Tom's Blog

Friday, July 21, 2017

A good year for purple and white prairie clover!

The prairies have benefitted greatly by the extensive rains from mid June-late July. Especially, our dry prairies on the South-facing Slope are lusher than we  have ever seen them. Virtually all prairie species are thriving, but two species that are particularly fine this year are purple and white prairie clover (Dalea purpurea and D. candida ). Even before they bloomed there were large amounts of plants on the south slope (Units 2 and 3). A week ago, white prairie clover was in full bloom, and this week it is purple prairie clover, which, because of its color, is spectacular. You can actually tell these two species apart in the vegetative stage, since D. purpurea leaves are smaller and more delicate.

Both of these species are characteristic of dry prairies, with D. purpurea (C value of 7) being more common than D. candida (C value of 8). Since it is a nitrogen-fixing legume, D. purpurea is often added to seed mixes for CRP plantings, although I doubt whether this delicate species adds significant nitrogen to the soil.

D. purpurea was present at Pleasant Valley Conservancy on the south slope (the “goat prairie”; Unit 1) even before restoration began (1995-97), and we have spread it widely from collected seeds. D. candida was not here and was introduced from seeds collected at two high-quality prairie remnants

Purple prairie clover on the South Slope. Lots of other species are thriving on this slope, including compass plant, lead plant, spiderwort, and all the warm-season grasses. Note also the oak grubs.

Purple prairie clover

Wednesday, July 5, 2017

Controlling invasive plants: skills versus strategies

The skills needed to remove invasive plants are deceptively easy to learn. Cutting, pulling, digging, and girdling require little formal training. (That’s why volunteers can be used.) Even spraying is a straightforward activity.

However, the strategies involved are much more difficult. DANGER! If you use the wrong strategy you may be doing more harm than good, or at least may be wasting your time. In my 25 years of restoration work I have watched some strategies completely fail, most of which were applied out of ignorance.

Key strategies: Recognition, identification, timing, choosing the appropriate technique, (mechanical or chemical?), team organization. Knowledge and judgement are key.

Developing strategies: Start with knowledge of the bad actors, read the scientific literature, government manuals (but don’t assume they are infallible). Use the Internet judiciously. Especially avoid undocumented suggestions from others. (Lots of misinformation is passed around.)

Learn the important plant characteristics: monocot or dicot; Latin name; life cycle; clonality; habitat; phenology; annual, biennial, or perennial; herbaceous or woody.

Important items: Early detection monitoring, location maps, risk assessment (triage, see below), measurement (size of population; scattered, patchy, massive), identification, timing (season), choosing the appropriate technique, (mechanical or chemical; often combined).

Understand herbicide chemistry, biochemistry, fate in soil or environment. Read the label. Experiment! Mark your experiments with flags or stakes. With rare exceptions, you can’t eradicate invasive plants without at least some use of herbicides.

Nothing can replace extensive field experience! Get out there and take notes

Risk assessment (triage). Place the target into one of these 5 categories
1.     Eradicate everywhere
2.     Eradicate in high-quality areas
3.     Control spread
4.     Control if time available
5.     Ignore [can’t stand competition?]

Early detection is important

Set up a thorough survey method; AT DIFFERENT SEASONS OF THE YEAR!!

Use of a plant’s characteristics to help detect it: fall color; flowering (especially important); early appearance; size; habitat (prairie, savanna, woodland, wetland); legacy effects (history of the site).

Keep coming back to sites already restored, because it is almost certain there will be more plants to deal with, either plants missed or new growth. Don’t assume the site is clean! Unfortunate but true.

Don’t let the word “native” seduce you. Among others, sandbar willow, Canada goldenrod, and smooth sumac are native, but are generally “malignant” under present conditions.

For successful invasive plant control, a strong work ethic is needed. Get it done!

Don’t let these things happen:
·       You pulled the wrong thing.
·       You sprayed the wrong thing.
·       You worked at the wrong time.
·       You worked at the wrong site.

If you are using contractors, monitor them closely. Until they have a “track record”, it is best to have a manager on the site while a contractor is working.

Monday, June 26, 2017

Bur oaks, tallgrass prairie, and fire

The bur oak (Quercus macrocarpa) is a common species associated with the oak savanna landscape. This species is also known to “invade” prairies, where it can, under appropriate conditions, become established. Bur oaks and prairies thus “go together”.

Fire is an important element in controlling the relationship between oak savannas and prairies. The bur oak is the most fire-resistant of the oaks. Even fairly small bur oak trees produce a fire-resistant, corky, bark. Depending on the intensity, such “grubs” can often “escape” fire. Once they get large enough, their fire resistance is so great that they can even tolerate relatively intense fires.

At Pleasant Valley Conservancy, the south-facing slope provides an interesting habitat for observing prairie/bur oak relationships. The upper part of the slope is an extensive bur oak savanna with many mature trees that have survived numerous fires during their lengthy existence. The lower slope is primarily tallgrass prairie, but is continually being “inoculated” from above by bur oak acorns.

Grove of mature bur oaks on the upper part of the south slope

When we first started restoration work at PVC, the south slope was quite wooded, with invasive shrubs and trees, including pines and red cedars. The prairie patches were small and scattered. After the slope was cleared of woody vegetation, the first burns we carried out were very poor. There was insufficient fuel to carry a fire, so we had to “force” it to burn by extensive use of the drip torch. Although the bur oaks were being heavily crowded by the invasive woody plants, they were still able to function because their canopies were above everything else. And because of the unsatisfactory fuel, flame heights were low and had little effect on the oaks.

In order to bring this ecosystem back to its full potential, beginning in 1998 we initiated a program of annual burning. For the first few years, with the poor fuel, burns were unsatisfactory, and we had to use headfires, lighting at the bottom of the hill and hoping the flames would carry to the top.

Gradually, the burns got better. It was in 2003 that the headfire, lighted at the bottom, carried to the top of the hill. (Because of the steep slope, a fire lighted from the bottom of the hill acts as a headfire even is there is no wind.) Since 2006 we have only burned the south slope as a backing or flank fire, starting at the top.
Burning the south slope as a headfire in 2003
A bur oak grub seen in 2010.
The large bur oaks have thrived on our annual burn schedule, and every few years make a large crop of acorns. Some of these acorns make it downhill to the “pure” prairie on the lower part of the slope, germinate, and form bur oak seedlings, often called "grubs". It was in 2010 that these seedlings were large enough to notice during a casual survey.

If the fire is hot, oak grubs are top-killed and then resprout later that season. This is SOP for oaks, and with annual burns they go through this cycle every year. Although their stems remain small, their root systems keep expanding, since the roots are not killed by the fire. (Soil is a very poor conductor of heat.)

This year (2017, see photo below) I discovered that some of these bur oaks have gotten out of the grub stage, perhaps for the first time, and their bark is now thick enough that the stems were not killed by the fire. I counted six bur oaks large enough to perhaps survive our annual burns.

Six small oak trees, at least two of which are out of the "grub" stage.
These are just at the top of the steep Pleasant Valley Road hill cut.
The tree on the right is also seen in the fire photo below.

As it happened, I got a photo of the burn moving across this area. The yellow arrow on the photo points to the largest bur oak.

Low intensity fire moving across the south slope.
The yellow arrow shows the location of the tree seen in the above photo.

What does the future portend for these bur oak “trees”? It seems likely that they will survive and thrive. Because they are at the bottom of the hill, they would likely survive even a headfire, because it takes some distance before the flame reaches its steady state height. However, due to competition, eventually there should be only one rather substantial tree, since the largest should eventually get big enough to shade out the rest. (Bur oaks are very shade intolerant.)

We already have examples of this further along the south slope, where there are scattered small bur oak “trees”. Walk along Pleasant Valley Road and take a look.

Does this mean that our tallgrass prairie will eventually turn into a bur oak savanna? Perhaps, although perhaps it will turn into what Steve Packard calls a “tallgrass savanna.”

Only time will tell. (The bur oaks are long-lived trees and have plenty of time.)

Wednesday, June 21, 2017

Detailed summary of the wetlands at Pleasant Valley Conservancy

Restoration work on the Pleasant Valley Conservancy wetland has been underway for over 15 years. This work has been carried out by Craig Annen and his company, Integrated Restorations (IR).

Recently, as part of a survey for hybrid cattails, Craig has prepared a detailed summary of the wetland, including an extensive species list which includes a Floristic Quality Index (FQI).

Craig's paper has now been posted on the PVC website and is available for download.

According to the report, the 35-acre complex is a mosaic of seven unique wetland types: riparian floodplain, emergent aquatic, open water, shrub-carr, peaty sedge meadow, wet prairie, and calcareous fen/spring.

View of the PVC wetland from the bench at the Far Overlook. Although there is a substantial stream running through the wetland, most of the water is from springs and seeps.

Early Autumn view of the wetland, showing the location of the boardwalk.

The wetland complex supports 163 indigenous species of native plants, all listed in the report. The Floristic Quality Index (FQI) has a value of 62.2, indicative of a remnant natural area of remarkable quality. Thirty-eight species have a coefficient of conservatism (C-value) greater than or equal to 7, and 16 species have a C value greater than or equal to 8. These values are indicative of remnants of high-quality and with the least amount disturbance. Thus PVC has been justified in placing high priority on its wetland restoration work.

One plant species, sweet Indian plantain (Hasteola suaveolens), is a species of Special Concern in Wisconsin.

A gallery of flower photos and further information on the wetland can be found on the wetlands page on the PVC website.

Saturday, June 10, 2017

Fire Management in Midwest Oak Savannas

We have been burning oak savannas and oak woodlands at Pleasant Valley Conservancy for 20 years. In the early years we made lots of mistakes, as there were no sources of good information on the use of fire. (The Internet was still in its early stages.) As the years have gone by, our mistakes have been less and the sizes of our burns have been bigger.

See past posts of Tom's Blog for summaries of our annual spring and fall burns. (To access posts of earlier years' burns, do a Search for "Fire" and "Savanna" in the search box.)

In 2015 I was asked to give a presentation on "Fire management in oak savannas" at the annual meeting of the Prairie Enthusiasts, which prompted me to assemble photos and data for a Power Point presentation. I finally found time this past winter/early spring to convert that presentation into a PDF, which is provided in this link.

Here is a brief precis from the introduction to the tutorial:

"Oak savannas are fire dependent communities. Fire management in oak savannas differs from that of prairies or oak woodlands. This document provides details on how to conduct an oak savanna burn.

Fire is especially important in oak savanna restoration. An oak savanna restoration project should not be initiated if fire is not an option. Ideally, fire should be used annually for at least 10 years. After 10 years, fire can continue to be used annually, but should be used at least two out of every three years indefinitely."

Early stage in an oak savanna burn. October 2002
This was the first time this savanna had been burned,
and to get good burn coverage the burn was run as a headfire.

The second photo shows the first burn we did in the ridge-top savanna (Unit 12B/11B). At that time, although there was good fuel (oak leaves), the fire did not carry well because of all the downed timber and coarse woody debris. Here Kathie is doing extensive interior lighting (stripping), literally "forcing" the savanna to burn. As the years went by, the savannas burned more readily and did not need so much work to burn.

The tutorial goes into details on the savanna burn process.

Friday, May 26, 2017

Should colorful invasive plants be controlled?

Many of the invasive plants that we deal with in restoration ecology are rather unremarkable in appearance, so one doesn’t mind getting rid of them. But there are also invasive plants that are colorfully attractive and there may be a temptation to let them be. Two species in this category are dame’s rocket (Hesperis matronalis) and creeping bellflower (Campanula rapunculoides). Both are decorative and would appear to be welcome additions to a native garden or prairie. But they aren’t, and should be eradicated.

Fortunately, because these two species are colorful, they are easy to spot. It would be an embarrassment to have a whole field of one of these plants.

Dame’s rocket
Although this plant is often mistaken for a woodland phlox, it is really a mustard (note the 4 petals). Like garlic mustard, it is often found in wooded areas, but it also invades open areas such as roadsides. This is one of those species that is often included in seed packets labeled “wildflowers”. To many people, “wildflower” implies “native”, but this species was introduced from Europe in the 1600s and is highly invasive.

Like garlic mustard, dame’s rocket is a biennial, and this gives a clue to control methods. The number one point is not to let it set seed. Cut the flower heads off or hand pull the plants before seed formation. Like garlic mustard, bag flowering plants, because even pulled plants can go on to make viable seeds.

Large infestations can be sprayed with glyphosate. Also, first year plants remain green in the fall long after native species have senesced and can be sprayed with glyphosate (again, like garlic mustard). [Native species that have senesced will not be affected by glyphosate. The rule with glyphosate is: if it’s green, it will be killed. Thus, when spraying with glyphosate keep an eye out for the green of fall regrowth of native species.]

In contrast with garlic mustard, colorful dame’s rocket is very easy to spot. With care, it should be possible to eradicate dame’s rocket from a site.

Dame's rocket moving into a wooded area

Creeping bellflower
Creeping bellflower is a perennial which spreads rapidly via rhizomes. It has the potential to form large clones. Its rhizomes can be up to 6” deep, with vertical storage roots. If cut or mowed, the plant will readily regenerate from rhizomes or perennial roots. The number one point is do not let it get started, because once established it is very difficult to eradicate.

Because of the deep roots and rhizomes, it is virtually impossible to get rid of creeping bellflower by digging without tearing up the whole yard. My approach is to handle it like a woody plant, which means cut the stems and treat the cut stems with 15-20% Garlon 4 in oil. Just a single spritz at the center of each cut stem is all that is needed. The herbicide will be translocated to the roots and rhizomes. [I verified this procedure by marking treated plants and checking them the following year.]

Large patches can be sprayed with glyphosate or an herbicide labeled for broad-leaf species.

I should emphasize that creeping bellflower is a very undesirable plant, despite its colorful character.

University of Wisconsin Extension has a good flyer on creeping bellflower, available at this link.


After the above post was made, we discovered two small populations of creeping bellflower in the Valley Prairie  at Pleasant Valley Conservancy. They were immediately killed  using our standard Garlon 4 in oil spritz technique. This involves finding the lower part of the plant with the bare stem and basal leaves, and spritz both. Within a week they were dead.

Kathie exhuming the base of each  creeping bellflower stem and spritzing with Garlon 4 in oil.
Five or six individual stems growing out of a cup plant patch.

American bellflower

There are two “native” species of Campanula which are attractive and desirable in a restoration. Harebell (C. rotundifolia) is a small, delicate perennial that is found individually or in small patches in dry or rocky habitats where it is free from competition from larger species. American bellflower (C. Americana) is an annual or biennial that reproduces exclusively from seed and is found scattered in wooded or savanna areas.

Monday, May 15, 2017

Shooting star: prairie or savanna plant?

This is shooting star (Dodecatheon meadia) time. At Pleasant Valley Conservancy, we had many sites where this species was remnant. Some even flowered before any restoration work, but lots had also been suffering along in deep shade and only flourished after brush clearing and a burn. Of course, we also collected seeds and used those to plant prairies in our former ag fields.

Shooting star is one of those species (like golden Alexanders and New Jersey tea) that do well in both prairies and savannas. There has been some good research on the growth and cultivation of shooting star, most importantly the nice paper by Paul Sorenson that was published in one of the North American Prairie Conference reports.

The photo below was taken the other day in the White Oak Savanna (Unit 12A), which was one of the first areas we restored (2001-2002). As soon as the brush was removed, shooting star bloomed extensively, and has been doing so ever since. (This unit is burned annually.)

Right now you should find shooting star in bloom in almost every prairie or savanna in southern Wisconsin.