Wetland Alterations

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History

Restoration Decisions: (and theory)

Case Studies

State of the Science

References

Created by:

Types of Alterations to Wetlands (World Wildlife Fund and The Conservation Foundation, 1988 in National Research Council, 1992).

Biological

• Grazing--consumption and compaction of vegetation by either domestic or wild animals.
• Disrupting natural populations

Chemical

• Changing nutrient levels--increasing or decreasing levels of nutrients within the local water or soil system; forcing changes in wetland plant community.
• Introducting toxics--adding toxic compounds to a wetland either intentionally (e.g. herbicide treatment to reduce vegetation) or unintentionally, adversely affecting wetland plants and animals.

Physical

• Filling--adding any material to change the bottom level of a wetland or to replace the wetland with dry land.
• Draining--removing the water from a wetland by ditching, tiling, pumping, and so on
• Excavating--dredging and removing soil and vegetation from a wetland
• Diverting water away--preventing the flow of water into a wetland by removing water upstream, lowering lake levels, or lowering ground water tables.
• Clearing--removing vegetation by burning, digging, application of herbicides, scraping, mowing, or otherwise cutting.
• Flooding--raising water levels, either behind dams or by pumping or otherwise channeling water into a wetland.
• Diverting or withholding sediment--trapping sediment through construction of dams, channelization, or other types of projects, thereby inhibiting the regeneration of wetlands in natural areas of deposition such as deltas.
• Shading--placing pile-supported platforms or bridges over wetlands, causing vegetation to die.
• Conducting activities in adjacent areas--disrupting the interactions between wetlands and adjacent land areas, or incidentally impacting wetlands through activities at adjoining sites.