Association of State Wetland Managers - Protecting the Nation's Wetlands.

The Compleat Wetlander: Agriculture and Wetlands Together Are Our Future

By Jeanne Christie

Worldwide about 50% of the wetlands have been lost – usually converted to uplands and most of the time those conversions have been to agriculture.  For example in the United States it is estimated that over 80% of the wetlands lost over the past 200 years were converted to agriculture.

It’s nothing new.  Conversions of wetlands to agriculture has occurred for millennia. But, in many areas this has become problematic particularly in the context of changing agricultureblog10115agricultural practices over the past century.  For example in peatlands in areas such as Southeast Asia these conversions lead to subsidence of the landscape and increased vulnerability to flooding.  In the U.S. subsidence of wetlands in coastal Louisiana is well documented due in part to the absence of natural flooding from the Mississippi River but also due to conversion of floodplain wetlands to agricultural uses.

waterfowl10115Over time changes in agricultural practices have led to dramatic decreases in biodiversity associated with agricultural wetlands.  For example meadows in Europe – moist grasslands and fens used for grazing and haymaking historically covered large acres with diverse vegetation that supported grassland birds, water fowl etc.  But the application of artificial fertilizers and deep drainage led to dramatic declines in wildlife populations.  In a similar vein, prior to the 20th century, rice paddies supported rich diversity of macroinvertebrates, fish and waterfowl throughout Asia.  Here too fertilizer and pesticide use have resulted in a dramatic decrease in biodiversity associated with rice fields.

But as cause and unwanted effects are better understood, there is change directed toward protecting wetlands on agricultural landscapes. For example, in Australia, there is growing recognition that healthy wetlands are important to agricultural production as well as environmental conservation.

agricul3Here in the U.S. water pollution from agricultural nonpoint source run-off is the leading source of pollution to rivers and lakes.  At least 20% of these agricultural lands were historically wetlands.  The drainage of these lands coupled with relocating and straightening streams can destabilize whole river systems leading to decades of headcutting and streambank erosion.  Thus while erosion rates of agricultural fields have decreased in response to improved conservation practices, erosion from streambanks continues to be a significant problem which will require different conservation practices to resolve.

The changes in agriculture over the past hundred years have yielded significant benefits in terms of food and fiber production.  But widespread conversions and management of the land and associated wetlands have also had adverse impacts.  They have damaged or destroyed wetlands and waterways, biodiversity, groundwater supplies and other natural resources.  The challenge is to figure out whether it is possible to move on to better management strategies that will support the production of food and fiber, but ag4also protect  and rehabilitate waterways, encourage the re-establishment of wetlands, increase biodiversity and more.  The ability to identify and implement practices that accomplish a broad array of benefits is crucial to the future.  The good news is that there are corporations, farmers, environmentalists, conservationists, agronomists and other scientists working to address this challenge.

 

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