Todd F. Hutchinson

Temporal and spatial patterns in fire occurrence during the establishment of mixed-oak forests in eastern North America

Abstract Question: What was the role of fire during the establishment of the current overstory (ca. 1870-1940) in mixed-oak forests of eastern North America? Location: Nine sites representing a 240-km latitudinal gradient on the Allegheny and Cumberland Plateaus of eastern North America. Methods: Basal cross-sections were collected from 225 trees. Samples were surfaced, and fire scars were dated. Fire history diagrams were constructed and fire return intervals were calculated for each site. Geographic patterns of fire occurrence, and fire-climate relationships were assessed. Results: Fire was a frequent and widespread occurrence during the formation of mixed-oak forests, which initiated after large-scale land clearing in the region ca. 1870. Fire return ranged from 1.7 to 11.1 years during a period of frequent burning from 1875 to 1936. Fires were widespread during this period, sometimes occurring across the study region in the same year. Fires occurred in a variety of climate conditions, including both drought and non-drought years. Fires were rare from 1936 to the present. Conclusions: A variety of fire regime characteristics were discerned. First, a period of frequent fire lasted approximately 60 years during the establishment of the current oak overstory. Second, fire occurred during a variety of climate conditions, including wet climates and extreme drought. Finally, there was within-site temporal variability in fire occurrence. These reference conditions could be mimicked in ongoing oak restoration activities, improving the likelihood of restoration success. Nomenclature: Gleason & Cronquist (1991).

Characteristics of mixed-oak forest ecosystems in southern Ohio prior to the reintroduction of fire

Contains 12 chapters describing baseline conditions of mixed-oak forest ecosystems in the context of a long-term study of prescribed fire effects.

An experimental evaluation of fire history reconstruction using dendrochronology in white oak (Quercus alba)

Dendrochronological analysis of fire scars on tree cross sections has been critically important for understanding historical fire regimes and has influenced forest management practices. Despite its value as a tool for understanding historical ecosystems, tree-ring-based fire history reconstruction has rarely been experimentally evaluated. To examine the efficacy of dendrochronological analysis for detecting fire occurrence in oak forests, we analyzed tree cross sections from sites in which prescribed fires had been recently conducted. The first fire in each treatment unit created a scar in at least one sample, but the overall percentage of samples containing scars in fire years was low (12%). We found that scars were created by 10 of the 15 prescribed fires, and the five undetected fires all occurred in sites where fire had occurred the previous year. Notably, several samples contained scars from known fire-free periods. In summary, our data suggest that tree-ring analysis is a generally effective tool for reconstructing historical fire regimes, although the following points of uncertainty were highlighted: (i) consecutive annual burns may not create fire scars and (ii) wounds that are morphologically indistinguishable from fire scars may originate from nonfire sources.

The distribution of a non-native (Rosa multiflora) and native (Kalmia latifolia) shrub in mature closed-canopy forests across soil fertility gradients.

Background and aimsA soil fertility gradient, ranging from infertile to highly fertile soils, may define whether or not a plant will establish and spread at a site. We evaluated whether or not such a fertility gradient exists for Rosa multiflora Thunb., a nonnative invasive shrub, and Kalmia latifolia L., a native problem shrub, in closed-canopy forests of the eastern U.S.MethodsWe sampled soil and vegetation at the regional scale, along four randomly located 1-km transects in 70+ year-old undisturbed forests in each of three national forests in Ohio, Pennsylvania and West Virginia. We also sampled soil, vegetation and leaf tissue at the local scale, from ten individual shrubs of each species in each national forest.ResultsRegional analyses showed a significant fertility gradient with Ohio being the most fertile and West Virginia the least. Soil fertility was associated with pH (most acidic in West Virginia and least acidic in Ohio) and elevation (highest in West Virginia and lowest in Ohio). At the local level, R. multiflora was associated with soil Ca:Al ratios greater than 0.5, and K. latifolia was associated with Ca:Al ratios less than 0.3. Rosa multiflora foliage contained higher concentrations of Ca, Mg, and K than K. latifolia, while K. latifolia foliage contained higher concentrations of Mn and Zn.ConclusionsOur research documents the importance of soil fertility as a predictor of the establishment of invasive and expansive shrubs. This study further shows that R. multiflora can establish and spread across a broader range of soil conditions than K. latifolia.

Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA.

Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to burn at lower intensities. Species effects, however, are confounded by topographic gradients that affect overstory composition and fuel bed decomposition. To examine the separate and combined effects of litter species composition and topography on surface fuel beds, we conducted a common garden experiment in oak-hickory forests of the Ohio Hills. Each common garden included beds composed of mostly oak and mostly maple litter, representative of oak- and maple-dominated stands, respectively, and a mixture of the two. Beds were replenished each fall for four years. Common gardens (N = 16) were established at four topographic positions (ridges, benches on south- and northeast-facing slopes, and stream terraces) at each of four sites. Litter source and topographic position had largely independent effects on fuel beds and modeled fire dynamics after four years of development. Loading (kg m-2) of the upper litter layer (L), the layer that primarily supports flaming spread, was least in more mesic landscape positions and for maple beds, implying greater decomposition rates for those situations. Bulk density in the L layer (kg m-3) was least for oak beds which, along with higher loading, would promote fire spread and fireline intensity. Loading and bulk density of the combined fermentation and humic (FH) layers were least on stream terrace positions but were not related to species. Litter- and FH-layer moistures during a 5-day dry-down period after a rain event were affected by time and topographic effects while litter source effects were not evident. Characteristics of flaming combustion determined with a cone calorimeter pointed to greater fireline intensity for oak fuel beds and unexpected interactions between litter source and topography. A spread index, which synthesizes a suite of fuel bed, particle, and combustion characteristics to indicate spread (vs extinction) potential, was primarily affected by litter source and, secondarily, by the low spread potentials on mesic landscape positions early in the 5-day dry-down period. A similar result was obtained for modeled fireline intensity. Our results suggest that the continuing transition from oaks to mesophytic species in the Ohio Hills will reduce fire spread potentials and fire intensities.

J. E. Keeley, W. J. Bond, R. A. Bradstock, J. G. Pausas, P. W. Rundel: Fire in Mediterranean ecosystems. Ecology, evolution and management

Botanists and ecologists have long been intrigued by ecosystem convergence, where similar ecosystems have developed in regions that are widely disjunct but that share a similar climate and landform. When I was introduced to the concept of ecosystem convergence in college, the Mediterranean-type climate regions (MTC) were used to illustrate the phenomenon. The five MTC regions, the Mediterranean Basin, and areas within California, Chile, South Africa, and Australia, all contain plant communities that are characterized by evergreen shrubs with sclerophyllous leaves. The regions also share an annual cycle of wet winters and very dry summers, which produces conditions conducive to fire occurrence nearly every year in the summer months. The authors’ primary thesis is that plant traits and communities in these regions have been shaped by the ‘‘climate-fire-geology filter’’. They emphasize that the importance of fire had not been understood in earlier comprehensive works on ecosystem convergence in MTC regions. Each author is based in one of the regions and has done extensive plant ecological research in that region, though none of the authors are from Chile. Section I, Introduction, sets the stage by describing the MTC and providing an overview of ecosystem convergence and fire in the five MTC regions. Chapter 1, Mediterranean-type Climate Ecosystems and Fire, is a succinct introduction to the geography, climate, and vegetation of the MTC regions; in addition to maps and landscape photographs, summary figures and tables provide an overview of important similarities and differences among the regions. This chapter also contains a glossary of commonly used terms (e.g., sclerophyllous leaves, obligate resprouter, lignotuber) that may not be familiar to readers. I referred back to this chapter a number of times. Chapter 2, Fire and the Fire Regime Framework, covers many aspects of fire regimes in the MTC regions, including fire frequency and seasonality, fuels, ignition, and fire behavior. Chapter 3, Fire-related Plant Traits, focuses on the postfire regeneration strategies (resprouting, seedbanking, serotiny, heatand smoke-stimulated germination) that are so intriguing from an evolutionary standpoint. Section II, Regional Patterns, contains a detailed chapter devoted to each of the five MTC regions, covering the core topics of vegetation types, fire regimes, postfire regeneration, land use, and fire management. However, each chapter is different in that it emphasizes topics that the authors believe are important or unique for that region. Throughout the book, there is emphasis placed on shrubland communities with crown fire regimes, which are common to all MTC regions. However, these chapters also describe other vegetation types within the MTC regions that occur under different environmental conditions and have different fire regimes. Examples T. Hutchinson (&) USDA Forest Service, Northern Research Station, Delaware, OH 43015, USA e-mail: thutchinson@fs.fed.us

C. A. Taylor, J. B. Taft, and C. E. Warwick (eds.): Canaries in the catbird seat: The past, present and future of biological resources in a changing environment

At the onset of Euro-American settlement (ca 1820), the landscape of Illinois was a diverse mixture of prairie (55% of the land) and forest, woodland, and savanna (42% of the land). Wetlands, including large expanses of wet prairies and marshes, occupied 24% of the state. However, with the advent of plowing and draining technologies in the mid-1800s, the landscape was largely converted to agricultural use. Among the major communities, prairies and wetlands were hit hardest: [99.99% of original prairie and [88% of original wetland area has been lost. Throughout the course of these dramatic changes, the biodiversity and ecology of the state have been documented by scientists in the Illinois Natural History Survey (INHS). Canaries in the Catbird Seat was published to commemorate the 150th anniversary of the INHS, in 2008. The book summarizes and recounts 150 years of biological monitoring and research by INHS (and other researchers) ‘‘in a language we hope is accessible to the broad audience of citizens interested in our shared natural heritage and in context with the wider scientific community.’’ The two major themes of the book are: (1) ‘‘that humankind has caused dramatic changes to ecosystems in Illinois and beyond,’’ and (2) ‘‘that sound science provided by biologists working at institutions such as INHS can be used to facilitate the recovery, wise use, and sustainability of our shared natural resources.’’ The current size and scope of the INHS (more than 200 researchers and support staff) is evident by the fact that its scientists are lead authors on 16 of the 19 chapters, which cover a wide range of disciplines. The title refers to the fact that INHS researchers have been and are in a unique position (James Thurbur’s ‘‘catbird seat’’) to ‘‘serve as environmental sensors (like the mineshaft canary) through observation and research.’’ The book is organized into three parts. Part 1, ‘‘Foundations for Inquiry: Institutional and Geological History’’, contains an introductory chapter on the history of the INHS and key early figures that included John Wesley Powell and Stephen Forbes and introduces the general habitat-types in Illinois. Another chapter provides a concise treatment of Illinois’ geological history and ecoregions. The glacial history and how it shaped landforms and vegetation is a good foundation for much of the book; maps in this chapter are very good. Part 2, ‘‘Biotic Changes in a Changing Landscape’’, contains 10 chapters that comprise two-thirds T. Hutchinson (&) USDA Forest Service, Northern Research Station, Delaware, OH 43015, USA e-mail: thutchinson@fs.fed.us