Tom's Blog

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
Actaea alba
White baneberry
Actaea rubra
Red baneberry
Adiantum pedatum
Maidenhair fern
Agastache nepetoides
Yellow giant hyssop
Agastache scrophulariaefolia
Purple giant hyssop
Anemone virginiana
Woodland thimbleweed
Apios americana
Hot peanut
Aquilegia canadensis
Wild columbine
Arisaema triphyllum
Asarum canadense
Wild ginger
Asclepias purpurascens
Purple milkweed
Aster lateriflorus
Calico aster
Aster novae-angliae
New England aster
Aster sagittifolius
Arrow-leaved aster
Bromus latiglumis
Ear-leaved brome
Campanula americana
Tall bellflower
Cimicifuga racemosa
Black cohosh
Cryptotaenia canadensis
Elymus riparius
Woodland wild rye
Erigeron strigosus
Daisy fleabane
Eupatorium purpureum
Purple joe-pye weed
Eupatorium sessilifolium
Upland boneset
Geranium maculatum
Wild geranium
Hackelia virginiana
Hasteola suaveolens
Sweet Indian plantain
Hydrophyllum virginianum
Water leaf
Impatiens sp.
Jewel weed
Lilium spp
Trumpet lily
Mertensia virginica
Monarda fistulosa
Wild bergamot
Napaea dioica
Glade mallow
Osmorhiza longistylis
Smooth sweet cicely
Phlox divericata
Woodland phlox
Podophyllum peltatum
Polygonatum biflorum
Smooth Solomon's seal
Prenanthes alba
Lion's foot
Ratibida pinnata
Yellow coneflower
Rudbeckia hirta
Black-eyed Susan
Smilacina racemosa
False Solomon's seal
Solidago flexicaulis
Zig-zag goldenrod
Solidago speciosa
Showy goldenrod
Solidago ulmifolia
Elm-leaved goldenrod
Tradescantia ohiensis
Common spiderwort
Trillium grandiflorum
Large-flowered trillium
Uvularia grandiflora
Veronicastrum virginicum
Culver's root
Viola soraria
Door-yard violet
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.

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.)