Many animals depend on vernal pools, especially for breeding. Most of these animals such as frogs, toads, turtles, and salamanders spend a majority of their life in nearby wetlands but migrate to breed or feed in productive vernal pools. Fingernail clams and air-breathing snails live their entire life in vernal pools and must burrow beneath leaves and mud when the pool dries until the water returns. Fairy shrimp produce eggs that remain in the dry pool after the adult's death and hatch after the pool refills.
There are probably a few thousand occurrences statewide. Vernal pools are typically small (i.e., generally under one acre) and may be overlooked as wetlands after the water draws down. A few documented occurrences have good viability and are protected on public land or private conservation land. This community has statewide distribution, and likely includes several high quality examples. The current trend of this community is probably stable for occurrences on public land, or declining slightly elsewhere due to moderate threats related to development pressure, alteration to the natural hydrology, and reduced protection regulations for isolated wetlands. This community has probably declined moderately from historical numbers likely correlated with logging and development of the surrounding landscape.
The number and acreage of vernal pools in New York have probably declined in recent decades as a result of reduced protection regulations for isolated wetlands. Their relatively small size and seasonal hydroperiod may have contributed to the decline with many occurrences going undetected as regulated wetlands.
The number and acreage of vernal pools in New York have declined moderately from historical numbers likely correlated to the alteration to the natural hydrology and direct destruction, in both forested and urban areas.
In 2001, the federal Supreme Court ruled that the US Congress did not give authority to the US Army Corps of Engineers (US ACE) under section 404 of the Clean Water Act to regulate the filling of isolated wetlands. This decision led US EPA and US ACE officials to issue guidance in January 2003 that made it more difficult for regulators to protect isolated wetlands, such as vernal pools (Brooks and Paton 2005). Vernal pools are threatened by development (e.g., agriculture, residential, roads) and its associated run-off (e.g., septic, silt, nutrients), habitat alteration (e.g., excessive logging, pollution, trash dumping), and recreational overuse (e.g., ATVs). Alteration to the natural hydrological regime is also a threat to this community (e.g., ditching, impoundments).
Where practical, establish and maintain a natural wetland buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the vernal pool. Buffer width should take into account the erodibility of the surrounding soils, slope steepness, and use of the surrounding upland by vernal pool fauna. Wetlands protected under Article 24 are known as New York State "regulated" wetlands. The regulated area includes the wetlands themselves, as well as a protective buffer or "adjacent area" extending 100 feet landward of the wetland boundary (NYS DEC 1995). Vernal pools seldom meet the size criteria for state regulated wetland. If possible, minimize the number and size of impervious surfaces in the surrounding landscape. Avoid habitat alteration within the wetland and surrounding landscape. For example, roads and trails should be routed around vernal pools, and ideally should not pass through the buffer area. Restore vernal pools that have been unnaturally disturbed (e.g., remove obsolete impoundments and ditches in order to restore the natural hydrology). Prevent the spread of invasive exotic species into the wetland through appropriate direct management, and by minimizing potential dispersal corridors, such as roads.
Specific management recommendations for vernal pools can be found in the following: 1) Best Development Practices: Conserving Pool-Breeding Amphibians in Residential and Commercial Developments in the Northeastern United States (Calhoun and Klemens 2002), and 2) Forestry Habitat Management Guidelines for Vernal Pool Wildlife (Calhoun and deMaynadier 2004).
When considering road construction and other development activities minimize actions that will change what water carries and how water travels to this community, both on the surface and underground. Water traveling over-the-ground as run-off usually carries an abundance of silt, clay, and other particulates during (and often after) a construction project. While still suspended in the water, these particulates make it difficult for aquatic animals to find food; after settling to the bottom of the wetland, these particulates bury small plants and animals and alter the natural functions of the community in many other ways. Thus, road construction and development activities near this community type should strive to minimize particulate-laden run-off into this community. Water traveling on the ground or seeping through the ground also carries dissolved minerals and chemicals. Road salt, for example, is becoming an increasing problem both to natural communities and as a contaminant in household wells. Fertilizers, detergents, and other chemicals that increase the nutrient levels in wetlands cause algae blooms and eventually an oxygen-depleted environment where few animals can live. Herbicides and pesticides often travel far from where they are applied and have lasting effects on the quality of the natural community. So, road construction and other development activities should strive to consider: 1. how water moves through the ground, 2. the types of dissolved substances these development activities may release, and 3. how to minimize the potential for these dissolved substances to reach this natural community.
Survey for occurrences statewide to advance documentation and classification of vernal pools. Finding occurrences with several pools forming a complex should be a priority. A statewide review of vernal pools is desirable.
Research is needed to fill information gaps about vernal pools, especially to advance our understanding of their classification, hydrology, floristic variation, and characteristic fauna. Research is needed to see if vernal pool species assemblages are related to the underlying bedrock (e.g., acidic vs. alkaline) and/or the surrounding forest type (e.g., needle-leaf evergreen vs. broad-leaf deciduous).
This community is widespread throughout New York State. It is probably represented by different regional variants.
This physically broadly-defined community may be worldwide. Examples with the greatest biotic affinities to New York occurrences are suspected to span north to southern Canada, west to Minnesota, southwest to Indiana and Tennessee, southeast to Georgia, and northeast to Nova Scotia.
Vernal pools are intermittently to ephemerally ponded, small, shallow depressions usually located within an upland forest. They are typically flooded in spring or after a heavy rainfall, but are usually dry during summer. Many vernal pools are filled again in autumn. The substrate is dense leaf litter over hydric soils. Vernal pools typically occupy a confined basin (i.e., a standing waterbody without a flowing outlet), but may have an intermittent stream flowing out of it during high water. Since vernal pools cannot support fish populations, there is no threat of fish predation on amphibian eggs or invertebrate larvae. Characteristic animals of vernal pools include species of amphibians, reptiles, crustaceans, mollusks, annelids, and insects. Vernal pool amphibians include spotted salamander (Ambystoma maculatum), blue-spotted salamander (A. laterale), Jefferson's salamander (A. jeffersonianum), marbled salamander (A. opacum), and wood frog (Rana sylvatica). Fairy shrimp (Anostraca) are obligate vernal pool crustaceans, with Eubranchipus spp. being the most common.
Individual vernal pools are typically small (<0.5 acre), are surrounded by upland forest with trees that overhang the pool, providing a continuous leaf litter substrate, and are generally sparsely vegetated and fishless. The presence of animals categorized as obligate vernal pool species (species that depend upon vernal pool habitat for their survival) helps confirm the identification.
Known examples of this community have been found at elevations between 50 feet and 1,890 feet.
Vernal pools are best observed after spring thaw when they are filled with melt water and breeding wood frogs start calling. April is generally a good month to visit vernal pools in New York (earlier to the south and later to the north). Repeat visits to the same vernal pool as the water draws down increases the chances of seeing the full array of characteristic vernal pool species at different stages of their life cycle.
This New York natural community encompasses all or part of the concept of the following International Vegetation Classification (IVC) natural community associations. These are often described at finer resolution than New York's natural communities. The IVC is developed and maintained by NatureServe.
Betula alleghaniensis (yellow birch)
Fraxinus americana (white ash)
Fraxinus pennsylvanica (green ash)
Quercus alba (white oak)
Quercus bicolor (swamp white oak)
Quercus palustris (pin oak)
Tsuga canadensis (eastern hemlock)
Ulmus rubra (slippery elm)
Lindera benzoin (spicebush)
Pinus rigida (pitch pine)
Vaccinium corymbosum (highbush blueberry)
Cephalanthus occidentalis (buttonbush)
Boehmeria cylindrica (false nettle)
Carex stricta (tussock sedge)
Eleocharis acicularis (needle spike-rush)
Lemna minor (common duckweed)
Onoclea sensibilis (sensitive fern)
This figure helps visualize the structure and "look" or "feel" of a typical Vernal Pool. Each bar represents the amount of "coverage" for all the species growing at that height. Because layers overlap (shrubs may grow under trees, for example), the shaded regions can add up to more than 100%.
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Brooks, R.T. and P.W.C. Paton. 2005. Introduction to the symposium: woodland vernal pools in northern temperate forests. Wetland Ecology and Management 13:211-212.
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Calhoun, A.J.K. and P. DeMaynadier. 2004. Forestry habitat management guidelines for vernal pool wildlife. MCA Technical Paper No. 6, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York.
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Huth, P. and D. Smiley. 1981. Shawangunk Vernal Pool Report. Daniel Smiley Research Center. Mohonk Preserve, Inc. New Paltz, New York.
Kenney, L.P. and M.R. Burne. 2000. A Field Guide to the Animals of Vernal Pools. Massachusetts Division of Fisheries and Wildlife, Natural Heritage and Endangered Species Program and Vernal Pool Association, Westborough, MA.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
New York State Department of Environmental Conservation. 1995. Freshwater Wetlands: Delineation Manual. July 1995. New York State Department of Environmental Conservation. Division of Fish, Wildlife, and Marine Resources. Bureau of Habitat. Albany, NY.
Paton, P.W.C. and W.B. Crouch III. 2002. Using the phenology of pond-breeding amphibians to develop conservation strategies. Conservation Biology 16(1):194-204.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
This guide was authored by: D.J. Evans
Information for this guide was last updated on: January 14, 2019
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Vernal pool. Available from: https://guides.nynhp.org/vernal-pool/. Accessed January 18, 2019.