Tom's Blog

Friday, November 11, 2011

Turning woods into prairie: part one

Most prairies planted de novo are derived from cropland or old fields. Planting into such habitats is reasonably straightforward and moderately inexpensive.

We have planted four prairies into such habitats, and our experience has been briefly described at this site. However, many natural areas contain sites that were once prairie, and because of fire suppression have turned into woods. This is often the fate of open areas in our part of the Midwest.

At Pleasant Valley Conservancy we have two prairies that were planted into wooded sites. One of these, the Sandhill Crane Wet Prairie, was small and was only moderately wooded.

The other site, which we call the East Basin, is a different story. This 5 acre site was out of view at the far eastern end of the Conservancy and was easy to ignore. However, it was so ugly that we decided we had to tackle it. I'm not sure that we would have started this restoration if we had known what we were getting in for, but once we got started, we had to keep going. Although we were able to obtain modest grants from the Landowner Incentive Program and the Wildlife Habitat Incentives Program, most of the restoration work was funded by our private Savanna Oak Foundation, Inc., with help at critical stages from volunteers.

We have now reached the end of the second growing season of this new prairie and I have prepared a detailed summary of what we did and how we did it. Perhaps more importantly, we have detailed records so I am able to provide concrete data on the restoration work (hours and dollar costs). The present blog post is Part One of a summary of what is a 40 page PDF document that I will eventually put on the web site.

At the time of the 1937 air photo, the East Basin was completely open, with essentially no trees or other woody vegetation. Because it faces south and southwest, it seemed reasonable that it might have been a prairie remnant, even though the slope is not nearly as steep as our main south-facing hill.

A pre-restoration walk-through of the East Basin

After we had finally decided to restore the East Basin, on October 1, 2007 I did a “walk-through” of the whole site. This proved to be a difficult undertaking, as the site was very brushy. The honeysuckles were huge, and it was hard to get through them. Because of the heavy shade, the understory was very sparse. Herbaceous plants included an occasional Eupatorium rugosum, sweet cicely, Hackelia, and Aster lateriflorus. There was a large aspen clone, later estimated to be more than 100 trees. There were also some small hackberries, and small and medium-sized black (or possibly Hill's) oaks. However, most of the large trees were elm, box elder, black walnut, and black cherry.

An air photo analysis by GIS showed that the East Basin had remained mostly open through the early 1960s. By 1968 hedge rows could be seen starting and by 1976, the E side was fully wooded. By 1990 the whole site was wooded and remained so until the site was cleared in 2008.

The soils of the East Basin are quite different from those in the rest of the Conservancy. The pH values are the lowest we have, between 5 and 6, are low in calcium, and quite sandy, with some areas being iron-rich.

The initial clearing began in December 2007 and extended through the whole month of January 2008. This was a fairly large snow year so most of the stumps were cut tall and had to be recut in the summer. The members of the logging crew were experienced restoration ecologists and were careful to avoid any damage to the site. To prevent resprouting, all trunks were treated with herbicide (triclopyr). Two or three of the crew operated chainsaws and two or three others dragged the brush and small logs to burn piles. Most of the cut trees were removed for fire wood, although a significant amount of trees of saw-log quality were transported to sawmills. Also, a neighbor moved in a small saw mill and turned the largest black walnuts into lumber.

The photo above is a view from the top of the East Basin, showing an early stage of tree clearing. The cut stump in the foreground, with green color, has been treated with herbicide (Garlon 3A) to prevent resprouting.

A lot of downed wood was generated and getting rid of it can be expensive. A barter arrangement was made with a Mount Horeb dealer in split firewood. He winched the down logs to the top of the hill. The logs were then cut to firewood length and allowed to age until summer, when they were split before further aging. Truckloads of firewood were removed in the late fall of 2008. Some cherry logs of saw-log size were donated to a neighbor who paid to have them winched to the town road where a sawmill operator could reach them.

The first spring after clearing the East Basin was an interesting experience. We had decided to wait to see what came up spontaneously before we started serious restoration work. The first thing that appeared was shooting star (Dodecatheon meadii), in several large areas. This fine prairie species is capable of remaining alive without flowering for many years beneath fairly heavy shade, and then when sunlight is brought in it immediately flowers. Data from the East Basin indicate that shooting star can remain alive but suppressed for at least 40 years.

In addition to good plants, there were many “bad” plants, including scattered brambles, honeysuckles, a few small buckthorns, and two patches of garlic mustard (the only place we have found it here).

Past experience had shown that once an area had been opened up and sunlight was available, exotic invaders thrive. Therefore, in the summer of 2008 we decided to eradicate them while they were still small. For this purpose, we sprayed all of the undesirable resprouts or small plants with Garlon 3A. Our regular crew did this job, moving systematically across the East Basin and spraying every plant seen. In addition to the shrubs mentioned, the crew also sprayed any Canada goldenrod, Canada thistle, or mullein, all invasive and very undesirable plants.

In my next post I will describe the steps we took to turn this orphan into a prairie, including cost data.


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