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World Wetlands Day 2016

February 4, 2016

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This week, we celebrated World Wetlands Day, an annual event held on February 2 to mark the anniversary of the adoption of the Convention on Wetlands in 1971 (more commonly known as the Ramsar Convention, after the Iranian city where the meeting took place).

Although often considered to be “only swamps,” there is tremendous diversity of wetlands throughout the world. The EPA defines wetlands as:

areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season. Water saturation (hydrology) largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants (hydrophytes) and promote the development of characteristic wetland (hydric) soils.

 Wetlands vary widely because of regional and local differences in soils, topography, climate, hydrology, water chemistry, vegetation and other factors, including human disturbance. Indeed, wetlands are found from the tundra to the tropics and on every continent except Antarctica. Two general categories of wetlands are recognized: coastal or tidal wetlands and inland or non-tidal wetlands.

We do find wetlands in urban areas, of course, in as great of a variety as anywhere else. Wetlands are incredibly important ecosystems for many reasons. They provide essential ecosystem services such as storm water management (a lesson we learned in the aftermath of Hurricane Katrina all too well), water purification, and valuable habitat for many species of both plants and animals.

Urban wetlands often need to function in multiple ways – as habitat, as corridors, as a provider of ecosystem services, and – perhaps controversially at times – as recreational areas for people. Zedler and Leach remarked in the late 1990’s that three sometimes competing roles (recreation, restoration, and research) for urban wetlands could coexist through thoughtful planning, although for obvious reasons the supporters of these sometimes competing uses can sometimes clash.

Studies have shown that urban residents value having wetlands nearby, in keeping with other research that shows that urban residents prize having natural environments near their residences. This proximity can even help to boost property values (leading at times to environmental justice issues when access to these areas is denied to poorer residents of cities).

But our urban wetlands are under tremendous pressure, often stemming from two closely-related threats: the conversion of wetlands to urban areas and the increased stress wetlands face due to hydrological changes in urban area (cities drawing water from wetlands to provide for their needs, or, conversely, discharging larger amounts of water due to increased impervious surface area, increased aquatic pollution, and so on).

The Ramsar Convention seeks to protect urban wetlands, just as it does wetlands in more rural areas. It even created an accreditation system for World Wetland Cities, where cities can apply to be given that title. At the same time, some researchers have pointed out that the Convention wasn’t ideally created to deal with urban wetland conservation, the focus in the early 1970’s being much more on rural wetlands. Hettiarachchi, Morrison, and McAlpine, 2015, for example, point to several weaknesses, including a lack of focus on environmental justice and and not enough recognition of the complex social, economic, ecological, and political systems to be found within cities. They then offer some interesting modifications that could address these shortcomings.

In urban areas (and perhaps elsewhere), the hands-on wetland conservation activities (as opposed to the equally important education and legislation activities) can be split into two broad categories:

  1. Protecting existing, intact wetlands: This is perhaps most true in rapidly spreading and growing cities, but also true for remnant wetlands in more established cities that aren’t spreading out as much.
  2. Restoring degraded wetlands: Wetlands that have already been degraded – or even destroyed – in urban areas are often the target of restoration or creation efforts. Sometimes these efforts focus on restoring the ability of the system to provide ecosystem services to the city, sometimes for habitat preservation and creation, sometimes for recreational/educational purposes, and sometimes for all of the above reasons – and possibly even more. David Pettit of the NRDC wrote an interesting blog post about wetlands restoration and creation projects in LA, as a good example.

So Happy World Wetlands Day (er…week?)! Next time you pass by a partially-submerged piece of land in an urban area, give it a wave.

(As a bonus, check out these satellite images of some of our world’s wetlands, courtesy of the European Space Agency!)

 

Boyer, T. and Polasky, S. 2004. Valuing urban wetlands: A review of non-market valuation studies. Wetlands 24(4): 744-755

Hettiarachchi, M., Morrison, T.H., and McAlpine, C. 2015. Forty-three years of Ramsar and urban wetlands. Global Environmental Change 32: 57-66

Mahan, B.L., Polasky S., and Adams, R.M. 2000. Valuing urban wetlands: A property price approach. Land Economics 76(1): 100-113

Zedler, J.B. and Leach, Mark K. 1998. Managing urban wetlands for multiple use: Research, restoration, and recreation. Urban Ecosystems 2: 189-204

 

 

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