Friday, October 4, 2013

Wetlands Restoration FAIL

In the Pacific Northwest there are several invasive species that wetlands managers attempt to control. These include animals such as bullfrog and nutria, as well as plants such as reed canary grass and Himalayan blackberry.

Certainly I applaud all efforts to restore wetlands. It is very encouraging to see such efforts and associated costs going in to try to fix some of the damage we humans have inflicted on this planet due to ignorance and greed. My complaint here is with the bird aspect of wetlands restoration.

When trying to restore wetlands, I'm not sure that managers are thinking long-term. The word is "succession." If you remember back to 7th grade science class, you will remember that this refers to the changing of habitats over time. So, scrape the land bare of all those evil invasive plants and level to create a shallow pond, plant some native shrubs and trees to shade out the reed canary grass and try to out compete the blackberries, and voilà: a restored wetlands, right? Well, not for long. You see, the wetlands tend to channelize over time, the grasses and sedges are replaced by trees, and the ponds dry up.

This action is sped up by a certain plant I call a "native invasive species." It is the willow. This pernicious weed is a favorite of wetland plant ecologists--it grows well--really, really fast and dense. It quickly gives the appearance of a restored wetlands.

As far as bird watching goes, willows tend to clog up and destroy wetlands. They block the view and reduce avian biodiversity. Instead of numerous ducks, herons, and sandpipers, a few rather uncommon yellow warblers and willow flycatchers are found in summer, and not much else the rest of the year.

Here, let me show you. I have birded at Jackson Bottom Wetlands in Hillsboro, Oregon, since the mid-1980's and watched the changes. I love this place and know and respect many of the people that work here. It is a sample of many other locations--not an indictment of this one locale.

Wetlands FAIL
Ducks Unlimited pond at Jackson Bottom Wetlands, Oregon. Created 2012.
Above is a newly restored wetlands. This was formerly an annually flooded grassy field (Meadow Mouse Marsh). In winter it may flood 8 feet deep after rains. It dries out almost completely in summer. In the past 2 years this new wetland has attracted numerous migrant shorebirds, breeding ducks, raptors, herons, and other birds. Wonderful. But do you see the problem? Planted rows of willows--native invasive species alert!

This pond is not too different from that created adjacent to this 25 years ago. Do you want to see what this older pond looks like now--and what this new one will look like in a few years?

pond
Pond at Jackson Bottom Wetlands, Oregon. Created about 1988.
What happened? Willow clumps grew up. The edges, rather than shallow and sloping as originally created, eroded and deepened. The bird species diversity that abounded for a few years immediately after the ponds were created are now reduced. Mudflats have disappeared and the open edges that birds wanted in order to watch for predators closed in. So they left. What happens next?

Assimilation.

Kingfisher Marsh
Kingfisher Marsh, Jackson Bottom Wetlands, Oregon.
Yes, there is some nice restored native wapato planted in a swale. But 3 years ago there were mudflats here, grasses, sedges, rushes: herons, shorebirds, ducks. Now? Well, it is on its way from being a grassy marsh (the intent) to a wooded swamp (not the intent).

The view stands (not to mention the huge and expensive back deck of the nature center) now look at nothing but dense willow thickets. Gone are the expansive views of the marsh. Forever.

When restoring wetlands, land use planners should plan in willow removal every 5 years. I recommend burning, as every little cutting of willow that falls on the ground will grow. I know this is completely opposite of recommended wetlands restoration theory. But I have warned you! The wetlands you think you are making today will soon be consumed by willows.

Oh, and one other thing since I am on my soap box, wetlands restoration planners.... The photography blinds and view stands should face north or west--not east or south into the early morning sun. Doesn't the person designing these structures have any insight into their use?

12 comments:

  1. Amen - left Jackson Bottom today wondering where the wetlands are - and to your point, thinking they are being destroyed.

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  2. Very informative. Thank you for sharing :)

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  3. Great post! Excellent food for thought too- hopefully someone in "power" will take note!

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  4. Excellent thinking....hope someone listens!

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  5. It sounds like you are complaining that one of the native plants they use to populate the wetlands makes it harder to bird. This is a pretty lame complaint.

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    1. I think the author very clearly notes that the avian biodiversity dwindles considerably as the habitat becomes of little use to many species. It is not just a matter of birding difficulties but rather difficulties for the bird species.

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  6. Here in Florida we are experiencing invasion of our local wetland patch by exotic Melaleuca, Brazilian Pepper and Australian Pine, as well as exotic vines and grasses.Although set aside as a water conservation area, eight years or so all maintenance ceased because of future plans to turn it into a reservoir. It is amazing how rapidly it turned from a recovering wet prairie into a woodland/savannah. Fauna changed accordingly, and after it is flooded all the terrestrial species must find new habitat.

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  7. Very interesting. Your pictures are worth a 1,000 words.

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  8. I have one word for you, beavers.

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  9. Greg, a question for you:

    If the willows were intermixed with other species, and if they were planted as boundaries, hedges or clumps rather than in rows, would that make a difference? If so, what other species would you plant with the willow to help create useful habitat? Willows are really important bio-remediating plants and, while I understand your points about pure restoration, I'm involved in habitat making on lands that AREN'T being restored and DO need fast-growing plants to create cover and food. It would be nice to have some suggestions about other useful plants that would go with the willow and could help make it work. Thanks! Cynthia

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    1. Interesting question, Cynthia. Other native wetland trees in western Oregon are cottonwood, ash, and alder. I'd plant ash over willow, as willows create impenetrable thickets at or in the water. Frankly, wetlands are so unstable--always ready to change into drier, habitats. Wetlands need constant readjustment and budget; it's not a once and done project. I would grade pond edges at least every three years to remove woody vegetation and keep a wide gradually sloping mudflats. Shorebirds migrating from the Arctic need our help now more than ducks--shallow mudflats, not duck donuts.

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  10. Fascinating post... and I have seen enough to agree as much as I love clumps of Willow. oooh especially the placement of viewing stands, they should have photographers design such things. :-)
    We had a seasonal wetland in my backyard growing up, a Quaking Aspen grove interspersed with Oregon Ash, a big Cottonwood or two, and a few large Ponderosa Pines around the edges. It was filled with Camas Lilies, a couple orchids, snowberry bushes, wild rose, Morels, frogs, deer and birds galore. Recently someone stripped much of that incredible area, and I cried.

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