Tom's Blog

Friday, September 8, 2017

Old-field thistle in an old field

Old-field thistle (Cirsium discolor) is a favorite plant of pollinators and birds. Goldfinches love them, and many wait until the thistle plant is mature (late August or early September) to nest.

At Pleasant Valley Conservancy, old-field thistle has been in our seed mix since restoration work began. However, since this thistle is a biennial, it moves around. Fortunately, seed viability is good, and colonization is generally successful. However, one hardly ever sees first year plants, which generally grow as low-lying rosettes.

The purpose of this post is to show the origin of this thistle's common name.

The east boundary of PVC is adjacent to a neighbor's field that has been used variously to raise cover crops for a near-by organic farming operation. Three years ago, cropping was abandoned, and this field turned almost immediately into an "old field." About three weeks ago, this field was almost a monoculture of Queen Anne's lace. Yesterday when I looked at it, a large number of old-field thistle plants had developed, more thistles than I had ever seen in one place.

This field is within yards of the PVC East Basin, a five acre restored prairie that has scattered old-field thistle plants.Although thistle seeds get around very well, I suspect that most of the "inoculum" for this field came from our East Basin next door.

According to Allen Stokes, who did a detailed study of goldfinch nesting in Lake Wingra marsh in 1944-1946, late-nesting goldfinches work very fast to complete their nest building and raise their young. This makes sense when one considers that in our area the weather could briefly "crash" at any time.

Incidentally, visitors to PVC generally miss completely the East Basin and the adjacent Ridge Prairie, because the main trail leads in the opposite direction. Now would be a good time for a detour in this direction.

The old field full of old-field thistle

Typical old-field thistle plant

Tuesday, September 5, 2017

Labor Day field trip: Now a Pleasant Valley Conservancy tradition

Kathie and I have been leading a Labor Day (1st Monday in September) field trip at Pleasant Valley Conservancy since at least 2002, possibly a year earlier. (I have sign-up lists going back to 2002.) Labor Day seemed to me then, and still does, an ideal time for a trip. Everyone is off work, the prairie grasses are in full bloom, and there are lots of great forbs in bloom.

The attendance that we have been getting seems to agree with me. In 2002 we had 15 attendees, and the number has been increasing ever since. Last year (2016) we had 35 and this year 45, which is the largest we have ever had.

I'm not really bragging about this. It just seems to me that a chance to see a restored oak savanna is something a lot of people are interested in. I'm just happy that Kathie and I are still able to lead this trip. (Although the last few years I have been leading from a Kawasaki Mule.)

Since this has been a wet summer, it is not surprising that the prairie grasses are really lush. The Indian grass and little bluestem on the South Slope were at their peak, and it was a joy to watch them blowing in the wind. Some people don't like a prairie dominated by warm-season grasses. I made the point that in mid-July the South Slope is a forbs-rich prairie, and forbs and prairie grasses get along very well together. See this link for a discussion of this point.

We generally get a few demon botanists on this trip, and this year was no exception. Scott Weber and Muffy Barrett, Chris Noll, and Raymond Roberts were all finding things that Kathie and I did not know we had. The prize this year was northern slender ladies' tresses (Spiranthes lacera), found by Raymond right off the trail. (At PVC last year, a week after Labor Day, Scott had found Spiranthes ovalis, another rarity.) These tiny orchids like disturbed grown, and most of our vegetation is too lush for successful habitation.

Labor Day 2005 trip pausing at the Far Overlook.
The large walnut visible in this photo has been removed and the prairie here is flourishingl

Part of the 2017 field trip group. This year we started and ended at the cabin.

Friday, September 1, 2017

Oak savanna restoration: when should the first burn be done?

When the first oak savanna burns were done at Pleasant Valley Conservancy in 1998 they were unsuccessful. The fire moved a few feet away from the drip torch line and then stopped. At the time we were told that “there aren’t enough oak leaves”, and this is why the fire did not carry.

With extensive experience doing oak savanna burns over the past 19 years, it is now possible to conclude that this explanation was incorrect. Take a look at the forest floor in the pictures of Kathie using a drip torch, both from 1998. There are plenty of oak leaves. After all, this is the first time in over 50 years that this oak savanna had been burned, and leaves had been falling ever since. Because of the slow decomposition rate of oak leaves, there was plenty of fuel, as the second photo especially shows. (Oak leaves are resistant to decomposition because of their high lignin content and rich array of tannins, which slow microbial activity.)

The reason the fire did not carry was because of all the coarse woody debris on the forest floor, and the dense tangle of living shrubs, mostly prickly ash, especially visible in the first photo. The fire movement is blocked by all the woody debris. Also, each standing woody stem blocks the movement of fire, and takes up space on the forest floor that would otherwise have a layer of oak leaves.

Trying to burn  the White Oak Savanna, April 1998. Note all the coarse woody debris and the tangle of brush in the background.
An area of the White Oak Savanna with good oak leaves, but the fire still did not carry well. Same burn as above

So why were we trying to burn?

We had taken our clue from prairie people, who knew that a simple burn could do wonders to rejuvenate a degraded prairie. (Think of the famous Muralt Prarie burn in 1975 in Green County!)

But oak savannas are not prairies. Degraded oak savannas have a heavy legacy of shrubs and coarse woody debris. We should never have burned anyway, because the fire would not get rid of the living shrubs. All it would do was top-kill them, and each plant would resprout from the base and send up new shoots, often a lot of them. Indeed, burning had the potential for doing more harm then good!

What we should have done was to clear the shrub layer (cut and treat with herbicide) and remove all the trees that were fire-sensitive and hence would not have been part of the original oak savanna. This was actually a central goal of the management plan, but the urge to burn was pretty strong. And this is what we did do, starting in these savanna areas in 1999.

Incidentally, the savanna shown in the photos is what we call the White Oak Savanna (Unit 12A/B). The photo shows what this savanna looks like in 2014, after clearing and annual burns for over 10 years. Now, when this savanna is burned, the fire carries very well!

White Oak Savanna in 2014, after over 10 years of annual burns.
These are the same trees that provided oak leaves in 1998.


Saturday, July 29, 2017

Story of a backyard open oak woodland: part 2

This is Part 2 of the saga of how we turned our small backyard from scrawny lawn to lush open oak woodland. Access Part 1 with this link.

Kathie and I live in the Village of Shorewood Hills and the word “wood” in the name is apropos. According to the early history of the village, there were open areas and then there were patches of woods that went back to presettlement times. The native trees are all oaks, mostly white (Quercus alba), although there are also some mature bur oaks (Q. macrocarpa). It’s a great area to live in, and although we have large branches hanging over the roof, so far we haven’t had any roof damage.

I think most gardeners would agree that you can’t get a good lawn if its too shady. After 36 years of mowing a scrawny lawn, and with lots of experience doing restoration work at Pleasant Valley Conservancy, we decided to turn our backyard into an open oak woodland.

Kathie started the conversion in the fall of 2011, so this is now the sixth growing season. The species list below shows 48 species, including 5 State-listed species. Pretty good, considering that the area is about 40 X 66 feet.

The original lawn was killed in the summer of 2011 with glyphosate and by late fall the ground was bare. It was planted with oak woodlands seed mix, and then hand-weeded the following summer. Each year a few new species have been added, and hand weeding continues.

Early summer 2012

Late summer 2017


The table gives the current flora. The only species on the list that might be questioned is the lily, whose identity is uncertain. This came from a former next-door neighbor, who did not like the color!

Latin name
Common name
State-listed
1
Actaea alba
White baneberry
2
Actaea rubra
Red baneberry
3
Adiantum pedatum
Maidenhair fern
4
Agastache nepetoides
Yellow giant hyssop
****
5
Agastache scrophulariaefolia
Purple giant hyssop
6
Anemone virginiana
Woodland thimbleweed
7
Apios americana
Hot peanut
8
Aquilegia canadensis
Wild columbine
9
Arisaema triphyllum
Jack-in-the-pulpit
10
Asarum canadense
Wild ginger
11
Asclepias purpurascens
Purple milkweed
****
12
Aster lateriflorus
Calico aster
13
Aster novae-angliae
New England aster
14
Aster sagittifolius
Arrow-leaved aster
15
Bromus latiglumis
Ear-leaved brome
16
Campanula americana
Tall bellflower
17
Cimicifuga racemosa
Black cohosh
18
Cryptotaenia canadensis
Honewort
19
Elymus riparius
Woodland wild rye
20
Erigeron strigosus
Daisy fleabane
21
Eupatorium purpureum
Purple joe-pye weed
22
Eupatorium sessilifolium
Upland boneset
****
23
Geranium maculatum
Wild geranium
24
Hackelia virginiana
Stickseed
25
Hasteola suaveolens
Sweet Indian plantain
****
26
Hydrophyllum virginianum
Water leaf
27
Impatiens sp.
Jewel weed
28
Lilium spp
Trumpet lily
29
Mertensia virginica
Bluebells
30
Monarda fistulosa
Wild bergamot
31
Napaea dioica
Glade mallow
****
32
Osmorhiza longistylis
Smooth sweet cicely
33
Phlox divericata
Woodland phlox
34
Podophyllum peltatum
May-apple
35
Polygonatum biflorum
Smooth Solomon's seal
36
Prenanthes alba
Lion's foot
37
Ratibida pinnata
Yellow coneflower
38
Rudbeckia hirta
Black-eyed Susan
39
Smilacina racemosa
False Solomon's seal
40
Solidago flexicaulis
Zig-zag goldenrod
41
Solidago speciosa
Showy goldenrod
42
Solidago ulmifolia
Elm-leaved goldenrod
43
Tradescantia ohiensis
Common spiderwort
44
Trillium grandiflorum
Large-flowered trillium
45
Uvularia grandiflora
Bellwort
46
Veronicastrum virginicum
Culver's root
47
Viola soraria
Door-yard violet
48
Zizia aurea
Golden Alexanders


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.