Tom's Blog

Sunday, November 29, 2009

Making a new boardwalk

It is not finished yet, but we have a good start on the boardwalk, which will go across our marsh to Pleasant Valley Creek. This project has been designed and directed by Jim Hess, with advice from Paul Michler, Kathie Brock, and others. Before the winter is out, and perhaps a lot sooner, we will be able to walk from the edge of the Crane Prairie, across the small free-flowing creek that is fed by our many springs, and reach Pleasant Valley Creek. This boardwalk is being built so that we can manage and restore our wetland, but it will also enable visitors to get out into the middle of the sedge meadow/cattail marsh.

The bridge across the creeklet near the Crane Prairie has been fabricated by Wickcraft, Inc. of Madison, and they generously provided free installation plus the wood for the bridge walkway. The rest of the boardwalk, around 200 feet, is being funded by Savanna Oak Foundation, Inc. The walkway is being laid upon 5 foot sections of used telephone poles that were donated by Madison Gas & Electric Company. We are grateful to all these entities for making this boardwalk possible.

The bridge was installed by Wickcraft in early November, and we made use of yesterday's fine weather to construct the first sections of the boardwalk itself. These were intended as a pilot project, to work out the "bugs" and confirm that Jim's design was satisfactory. Yes, it was!

The walkway is being fabricated in 10 foot self-contained sections which are then brought to the site and fastened to the 5 foot telephone poles, which are being laid down across the marsh. Each section is being fastened to the next by spacer boards that are bolted in place. When completed, the walkway on each side of the bridge will consist of a single long unit.

The photo at the top shows our construction crew working in the barn. Kathie and Rex sawed the deck boards to size, Marci and Susan arranged the boards in place and drilled the pilot holes for the self-threading screws, and Jim and Paul screwed the deck boards into place. The holes for the spacer boards were drilled and two 10-foot sections were bolted together to make sure the design would work. Then the two sections were taken apart for transportation to the site.

To reach the site, we are driving along the fire break that separates the Crane Prairie from the wetland. Although the fire break is getting enlarged by the delivery truck, no harm is being done because the prairie plants have all senesced. The Prairie should bounce back next spring, after it has been burned.

At the site, the 5 ft telephone poles are spaced 10 feet apart and the walkway units placed on top. Two people can carry the 10-foot section, one on each end, although to reduce the load, 4 people were used. We now have two sections, the prototype, in place.

Even with only two sections and the bridge in place, one already has access to Pleasant Valley Creek, because at this time of year the cattail marsh is not very wet (although I used rubber boots).

Now that the prototype has been proved, we hope to be able to complete the boardwalk within the next month. Once it is completed, we will be able to start thinking about some restoration work. Already, I have discovered several large honeysuckle bushes that must be cut down!

Thursday, November 26, 2009

Soil pH/Calcium and buckthorn distribution

I am studying the distribution of buckthorn in relation to soil calcium and pH. This started because there was an interesting distribution of buckthorn at Pleasant Valley Conservancy which was possibly related to bedrock formations.

Pleasant Valley Conservancy is in the Driftless Region of southwestern Wisconsin, which means that there is no glacial drift over the bedrock. Geologist Bob Dott used field observations and well logs from the Wisconsin Geological and Natural History Survey (WGNH) to construct a bedrock map of the Conservancy. Later, the WGNH kindly sent me an unpublished bedrock map of Dane County which was georeferenced so that I could bring it directly into ArcGIS (see abbreviated version of this map, below).

In our early restoration work it appeared that buckthorn was everywhere, but as we began to get it under control I discovered that it was much more common on the western (higher) than on the eastern (lower) part of the Conservancy. The top of the property, which has what I call the "Dolomite Cap", was where we were finding buckthorn, and as one moved off the Cap, toward the eastern end, the buckthorn diminished and essentially disappeared. In addition, there is a narrow (20 foot) dolomite layer between the two major sandstone layers, called the Black Earth Dolomite (shown by the arrows on the map).

I knew from the work on buckthorn in England (where it is native), that it is found primarily in high-calcium areas. (The English consider this species to be a "calciphile".) Since a major constituent of dolomite is calcium/magnesium carbonate, it seemed reasonable that soil calcium would vary with the composition of the bedrock. Some preliminary work several years ago was encouraging, so this year I have been pursuing this further. I have taken soil samples across the Conservancy, marked their locations with GPS, and had pH values and calcium concentrations assayed (by the U.W. Madison Soil and Plant Analysis Laboratory).

The variation in pH and calcium across the Conservancy is very wide, and the distribution is related in a complicated way to the underlying bedrock. All of the soil samples from the dolomite cap area are high in calcium and are alkaline in pH. In addition, the soils on the whole south slope, even those where the underlying bedrock is sandstone, are also high in Ca and pH. This seems reasonable because these south slope soils are riddled with small dolomite fragments, which have come down from the dolomitic outcrops above. (The NRCS soil survey calls these soils "Stony".) Finally, the narrow zone of the Black Earth Dolomite also has soils high in Ca and pH.

As the map shows, the east side of the Conservancy, which is away from the Dolomite Cap, has soils that are low in pH, all below pH 7, and mostly below pH 6. In the East Basin, which is the farthest from the dolomite, most of the soils are in the range of pH 5.

For anyone interested in the biogeography of buckthorn, these results are intriguing. A good research project would be to study the distribution of buckthorn across southwestern Wisconsin in relation to Ca. I have noticed wide areas of Iowa County that are buckthorn-free. Perhaps this is why?

For simplicity, this map shows the pH values, which correlate quite well with the Ca concentrations. A higher resolution version of the above map, in PDF, can be found on my web site.

Wednesday, November 25, 2009

Sweet clover: last fall spraying

As readers if these posts know, sweet clover (Melilotus albus and M. officinalis) is one of our major scourges of the summer. It has a very long-lived seed bank and the seeds are stimulated to germinate by burning. We spend a lot of the June-July period hand-pulling it.

Sweet clover is a biennial, and like many other nonnative species (garlic mustard, for instance) it has a long fall regrowth period. These first-year plants will overwinter and become the large flowering plants that we will be pulling next summer.

Late fall is an ideal time to spray these sweet clover plants with glyphosate. Since they remain green, they will take up the herbicide and will be killed. And since virtually all native species have died back for the winter, there is no worry about killing any "good" plants. Also, glyphosate has no soil-residual, so there will be no herbicide present next spring. (The glyphosate concentration recommended on the label should work fine.)

I did a study where I marked a large patch of sweet clover during this fall regrowth period and sprayed it with glyphosate. There was no growth the following spring/summer, and the area continues to remain free of sweet clover four years later.

Today, Susan, Marci, and Amanda cruised our major sweet clover areas and sprayed all visible plants. On the south slope, where sweet clover has been especially bad, the green plants are small but reasonably visible among the clumps of little bluestem grass (see photo). Although not as easy to spot as fall regrowth of garlic mustard or hedge parsley, they can be found, and every sprayed plant will be one less plant to have to pull next summer.

How about hand-pulling now instead of spraying? Unfortunately, it does not work. The root crowns of these sweet clover plants are still very delicate, and the stems break off if hand pulled. You have to dig them up, using a sharp knife, a rather time-consuming job.

Our fall foliar spraying activities are now over for the year. When the temperature drops below freezing, aqueous spraying is difficult to do. We are now tooling up for winter herbicide work, using Garlon 4 dissolved in bark oil to control woody invasives, either as a cut stem treatment or by basal bark.

Monday, November 23, 2009

Prairie dropseed in winter

Prairie dropseed (Sporobolus heterolepis) is one of those conservative prairie species that has a quite restricted distribution in Wisconsin and elsewhere. According to Cochrane and Iltis, it is an indicator of unplowed and dry remnant prairies. Its specialized distribution is indicated by its high Coefficient of Conservatism (10). In Wisconsin it is found almost exclusively south of the Tension Zone.

Right now is an excellent time to look for prairie dropseed. Its characteristic colony structure and distinctive color make it stand out in prairies, since almost all other species have turned a drab brown or gray.

We originally had prairie dropseed only in the two prairie remnants (Units 1 and 4), where it has continued to thrive during restoration. In addition, we have been able to get it established in several sandy or dry areas, either from seed or from transplants. Today Kathie and I climbed the south-facing slope (Unit 6; photo above) and were pleased to see several well-established colonies, which we planted back in 2001. As noted, they were easy to spot from the characteristic color.

Even more exciting, when we reached the top of the slope and stepped onto the Rocky Overlook, we found a large number of prairie dropseed colonies that we did not know were there. Kathie is fairly certain she did not throw seeds into this area, and we certainly did not transplant them. In fact, since they are growing right out of the dolomite, it is a surprise that they have become so well established. (See photo below)

Strange that we had not noticed these colonies earlier this summer, when they would have been bright green.

We have also been able to get prairie dropseed established well in the dry sandy area at the southeast corner of the Pocket Prairie.

There are several other relatively rare species that are easy to spot right now because of their distinctive fall colors. More on these in a later post.

Saturday, November 21, 2009

GIS Day Expo at UW-Madison

Yesterday I attended GIS Day at the Memorial Union. This annual event is held throughout the world as part of National Geography Awareness Week. GIS (Geographic Information Systems) has become a major set of tools for dealing with spatial information. As readers of this blog know, I have been using GIS tools extensively in my work in restoration ecology.

A large number of local organizations, governmental, educational, and commercial, participated in yesterday's event. There were many quite interesting exhibits, plus a full day of 30 minute presentations on various aspects of GIS. Here is a list of presentations that I found especially interesting:

1. Sam Batzli: is a nonprofit activity through UW that provides high quality georeferenced images for all Wisconsin counties.

2. Leah Ujda: Historic maps and spatial materials provided without charge by the UW Digital Collections Center. A huge number of historic maps and documents have been scanned and are provided free and without advertisements.

3. Aaron Stephenson of GeoAnalytics discussed the use of "mashups" to create one's own web mapping applications. A mashup is a web page or application that combines material from two or more separate sources. This is a huge area of interest which has just arisen in the past few years.

4. Staff members from the Natural Resources Conservation Service (NRCS) presented background on use of flight-controlled laser imagery (LIDAR) to create high-resolution elevation data for use in GIS images. One major application at NRCS is in construction of soil maps with more accurate information on slope and aspect.

5. The New U.S. Geological Survey topographic map was discussed by Dick Vraga of USGS. The traditional paper topographic map is being superceded by digital versions, with increased information and accuracy. The National Map Seamless Server is the source.

6. Mark Wegener of the UW Arboretum discussed the new interactive Arboretum map which is now under development. It should be available for the public early in 2010.

The GIS field is so vast that it is a challenge to isolate the portions that are most useful. Just learning the software is a major effort. However, the work that I have done so far over the past year has been extremely useful, and I am committed to forging ahead.

Wednesday, November 18, 2009

Late fall control of hedge parsley

Hedge parsley (Torilis japonica) is a newly "emerging" invasive plant that has recently become of considerable concern. In a sense, we at Pleasant Valley Conservancy have been one of the "pioneers" in hedge parsley control, since we have been controlling it for almost 10 years.

Many people have not been aware of the widespread distribution of hedge parsley in southern Wisconsin. The U.W. Madison Herbarium shows it present in just a few counties in the state (including Dane County). The first Dane County collection in the Herbarium archives was made by Olive Thomson in 1982, and her husband John made more collections later. Kathie deposited the first collection from Pleasant Valley Conservancy in 2004. Here is a link to the Herbarium web site.

Because it has only recently become known, many landowners do not know they have it. I have seen it in large infestations in several sites in southern Wisconsin.

It is a relatively inconspicuous member of the carrot family, and only when it is flowering is it easy to spot in a natural area. Its preferred habitat is shady wooded areas (fairly similar to garlic mustard). It is what is called a "winter annual". It sets seed in late summer, and the seeds germinate in the same fall, forming first-year plants that overwinter. The seeds are very sticky (much more so than those of garlic mustard) and are presumably transported by animals.

Our preferred method of control of hedge parsley is by handpulling in mid summer, when it is in flower. However, like garlic mustard it can also be controlled by spraying in late fall, when the new plants are still green. Yesterday Susan, Marci, and Amanda spent the afternoon spraying (with glyphosate) on our ridge top, in areas that we knew from previous work were infested.

Unfortunately, spraying hedge parsley in wooded areas is difficult, because the plants are often covered with leaves, so that herbicide coverage is often spotty. However, there were plenty of lush green leaves visible. Glyphosate is the herbicide of choice because this time of year all the native plants have senesced, and because glyphosate has no soil-residual, it has no effect on these natives.

Monday, November 16, 2009

Planting the East Basin

On Saturday we planted the East Basin, a major job and a satisfying end to a lot of hard work this fall. We had 18 volunteers and we could not have done it without them.

If you have been following these blogs, you know that the East Basin is the final area at Pleasant Valley Conservancy to be restored. It is a 4.5 acre basin that historically was completely open and probably a prairie remnant. During many years of neglect, it gradually filled in with weed trees and invasive shrubs, and when we started restoration it was completely impenetrable. Trees included elm, box elder, cherry, and black walnut, all of which were removed. In addition, there was a large clone of about 100 aspen, which had to be girdled and allowed to die.

We started the restoration work in the early winter of 2007, which unfortunately turned out to be a very heavy snow year. We finished the restoration work about 2 weeks ago, when we burned a large number of piles of now-dead aspen logs.

We have been collecting seeds for planting in the East Basin for the past two years. These seeds are now on the ground!

Planting the East Basin was not your ordinary prairie planting. This is hilly terrain, with a rather complicated topography. Parts of the basin face east, parts south, and parts southwest. There is also an erosion gully in the middle, and an area at the bottom of the gully which is flat and has a wet mesic character.

We had three separate seed mixes, dry mesic, mesic, and wet mesic. Each of these mixes had upwards of 100 species of forbs. The dry mesic mix had a lots of little bluestem and side oats, with smaller amounts of Indian grass. The mesic mix had more Indian grass and less of the other two grasses. The wet mesic mix had Indian grass plus other grasses that prefer wetter habitats, such as bluejoint grass.

Kathie, Susan, and I spent several days laying out the area for planting. Because of the complex topography, we could not simply have rectangular planting areas, such as used when ag fields are being planted to prairie. Once we had the area laid out, Kathie and I then used a GPS to measure the acreages. The GPS Tracks were then uploaded to my computer and ArcGIS was used to create a map of the whole planting area. Each person was given a copy of this map with their planting unit marked. (I'd be happy to send a copy of the final map to anyone interested.)

On the day of the planting, the weather was fortunately relatively warm and partly sunny. Our PVC crew arrived early and distributed the buckets of seeds to the various planting units. (Each unit had 2 or 3 buckets.) At 10 AM the volunteers arrived, and we transported them to the top of the hill with our pick-up truck. Planting started at about 10:15 and finished at 11:45 AM. After the planting, we had a "debriefing" at which the details of the project were discussed. This was followed by lunch at our cabin.

The photo above shows part of the area being planted.

A lot of "prep" work was done before planting. In 2008 members of the PVC crew covered the whole area with backpack sprayers, treating any woody resprouts with herbicide. Also, dozens of mullein plants were sprayed, as well as patches of Canada goldenrod. Also, there were two patches of garlic mustard (the only serious garlic mustard infestations at PVC), which have been sprayed two separate years. This past summer, the whole area was sprayed with glyphosate twice, to eliminate annual and perennial weeds. (See the photo at the end of this post.) Finally, a couple of weeks ago I walked over the whole area and sprayed motherwort and other fall-growing perennials with glyphosate.

When we burned the aspen piles, we also picked up all of the larger sticks and logs and threw them on the piles. The goal was to create as much bare ground as possible, so that the seeds would find homes.

Our final task before winter is to put out some hay bales in the erosion-prone areas to keep the soil from washing away during winter or spring rains. We'll get this job done in the next few days.

I look at the restoration of the East Basin as a "pilot" project for what might be done in other former prairie areas that have become wooded and brushed in. Hopefully, there will be a prairie here in a few years!

The photo below shows what the East Basin looked like last summer (at the time of spraying, and before the dead aspens were cut).

Wednesday, November 11, 2009

Indian summer: an ideal time to burn oak woods

Although we were not able to burn this fall (too busy getting ready to plant the East Basin), the last week has been ideal burn weather. This is the period commonly called "Indian Summer" in the upper Midwest.

What is Indian Summer? This is a period of warm, sunny, dry weather that follows several sharp cold periods. The cold periods bring about the senescence of native plant species and hasten leaf fall. The following warm period is ideal for burning prairies, wetlands, or woods.

Indian Summer is is an especially good time to burn a bur oak woods, because the leaves of this species get dumped all at once over a period of a week or so. (White and black oak leaves tend to hang on most of the winter, gradually coming down.) When the bur oak leaves fall they are already well "cured", and because of their curls, do not fall flat on the ground. Thus, fire carries well. It is especially valuable to do a fall burn if you are planning to plant the understory. The burn opens up the forest floor so that the planted seeds get to the soil surface.

Spring burns can of course also be done, especially if one is not planting. However, for woods burns early spring ephemerals may already be up and will be knocked back by a spring burn. This is never a problem with a fall burn.

According to William McClain, an ecologist with the Illinois Natural History Survey, Native Americans generally burned in the fall, and this may be one reason why this season is called "Indian" summer.

Here is a brief history of Indian Summer weather.

Monday, November 9, 2009

Great time for prairie planting

Now that the seeds have all been collected, work turns to getting these seeds on the ground. After an unsettled October, the weather has turned great, and prairie planting can be done.

For over 10 years, Kathie and I have been helping Madison Audubon Society plant prairies at their Goose Pond Sanctuary. Seed collecting begins in early September and continues through early November. Once the seeds are dry, there is lots of seed cleaning work, with the hammer mill, the fanning mill, and various other seed screening activities. The goal is to get the seeds into a state so that they can go into seed mixes and get distributed on the ground. Some species can be virtually purified (for instance: stiff gentian, wild indigo, potentilla, milkweeds), whereas others need only be stripped from seed heads and given a partial cleaning (for instance, most goldenrods and asters).

This year, Madison Audubon planted 9 acres of new prairie at Erstad Prairie, a 60 acre site 3 miles NE of Goose Pond. Erstad Prairie is adjacent to Schoeneberg's Marsh, a 585-acre Waterfowl Production Area of the U.S. Fish and Wildlife Service, and is a prime nesting site for yellow-headed blackbirds and black terns.

About 30 people participated. Some spent their time making seed mixes or finishing the seed cleaning, some helped plant the prairie, and others did both. The weather was unusually fine and the job got done expeditiously.

The "field" had been planted last fall to winter wheat, which was harvested in mid-summer. Later, the whole field was sprayed with glyphosate herbicide to kill the annuals and other plants which grew this summer. At the time of planting, most of the field was bare, with occasional annuals which had already died out.

The field had been marked off in 1/2 acre parcels. Five buckets of prairie seed were used for each parcel, plus another bucket that contained some of the heavier species mixed with cracked corn as a carrier. Two people were assigned to each parcel. Each person had the responsibility of hand broadcasting the seeds from two buckets, and the fifth bucket was shared. One challenge here was to be sure you kept within your own parcel. Large red traffic cones are placed at each corner as guides. You start out at one corner, walk toward the other, throwing seeds out as you go. The other challenge is to make the seed last through the whole parcel. After a bit of time, you get the feel for how well the seeds are going to last.

We started planting about 1:00 PM and were finished around 2:30 PM. In all, a great day!

Friday, November 6, 2009

Removing major trash dump

Yesterday we spent several hours clearing out a major trash dump at the NE corner of the East Basin. There was a lot of history there! We found a license plate from 1942, shingles and gutters from a building, lots of glass bottles, rusted relics of vehicles, tractors, etc., plus much barbed wire. This dump was just inside the fence along our property boundary. Out of sight, out of mind.

While this dump was there, a whole nice grove of white oak trees developed. Some of these trees were at least 50 years old. We burned this grove on Tuesday, which removed lots of leaves and made it easier to for us to haul out the junk.

We drove our truck nearby and tossed the large pieces directly on the bed. The small pieces were put in heavy-duty trash bags. I had to make a special trip to the hardware store to buy more bags. We ended up with at least a dozen bags, if not more.

Barbed wire is especially annoying. It is hard to believe how much barbed wire we have removed at Pleasant Valley Conservancy over the past 12 years! When you think you have it all, you find another patch. In addition to the barbed wire along the fence, this dump site had large amounts of small barbed wire fragments. We started piling it up and before we were finished we had a pile about 4 feet tall and 3 X 4 feet in area.

Barbed wire is a good indication of how much grazing must have occurred at Pleasant Valley Conservancy. Everything that could not be cropped must have been grazed. Fortunately, grazing ceased a long time ago, and lots of "good" plants recolonized. For instance, lots of shooting star plants are in the area of this trash dump.

Wednesday, November 4, 2009

Keeping the goldenrod seed heads straight

This year, some of the late goldenrods are just ready to collect. There are actually three goldenrod species that are "ready" now, but only two of them are worth collecting. With experience, these three goldenrods are fairly easy to tell apart, but since they are all in seed set right now, one has to pay attention to be sure they don't get mixed up.

Showy goldenrod (Solidago speciosa), in particular, seems to have been slow in forming good seed heads, but yesterday they were just perfect for collecting. Showy goldenrod is colonial, forming compact patches, with all the stems arising from a single root stock. Its stems are smooth and red, and its seed heads are columnar.

We have showy goldenrods growing all over Pleasant Valley Conservancy, in both prairies and savannas, but they are all descended from a single small prairie remnant that is at the east end of Toby's Prairie. This is still one of our best collecting sites for this handsome species.

Gray goldenrod (S. nemoralis) is a dry-site species that thrives fairly well, and we have been collecting lots of seeds this year to use in our East Basin seed mix. It is a fairly small species and is neither clonal or colonial. Its inflorescence is small and the flowers are all formed from one side, so that the flower head has a tendency to nod. (One common name for this species is "nodding goldenrod"). An important diagnostic characteristic of gray goldenrod are the white hairs on the stem, which are generally more visible now when the plant is in seed.

Gray goldenrod is a very desirable species in planted prairies, and does especially well in a dry-mesic seed mix.

The third species, Canada goldenrod (S. canadensis), does not need any help from us. In fact, we spend a fair bit of time each season trying to get rid of it. Canada goldenrod is a clonal species, spreading by rhizomes, and can form large patches. Its seed heads are loose and spreading. Although the seed heads seem quite distinct in the photos shown here, in the field it can actually be mistaken for either of the other species, since its flower heads often have several other types of structures. Thus, it is very important to avoid this goldenrod when seed collecting!

Small burns in the East Basin

We are getting ready to plant the 5-acre East Basin on the weekend of Nov 14-15. Most of this unit is cleared and ready to plant, but we had two areas that needed burning. Yesterday we had successful burns of both.

The first area was the long, narrow strip shown in the above photo. This area had originally been part of the Ridge Prairie planting (seen on the right), but in the process of clearing the East Basin we had to disturb this area a lot, including creating the access road shown in the photo. Because there was little "good" vegetation left, this area was sprayed twice last summer with glyphosate. Thus, the burn was intended to get rid of the dead thatch.

The weather was very clear and sunny, with low humidity, so the burn went very well. The main concern was spot fires in the adjacent Ridge Prairie, but since the wind was out of the west, this proved not to be a problem.

The second area was a small white oak savanna at the northeast corner of the unit. Since this was an area with well established trees, we did not clear this during the restoration work. It will be planted as savanna rather than prairie. The burn here was done to get rid of all the newly fallen oak leaves so that the seeds could reach the soil surface. Since the leaf cover was not continuous (as seen, a lot of the leaves had not fallen yet), the burn was patchy and we had to light a number of separate strips. In getting ready for this burn, a leaf blower was used to blow the leaves away from the bases of the white oaks. Although this was not absolutely essential (white oak bark is fairly fire-resistant), it was a useful precaution, and fairly easy in such a small area.

Monday, November 2, 2009

Seed germination studies

Since most of the seeds we need have been collected, it's time to think about seed quality. How "good" are the seeds were are getting?

It's a relatively simple thing to check seeds to see if they have embryos, but that doesn't necessarily mean they will germinate. For the past several years I have been running germination tests in petri plates. I put a circle of filter paper (paper towel would do as well) in the bottom of the petri plate, moisten the paper, and add about 25 seeds. I usually do at least 2 plates of each species.

The plates are wrapped with Saran and put in the refrigerator for a month or so to induce them to germinate. (The seed biologists call this procedure stratification.) Then the plates are remoistened and brought to room temperature under fluorescent lights or in the greenhouse. They are rewetted as required and checked daily for germination. Care is taken to be sure the seeds are not overwetted, as this may result in mold growth. If they have not germinated in a month or two, I assume they are not going to germinate (but see below).

The photo shows a purple milkweed germination test. The seeds have broken out of their seed coats and have sent out long roots.

In 2008 I ran 25 different germination tests, with quite variable results. Some species germinated very well, some did moderately well, and some did very poorly. A few species did not germinate at all. The highest germination percentages were found with the milkweeds, almost all of which germinated very well. (See results below)

Butterfly milkweed: 84%
Short green milkweed: 84%
Poke milkweed: 86%
Purple milkweed: 100%

Eupatorium sessilifolium, a Special Concern species, germinated very poorly, around 2% at best (some batches did not germinate at all).

Two other Special Concern species did better: sweet Indian plantain, 28%; Giant yellow hyssop, 52%. With Napaea, another Special Concern species, the higherst percent germination was 6%.

I tested three grasses: Indian grass, 58%; little bluestem, 16%; and prairie dropseed, 22%. (These were tested without the cold treatment, since grasses don't require this.)

Not all plant species are induced to germinate by the cold, moist treatment described above. Some species require other kinds of treatments. There are reference books that provide details.

Although these tests are fairly quick and easy, and mimic what the seed testing laboratories do, not all seeds germinate in this short time period. The seed testing labs have an alternate procedure, the tetrazolium test, which checks to see if the seeds are viable. This measures the ability of the seed tissue to metabolize the tetrazolium compound and produce a colored product that can be seen by the eye. If the seed does not germinate but is tetrazolium positive, then the seed lab concludes that the seed is alive but dormant. (There are also other, more technical, methods of checking seed viability.) The advantage of buying seeds is that the seed companies sell based on pure live seed (PLS). If you collect your own seeds, you are assured a local genotype, but viability is not guaranteed. With seed of unknown viability, much higher planting seed densities are required.

The above is a very abbreviated discussion of a complicated process. For more on seed quality, see The Tallgrass Restoration Handbook (Packard and Mutel) or A Practical Guide to Prairie Reconstruction (Kurtz).

Control of brush along a stone wall

At Black Earth Rettenmund Prairie we have a nice stone wall on the west side of the property. This is a hand-built wall that was constructed by our neighbor from stones he found on his ag field. The wall is really a cultural feature of the prairie and is something we want to preserve and protect.

For that reason, we have always kept it from getting black when we burn that area. We wet down a strip next to the wall, and the wall itself, so that flames don't reach it. (See photo below)

One problem with protecting the wall is that the brush that inevitably grows is not killed, so eventually a rather nasty brush border develops, on both sides of the wall. All sorts of brush was present, including honeysuckle, buckthorn, sumac, and brambles.

Yesterday our volunteer work party dealt with this brush border. One person operated a Stihl brush cutter and five of us followed along with spray bottles of Garlon 4 in oil. This is the best herbicide to use, because it works on all the various species, and the herbicide penetrates the bark of the cut stem as well as entering through the open cut itself.

With a group of people treating, it is virtually ensured that all cut stems will be treated. One or two people follow close after the brush cutter and treat the most obvious stems (usually the largest) whereas several others trail behind and do "mop-up".

It took us about an hour to deal with the whole area, after which we collected seeds for the rest of the afternoon. The weather was mostly sunny and pleasant.