The temperature isn’t the only thing heating up around Duck Creek this summer. The construction activity on the area is also increasing.
On Friday, July 8, the Conservation Commission approved the contract work for Units A and B. Last fall we presented the main concepts of this work (see "Units A and B Plan" link below). If you made it to the Duck Creek Office over the last nine months you may have seen the engineering plans on the wall. During the last week we’ve prepared for the beginning of the dirt work by planning for the end of construction. Between now and then, there is quite a list of dirty deeds.
Wetland plant response to flooding
Units A and B were one of the first parts of Duck Creek to drain after April’s deluge of rain and widespread flooding. Since then wetland plants like millet, smartweed and sedges have germinated in the moist soil conditions and have grown considerably. Typically, this kind of production is the goal of our summer wetland management. By shallowly flooding these wetland communities in the fall, migrating waterfowl can forage on the abundant seeds, plants and invertebrates and refuel before continuing their journey south. This year we have a slightly different purpose. However, it is still beneficial to know “what” and “how much” vegetation has been produced.
Good millet production
Wild millet (Echinocloa crusgalli), also known as barnyard grass, has a large seed head and is an important food for waterfowl. Wetland biologists can estimate millet production by measuring the seed head size and stem density. This helps in comparing years and conditions and learning how to tweak our wetland management practices over time. Last week we took 20 measurements of the millet in Unit A to get a quick snapshot of our production this season. Expectedly, the density of millet varied quite a bit as across the sampled area, but on average we had 500 pounds per acre. In locations were we had higher stem densities we came up with 700 to 1,400 pounds per acre. This is good for Duck Creek, especially since it is fairly early in the growing season. Unfortunately, we can’t use this to feed the ducks this year because of the dirt work, but it will still go to good use.
Wetland construction and soil disturbance
One of the downsides of moving a lot of dirt around is that it will remove valuable topsoil from certain locations. Research has shown that created wetlands often have lower soil organic matter than natural wetlands and therefore may not have the same plants (if any) right after restoration. At this point you might be saying, “Hold up, did you say soil organic matter…and did you also say no plants?”
Bear with me, I’ll try to show you how this all comes together without getting too technical.
Soil organic matter is made up of living, dead and decaying critters (from worms to microbes) and plants. It generally occurs within the first few inches to a foot of the soil surface and is critical to soil quality. The amount of organic matter in the soil influences soil moisture, soil infiltration, availability of nutrients, presence of microbes and invertebrates and root development. When this layer is removed, plant development and survival may be limited.
Perhaps you’ve seen the giant “salad shooters” that distribute straw along road-ways after a construction job. Or maybe you have placed straw or compost in your garden. Applying mulch and incorporating it into the soil are a couple ways to reduce erosion and improve soil moisture after heavy soil disturbance. The straw helps “jump-start” the soil by serving as a food source and substrate for microbes and worms to reclaim the site. Once you get the critters back, then other nutrients and soil conditions help plants become re-established.
Baling vegetation for plant reclamation
So where will we get the mulch? This is where all this information will come full circle.
Remember the millet we measured in Unit A?
Over the last week we have mowed, raked and baled approximately 50 acres of vegetation. We’ll save these for the end of the dirt work. At that time we’ll have one of our own big “salad shooters” redistribute the Duck Creek vegetation over the disturbed areas. The mulch will help minimize erosion along our gradually sloping levees. In the lower scoured areas we will distribute and mix the straw into the soil to increase the soil’s organic content. We will incorporate lime and fertilizer as well. These “dirty deeds” should help us improve the soil quality and “jump-start” the microbes and plant communities in Unit A. By having a quicker turnaround we can continue to provide productive habitat for waterfowl and quality hunting experiences for you and me.