I am Sibylla Brown. I was born in Germany in 1940. In 1946 my father, a German Operation Overcast scientist, was brought to the U.S. My family followed him to the U.S. in 1947, settling in Cedar Rapids Iowa in 1950. I married my husband, Bill in 1962. Bill practiced dentistry in Des Moines for over 40 years. In 1993 we sold our house in Des Moines and moved to a 200 acre farm in Decatur County, Iowa. Except for a small vineyard we had no plans to farm our land. But we did want to take care of it, particularly the overgrown oak and hickory woodlands. We began timber stand improvement in 1993. When we learned our land was actually a rare oak savanna remnant we implemented prescribed fire. I keep monthly journals to record our activities and observations. These posts summarize them.
Winter arrived here three days after Christmas when we had our first winter storm – five inches of snow alternating with freezing rain and sleet. My favorite activity on such winter days is to curl up in front of the wood stove with a good book. Last month it was Andrea Wulf’s The Invention of Nature, a Christmas present from my son Chris. This biography of Alexander von Humboldt explores how the visionary German naturalist created modern environmentalism. His writings inspired many not only Charles Darwin, but Henry David Thoreau and John Muir.
Many believe that climate change is a twentieth and twenty-first century problem. But as Alexander von Humboldt observed climate change began much earlier. It is based on the human presumption that nature was created to serve man. From Aristotle who believed that “nature has made all things specifically for the sake of man” to the Cartesian belief that it is man’s responsibility to bring order out of chaos, we have “improved” on nature by plowing the soil, by straightening our streams and rivers, and destroying our woodlands.
Humboldt formed his most important concepts during his five-year journeys (1799-1804) through South America. Based on observations he made in those years he realized that everything in nature is connected. Around Lake Valencia in Venezuela, for example, he observed how clearing the forests and diverting water to irrigate their fields the planters had caused the lake’s water level to fall precipitously. Their agricultural practices were also depleting soil fertility and destroying the soil’s ability to retain water.
“When forests are destroyed, as they are everywhere in America by the european planters, with an imprudent precipitation, the springs are entirely dried up, or become less abundant. The beds of the rivers, remaining dry during a part of the year, are converted into torrents, whenever great rains fall on the heights. The sward and moss disappearing with the brush-wood from the sides of the mountains, the waters falling in rain are no longer impeded in their course: and instead of slowly augmenting the level of the rivers by progressive filtrations, they furrow during heavy showers the sides of the hills, bear down the loosened soil, and form those sudden inundations that devastate the country.” Wulf, p. 57-58. Humboldt, p. 150-151
At Timberhill we have learned that these changes are not irreversible. When we purchased West Creek in 2004 the banks of creek that separates this unit from the rest of our property were eroding and the creek was cutting deeper and wider. Since only the ridge tops and a bottom field had been plowed and there had been some grazing the land still contained remnant prairie and wetland. The biggest problem was the red cedar, shingle oak, and honey locust trees that had invaded in the prairies. We began restoration by burning the property three years in a row. That helped control much of the underbrush and made it easier to thin the invasive trees. In 2008 Shelterwood Forestry girdled the honey locusts and began felling the shingle oaks and red cedars. (We kept the elms because they would bring morels.) Bill and I burned the red cedar carcasses in midsummer when they were fully dried out and surrounded by green grasses.
Although Humboldt included the destruction of the forests as one of the the reasons for river flooding it was actually destruction of the native habitat. We removed the trees in this unit because West Creek was originally all prairie. Restoring the prairie vegetation restored the hydrology and curbed the erosion.
Each year as the grasses and sedges increased in the restored prairies we noticed a decrease in stream erosion. To our surprise the creek was actually decreasing in width.
The photo above shows the creek upstream of our property.
Here you can see the creek below our restored prairie. It is half as wide here as it is upstream.
Andrea Wulf, 2015. The Invention of Nature. New York. Knopf
Alexander Von Humboldt (translated by Jason Wilson). 1995. Personal Narrative of a Journey to the Equinoctial Regions of the New Continent. New York. Penguin Classics.
Despite the mild fall and winter weather so far this season we have not been able to do as many prescribed burns as we would like. In order to reduce the impact on the invertebrates we always burn during the dormant season after the first hard frost. That is usually between mid-November and March 15. However, hard frost was late this year, not until November 21. After that it was either too windy or too wet every weekend that our volunteer burn crew was available. Thankfully, a professional crew offered to help. On December 11, my husband, Bill, and the crew burned our West Creek unit.
We purchased West Creek in 2004. At that time it consisted of two crop fields, a small wetland, degraded native prairie, and a sedge meadow. There were also several seeps where water is discharged from underground sand veins. This unit is separated from the rest of Timberhill by a small, sandy creek. The creek provides an excellent firebreak to the east and as does the wide trail through the woodland along our south fenceline. Mowed strips separate West Creek from a cornfield on the west. A small remnant prairie is in the ravine that intersects the cornfield. We also mow a break along our north property line. Keeping the fire from spreading into adjacent prairie remnants north and west of our land can be challenging on a windy day. So we need an experienced crew.
When we purchased West Creek there was no difference between our prairie remnant and the neighbor’s. In the above photograph Timberhill is on the left and the unmanaged remnant begins at the tree line on the right. As you can see red cedar now dominates the unmanaged remnant. The native plants are gradually disappearing. In 2004 I counted nine butterfly milkweed plants there. In 2015 I could only find one. In 2004 I counted two blooming butterfly milkweeds in West Creek. Now there are over thirty, including some in the old cornfield.
Our goal is to restore West Creek diversity – by increasing floristic quality in the prairies, expanding the prairie cordgrass and tussock sedge wetland, and improving groundwater availability. Management has been limited to annual prescribed fires, invasive tree removal, and seeding the old fields with warm season grass collected in the remnants. In nature everything is connected. Fire has stimulated the grasses, sedges, and wildflowers. Infrequent and rare butterflies that require a specific conditions now inhabit the property. We regularly see Dion skippers in the restored sedge meadow. In June and early July Edwards’ hairstreaks nectar on the butterfly milkweed and dogbane in shingle oak scrub above the sedge meadow. Regal fritillaries are also a common site in June and July.
Dion skippers are usually found in northern Iowa. When he saw my specimen a butterfly expert told me, “I would never have expected to find that here.” (This species is restricted to wetlands with broad-leaved sedges.) In Iowa Edwards’ hairstreak is considered rare and very local. Regal fritillaries are infrequently found in wet prairie remnants. The larvae overwinter in leaf duff. Finding these species in West Creek is a strong indication that infrequent and rare butterflies survive our frequent annual burns.
At Timberhill burn season usually begins in November after the first hard frost. Our house sits in the middle of the 200 acre savanna restoration. There is a mowed area around the house (some grass, but mostly dandelions and clover). North, south, and east of that are the driveway and concrete outside the garage. To the west, however, there is only a buffer of mowed grass and forbs between the house and restored prairie. Abundant in warm season grasses, we burn this prairie very carefully. Flames can easily reach 20 feet or more. It is also where we begin our prescribed burns.
In order to have the least impact on the invertebrate habitat we burn annually. Annual fire burns up through the dried blue stem and Indian grasses leaving much overwintering insect habitat. Plant stalks and unburned tufts of grass remain after each prescribed fire. When I walked through this burn area last year, for example, I found a sheet of newspaper that I had used as mulch in the nearby vegetable garden. It was not even scorched – the fire had burned right over it.
We burned on the pond prairies on November 20. Using the trail mower Clint, our weekend helper, had mowed firebreaks around the north and east pond prairie. Two highly experienced practitioners helped Bill with the burn. They began northwest of the pond lighting a small section at a time. Once fire had moved through each section they continued east and then south between the house and the pond. It took only an hour. I am always relieved when this is done.
The late fall weather has been so mild that butterflies were still flying the last week of November. On November 23 a mourning cloak and a gray comma flew in front of me on the West 40 savanna trail. On November 11 we painted moth bait on the white oaks along the driveway. Five moth species that settled on the bait were Bicolored sallow moth, Green cloverworm moth, Lunate zale, Anyworm moth, and Variegated cutworm moth.
The first week of October we decided to try moth baiting in the hickory grove in our West 40 unit. This woodland was a horse pasture until 1938 when the owners bought a tractor and no longer needed horses to pull their plow. After grazing ceased the meadow grew up into a shagbark hickory (Carya ovata) woodland. When we purchased it in 2001 is was heavily overstocked. We thinned the woodland in 2002, felling over 50% of the trees. A groundcover of wildflowers, grasses, and sedges is now well established under the canopy.
For moth bait we mixed stale beer, molasses, brown sugar, overripe bananas, and yeast in a bucket and let it ferment overnight. Shortly before dusk the next day we walked along the trail that winds through the woodland, first west then south where it separates a native prairie remnant from the shagbark hickory. Carrying the bucket of moth bait we brushed the intoxicating syrup on the shags of trees closest to the trail. I had hoped to attract some underwing moths to the bait. When I checked the baited trees before sunrise the next morning I was disappointed – no underwings. The only moth of interest was a stem borer which I collected.
It was not a species I had collected before. Searching my field guides I tentatively identified as P. birdi, Umbellifer stem borer. (Water hemlock, its larval food source, is found in the nearby prairie remnant.) For confirmation I asked my friend who knows this genus well. His first reaction was,
“A Papaipema at bait–I wouldn’t have expected that! I’ve never heard of them coming to bait.” He asked me to send him a photograph. His response was a big surprise. “I think this is a MUCH better moth than birdi. I think it is marginidens but I will see if I can get additional opinions. I believe there is a single Iowa record from a savannah type oak woodland remnant in Story County.” The specimen I collected was in fact confirmed to be Papaipema marginidens, Brick-red borer moth. A nice find.
When we began moth lighting I was overwhelmed by the number and diversity of specimens. I was too inexperienced to identify all of them. Instead I began with the easy ones, the giant silkworm and sphinx moths. Now I realize I should have been focusing on the underwing (Catocala) moths. Catocala forewing patterns resemble tree bark and hindwings are either all black or brightly colored with black bands. Over 100 species are found in North America. Since the larvae of many species of this large group feed on trees found at Timberhill and in the adjacent unmanaged woodlands we should be able to find 40 to 50 species. (The larvae of 20 species feed on hickory leaves.) So far I’ve only collected thirteen oak, hickory, plum, and willow feeders.
Butterflies were on wing through the end of October. Most abundant were the anglewings and Buckeyes. Gray commas and Question marks (anglewings) settled on the baited shagbark hickory by day. For several days after baiting the trees we saw 4 to 5 specimens on each trunk. These were the second brood that will overwinter as adult butterflies under loose bark, openings in fallen logs, and hollow trees.
We saw Buckeyes daily in West Creek. All were fresh looking specimens that had bred on the abundant slender false foxgloves in this unit. Common checkered skippers were also seen skipping ahead of us on the trails when we took our daily walks.
At the end of the month we were pleased to see Turkey vultures still soaring overhead. They are usually the last migratory species to head south for winter. As long they are flying winter will wait.
(Besides Jim Durbins’s Insects of Iowa site there are two excellent resources available for more information: Theodore Sargent’s Legion of Night portions of which are available online and Owlet Caterpillars of Eastern North America by Wagner. Schweitzer, Sullivan, and Reardon.)
I am continually in awe of nature’s power to restore itself. A prime example is the old cornfield in our West Creek unit. It was farmed continuously from 1937 until 2005 when Bill and I took it out of production. Each fall for the next three years we seeded it with big bluestem and Indian grass that we had harvested from the adjacent prairie remnant. We didn’t plant or seed anything else. We burned each field annually during the dormant season. Now a colony of Henslow’s sparrows nests in the tall grass each summer.
When I surveyed the field last month I was surprised by how diverse it had become. Slender and eared false foxglove have spread throughout the field contrasting with the white, blue, and purple asters. Scattered throughout the field were clumps of bottle gentian, an uncommon plant. Best of all I counted 27 great plains ladies’s tresses orchids. The late bloom and strong sweet fragrance of coumarin from the spiral of white flowers confirmed that they were Spiranthes magnicamporum and not Spiranthes cernua.
Hearing a bumblebee I turned and watched it land on one of the closed gentian blossoms. It quickly separated the petals and disappeared inside to gather pollen. Then he reappeared and moved on to the next blossom. Buckeye butterflies were nectaring on showy goldenrod. I even found a Buckeye caterpillar feeding on a slender false foxglove.
Fritillary butterflies were still flying in late September. The last Great spangled fritillary I saw on September 23 was pretty beat up with hardly anything left of his hindwings. However, the Meadow and Variegated fritillaries still looked reasonably fresh. Eastern commas were also flying at the end of September and Black swallowtails were on the tall thistles. (In the vegetable garden black swallowtail caterpillars were devouring the parsley and dill.)
The last week of September we set the moth trap on the terrace west of the house and caught a five spotted hawk moth and two underwing species: Robinson’s underwing (Catocala robinsonii) and Youthful underwing (Catocala subnata). On Robinson’s the forewing is pale gray and hindwing is black with a narrow white fringe. The underside is boldly patterned with prominent black and white bands. The more colorful Youthfull underwing has golden yellow banded hindwings that contrast sharply with the pale gray forewings.
Fall mushroom season began on September 29 when I collected the first wax cap, a Hygrophorus subsalmonius. It is easily identified by its viscid orange cap and white gills. Purple gilled Laccaria ochropurpurea was fruiting in clumps throughout the East Savanna. Russulas (brittle cap) mushrooms were also abundant. Chanterelle season continued into September. I collected the last fresh specimen on September 15. But I was disappointed by the dearth of King boletes, a choice edible that usually fruits in the East Savanna in September.