You may remember a few posts recently about the prairie burn in the Loess Hills. John posted this to the native plants and insect lists but does not have an account on this one so asked that I post it for him. I think it gives us all some perspective on the incredible balance needed to restore and maintain our natural areas.
Ann Johnson, Norwalk ----- Original Message ----- From: Pearson, John [DNR]<mailto:[email protected]> To: [email protected]<mailto:[email protected]> Sent: Monday, June 14, 2010 12:08 PM Subject: [IOWA-NATIVE-PLANTS] Sylvan Runkel Preserve burn The May 2010 prescribed burn at Sylvan Runkel State Preserve impacted the Loess Hills Prairie Seminar and has raised many questions about its timing, size, landscape context, and effect on the Nevada Buckmoth. I would like to take this opportunity to discuss these important points. As a prairie manager, botanist, and insect enthusiast, I feel that I have a foot in both camps in the conservation conflict over prescribed burning and want to find workable solutions. Timing This years burn on May 26 was latest conducted on the preserve in over 30 years of prescribed fire management. Because of its location at the home site of the Loess Hills Prairie Seminar (June 4-6), it caused a major problem for the Seminar. With their primary field trip locality blackened and with only a week to react, organizers and presenters were forced to scramble to find alternate locations for long-planned activities. Inadequate consideration of the effect of the burn on the Seminar and lack of communication from DNR to the Loess Hills Seminar organizers are regrettable and will not happen again. DNR staff involved with the burn have apologized to Seminar organizer Dianne Blankenship and I would like to broaden this apology to all who were adversely affected by this event. I also want to explain that the late burn did have a biological rationale. Prairie managers (in DNR and in other agencies) have been conducting April burns as a standard practice throughout the state for many years. Studies comparing early vegetation records with later vegetation records, such as those at Hayden Prairie, at Sheeder Prairie, and at Kalsow Prairie, point to the conclusion that periodic burns repeatedly applied in April gradually reduce the spring flora in favor of tall, late-season grasses (which themselves impose high competition on short forbs). Repeatedly stressing the same group of species likely has a similar depressing effect on other organisms as well. Varying the timing of burns has identified as a solution to this diversity-diminishing monotony. That rationale prompted our manager to conduct a late May burn. Although others may question this decision on other grounds, I nonetheless feel it is important for everyone, whether you agree or disagree with the decision, to at least know that this burn was well-intentioned from an ecological basis. It is certainly true that other non-April dates could be selected that would not impact the Loess Hills Seminar as this late May event did. Decisions concerning non-traditional burn dates will take that clearly into account in the future. Size - Within the 330-acre Sylvan Runkel Preserve, there are 121 acres of remnant prairie. In 2010, 107 acres of this were burned, or 88%. Here is the map showing the burned prairie in red; unburned prairie in green (for scale, the preserve is 1 mile wide east-west and ½ mile wide north-south): http://i103.photobucket.com/albums/m149/JoPears5/Sylvan%20Runkel%20Preserve/ runkelburn.jpg . A review of past burn records reveals that prior to 2010, the prairie has been burned at this size five times starting in 1991. Two smaller burns in 1995 and 1996 affected the east and west halves of the preserve. All three burns from 1999-2007 were 107 acres. The size of the 2010 burn was thus not larger than normal, but its large size was plainly visible during the Loess Hills Seminar this year due to its late May burn date; previous burn dates in April had allowed the big burn to green up (and color-up with flowers) by the time of the Seminar. Prompted by this years burn, my background research discovered confusion among DNR offices regarding the number of burn units designated in the preserve (some were under the impression that there were two burn units, others just one). In the near future, DNR staff will be revisiting the issue of number and size of burn units at the Runkel Preserve and exploring ways to add additional firebreaks. Although we will be revisiting burn unit design, I feel it necessary to explain why large burn units are commonly used across the state by the DNR. Given that DNR manpower resources are finite and that small burn units require as much effort to manage as large burn units (considering all aspects of travel, site preparation, and mop-up in addition to the act of burning), a statewide dilemma arises for choosing between two general strategies: 1) burning many sites with few large burn units versus 2) burning few sites with many small burn units. Wanting to maintain all tracts of grassland that it owns, the DNR has traditionally chosen the first strategy because it maintains grasslands while the alternative lets untreated sites become permanently encroached with brush; managers pursuing the first option do so with the belief that it is the best choice under the circumstances to preserve the very existence of prairie habitats. Many insect conservationists would choose the second option because large burns, despite maintaining prairie, are regarded as a "pyrrhic victory" due to insect mortality. I hope everyone can see that the most effective solution to this dilemma would be to increase resources available to conservation agencies, enabling them to manage all sites as intensively as needed. I look forward to the day when prairie conservationists, state leaders, and the people of Iowa succeed in making that happen. Short of that, the contrasting benefits and detriments of few/large versus many/small burn units will remain a source of tension within the prairie conservation community. Nonetheless, a partial solution could be to manage most sites with the few/large approach and selected sites with the many/small approach. This selective approach has been employed to apply special management effort at other state preserves and could be used at Sylvan Runkel Preserve as well. Although previous administrators and managers preferred the Runkel Preserve burn unit be large, current administrators and managers are open to modifying that plan if safe and reasonable alternatives can be identified. Landscape context In a June 4 blog entry forwarded to the Iowa Native Plants Listserv, Ted MacRae eloquently described the problem of using fire in face of the historic loss and fragmentation of prairie with which we in the Midwest are all too familiar: Such processes [fires of unpredictable scale, intensity, and frequency [that] operated within a vastly larger scale to create a shifting mosaic of natural communities in various stages of ecological succession] cannot be recreated on todays severely fragmented landscape, where the precious few remaining tracts of native habitat are relatively to extremely small and more often than not separated from each other by vast expanses of homogeneous and inhospitable habitat (e.g., agricultural, urbanized, or severely degraded lands). It is in that context that I have great concerns about how aggressively fire has been used in recent years on our states natural areas and the impact this is having on insect populations specialist and generalist alike Furthermore, as rapidly and aggressively as fire has been adopted on our few, small, widely disjunct remnants, the opportunity for proper investigation of those potential effects may be gone." Prefaced by this picture of prairies as islands in a sea of altered landscape, his next sentence goes on: "A particularly egregious example of the lack of consideration being given to prairie invertebrates in designing fire management plans is shown in Iowas Sylvan Runkel State Preserve [due to] a late May burn and the impact of that burn on a resident population of Nevada buck moths (Hemileuca nevadensis). Teds essay raises two points: 1) the landscape context of the Runkel Preserve burn and 2) effects on the Nevada Buckmoth. I will deal with these subjects sequentially, starting here with the general issue of landscape context and discussing the specific issue of buckmoths in the following section. Although I agree with the main point of Teds essay that prescribed burning needs to consider effects on insects, I feel it necessary to point out that the prairie in the Sylvan Runkel Preserve is not small, unconnected, isolated, or disjunct. In contrast to the more typically Midwestern situation of prairie remnants widely separated by broad expanses of cropfields or other inhospitable land uses, the prairie in the Runkel Preserve is part of a larger landscape that consists of numerous remnants in close proximity. One way of viewing the Runkel prairie and its burn from a landscape perspective is to look at the natural boundary of the prairie instead of the administrative, human-defined property boundary. As highlighted by this map (http://i103.photobucket.com/albums/m149/JoPears5/Sylvan%20Runkel%20Preserve /ridge.jpg ), one can see that the 121-acre prairie contained within the Preserve is an integral part of a larger, 3-mile long, 508-acre ridgetop prairie (the Runkel Preserve is highlighted in orange). The extreme southwestern end of this ridge (south of the preserve) is a small, heavily grazed pasture, but north of the preserve the ridge forks and crosses northwest and northeast into an extensive mixture of high-quality prairie on lightly grazed prairie-pasture on private land (http://i103.photobucket.com/albums/m149/JoPears5/Sylvan%20Runkel%20Preserve /2010-06-04025.jpg ) and ungrazed prairie on the Loess Hills Wildlife Area. None of this extended prairie was burned in 2010. Placed in context of its landscape, the 107-acre burn of the preserve prairie represents 21% of the total prairie of which it is a part. If the prairie in Sylvan Runkel Preserve was indeed small and isolated, I would agree that an 88% burn would be egregious (to use Teds term), but would this adjective still apply now knowing that this prairie is part of a large, interconnected complex in which the burned parcel is a small portion? Nevada Buckmoth A specific example of the threat of burning to insects cited in Ted MacRaes essay was of the Nevada Buckmoth, a rare moth recently discovered in the Runkel Preserve by Aaron Brees. Concern over this threat was heightened when it was realized that the Runkel prairie had been burned as one large unit instead of one of two smaller units. If there were no unburned patches within the preserve to harbor survivors and no suitable habitat outside of the preserve to serve as sources of recolonization, the possibility that the buckmoth population had been destroyed by the prescribed fire was haunting. Evidence for survivors in the burned prairie was not encouraging: on May 29 (three days after the burn), Aaron Brees found a small group of live larvae clinging to a partially burned redroot shrub (Ceanothus herbaceus, its larval host plant) in the preserve, but without sufficient food resources remaining on the shrub to support them; although a comprehensive search of the entire perimeter of the burn was not conducted, his meager findings indicated that prospects for finding survivors were bleak. On June 6, DNR biologist Doug Chafa found patches of unburned redroot within the Runkel Preserve burn, but found no buckmoth larvae on them. And although unburned prairie in the lightly grazed private pasture immediately adjacent to the burned area is high-quality in a general floristic sense, it contains little redroot to serve as hosts for off-site buckmoth larvae (see discussion below). Farther to the northeast, the ridge crosses onto public land supporting high-quality prairie that does contain large stands of redroot; encouragingly, numerous buckmoth larvae feeding on redroot were discovered here on June 10 by Doug Chafa and Steve Watts. Additional surveys are planned and hopefully will turn up additional buckmoth populations. As I mentioned above, high-quality prairie is present on both sides of the north border of the Runkel Preserve, but with an important contrast as it relates to the needs of the Nevada Buckmoth. Redroot is a common plant on the Runkel Preserve, in the Loess Hills Wildlife Area, and elsewhere in the Loess Hills, but as I stood at the boundary pictured above on the opening day of the Loess Hills Seminar (Friday, June 4), I was struck by its paucity on the private prairie just beyond the preserve border. Although I did not cross the fence to explore the area thoroughly, I carefully scanned it with binoculars from the fence. While the prairie-forest ecotone in the preserve behind me was liberally dotted with redroot plants and patches in a band between the open prairie and thickets dominated by dogwood and elm, I failed to spot any redroot along the same line on the private side of the fence; instead the dogwood-elm community contacted the prairie directly. I am sure redroot must be present in the private prairie, but the difference in abundance was striking. The general habitat, topography, and soil appeared identical, so how to explain the difference? I suspect the answer, paradoxically, lies in the repeated use of fire on the public side contrasted with light grazing and no burning on the private side. When the Runkel tract was acquired to become part of the Loess Hills Wildlife Area in the 1970s, it was a heavily grazed pasture. Thirty-five years of rest from grazing accompanied by prescribed burning has transformed the old pasture into the high-quality prairie that exists here today. As a fire-adapted prairie shrub, redroot is stimulated by fire, forming stands where fire has worked to retard the encroachment of dogwood and elm. Prairie management over the decades has evidently created an environment to which buckmoths are attracted and in which buckmoths can thrive in non-burn years. This success has introduced a new conundrum: fire that enhances growth of the buckmoth's host plant is also capable of destroying the buckmoths themselves. Ecologists describe conundrums of this nature as an ecological trap: improved habitat serves as bait while management actions that created the improvement impose a snap at their moment of application. Is there a way out of this ecological trap? I believe there are adjustments to prairie management at the Runkel Preserve that can be taken to maintain success in restoring prairie vegetation while minimizing mortality of insects attracted to the restored vegetation. Two adjustments that could be implemented at the Runkel Preserve are division of burn units (discussed above) and the use of prescribed grazing. Prairie ecosystems developed over thousands of years under the influence of fire and grazing, but prairie management efforts in Midwest nature preserves over the past 40 years have depended heavily on the use of fire without grazing. Lacking suppression by grazing animals, brush encroachment onto prairie preserves has become a severe problem in many places. Periodic fire is partially successful at stemming this encroachment, prompting managers to apply it with increasing frequency in an effort to contain the worsening problem. Reintroduction of grazing to prairie preserves would help solve this problem, but not simply by a return to the chronic, heavy grazing pressure from which the preserves were rescued earlier in their history. Scientifically calculated doses of grazing pressure, adjusted for stocking rate and duration and coordinated with prescribed burns in ways that mimic natural disturbance, offer an ecologically viable and more insect-friendly alternative to our present dependence on fire-only treatments. The DNR is presently engaged in this initiative through support of patch-burn grazing studies in southern Iowa and through support of improved grazing practices on selected prairie-pastures in northwest Iowa. However, not all prairie conservationists are convinced that grazing can be beneficial (pointing to abundant examples of abusive grazing on private pastures); this skepticism will need to be overcome if universal support of this initiative is desired. Nonetheless, I believe that prescribed grazing can have a positive role in managing prairie preserves and look forward to an expansion of the DNRs current effort. In closing, I hope this note helps to answer questions that concerned people have about this years burn at Sylvan Runkel Preserve. It had a disruptive effect on the Loess Hills Seminar and burned nearly all of the prairie within the Preserve, including the habitat containing the then-known population of the Nevada Buckmoth. Its large burn effect within in the preserve may have been mitigated by the presence of extensive prairie remnants in the landscape adjacent to the preserve, but the patchiness of buckmoth host plants makes this interpretation more difficult, although the late-breaking discovery of at least one off-site population is encouraging. It is evident that prairie management on the preserve and surrounding wildlife area has promoted prairie vegetation and produced attractive habitat for the buckmoth and a variety of other prairie organisms, but it has also established an ecological trap that requires consideration of adjustments to prairie management in the preserve. Discussion has already started and will continue. Your understanding, support, and constructive criticism will help this process along. --- Please contribute your sightings to our list; it is only as good as members make it! --- Birding channel recommendation for FRS/GMRS radio use: Primary selection; channel 5/0 , alternate selection; channel 6/0 --- This mailing list is sponsored by the Iowa Ornithologists' Union. Membership available on-line at http://www.iowabirds.org/iou/membership.asp. ----- You are currently subscribed to ia-bird as: [email protected]
