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Upper Floodplain Hardwood Forest

Scientific Name: Hardwood River Terrace Forest; State Rank: S3

Picture showing interior of Upper Floodplain Hardwood Forest

Community Description: An almost complete canopy is dominated by sugar maple, red oak, or yellow birch, with red maple and ash often common and basswood or black cherry occasional. The understory is open and shrubs are sparse. The lush carpet of herbs changes from spring ephemerals such as trout lily and bloodroot to variable cover of mixed graminoids and forbs in summer. Bryoid cover is minor. Back to top.

Soil and Site Characteristics: Sites occur on slightly elevated terraces flanking low-gradient rivers at elevations typically <1,000’. Flooding is occasional, sometimes less frequent than annually. These forests have lower frequency and duration of flooding than silver maple floodplain forests. Most known examples are along medium to larger rivers. Soils are fine sand or silt, usually with good drainage capacity and relatively high nutrient levels; pH is 5.0-6.2. Back to top.

Picture showing ecologists working in Upper Floodplain Hardwood Forest community

Diagnostics: Sites occupy floodplain or river terrace settings with mineral soil. The canopy is dominated by sugar maple, red oak or yellow birch. Silver maple and red maple may be present. A dense herb layer that includes species not typical of wetlands (e.g. starflower, zig-zag goldenrod, big-leaved aster, silvery spleenwort). Sensitive fern is often present but not dominant. Spring ephemerals are often abundant. Back to top.

Similar Types: On large rivers, Silver Maple Floodplain Forests are often adjacent to these forests, occurring between them and the channel, and are dominated by silver maple. Red Maple Swamps have red maple dominant, and have soils that are flooded or saturated throughout the growing season. Northern Hardwoods Forests, Enriched Northern Hardwoods Forests, and Oak - Northern Hardwoods Forests can be similar in canopy composition but are not in the floodplain or terraces of a river. Hardwood Seepage Forests occur along small stream drainages, usually sloping with steeper gradients. Back to top.

Conservation, Wildlife and Management Considerations: Virtually all of these forests have been harvested, and many have been converted to agriculture. Non-native plant species such as Japanese knotweed and Asiatic bittersweet, which may displace those native to our area, represent a threat to the integrity of these forests and have degraded at least some Maine examples.

The northern waterthrush, barred owl, belted kingfisher, bank swallow, scarlet tanager, and green heron are associates of this community type. Wood turtles overwinter in river channels and forage in floodplain forests where they may feed on amphibian egg masses in vernal pools. The silver-haired bat often roosts in riparian habitats in trees with loose bark. Fairy shrimp may also occur in isolated vernal pools. Back to top.

Distribution: Throughout Maine, New England, and New Brunswick. Landscape Pattern: Large Patch. Back to top.

Map showing distribution of Hardwood River Terrace Forest communities in Maine map legend

Characteristic Plants: These plants are frequently found in this community type. Those with an asterisk are often diagnostic of this community.

  • Canopy
    • Basswood*
    • Black cherry*
    • Green ash*
    • Red oak*
    • Sugar maple*
    • Yellow birch*
  • Sapling/shrub
    • American elm
    • Choke cherry
    • Musclewood*
    • Nannyberry*
    • White ash
  • Herb
    • Bloodroot
    • Blue cohosh
    • Jack-in-the-pulpit
    • Lady fern*
    • Ostrich fern*
    • Sensitive fern
    • Silvery spleenwort*
    • Tall meadow-rue

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Associated Rare Plants

Associated Rare Animals

  • Wood turtle

Examples on Conservation Lands You Can Visit

Example County
Trout Brook, Baxter State Park Piscataquis Co.
Wassataquoik Public Lands Penobscot Co.
West Branch Piscataquis River, Appalachian Trail Piscataquis Co.

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Picture showing Upper Floodplain Hardwood Forest community