State 1
Reference State (minimally-managed)

The floodplains site is a riparian complex, consisting of several distinct soils and plant communities that predictably occur on fluvial surfaces found along major rivers. Stream banks, point bars, and other fluvial surfaces closest to the water are the most dynamic component in the complex as erosion and deposition regularly re-arranges the location and specific soil properties of these surfaces. The proportion of each component in the riparian ecological site complex varies with disturbance.

Characteristics and indicators. Frequently-disturbed stream banks are dominated by herbaceous and lesser disturbed floodplains and natural levees support more woody vegetation. Trees tend to dominate on floodplains where disturbances are less frequent and soils are more stable while upper terraces receive the least amount of flooding and disturbance tend to support more upland species.

Resilience management. The construction of dams and bank armoring structures tend to reduce the frequency of disturbance on floodplains, resulting in a greater proportion of forested communities following the construction of these structures. High intensity floods are likely to occur infrequently in these systems, however, their effects are not currently understood.

Community 1.1
Alder Floodplain

These are shrub-dominated floodplains characterized by speckled alder and an assemblage of grasses and herbs indicative of alluvial conditions. Heath shrubs and peat are sparse or absent. These sites occur along medium to large moderate to high energy riverbanks that are seasonally flooded and subject to ice scour, typically on mineral soil. (Gawler and Cutko, 2010)

Resilience management. Maine Natural Areas Program State Rank: S4 Apparently Secure – At fairly low risk of extinction or elimination due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors. The rivershore habitat of this natural community suggests that direct threats from development are relatively low though excessive watershed development would likely increase the volume and intensity of runoff and potentially alter riverine structure and community composition. Additionally, hydrologic alteration (i.e., impoundments) would compromise the disturbance regime, but new dams are unlikely on medium and large rivers. (Gawler and Cutko, 2010)

Forest overstory. Alders dominate and comprise >30% cover

Community 1.2
Balsam Poplar Floodplain Forest

These partly open to closed canopy forests are dominated by balsam poplar and occur along medium-sized rivers. This association includes a wide range of early seral, wetland, and floodplain species. Sites occur on seasonally inundated floodplains or slightly elevated terraces flanking low gradient rivers in central and northern Maine. Sites are often embedded within a matrix of open oxbows and shrub thickets. These forests have lower frequency and duration of flooding than Silver Maple Floodplain Forests. Soils are alluvial fine sand or silt, usually with good drainage capacity. (Gawler and Cutko, 2010)

Resilience management. Maine Natural Areas Program State Rank: S2 Imperiled in Maine because of rarity (6-20 occurrences or few remaining individuals or acres) or because of other factors making it vulnerable to further decline. The few known examples of this type have been influenced by past disturbances, including harvesting, beaver damage, and potentially fire. As a result, long term successional trends are not clear. Exotic plant species, which may displace those native to our area, may be easily transported to sites by river waters and represent a threat to the integrity of these forests. The biggest threat may be hydrologic alteration. All known sites in Maine are on private land. (Gawler and Cutko, 2010)

Community 1.3
Dogwood Willow Shoreline Thicket

Sites occupy shores of larger rivers, below the annual high-water line, in areas somewhat protected from the extremes of ice scour and flooding. Riverbanks are moderate to steep, not flat; the silty to sandy soils are not constantly saturated. Successional dynamics have not been studied, but at least some sites appear to persist through disturbance. Dense riparian shrub vegetation (>80% cover) is dominated by a mixture of red osier dogwood and shrub willows. Alders may be present but are not dominant. A band of bush-honeysuckle often forms at the upslope edge where the shrub vegetation abuts upland forest. Herb richness may be high in openings among the shrubs and may include some calciphiles as well as more widespread species. Bryoids are minor and consist of bryophytes rather than lichens. More study of alluvial shrub communities is needed. (Gawler and Cutko, 2010)

Resilience management. Maine Natural Areas Program State Rank: S2 Imperiled – At high risk of extinction or elimination due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors. Natural river hydrology, with annual fluctuations, is important in the maintenance of this community. These areas receive little direct use but may be affected by adjacent land use, so an intact buffer of adjoining upland would be helpful. No studies of the dynamics of this community have been done. (Gawler and Cutko, 2010)

Community 1.4
Hardwood River Terrace Forest

These ecological sites occur on slightly elevated terraces flanking low-gradient rivers at elevations typically <1,000’. Flooding is occasional, sometimes less frequent than annually. 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. The overstory provides almost complete canopy cover, while understory is open and shrubs are sparse. The lush carpet of herbs changes from spring ephemerals to variable cover of mixed graminoids and forbs in summer. Bryoid cover is minor. (Gawler and Cutko, 2010)

Resilience management. Maine Natural Areas Program State Rank: S3 Vulnerable – At moderate risk of extinction or elimination due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors. 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.(Gawler and Cutko, 2010)

Community 1.5
Silver Maple Floodplain Forest

These ecological sites occur on plains flanking low gradient rivers, within the reach of seasonal floods, at elevations <700’. Soils are fine sand or silt, usually with good drainage capacity; the water table fluctuates. Relatively high nutrient levels result from sediment deposition of annual floods; pH is typically 5.0-6.2. These forests are dominated by silver maple (>60% cover). Associates include red maple and American elm (up to 30% cover) or, in a few locations, bur oak (up to 25% cover). Widely spaced trees, many with multiple trunks, give a park like feeling. The understory is open and shrubs are sparse. Musclewood may be present and is a good indicator. The lush carpet of herbs changes from spring ephemerals to dense fern cover in summer. Bryoid cover is minor. Some forests have a berm adjacent to the river channel, and herbaceous species composition here is different from the lower elevation interior of the floodplain. These forests have higher frequency and duration of flooding. (Gawler and Cutko, 2010)

Resilience management. Maine Natural Areas Program State Rank: S3 Vulnerable – At moderate risk of extinction or elimination due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors. Although a number of sites have been cleared or pastured in the past, current shoreland regulations provide increased protection to a number of these sites. Exotic plant species such as Japanese knotweed, which may displace those native to our area, also represent a threat to the integrity of these forests and have degraded some Maine examples. Several of the known examples are formally protected from conversion. (Gawler and Cutko, 2010)

State 2
Semi-natural State

Shifts in ecological site composition, functionality, and dynamics driven by natural disturbances, processes, and pressures (may have some anthropogenic influences). More research is needed to determine the extent of the Semi-natural state associated with this ecological site.

Community 2.1
Invasiveness and Biological Introductions

Introduction of invasive species, pathogens, and/or pests resulting in shifts in ecological site composition, functionality, and dynamics. More research is needed to determine the extent of these effects on the semi-natural state associated with this ecological site.

Community 2.2
Transitional Marsh or Wetland

Hydrological alteration of sites that can include the removal or addition of dams, barriers, structures, or actions that temporarily or permanently alter watersheds or the fluvial geomorphology of rivers and streams. These actions strongly influence site functions, dynamics, and composition that promote a semi-natural state as opposed to either extremes of hydrological alteration within the reference state and cultural state.

Pathway 2.1a
Community 2.1 to 2.2

introduction of non-native species, pests, and/or pathogens; shifts in community composition to native species weediness

State 3
Cultural State

Shifts in ecological site composition, functionality, and dynamics that are primary driven by anthropogenic disturbances and pressures (may have some associated natural influences). Cultural state used for plantations, cultivated cropland, pastures, or hayland primarily formed by hydrological alteration. More research is needed to determine the extent of the cultural state associated with this ecological site.

Community 3.1
Drained Cropland

Community 3.2
Pasture and Hayland

Pathway 3.1a
Community 3.1 to 3.2

hydrologic alteration, clearing, tilling, crops planted/seeded, hay planted/seeded, mechanical disturbance

Transition T1A
State 1 to 2

hydrologic alteration, increased annual precipitation or significant flooding event, timber management/harvesting, introduction of non-native species, pests, and/or pathogens; shifts in community composition to native species weediness

Transition T1B
State 1 to 3

Hydrologically-altered. Management of sites can include the addition of dams, barriers, structures, or actions that temporarily or permanently alter watersheds or the fluvial geomorphology of rivers and streams. These actions strongly influence site functions, dynamics, and composition promoting an intended cultural state.

Restoration pathway R2A
State 2 to 1

Hydrologically-altered. Management of sites can include the addition or removal of dams, barriers, structures, or actions that temporarily or permanently alter watersheds or the fluvial geomorphology of rivers and streams. These actions strongly influence site functions, dynamics, and composition restoring sites back to a reference state. Management to control, remove, or alter invasive species, pathogens, and abnormal physiology to restore sites to a reference state. Native plantings and seedings.

Transition T2A
State 2 to 3

Hydrologically-altered. Management of sites can include the addition of dams, barriers, structures, or actions that temporarily or permanently alter watersheds or the fluvial geomorphology of rivers and streams. These actions strongly influence site functions, dynamics, and composition promoting an intended cultural state.

Restoration pathway R3A
State 3 to 1

Hydrologically-altered management of sites that can include the removal of dams, barriers, structures, or actions that temporarily or permanently alter watersheds or the fluvial geomorphology of rivers and streams. Coupled with native plant establishment through seeding and planting, these actions can strongly influence site functions, dynamics, and composition, restoring sites back to a reference state.

Restoration pathway R3B
State 3 to 2

Hydrologically-altered management of sites that can include the removal of dams, barriers, structures, or actions that temporarily or permanently alter watersheds or the fluvial geomorphology of rivers and streams. Coupled with native plant establishment through seeding and planting, these actions can strongly influence site functions, dynamics, and composition, restoring sites back to a semi-natural state.