Physiographic features

This ecological site occupies the highest portions of the Staten Island landscape. A distinct ridge primarily composed of serpentinite abruptly rises above the neighboring glacial sediments overlying Cretaceous and Triassic deposits. Local relief is 25 to 245 feet (8 to 75 meters). These sites are on summits, shoulders, and backslopes of ridges, with slopes ranging from 0 to 60 percent (mean slope of 25 percent).

No water table is found within the unconsolidated soil material overlying the serpentinite bedrock. The depth of soil over bedrock naturally represents the limit of field observation of water table and other properties. However, due to the geomorphic position of this site, it is with confidence that no water table is found within 60 inches (1.5 meters). The reported water table depth of 60 inches represents the maximum depth reported for ecological site descriptions and should be interpreted as greater than 60 inches.

Table 2. Representative physiographic features

Climatic features

In winter, the average temperature is 34.2 degrees F and the average daily minimum temperature is 27.4 degrees. The lowest temperature on record, which occurred on January 18, 1982, is -13 degrees. In summer, the average temperature is 68.0 degrees and the average daily maximum temperature is 81.9 degrees. The highest temperature, which occurred on July 3, 1966, is 105 degrees.

The average annual total precipitation is about 46 inches. Of this, about 33 inches, or 72 percent, usually falls in April through November. The growing season for most crops falls within this period. The heaviest 1-day rainfall during the period of record was 7.80 inches on August 14, 2011. Thunderstorms occur on about 15 days each year, and most occur in July.

Monthly precipitation in Staten Island is fairly uniform throughout the year (DeGaetano, 1999). However, on average, potential evapotranspiration exceeds precipitation during summer by 1.5 to 4.7 inches (4 to 12 cm). Occasional drought is a normal, recurrent feature of virtually every climate in the United States. However, even with a temperate moist climate, normal fluctuations in regional weather patterns can lead to periods of dry weather. The last severe droughts in New York State occurred in the mid-1960s and again in the early and mid-1980s (New York City Office of Emergency Management, 2009). Weather that brings 62 percent of normal precipitation or less occurs only one year out of 50 in New York City (Willeke, Hosking, & Guttman, 1994).

The average seasonal snowfall is 25.0 inches. The greatest snow depth at any one time during the period of record was 28 inches recorded on February 18, 2003 and February 4, 1961. On an average, 42 days per year have at least 1 inch of snow on the ground. The heaviest 1-day snowfall on record was 21.6 inches recorded on February 17, 2003.

The Atlantic hurricane season runs from June through November. The estimated return period for hurricanes passing within 50 nautical miles of Staten Island is 19 years (NOAA NWS, 2013). The return period for major (i.e. category 3 or greater) hurricanes is 74 years. Staten Island has no recorded direct or indirect hurricane strikes from 1900-2005, however the nearby New York and Kings counties each have category 3 hurricane indirect strikes recorded in 1938 and 1944 (Jarrell, Hebert, & Mayfield, 2010).

Future projections indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2 to11 percent by 2100 (Knutson et al., 2010).

Table 3. Representative climatic features

Influencing water features

There are no water features influencing this site.

Soil features

This ecological site is represented by soils in the Inceptisols soil order. Major soil series for this ecological site are Todthill and Wotalf. Map units having these soils as major components make up approximately 85 percent of the ecological site. The remaining 15 percent include serpentinite rock outcrop miscellaneous areas with inclusions of Wotalf and Todthill soils.

These soils have a mesic soil temperature regime, an udic soil moisture regime, and mixed mineralogy (Soil Survey Staff, Official Series Descriptions, 2013). They are shallow or moderately deep to a lithic contact (serpentinite bedrock) and have a loamy-skeletal particle size class.

A seasonal high water table is generally not observed in the soil above the bedrock contact (within 40 inches). The soil series associated with this ecological site are interpreted to be well drained according to New York drainage class standards. Saturated hydraulic conductivity in the soil material is moderately high and high (Soil Survey Staff, 2013).

Soils associated with this ecological site formed in a loamy till mantle overlying consolidated serpentinite bedrock. The till mantle is of mixed origin (serpentinite, red acid sandstone, siltstone, and shale), due to the flow direction of the glacial lobe that deposited material upon the serpentine ridge. Though this mantle is not formed of weathered serpentinite alone, these shallow to moderately deep soils express chemical properties associated with residual serpentine soils. The chemical properties include elevated levels of certain trace metals (e.g. chromium, nickel, and cobalt), low calcium-magnesium ratios, high pH, and elevated base saturation (Rabenhorst, Foss, and Fanning, 1982). This serpentine chemical signature provides an environmental stress allowing for the unique ecological states associated with this site. However, these unique chemical properties are less well expressed than their residual analogs that are found south of the terminal extent of the Wisconsinan glaciation (i.e. Maryland and Pennsylvania).

Where the till mantle thickens to greater than 40 inches (1 meter), the serpentine chemical properties are not well expressed or are absent. This ecological site is not correlated to these deep till components (Cheshire and similar soils).

The available water capacity values have a wide range due to the variable depth to bedrock contact. Expressed in total inches, the available water capacity range covers soils as shallow as 10 inches with high fragment content to soils as deep as 40 inches with relatively lower fragment content.

Table 4. Representative soil features

Animal community

Serpentine sites on Staten Island are typically small and isolated. A few sites are embedded in a larger area of natural areas and parklands known as the “The Greenbelt.” Wildlife habitat of serpentine sites, when viewed in context with the larger setting of “The Greenbelt,” provides for a variety of common suburban wildlife, including mammals, birds, reptiles, amphibians, arthropods as well as a rich variety of plants. (http://www.nycgovparks.org/greening/wildlife). In fact, “The Greenbelt” at Staten Island is considered one of the most biologically diverse places in New York City.

Wildlife habitat specifically limited to the more open serpentine habitats, such as the grasslands and barrens have been identified as important habitat for Lepidoptera e.g., the Arogos skipper (Atrytone arogos) (Matteson and Roberts, 2010). Recommendations to conserve butterfly and moth species include maintaining the open sites free from human disturbance, assessing the status of host plants, and increase monitoring and management of Lepidoptera and associated habitats.

Hydrological functions

Serpentine Till Uplands are mapped well drained but tending to excessively drained in stony barren sites. Surface runoff is medium or high in most areas. Coarse-textured soils with high percolation may have lower surface runoff rates. The severity of runoff increases directly with slope, and shallowness to bedrock.

Recreational uses

Due to the conservation significance of serpentine sites, recreational uses are limited. Most of the exposed serpentine on Staten Island is located within the The Greenbelt. The Greenbelt consists of 2800 acres of natural areas and traditional parklands, most of which is available for passive recreation. An extensive system of six major hiking trails exist which traverse through the serpentine areas. Centrally located, the Greenbelt Nature Center is a hub for a wide variety of activities and programs relating to The Greenbelt history, geography, flora, and fauna. Serpentine Art and Nature Commons manages an 11.5 acre serpentine site as a natural area on the slopes of Gryme Hill: open to hiking, schools, and interested groups.

Wood products

None.

Other products

None.

Other information

Conservation Measures

The serpentine till upland ecological sites on Staten Island are a small part of a limited and narrow, discontinuous band of a few disjoint serpentine sites located along the eastern edge of the Appalachian mountain system (Brooks, 1987). Due to the unusual nature of serpentine soils, the “serpentine syndrome” (Jenny, 1980), the associated flora and fauna include a large number of unique and uncommon species, which for several decades have become imperiled as a result of human disturbance. Consequently, conservation measures are necessary to sustain these serpentine ecosystems as follows: (1) desired conditions, (2) threats, (3) conservation management and strategies, and (4) inventory and monitoring.


(1) Desired conditions:
Desired conditions are attributes considered essential to maintaining the ecological character of an ecological site.

(i) Protect and conserve (restore, maintain, and enhance) serpentine sites and landscape context. Protect existing and potential serpentine sites from further loss or degradation of habitat due to development, or habitat conversion due to lack of management. Follow conservation goals to sustain a suite of serpentine habitats, including the plant communities of high stewardship value and the imperiled flora and fauna.

(ii) Conserve serpentine plant communities of highest stewardship value and component species (New York Natural Heritage Program, 2013). Plant community conservation priorities are the more open vegetation forms: (i) the reference phase serpentine grassland: little bluestem–Indiangrass (Schizachyrium scoparium–Sorghastrum nutans), and (ii) the [excavated] serpentine barrens state: little bluestem –white heath aster (Schizachyrium scoparium – Symphyotrichum ericoides. Secure serpentine species composition and richness, and address “focal” species issues of conservation status as well as invasive species. Secure populations of serpentine species of conservation status known to be present:
o green comet milkweed (Asclepias viridiflora) [threatened],
o purple milkweed (Asclepias purpurascens) [listed and ranked but unprotected],
o globose flatsedge (Cyperus echinatus) [endangered],
o velvet panic grass (Dichanthelium scoparium) [endangered].
Also, consider securing populations of serpentine species of conservation interest formerly present and consider translocation of populations of species at peril from similar serpentine sites, in consideration of future climate change scenarios.

(iii) Maintain or emulate ecosystem processes and patch dynamics. Historically, periodic, almost regular disturbances, such as fire and drought were necessary to maintain the mosaic of open and nutrient-poor character of serpentine sites as dynamic patches of habitat. Because a certain level of fire suppression is needed to provide for the safety of persons and property in the surrounding human settlements, the lack of fire has somewhat disrupted the cycle of serpentine patch dynamics. Without disturbance, the metapopulations of serpentine flora and associated fauna (especially lepidoptera) are extirpated without opportunities to return. Consequently, adaptive management practices are recommended to find alternatives to recreate the patchwork of open grasslands and barrens.


(2) Threats:
Threats to the upland till serpentine ecological sites are related to, and amplified by, the surrounding dense urban and suburban settlement of Staten Island (New York Natural Heritage Program, 2013). Principal threats include:

(i) Fire suppression and succession to woody overgrowth. Fire was the most important agent to maintain open, serpentine grassland habitats and to reduce organic matter accumulation at the soil surface. Hence, fire suppression has facilitated the succession of grasslands to woodlands at many locales. Large scale prescribed burns are unfeasible due to reasonable concerns over the safety of persons and property. Whether small, localized prescribed burns are effective or practical remains to be determined. Alternatives to fire may be tree cutting, land clearing, and removing biomass. Lack of fire also allows the accumulation of surface organic matter that increases the available water-holding capacity of the surface soils and nutrient availability and water-holding capacity to some degree.

(ii) Invasive and incursive species displacing native species. Invasive non-native plants and weedy incursive native plants displace native species and hasten succession to woody vegetation. The list is much longer, but the most problematic invasive species are: black locust (Robinia pseudoacacia), tree of heaven (Ailanthus altissima), multiflora rose (Rosa multiflora), Oriental bittersweet (Celastrus orbiculatus), Aralia elata (Japanese angelica tree), honeysuckles (Lonicera spp.), and common wormwood (Artemisia vulgaris).

(iii) Human disturbances, human-transported material, and off-trail impacts. Surrounded by dense urban and suburban settlements, the natural areas surrounding the serpentine sites are, unfortunately, used as dumping grounds. Much of the natural areas, especially The Greenbelt, are heavily used recreation areas, subject to human disturbances, such as off-trail biking and hiking that negatively impact the serpentine habitat.

(iv) Critically low or lost populations of conservation species associated with habitat decline. Habitat loss or decline is especially serious for the small isolated patches of open serpentine sites on Staten Island. The risk of extirpation (localized extinction) increases with shrinking available habitat. Extirpation of much of the serpentine flora has already happened (Reed, 1986). Large numbers of extirpated flora and precariously small numbers of remaining species warrant a comprehensive plant species reintroduction plan.

(v) Climate change scenario. Climate change in New England is trending toward extremes. Even with higher temperatures, greater droughtiness, and more severe and frequent precipitation events, the open, grassland and barren serpentine sites are expected to be somewhat resilient. Higher temperatures may lead to greater decomposition and hence less net organic matter accumulation. With more frequent droughts to stress woody plants, and less stress-tolerant invasives, serpentine grasslands and barrens would be better able to resist forest invasion. Also, with more frequent and severe precipitation, greater localized soil erosion will keep sites more open as desired.


(3) Conservation management strategies:
Improve the ecological conditions conducive to serpentine sites:

(i) Limit or control human access to sensitive areas. Much of the serpentine areas such as The Greenbelt and Serpentine Arts and Nature Commons are already enclosed with fencing, so additional fencing may be locally limited, if warranted. Due to maintenance and aesthetic issues, structural enclosures are, at best, considered as a last resort. Clearly designating and marking approved trails and closing unwanted social trails can effectively reduce human disturbances. Redirecting trails to avoid crossing sensitive areas or at least limiting trails to the periphery is desirable. Outreach opportunities exist through local conservation organizations, such as The Greenbelt Nature Center and the Serpentine Arts and Nature Commons, to foster a cult of responsibility aspired to protect and conserve serpentine sites.

(ii) Control invasive and incursive species (New York Natural Heritage Program, 2013). Because of the close proximity of serpentine sites to urban and suburban settlement as sources of plant propagules, the issue of aggressive non-native invasive plants and incursive native plants will always be a chronic problem. An invasive species management plan should address species-specific treatments. For example, root-sprouting woody plants such as black locust (Robinia pseudoacacia) and tree of heaven (Ailanthus altissima) are typically left intact and treated with a basal bark herbicide application to prevent suckering. Broadcast herbiciding is not recommended to avoid non-target, and sensitive plant species.

(iii) Mechanically remove soil surface organic matter or add serpentine parent material. Invasive or incursive plants are especially problematic in sites with better fertility and water-holding capacity because of appreciable surface organic matter accumulation. This also holds true for sites where the serpentine residuum is mixed with overlying till that dilutes the serpentine nature of the soil. Removal of the top few centimeters of organic matter accumulation and soil will not only expose the serpentine substrate desired for restoration, but may also expose the buried the seed bank, a potential source of serpentine plants. It may also open the site up to plant invasion. Likewise, adding serpentine parent material to the topsoil will restore the serpentine character of the soils, desirable for restoration. It may also introduce additions to the seed bank with plants more characteristic of serpentine sites and invasive plants as well. Invasive plants and, more typical serpentine plants alike, will germinate in the first flush, but usually the characteristic serpentine plants are more likely to persist under the restored serpentine and droughty soil conditions. Seeding and planting desirable species is a further enhancement.

(iv) Conduct localized, low-intensity prescribed burns. Large scale prescribed burns are presently considered unfeasible on Staten Island due to concerns over the safety of persons and property. Localized low intensity burns using a propane torch wand such as a weed dragon can focus the burn on woody invasives and emerging woody shoots. Historically, wildfires were most likely during the growing season; the timing of localized burns should suit the management objectives. The frequency of torching and smoldering the organic matter or topsoil remains to be tested, but it may reduce organic matter and the surface seedbank where a flush of invasives is anticipated.

(v) Reintroduce and augment characteristic serpentine plant species (including host plants for Lepidoptera). Small, isolated, patchy habitats of serpentine grasslands and barrens of Staten Island have long suffered extirpations because of small metapopulations. Many of the serpentine plant species that were once present may be suitable for reintroduction. This mimics nature’s reestablishment, except on a shorter time scale. Seed collection and banking conducted by the Greenbelt Native Plant Center can provide local genotypes as source materials. Seed sources may include other ex-situ conservation plant centers. Local genotypes may also be “rescued’ from nearby serpentine patches on Staten Island or from nearby Pennsylvania. Furthermore, in light of pending climate change, and the disjointed nature of serpentine areas throughout the east coast, it follows that serpentine plants with more southern affinities may be transplanted to augment the existing serpentine flora of Staten Island and as a conservation measure to sustain the regional serpentine flora.

(vi) Establish and maintain native buffers. In designated natural areas, natural buffers are typically recommended to insulate more sensitive areas from human disturbance. Fortunately, much of the serpentine areas embedded in The Greenbelt are sufficiently buffered with vegetation, which must be managed to exclude invasive or incursive plant species.

4. Inventory, monitoring, and research are needed (New York Natural Heritage Program, 2013).
Determine the nature, status, and identity of entities associated with serpentine under conservation management: e.g., soils, flora and fauna, vegetation.

The type and scope of inventory, monitoring, and research will be determined by the individual specific project objectives. The objectives may be, for example, a simple tally of plants or butterflies, or determining the effects of a specific management. Inventory, monitoring, and research designs and protocols are varied in scope and durations, and range from description to quantification using a wide range of technologies including GIS.

Inventory data references

The data contained in this document is derived from the analysis of field inventories (relevé plots and reconnaissance notes collected by MLRA Soil Survey Office 12-TOL with assistance from the NYC Greenbelt Native Plant Center, supplemented by plots data from NYSDEC-Natural Heritage Program), and literature interpretations (by MLRA Soil Survey Office 12-TOL), and communication with partners:
NYSDEC - New York Natural Heritage Program and
NYC Greenbelt Native Plant Center
New Jersey NRCS

Type locality

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Approval

Nels Barrett, 1/13/2020