Susan Galatowitsch: Recreating a Diverse Sedge Meadow

Sue Galatowitsch is an assistant professor of landscape ecology at the University of Minnesota, in the Departments of Horticultural Science and Landscape Architecture. She has worked in wetland ecology and wetland restoration for 15 years with the State of Colorado and as a researcher.

We spoke with Ms. Galatowitsch about Spring Peeper Meadow, a project to recreate a diverse sedge meadow from a drained and degraded 8-acre site adjacent to the Minnesota Arboretum in Chanhassen, Minnesota. The project, initiated in 1995, has been funded by the Legislative Committee on Minnesota Resources and the Minnehaha Creek Watershed District, a special district encompassing a part of Minneapolis and 29 other cities within the metropolitan area to the west.

WaterLaws: Please tell us about Spring Peeper Meadow.

Ms. Galatowitsch: Spring Peeper Meadow is an attempt to restore wetland to resemble the natural wetland – the plant and animal communities and the hydrology that you would expect in a natural wetland. This hasn't been an explicit goal of many restorations. Typically, wetland restoration is to accomplish a specific, usually socially needed, function like improving water quality or retaining stormwater. Recreating an ecosystem has been left to chance. But creating a wetland that looks like one is one of the first important steps to saying we can actually mitigate the loss of wetlands through restoration.

WaterLaws: What's the status of the project?

Ms. Galatowitsch: We would say we are completing Phase I of the establishment phase. We went through a time of site preparation and planning and then the reflooding of the site and the planting. Of some 190 species planted at the site, we've subsequently observed some 65 percent. This rate of establishment is far greater than the 25 to 35 percent establishment rate attained in other restorations. We've worked particularly hard on the sedges: tussock sedge (Carex stricta), bottlebrush sedge (Carex comosa), woolly sedge (Carex pellita) and lake sedge (Carex lacustris). We've seen Virginia rails and sedge wrens as well as a good diversity of amphibians, including chorus frogs. No Spring Peepers yet, though.

Now we are moving to a long-term management phase, assessing how we are going to manage the site over time to sustain the biodiversity that we have been able to establish in the last four years.

WaterLaws: How does the approach to restoration differ when you are seeking to recreate a biodiverse natural wetland?

Ms. Galatowitsch: The issue has been how to get high vegetation diversity. We are assuming that if we can end up with a very diverse plant community, with the communities that are typical in a natural wetland, especially at the interface between the uplands and the deeper water area, the wetland will be able to sustain more animal species and so forth. For a higher plant diversity you need to do a couple of things that haven't commonly been done in Minnesota or elsewhere.

The first is a thorough job of site preparation. If you are interested in high plant diversity you really need to rid the site of especially invasive perennial weeds. Our site preparation took about 18 months, a pretty long period of time compared to the site preparation that occurs in a month to three months tops. Spring Peeper had a cover of reed canary grass, an invasive perennial weed that is probably the most difficult weed to control in restorations in Minnesota. So we had as difficult a setting as probably one might find for this kind of restoration. Restorations of just-cultivated corn and bean fields are generally not going to require 18 months of site preparation.

Second is getting the full array of plants that you would expect to occur on a site like this. This required a lot of hand-selection of seeds and hand propagation. One of the biggest problems with a restoration like this is the constraint imposed by plant availability. If you are limited to the plants that are available currently from nurseries, you will end up with a very small plant list. We used commercial products, but for the most part we were very preoccupied with gathering the plant materials and growing them on our own. If this is going to be feasible for other people to do, we are going to have to have improved commercial availability of plants because not everybody has the greenhouses or the staff to do what we did.

Third, we paid a lot of attention to the water level immediately after planting because we had invested so much energy and money in putting the plants into the ground. Often times after planting is done, the site is left to basically establish on its own, and there isn't a lot of control of the hydrology. Stabilized water levels while plantings are establishing themselves is critical. Otherwise, only more bounce-tolerant plants will remain and diversity will be reduced.

WaterLaws: Does the emphasis placed on controlling dominant species require additional efforts after the 18 months of site preparation?

Ms. Galatowitsch: You can't truly ever rid a site of its invasive perennials. Most of our landscapes have a lot of weeds in them now so you can expect that to be a recurrent problem. We still weed very carefully and we do spot inspections to make sure we don't have weed populations getting out of control. Long-term weed management probably is essential for maintaining the diverse set of plants that we installed on the site.

WaterLaws: Can you speak a bit about the cost of what you have done and how that compares with creating a wetland that will serve a simple water management function.

Ms. Galatowitsch: The cost of doing this is quite high. The cost of this project so far, not including land purchase, is several hundred thousand dollars. For a marsh that is about 8 acres, that's pretty steep. Certainly, if you were to just install water control structures and re-flood the site, you could expect to spend maybe $2,000. It is an interesting issue. Probably the most important point is that if a wetland is to be lost in the landscape due to some other land use conversion, if it is a very diverse wetland, comparable to the kind of thing we are trying to recreate at Spring Peeper, its value might be understood to be great simply because of the cost of restoring it. Its destruction is, in a sense, less likely to be undone.

WaterLaws: Can attention at the regulatory level to distinctions in wetland quality be a driving force to create the market for research, for the types of seedlings that are needed, and improve the cost feasibility of this type of restoration?

Ms. Galatowitsch: I have heard of some projects where the mitigation or replacement ratio would allow an offset of quality for quantity. That also might be something that occasionally is negotiated.

If there were greater attention in restoration work to improving vegetation diversity and overall wetland value, then certainly there would be a larger market for plants and we would be doing an overall better job at mitigating wetland conversion. If the plants were available, some of the costs that we experienced wouldn't be incurred by people doing restorations because they would be able to purchase the plants commercially and not have to have the facilities and staff to grow them. But there remains a big premium on long-term vegetation management. Most restorations have really been more of a "walk-away" project, where it is assumed that they are going to take care of themselves over time. What we really don't know is how to sustain quality over time. That is something we will learn from Spring Peeper.

WaterLaws: If ongoing maintenance is done conscientiously, can it be done by volunteers, or are you necessarily going to have the expense of skilled people?

Ms. Galatowitsch: Well, we have a lot to learn about what long-term management is going to consist of. Certainly some of the initial site preparation is not a good volunteer activity because it involves things like burning, use of pesticides, and tillage. After initial site preparation, often times what remains is hand-weeding, some clipping and maybe some wick application of herbicide. Once it gets to that level, it may be a good activity for volunteers. A knowledgeable person will be needed to direct and coordinate efforts. The other issue will be identification of the weeds. Do the volunteers know their wetland plants well enough to be able to identify the plants at an early-enough stage to be able to distinguish desired from undesired species? The first couple of years after planting you probably shouldn't rely on volunteers.

If there is an overall benefit from being on the site, then that might be adequate motivation to attract volunteers. I guess the best thing I can say for weeding is that it keeps you out in the middle of the wetland for a couple of hours and you can see some incredible things. You will see bird nests, amphibians, and you will get a real close-up view of a wetland, usually at eye level. That is something often times we don't take time to do. From that perspective it will be easier to enlist volunteers if our restorations recreate truly interesting ecosystems. I think we are approaching that at Spring Peeper.

WaterLaws: Can you explore the relationship between the diversity, the habitat and the aesthetic value on the one hand and function on the other? If we are restoring to a more rigorous natural wetland standard, are we getting increased function, whether water quality or quantity management? Or is a more natural, diverse wetland a less functional one?

Ms. Galatowitsch: You could put in a network of high quality wetlands and they would function very nicely for a whole variety of purposes. However, if you wish to really intensively use a site for one of those specific purposes, the wetland isn't going to be able sustain a diverse wetland community and it doesn't resemble a natural wetland much at all. It becomes more of an engineered facility, a sewage treatment pond as much as a natural wetland. Stormwater detention basins often times have such an incredible hydrologic fluctuation that they really have a very limited ability to sustain any level of biodiversity. Clearly there are tradeoffs. If we have an intensive need to load stormwater or load agricultural or urban pollutants, it may be a good idea to have some wetlands that essentially become kidneys for that purpose; they become primary treatment basins and separate from wetlands in which we are actually trying to sustain diversity.

WaterLaws: Might you speak specifically about phosphorous?

Ms. Galatowitsch: Phosphorous is going to be coming into a wetland mostly from surface runoff. Phosphorous will come off of grass surfaces immediately after rainfall and after a fertilizer application. The other major contributors to phosphorous are animals. For example, geese in high populations leave plenty of droppings, and those contribute to very high phosphorous loads. Phosphorous coming into those wetlands is going to contribute to high algae blooms. As you know, this is a significant concern for the Minneapolis Chain of Lakes.

Vegetation and soils are not a perfect sink for phosphorous like they are for nitrogen. Phosphorous will bind to sediment and settle out, and you can get phosphorous removal in a wetland for a period of time. However, eventually the system becomes overloaded and will export as much phosphorous as it takes in. It may be a matter of decades, but certainly it is not as it is for nitrogen, where a wetland can continue to take up nitrogen for an almost infinite period of time. So, in our urban areas, wetlands are rather imperfect solutions for phosphorous control.

On the other hand, it makes sense to have wetlands in those receiving positions, those sort of kidney locations, even if it is for a 10-year period. A treatment-facility sort of wetland, as is being done along the Minneapolis Chain of Lakes, makes a lot of sense if you are going to go in and maintain the site. In other words, dredge out the sediment and remove the phosphorous that way. Some wetlands are really designed to accommodate that kind of use and that makes sense. It suits a very different purpose than what we did at Spring Peeper. It makes sense to have both wetlands if a heavily functional wetland precedes a more diverse wetland and serves as a receiving basin.

WaterLaws: In that case, are there particular methods that you can use to prevent the invasion of the downstream wetland by the species that are in your functional wetland?

Ms. Galatowitsch: If there is a good surface water connection between the two, there is going to be trouble and we really don't know ways to stop that dispersal, especially for our water-dispersed species, like purple loosestrife and reed canary grass. Cattails blow everywhere. You will want to avoid a direct surface water connection between the primary treatment wetland and a wetland set up for biodiversity. That can be very difficult, though. I very well could imagine that you are going to have continual weed maintenance. On the other hand, it is better to at least keep an eye on the weed populations and try to control them in the long-term and at least try to separate function from biodiversity. Try to reduce dispersal and manage the high-quality site as best you can.

WaterLaws: It sounds like the best approach is to limit upstream pollutant loading and stormwater flows in the first place.

Ms. Galatowitsch: That would be a much preferable solution: increasing infiltration higher up in the watershed using things like bio-infiltration swales, reducing impervious surface, reducing curb and gutter, keeping the more permeable soils available for infiltration. Certainly, if you are restoring a wetland with the goal of biodiversity, if you are going to make the investment in a high-quality wetland, it makes a lot of sense to also look upstream for ways to limit pollutant loadings and increase infiltration.

WaterLaws: A final word?

Ms. Galatowitsch: I would encourage people to come out and visit Spring Peeper for themselves. It is open to the public, there is a nice boardwalk on the site, and there are great interpretive signs that explain what we are attempting. I hope it will be an interesting place for people to visit over the years and see how the story unfolds, whether we succeed in recreating a truly high-quality ecosystem. The site is at the Minnesota Arboretum, about 20 miles west of Minneapolis, off of Highway 41 and 82nd Street in Chanhassen.

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