Special Modifiers


Many wetland and deepwater habitats are man-made, and natural ones have been modified to some degree by the activities of humans or beaver. With the exception of Beaver, all of the Special Modifiers describe human alterations to wetlands. Since the nature of these modifications often greatly influences the character of such habitats, special modifying terms have been included here to emphasize their importance. The following Modifiers should be used singly. It may be difficult, in some instances, to choose the single Special Modifier that best describes the landscape modification. Because the Diked/Impounded Modifier is crucial for use in coastal watersheds as denoting wetland modifications for sea level rise models, it will be given priority over any other Modifiers (e.g., spoil areas that have been diked or impounded should be classified using the Diked/Impounded Modifier, not the Spoil Modifier.) 


Beaver -  These wetlands have been created or modified by beaver (Castor canadensis). Dam building by beaver may increase the size of existing wetlands or create small impoundments that are easily identified on aerial imagery. Such flooding frequently creates Dead Forested or Dead Scrub-Shrub Wetland initially, followed in a few years by Aquatic Bed and Emergent Wetland. 


Partly Drained/Ditched - A partly drained wetland has been altered hydrologically, but soil moisture is still sufficient to support hydrophytes. Drained areas that can no longer support hydrophytes are not considered wetland. This Modifier is also used to identify wetlands containing, or connected to, ditches. The Partly Drained/Ditched Modifier can be applied even if the ditches are too small to delineate. The Excavated Modifier should be used to identify ditches that are large enough to delineate as separate features; however, the Partly Drained/Ditched Modifier also should be applied to the wetland area affected by the ditching. 


Farmed - Farmed wetlands occur where the soil surface has been mechanically or physically altered for production of crops, but where hydrophytes would become reestablished if the farming were discontinued. Farmed wetlands should be classified as Palustrine-Farmed. Cultivated cranberry bogs may be classified Palustrine-Farmed or Palustrine Scrub-Shrub Wetland-Farmed. 


Managed -  This modifier is used to identify wetlands where water inputs are controlled to achieve a specific water regime or habitat type. Water control structures in combination with dikes and impoundments are common. 


Excavated - This Modifier is used to identify wetland basins or channels that were excavated by humans. 


Diked/Impounded - These wetlands have been created or modified by a man-made barrier or dam that obstructs the inflow or outflow of water. 


Artificial Substrate - This Modifier describes concrete-lined drainageways, as well as Rock Bottom, Unconsolidated Bottom, Rocky Shore and Unconsolidated Shore where the substrate material has been emplaced by humans. Jetties and breakwaters are examples of Artificial Rocky Shores. 


Spoil - The Spoil Modifier is used to describe wetlands where deposition of spoil material forms the primary substrate type. By definition, spoil is material that has been excavated and emplaced by humans. Ancillary data may be needed to accurately identify spoil in areas such as reclaimed strip mines that have become revegetated.

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