A Savanna Someday
By Jean Snodgress
I gathered, along with hundreds of other volunteers, in a 9.4 acre soybean field, recently acquired by the Indian Creek Nature Center. Girl Scouts, Boy Scouts, church groups, families and other students of all ages had come together to restore the land. Our task was to plant, mulch and water the thousands of tiny seedlings that resembled bare twigs more than trees. Trees Forever and Alliant Energy’s Branching Out grant program sponsored the trees. The Department of Natural Resources District Forester had drawn up a woodland stewardship plan. It was up to us volunteers, under the leadership of the Nature Center staff, to make sure the trees were planted properly.
Up until then, my tree planting experience consisted of transplanting a single black walnut from my grandparents’ farm to my backyard as a middle school student. My tree-tending experience consisted of failing to understand, as a second grader under a blazing hot August sun (once again on my grandparents’ farm) how the little row of foot-high pines that we were painstakingly watering with a bucket, could ever serve as a windbreak or even what a windbreak was.
Now, as a college student—with an undeclared major but studying Russian, philosophy, and English—armed with a shovel and a wheelbarrow, I took the task of planting my little bundles of trees seriously. The bare root oaks and ashes I was responsible for were mulched and watered properly, but with little thought to the history of the land, the future of the trees (beyond giving them a good start), or my own future.
I leaned on a fire rake, with a handful of volunteers ranging in age from a retiree to a home school student, listening to the flames crackle up the hillside. It was the same hillside I had stood on nine years earlier. This time I was the staff, listening to the land for direction, encouraging and working with volunteers to manage what will become a savanna.
I did not question whether it had been a good decision to burn the field. Though I knew the oaks we planted were still in there someone, many were buried in thick overgrowth, and many were still no taller than when I had planted them. Invasive multiflora rose and honeysuckle bushes were overtopping the oaks. Poison ivy vines thicker than the planted black cherry and basswood saplings were weaving their way through the planting. Fast growing boxelders and dogwoods were popping up everywhere. Many of the saplings were gnawed into shrubs by an over-populated deer herd. The trees were in desperate need of a lot more care if they stood a chance of thriving and creating a savanna.
A controlled burn was the most logical course of action. It would set back the woody brush invading the space; it would expose the soil, allowing native seeds, drifting in from the adjoining prairie, to become established. To let such a profound and large undertaking as the re-creation of a savanna go the way of so much of Iowa’s other woodlands seemed unthinkable.
For the thick, dark, tangled masses of young trees I had grown up calling woods were neither a healthy forest nor a healthy savanna, but rather an ecological disaster. Today’s woods are light-starved, fire-deprived and invaded by exotic species. The mature oaks and hickories that once graced the hilltops was our first ecosystem to almost disappear. Of the original estimated 12 million hectares of savanna in the Midwest that was here when the settlers first arrived, only .02 percent remains. Many of the trees fell before the saw, their progeny suppressed by the plow. The wood went to build farms, heat houses and fuel steam engines. The rich woodland soil was easy to plant crops in, much easier than trying to plow through the thick, tough prairie roots. The bulk of the prairies would vanish next under the sharp steel plow blades, the wetlands eventually succumbed to tiling.
Of the savannas that remained, the initial clear cutting paved the way for other species to gain a toehold and out compete the slow growing oaks. The shadows of former savannas can still be seen in the hills: large oaks with dead lower limbs, overtopped by fast-growing, shade-tolerant poplars and black locust trees, and no young oak saplings to replace the aging wolf trees. Hundreds of thousands of acorns will litter the ground under oaks during a good year, and many of those will sprout. But after the first year or two of growth, only those that sprouted in sunny places will stand a chance of maturing.
Savannas, once created by people through fire, can only be restored and managed by people through fire. From roughly 4,500 years ago until settlement, the oak hickory savannas had survived and thrived throughout the Midwest. Heavily dependent on regular fires set by Native Americans, the borders of the habitat had shifted and changed, but the savanna was always present. The oak savannas were once sculpted by the fires that would race through the prairies and up the hills. Until the fire reached the deep, damp shade of the forest, north facing hillsides, or bottomlands and petered out, it left behind charred grasses, seedlings and smoking stumps. Hard maples, birch, and boxelder, unprotected by the thick corky bark endemic to the oaks, would burn. The oaks, still standing, would be left to grow in open sunlight. The unique, richly diverse mix of ancient oaks and young saplings, woodland wildflowers and prairie grasses, made the boundary between the prairies and the woods indistinguishable.
Since the mid 1980s, the Indian Creek Nature Center had been conducting restoration burning in its established woods; not all of the woods and not every year, but it was making a difference. Light starved oaks, laden with dead lower limbs, were regenerating leaf-covered branches well below the canopy. The earliest restorations were open and easy to walk through; little bluestem was creeping up the south facing hills to grow next to the trillium. Volunteers and staff used chainsaws, bowsaws, shovels and pruners to help the process along, but once opened through mechanical means, the woods could be kept open through fire.
The planting was the first the Nature Center had done on such a scale; much of the land work was focused on recreating prairies and restoring overgrown woodlands, so I had some concerns with the burn that normally were not issues.
The first was if I had managed to find and pull off all of the flexible plastic pipe usually secured around some of the young trees, protecting them from deer and rabbit browse. A typical grass or savanna fire does not create enough heat to kill healthy oaks trees, but plastic burning and melting against the bark of a young tree surely would.
I also wondered if any of the oaks would suffer, if not permanent damage, than at least a significant setback. In many cases, the grasses were taller than the trees, so oak leaves and bud tips would be vulnerable. But without the fire, there was no hope of bringing this ecosystem back from the edge of extinction. Young oaks had survived fires before.
It would take Boy Scout Michael Buh—a young man working to achieve the rank of Eagle Scout—to help me realize just how successful the planting had been, validate the decision to burn, and decide to take the next step in the restoration process. The oaks I had carefully planted, worried about through the fire, and guarded whenever I had the means to guard them needed to be thinned.
Michael was looking for an Eagle Scout service project, and he wanted something that would not only help the environment and the Indian Creek Nature Center, but would also provide his troop with skills they would not necessarily get anywhere else. He was intrigued with the possibilities of a tree survey on the planting, the high-tech merging of Global Positioning System (GPS) technology with the skill of tree identification.
I was intrigued with the possibility of having data to actually measure a restoration. Observations of success or failure are abundant in the field and can guide decisions, but without actual measurements there are many unknowns. Unfortunately, land protection and restoration go hand in hand with limited resources. The time and resources to scientifically measure results are usually nonexistent. The philosophy is to follow sound management principles and pay attention to what happens; which animals return or disappear, which plants grow faster or die back. In many instances, there is no record of what had been done, when or why. With the trees, I had a record of exactly what had been planted and when.
It was a hot humid day when Michael guided his scout troop out to the site. The boys started early and dew still clinging to the native Indian grass, exotic brome grass and exotic Queen Anne’s lace quickly drenched them. Trees, the dominating force in a savanna, in the young re-establishment appeared as mere incidentals, small tufts of oak leaves hidden amongst the Maximilian sunflowers and wild rose bushes.
Being sopping wet on a hot, humid day, confronted with thick tangles of thorn did not slow the boys down. They went in with Garmin handheld GPS units, measuring tapes, tree calipers and spray paint cans to mark trees as they were measured and identified. Michael had prepared leaf books for each team, so they could distinguish one species from another. Of the original 4,200 oak trees planted, the boys located 26 percent: 150 bur oak, 788 white oak, 127 red oak, and 23 black oak.
Oaks alone do not form the tree canopy of a savanna and we had planted 600 white ash, 300 basswood, 300 black cherry, and 300 black maple alongside the oaks, and at least some are still growing. However, Michael and I had decided that by the time GPS technology, tree measuring techniques, survey methods, and oak leaf identification were accomplished, the project would more than meet the requirements of an Eagle Scout Service project and would provide the Nature Center with sufficient data to continue restoring the savanna.
The boys came out knowing how to measure a tree and distinguish between a bur oak and a black oak, and the knowledge that their work was critical in developing future tree management decisions. It would determine which species we might replant and which we would cut. It would establish baselines for comparing species survival with and soil and slope. In future decades it could provide a baseline in measuring everything from oak survivability to growth rates. And the maples and the black cherries are reproducing, albeit slowly, around the Nature Center on their own. As species, they are not dying faster than they are sprouting.
The smell of fresh woodchips fills the air as I cut through a young bur oak. Choosing which oak to drop is a far more ambivalent decision than the ones I normally make as a land steward: white oak or mulberry; shagbark hickory or Siberian elm; black cherry or black locust. It is easy to prioritize removing the invasive trees that do not belong in the landscape. Cutting trees growing out of their ecological context is also a straightforward decision. Usually the last tier of trees to be removed in a restoration are the common ones, such are hackberry and black cherry. They are desirable but abundant throughout the area, reproduce rapidly and grow fairly quickly, and removing a few to make room for more oaks is understandable.
Choosing the bow saw over the chainsaw was simpler than choosing which oaks to cut. It seemed unnecessary to disturb the peace with a chainsaw. The trees were not yet five inches in diameter, big enough to work up a bit of a sweat cutting through, not enough to warrant the harsh smell of burning two-cycle oil in the air. If Michael’s data was not compelling enough to convince me to start thinning the young oaks, a project I had tackled earlier in the spring was.
Along the edges of established woodlands, I had spent a week unearthing mostly-shaded oak saplings from overgrown honeysuckles, blackberries, and multiflora rose. The trunks were bowed at 90 degree angles, in a desperate attempt to reach a bit of sunlight. Some had no more than two dozen leaves, with branches protruding awkwardly skyward, in a gross caricature of the graceful silhouette of an oak tree. The rattiest looking I had cut at the ground and flagged to find later, after spending hours with volunteers freeing them from their canopy.
The canopy, far from shading one from the sun or allowing the sun-dappling to reach the ground in an exquisite display of leaf-shadow and light in a true savanna, started at ground level and ended about nine feet off the ground. It was a snarl of unhealthy, woody growth.
Those oaks I did not hesitate to cut. Oaks will readily stump sprout, and with some attention the second time around, nourished by an already established strong taproot and protected from shady growth and deer browse, they will thrive. Given time and space, they can develop into the iconic massive oaks, standing more than 100 feet tall, with boughs stretching outward as high as the tree is tall; trees of stature that few enough of us have ever seen.
Preventing degradation is preferable to trying to repair damaged ecosystems. It requires fewer dollars, fewer hours, and has much higher success. So thinning the healthy stands of young oak saplings, each tree still growing straight with sprawling lower limbs paralleling the ground, abounding with leaves, and buds well above the deer browse line is a simple, logical, and basic tenant of wise land management.
In the field, the matter was less obvious. The bottom branches of the trees were touching, but as of yet there was no storm damaged tops, no double leaders, no reaching towards available daylight or leaning away from a neighboring tree. Nothing was wrong with any of the trees, nor was there anything wrong with their location.
The basis of cutting so often revolves around listening to the landscape; what should be here, what is still healthy, what has the best chance of remaining healthy. The bur oaks and white oaks I would be removing from the soft ground had obviously been planted in the right place, and were getting the nutrients they needed.
The trees were already providing habitat for song sparrows and robins. DeKay snakes slithered away slowly; indigo buntings darted in and out of the branches. There were few natural cues for me to follow; only the knowledge that oak trees need sunlight and the oak savanna is a landscape in more peril than better known tallgrasss prairie.
I finally made my selection based on how far apart the trees were growing from one another, and I cut sparingly. Having never stood under the spreading boughs of an old growth oak savanna, it is difficult for me to imagine just how far apart the trees will need to be, someday. Many more thinnings will need to take place in the next three hundred years. The quandary I was in was a testament to the success of the planting thirteen years earlier, and that hundreds of volunteers come out every year to help restore the savannas is a testament to the value it has.
These are trees that will never be measured in board feet and whose worth will not be in providing shade to a house or city street. Their value lies instead in their ability to control erosion, create healthy soils, sequester carbon, and provide a place for wildlife to thrive. More importantly, their value lies in their potential to someday, as long as people stay involved with them, mature into a savanna.
No one who stood there in 1995 or in 2008 will ever see one of those trees vie for biggest oak tree in the state record, or mature beyond a wonder tree into a snag. The bluebird boxes will need to remain, an obvious totem, not to the natural beauty of an untrammeled wilderness, but to a landscape carefully managed to be healthy and vibrant. A place for people to care for the land, and in doing so care for the pileated woodpeckers, the brown creepers, the bobcats and coyotes.
Though the land is protected through a conservation easement, the future is not certain. Red oaks on private property in adjacent woodland have oak wilt, a disease that threatens their survival as a species. The populations of butternuts and elms, once companion trees to oaks and hickories, have been decimated by butternut canker and Dutch elm disease respectively, forever changing the composition of the woods. The ranks of invasive species are ever expanding, from the now commonplace garlic mustard and honeysuckle to the emerald ash borer lurking on the borders of the state. It will not be the same savanna the settlers saw, a handful of tree-topped knolls breaking through the sea of prairie grass. The habitat will be a refuge, bordered by asphalt roads and bluegrass lawns. But it will be a savanna, painstakingly crafted and maintained by the people who love it. A savanna that can survive only as long as the community remains involved caring for it.