Summary

Did you know?

Riverside sand and gravel bars provide favorable habitat for certain rare plants, such as swordleaf rush (Juncus ensifolius), dwarf bulrush (Lipocarpha micrantha), Carey's smartweed (Persicaria careyi), and low sand cherry (Prunus pumila var. depressa). However, these habitats are subject to multiple natural and human disturbances, making them particularly vulnerable to invasion by exotic plant species, such as Japanese knotweed (Reynoutria japonica var. japonica) and purple loosestrife (Lythrum salicaria). Ice scour and spring flooding from snow melt are natural processes that contribute to the dynamic nature of the plant communities and the substrate of riverside sand and gravel bars. In addition, artificial water-level fluctuation through the regulation of dams and reservoirs can influence these communities and the organisms that inhabit them.

State Ranking Justification

There are probably several hundred occurrences statewide. A few documented occurrences have good viability and several are protected on public land or private conservation land. This community is limited to the rivers and streams with sand or gravel substrate in the state, and there are only a few 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 that include alteration to hydrology, shoreline development, instream gravel mining, and invasive species.

Short-term Trends

The number and acreage of riverside sand/gravel bars in New York have probably declined slightly in recent decades as a result of shoreline development, alteration to the hydrology, instream gravel mining, and invasive species.

Long-term Trends

The number and acreage of riverside sand/gravel bars in New York have probably declined moderately from historical numbers likely correlated to the alteration of natural hydrology from impoundments, shoreline hardening, and instream gravel mining.

Conservation and Management

Threats

Riverside sand/gravel bars are threatened by development (e.g., residential, agricultural, industrial) in the surrounding landscape. Structures built along the shoreline (e.g., riprap, boat launches) are a particular threat to this community. Other threats include habitat alteration (e.g., instream gravel mining, road crossings, logging in adjacent floodplain), and relatively minor recreational overuse (e.g., boating, ATVs, trampling by visitors, fishing, trash dumping). Threats to rivers may apply to the riverside sand/gravel bars (e.g., pollution, nutrient loading, sedimentation, impoundments, flooding, water release for rafting). Several riverside sand/gravel bars are threatened by non-native species.

Conservation Strategies and Management Practices

Where practical, establish and maintain a natural riparian buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the riverside sand/gravel bar. Avoid habitat alteration along the shoreline and surrounding landscape. Restore riverside sand/gravel bars that have been affected by unnatural disturbance (e.g., remove obsolete impoundments in order to restore the natural hydrology). Reduce or eliminate instream gravel mining from the best examples of riverside sand/gravel bar. Prevent the spread of invasive exotic species into the riverside sand/gravel bars through appropriate direct management, and by minimizing potential dispersal corridors, such as roads and bridges. Maintain or restore the natural flood and ice scour regime.

Development and Mitigation Considerations

Where practical, establish and maintain a natural riparian buffer to filter storm-water, pollution, and nutrient run-off from surrounding uplands and to capture sediments before they reach the riverside sand/gravel bar. Avoid habitat alteration along the shoreline and surrounding landscape. Minimize potential dispersal corridors for exotic species, such as roads and bridges. Maintain or restore the natural flood and ice scour regime.

Inventory Needs

Survey for occurrences statewide to advance documentation and classification of riverside sand/gravel bars. Continue searching for large sites in good condition (A- to AB-ranked).

Research Needs

Research composition of riverside sand/gravel bars statewide in order to characterize variations and to clearly separate this community from cobble shore and cobble shore wet meadow.

Rare Species

• Carex emoryi (Emory's Sedge) (guide)
• Cicindela ancocisconensis (Appalachian Tiger Beetle) (guide)
• Cicindela marginipennis (Cobblestone Tiger Beetle)
• Cornus drummondii (Rough-leaved Dogwood) (guide)
• Cyperus subsquarrosus (Small-flowered Dwarf Bulrush) (guide)
• Equisetum pratense (Meadow Horsetail) (guide)
• Juniperus horizontalis (Creeping Juniper) (guide)
• Lampsilis cariosa (Yellow Lampmussel) (guide)
• Ligumia nasuta (Eastern Pondmussel) (guide)
• Myriophyllum pinnatum (Cut-leaved Water Milfoil) (guide)
• Polygonum buxiforme (American Knotweed) (guide)
• Progomphus obscurus (Common Sanddragon) (guide)
• Prunus pumila var. depressa (Dwarf Cherry) (guide)
• Solidago ohioensis (Ohio Goldenrod) (guide)

Range

New York State Distribution

Riverside sand/gravel bars are widespread throughout New York State. They are probably represented by different regional variants.

Global Distribution

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.

Best Places to See

• Zoar Valley Multiple Use Area
• Batten Kill (Washington County)

Identification Comments

General Description

A meadow community that occurs on sand and gravel bars deposited within, or adjacent to, a river channel. The community can manifest in a variety of ways depending on rates of deposition and erosion of the sand or gravel substrate. Physiognomic variants include very sparse vegetation, tall or short herbs, dwarf shrubland, shrubland, or sparse woodland (Edinger et al. 2002).

Characters Most Useful for Identification

Riverside sand/gravel bars can be found along streams throughout New York State. This community is identified by shoreline environments consisting of exposed, well-drained bars composed of sand and gravel (particles smaller than 10 cm in diameter). While the ratio of sand to gravel certainly varies from one occurrence to the next, a common proportion is roughly 70% sand to 30% gravel.

Elevation Range

Known examples of this community have been found at elevations between 98 feet and 1,500 feet.

Best Time to See

While this community can be indentified anytime during the snow-free seasons, it is most enjoyable to visit during the growing season, from late May through summer, when plants are flowering and water temperatures are conducive to wading.

Riverside Sand/Gravel Bar Images

Riverside sand/gravel bar along Batten Kill near Eldridge Swamp.
Gregory J. Edinger

Riverside sand/gravel bar along Batten Kill near Eldridge Swamp.
Gregory J. Edinger

Riverside sand/gravel bar along Batten Kill near Eldridge Swamp.
Gregory J. Edinger

Previous Next

Classification

International Vegetation Classification Associations

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.

• Twisted Sedge - Indian-hemp - Flatsedge species Riverbed Vegetation (CEGL006536)
• Laurentian Cobble-Gravel Rivershore Vegetation (CEGL002304)
• Black Willow - Willow species / Twisted Sedge - Indian-Hemp Wet Shrubland (CEGL006065)

NatureServe Ecological Systems

This New York natural community falls into the following ecological system(s). Ecological systems are often described at a coarser resolution than New York's natural communities and tend to represent clusters of associations found in similar environments. The ecological systems project is developed and maintained by NatureServe.

• Central Appalachian Stream and Riparian (CES202.609)
• Laurentian-Acadian Floodplain Forest (CES201.587)
• Laurentian-Acadian Wet Meadow-Shrub Swamp (CES201.582)

Characteristic Species

• Trees > 5m

  • Acer saccharum (sugar maple)

• Shrubs 2 - 5m

  • Platanus occidentalis (eastern sycamore)
  • Populus deltoides
  • Salix interior (sandbar willow)

• Shrubs < 2m

  • Platanus occidentalis (eastern sycamore)
  • Populus deltoides
  • Prunus pumila var. depressa (dwarf cherry)
  • Salix interior (sandbar willow)

• Vines

  • Clematis virginiana (virgin's-bower)

• Herbs

  • Apocynum cannabinum (Indian-hemp)
  • Bidens frondosa (devil's beggar-ticks)
  • Calamagrostis canadensis
  • Daucus carota (wild carrot)
  • Doellingeria umbellata var. umbellata (tall flat-topped white-aster)
  • Dryopteris intermedia (evergreen wood fern, fancy wood fern, common wood fern)
  • Eupatorium perfoliatum (boneset)
  • Eutrochium maculatum var. maculatum (spotted Joe-Pye-weed)
  • Lycopus americanus (American bugleweed, American water-horehound)
  • Lythrum salicaria (purple loosestrife)
  • Matteuccia struthiopteris
  • Melilotus officinalis (yellow sweet-clover)
  • Panicum capillare
  • Solidago gigantea (swamp goldenrod)
  • Veratrum viride (false hellebore, Indian corn lily)
  • Xanthium strumarium

Similar Ecological Communities

• Calcareous shoreline outcrop (guide)
  Calcareous shoreline outcrops are on calcareous rocks such as limestone and dolomite. Whereas, riverside sand/gravel bars are on unconsolidated sand and gravel.
• Cobble shore (guide)
  Cobble shore communities occur on well-drained cobbles, rocks that range from 10 to 25 cm in diameter. The smaller particles composing sand/gravel bars are usually much less than 10 cm in diameter.
• Cobble shore wet meadow (guide)
  Riverside sand/gravel bars are terrestrial communities that occurs on well-drained sand and gravel bars deposited within, or adjacent to, a river channel. Whereas, the soil underlying cobble shore wet meadows is hydric and the vegetation is predominately hydrophytic.
• Riverside ice meadow (guide)
  Riverside ice meadows occur on gently sloping cobble substrates and bedrock outcrops along large rivers in areas where winter ice floes are pushed up onto the shore, forming an ice pack that remains until late spring. Such unique ice dynamics are absent from riverside sand/gravel bar communities.
• Shoreline outcrop (guide)
  Shoreline outcrops are on bedrock outcrops of non-calcareous rocks such as anorthosite, granite, quartzite, sandstone, gneiss, or schist. Whereas, riverside sand/gravel bars are on unconsolidated sand and gravel.

Vegetation

Additional Resources

References

Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero (editors). 2014. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke’s Ecological Communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY. https://www.nynhp.org/ecological-communities/

Edinger, Gregory J., D.J. Evans, Shane Gebauer, Timothy G. Howard, David M. Hunt, and Adele M. Olivero (editors). 2002. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke's Ecological Communities of New York State. (Draft for review). New York Natural Heritage Program, New York State Department of Environmental Conservation. Albany, NY. 136 pp.

New York Natural Heritage Program. 2023. New York Natural Heritage Program Databases. Albany, NY.

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.

Links

• Ausable Point Campground
• Cobb Creek State Forest
• Deer River Gorge

About This Guide

This guide was authored by: Aissa Feldmann

Information for this guide was last updated on: May 4, 2020

Please cite this page as:
New York Natural Heritage Program. 2023. Online Conservation Guide for Riverside sand/gravel bar. Available from: https://guides.nynhp.org/riverside-sandgravel-bar/. Accessed October 3, 2023.