LEARNING & EXPLORING

ORV Detail - Unique Species and Natural Communities

Additional Unique Species and Natural Communities Documents

Plant and Natural Community Survey 03 Summary - PDF from Watershed Management Plan

The following text is an excerpt from the Watershed Management Plan Chapter VI.

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1. Outstanding Resource Value

The rarity, diversity and abundance of species and natural communities in the Eightmile River Watershed tell a significant amount about the quality of the watershed ecosystem and its biological diversity. The size and quality of habitat, along with the physical, biological, chemical and hydrologic conditions of the water all interrelate with and influence the species and communities that are found in the Watershed. The species and communities, whether rare or common, are important to overall ecosystem function. From insects, to birds, to mammals they all play a role in ecosystem health and their presence or absence can cause significant effects to overall ecosystem quality.

A number of different research analyses were completed over the course of the Study to understand the species and natural communities of the Eightmile River Watershed. All were led by William H. Moorhead. A summary of his findings and reports follows.

A three week field survey of the botany and natural communities in the watershed performed by Moorhead, in the summer of 2003 approximately doubled the number of extant occurrences of state-listed rare plants known in the Eightmile watershed, bringing the total of known extant State-listed plant occurrences in the watershed to 54 occurrences. Eleven of these species are also New England regional rare species, and several of these occurrences are of regional significance.

Moorhead also surveyed for natural communities and reported that approximately 100 occurrences of natural communities in the watershed were “significant”. Communities were deemed significant on the basis of rarity, uncommonness or restricted occurrence (factoring in threats, and rate and magnitude of decline over the last century), high native-species-richness (often including multiple rare and uncommon plant species), and/or exemplary character and/or condition (especially with respect to relative prominence of exotic and/or invasive species). Eighteen of the communities were ranked as being exemplary for biodiversity significance.

Potentially the most important biodiversity features of the Eightmile River watershed are the extensive meta-occurrence of so-called “warm-season” grasslands, which include, more frequently, little bluestem dominated grasslands, and, less frequently, big bluestem dominated “prairies”. These dry to seasonally wet/dry grasslands, which require periodic anthropogenic disturbance (fire or mowing) to persist as open-canopy communities, represent among other things an important reservoir of native genotypes of grass species whose seeds of non-local origin are purchased and planted at considerable expense by land managers in efforts to create warm-season grassland habitat around New England. There appears to be a strong positive correlation between the occurrence and prominence of the tall-grass prairie species and the occurrence of rare and uncommon herbaceous species, and a similar, but somewhat weaker, positive correlation between little bluestem dominated grasslands and the occurrence of rare and uncommon herbaceous species.

The quantity of “at-risk” plant and animal species known from the Eightmile River watershed is substantial. A summary of species considered to be “rare”, “threatened”, or “endangered”, in a state, regional, and/or global context, and species that have been identified by various organizations as of special concern for conservation, due to documented declines and threats, such as loss of habitat, shows a total of 155 such species in the watershed. This list is comprised of 32 vascular plants, 6 amphibians, 81 bird species, 8 fish species, 12 invertebrate species, 7 reptiles and turtles, and 9 mammals.

In addition to the information provided above, there are several ways in which the regional biodiversity significance of the Eightmile River Watershed may be assessed. One way is to compare the number of rare species found in the Eightmile to other watersheds of comparable scale in the region. Toward this end, in late 2004, Natureserve.org was commissioned by the Eightmile River Wild & Scenic Study Committee to create a tally of extant rare species for all of the drainage basins of similar size in New England. This analysis was a first of its kind in New England.

The Eightmile River mainstem watershed, a sub-watershed of the entire Eightmile River Watershed, ranks among New England regional and sub-regional basins as having one of the highest concentrations of extant rare species. When the Eightmile mainstem watershed is ranked among the 417 New England regional basins in terms of number of extant rare species per unit basin area, it ranks in the 96th percentile in terms of extant total rare species/unit basin area, and in the 99th percentile, in terms of extant globally rare species/unit basin area. Other analysis of the Eightmile mainstem basin found similar results.

Overall the combination of species and natural communities offer the rarity, abundance and diversity that support a biologically diverse Eightmile River Watershed ecosystem. This combination is something that is clearly unique and exemplary not only within Connecticut but throughout New England, and as such qualifies as an outstanding resource value for the Eightmile River Watershed.

Two reports on the unique species and natural communities of the Eightmile River Watershed can be found in Appendix 4: Outstanding Resource Value Report and Unique Species and Natural Communities and Appendix 6: Outstanding Resource Value Report – The Watershed Ecosystem.

See Map [4]: Habitat Diversity and Map [5]: Rare Species Areas and Significant Natural Communities

2. How Unique Species and Natural Communities are Threatened

An analysis of potential threats to the species and natural communities of the Eightmile River Watershed identified 16 activities that could significantly degrade this outstanding resource value. Most of the threats identified to potentially impact the quality of unique species and natural communities were ranked as “highly likely” for causing an impact making this outstanding resource value the most vulnerable of all to degradation, with water quality and the watershed ecosystem close behind.

As with other outstanding resource values, impacts from development activities were identified as a major source of potential degradation. Activities including increases in impervious surfaces, the spread of suburban lawns, degrading riparian corridors, altering or filling small streams and wetlands, and fragmentation of habitat caused by new development activity all have great potential to impact the diversity, rarity and abundance of unique species and natural communities in the Eightmile River Watershed.

The large unfragmented blocks of land, from 500 to over 2,500 acres in size, are a critically important asset for the Eightmile River Watershed. Habitat fragmentation occurs when a large region of habitat has been split into a collection of smaller patches. This happens typically when land is converted from one type of use to another. For example, a forest habitat may become fragmented when a road is built across it. The road divides the single large continuous patch of forest into two smaller disconnected patches.

Fragmentation can cause, among other things: a reduction of total habitat area; vulnerability for species forced to migrate to other habitat patches; the isolation of populations leading to a decline in population size and quality; and edge effects altering habitat, species composition, microclimates, and vulnerability to predation.

Invasive species are another substantial threat to the abundance, diversity and rarity of species and communities currently in the Eightmile River Watershed. Species such as purple loosestrife, multiflora rose, phragmites and Japanese barberry, which already dominate in certain areas, have the potential to cause significant degradation of species and natural community habitat if not managed appropriately. Also, water chestnut, a very aggressive aquatic invasive plant was discovered in Hamburg Cover. Water chestnut like other aquatic invasive plants has the potential to infest waterbodies and critical environmental habitats. The single plant that was found was removed, however water chestnut seed may be able to produce new plants for up to 12 years. Deer were also identified as a nuisance species that are causing significant damage to plants and trees across the watershed.

3. Existing Protections and Gaps

In order to understand potential additional protection needs for unique species and natural communities a comprehensive review was completed of current protection measures planned and implemented at the local, state and federal level.

Some of the key protection tools currently in place include:

Each community has local inland wetland regulations, including upland review areas, to protect wetland functions and values.
Open space planning and acquisition is occurring, especially in Lyme, to help prevent habitat fragmentation and protect important habitats.
East Haddam requires conservation subdivision design that calls for identifying wildlife habitats and state-listed rare species.
East Haddam inland wetland regulations include a 400-foot review area around vernal pools.
East Haddam requires new stormwater systems to be designed following the state stormwater quality manual.
Net buildable area calculations are required for determining lot density of subdivisions for all three towns, supporting areas more suitable for building and protecting areas more sensitive to development.
The State endangered species act helps protect state threatened and endangered species associated with state funded, conducted or permitted projects.
The Gateway Zone in Lyme includes protection of riparian areas through a zoning setback requirement of 50 feet for no vegetative cutting and 100 for no structures.
The Eightmile River is an officially-designated state greenway.

Gaps in protection were identified as a result of comparing known threats to unique species and natural communities with existing protection measures. Primary gaps in protecting unique species and natural communities were found to be associated with:

New as of right agricultural uses affecting wetlands and watercourses
Suburban lawns
A lack of current and comprehensive unique species and natural community information
Watercourse crossings
Regulating timber cutting operations
Limited powers of state endangered species act
Assessment and control of invasive species
Limitation of public and private funds for protecting key parcels of land
The impact of poorly planned development affecting intact habitat areas and causing habitat fragmentation

4. Unique Species and Natural Communities Protection Goal

The unique species and natural communities goal for the Eightmile River Watershed is to recognize and protect the unique, rare, declining and common plants, animals and natural communities of the Eightmile River Watershed that are vital to the area’s rich biodiversity.

5. Unique Species and Natural Communities Indicators

a. Species and Natural Community Rarity
b. Species and Natural Community Diversity
c. Species and Natural Community Abundance
d. Presence of large, contiguous habitat blocks
e. Natural Hydrology and Unimpaired Water Quality
f. Aquatic and Upland Habitat Connectivity
g. Natural Cover
h. Invasive Nuisance Species