Natural Communities of NH -- Photo Guide

Sycamore floodplain forest  (S1)


Sycamore floodplain forests are dominated by sycamore trees and often feature a tall, well developed musclewood shrub layer. In New Hampshire, this regionally uncommon community is known only from low floodplains of the Ashuelot River north of Surry Mountain Lake in Surry, the North River in Lee, and Great Brook in Walpole. Sycamore reaches the northeastern limit of its range in southern New Hampshire and southwestern Maine. In New Hampshire this community is restricted to minor river floodplains the southern part of the state.

The channel substrate is largely cobble and flood events appear to be “flashy” in nature. Soils are sandy loam, sand, or gravelly sand. The pH measured from one soil profile was 5.3. This community has a relatively high plant species richness compared to other floodplain forest community types.

This floodplain forest community may form a mosaic along with several other community types as part of a larger temperate minor river floodplain forest system. Associated floodplain communities may include other types of forested floodplains, riverside sand and gravel barrens, shrub thickets, and emergent marshes. Semi-rich mesic sugar maple forest occurs on some river terraces adjacent to this floodplain community.

Characteristic vegetation: Dominated by a sparse to moderately well developed canopy of sycamore (Platanus occidentalis) with a tall, well developed musclewood (Carpinus caroliniana ssp. virginiana) understory layer. Tree canopy associates include red maple (Acer rubrum), sugar maple (Acer saccharum), American elm (Ulmus americana), bitternut hickory (Carya cordiformis), and less frequently butternut (Juglans cinerea). Where flooding is more frequent, the woody shrub and sapling layer is often absent. In these areas, there is a tall, dense herbaceous layer dominated by jumpseed (Polygonum virginianum), ostrich fern (Matteuccia struthiopteris var. pensylvanica), and bluejoint (Calamagrostis canadensis).

The smooth upper trunks of sycamore trees are usually very recognizable. They feature a characteristic mottled and exfoliating bark patterning, but this pattern fades lower down on the trunks where the bark becomes darker and rougher. 


Good examples of this community occur along the Ashuelot River (Surry) and Great River (Walpole).

Sycamore floodplain forest sometimes occurs as part of a larger temperate minor river floodplain forest system.


Sycamore floodplain forest along Great River in Walpole (photo by Ben Kimball)
Sycamore floodplain forest along Great River in Walpole (photo by Ben Kimball)

Sycamore floodplain forest along Great River in Walpole (photo by Ben Kimball)
Sycamore floodplain forest along Great River in Walpole (photo by Ben Kimball)


A sycamore tree along the narrow floodplain at
St. Gaudens National Historic Site (photo by Ben Kimball)

Sycamore tree along Great River in Walpole (photo by Ben Kimball)
Sycamore tree along Great River in Walpole
(photo by Ben Kimball)

 Sycamore floodplain forest along Blow-Me-Down Brook (photo by Ben Kimball for the NH Natural Heritage Bureau)
Sycamore floodplain forest along Blow-Me-Down Brook in Cornish (photo by Ben Kimball)

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