buffers are not ecologically intact in all locations.
Condition and size are important attributes of wetland quality. However, the surrounding lands also determine the integrity of these ecological systems, by influencing the ecological processes that sustain them. Development and excessive (or poorly managed) logging operations within a watershed are two factors that could impact wetland quality as Hanover continues to grow.
A Note About Forest Management
While the removal of timber from forests may alter natural patterns and ecological processes, careful timber harvesting in appropriate areas does not necessarily reduce the biodiversity value of a particular landscape. Good Forestry in the Granite State: Recommended Voluntary Forest Management Practices for New Hampshire (NH-FSSWT 1997) presents a description of Best Management Practices (BMPs) that can help protect natural resource values in managed forests (e.g. buffers, low-impact harvest practices, utilization of principles of sustainability, etc.). While most rare species and exemplary natural communities occur in habitats with little human alteration, managed timber lands can also contain viable populations of rare species if their presence is known and understood by foresters. On the other hand, inappropriate or incompatible forestry practices (i.e., those that do not follow known BMPs) can threaten biodiversity and reduce the future productivity of forest stands.
Current Conservation Lands
One of the many Geographical Information System (GIS) data layers for the state of New Hampshire that is housed with the GRANIT database at the University of New Hampshire catalogs and displays current conservation lands. This data layer originates from mapping by the Society for the Protection of New Hampshire's Forests. These lands are currently recognized as being under some form of protection, whether formally on informally. While these data are updated regularly, the current information may not include all lands under such protected status.
Conservation status is divided into three levels of protection and one Developed Public Lands category (GRANIT 1999; Figure 1):
- Permanent conservation land: Land protected from development through conservation easement, restrictions, or outright ownership by an organization or agency whose mission includes protecting land in perpetuity; more than 50% of the area will remain undeveloped;
- Unofficial conservation land: Owned by an agency or organization whose mission is not conservation, but whose intent is to keep the land for conservation, water supply protection, passive recreation, or educational purposes. Not permanently protected.
- Unprotected open space land
- Developed public land; including land having active recreational use on more than 50% of its area, e.g. beaches and picnic areas.