Abstract. Changes in vegetation and fuels were evaluated from measurements taken before and after fuel reduction treatments (prescribed fire, mechanical treatments, and the combination of the two) at 12 Fire and Fire Surrogate (FFS) sites located in forests with a surface fire regime across the conterminous United States. To test the relative effectiveness of fuel reduction treatments and their effect on ecological parameters we used an informationtheoretic approach on a suite of 12 variables representing the overstory (basal area and live tree, sapling, and snag density), the understory (seedling density, shrub cover, and native and alien herbaceous species richness), and the most relevant fuel parameters for wildfire damage (height to live crown, total fuel bed mass, forest floor mass, and woody fuel mass).In the short term (one year after treatment), mechanical treatments were more effective at reducing overstory tree density and basal area and at increasing quadratic mean tree diameter. Prescribed fire treatments were more effective at creating snags, killing seedlings, elevating height to live crown, and reducing surface woody fuels. Overall, the response to fuel reduction treatments of the ecological variables presented in this paper was generally maximized by the combined mechanical plus burning treatment. If the management goal is to quickly produce stands with fewer and larger diameter trees, less surface fuel mass, and greater herbaceous species richness, the combined treatment gave the most desirable results. However, because mechanical plus burning treatments also favored alien species invasion at some sites, monitoring and control need to be part of the prescription when using this treatment.

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The 12-site National Fire and Fire Surrogate study (FFS) was a multivariate experiment that evaluated ecological consequences of alternative fuel-reduction treatments in seasonally dry forests of the US. Each site was a replicated experiment with a common design that compared an un-manipulated control, prescribed fire, mechanical and mechanical + fire treatments. Variables within the vegetation, fuelbed, forest floor and soil, bark beetles, tree diseases and wildlife were measured in 10-ha stands, and ecological response was compared among treatments at the site level, and across sites, to better understand the influence of differential site conditions. For most sites, treated stands were predicted to be more resilient to wildfire if it occurred shortly after treatment, but for most ecological variables, short-term response to treatments was subtle and transient. Strong site-specificity was observed in the response of most ecosystem variables, suggesting that practitioners employ adaptive management at the local scale. Because ecosystem components were tightly linked, adaptive management would need to include monitoring of a carefully chosen set of key variables. Mechanical treatments did not serve as surrogates for fire for most variables, suggesting that fire be maintained whenever possible. Restoration to pre-settlement conditions will require repeated treatments over time, with eastern forests requiring more frequent applications.

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A method to better monitor landscape-level fire characteristics is presented. Three study areas in southern Ohio oak-hickory (Quercus-Carya) forests were established with four treatment areas of ~20 ha each: control (C), burn only (B), thin only (T) or thin plus burn (TB). Two independent measures useful for qualitatively characterising fire intensity were established on a 50-m grid, resulting in over 120 sampling locations at each site, in the burned areas: aluminum tags painted with temperature-sensitive paints, and logger-probe units that logged probe temperature every 2 s during burns. Fires were conducted in spring 2001. The logger-probe units allowed five measures qualitatively related to fire intensity or timing to be calculated at each grid point: maximum probe temperature; duration of probe temperature above 30°C; a heat index, defined as the summed temperatures above 30°C; time of maximum temperature; and estimated rate of spread. Maximum temperatures recorded by the two measuring systems were highly correlated (r2 = 0.83). Relative to painted tags, logger-probe units provide information useful for assessing some other components of fire behaviour. The temporal recording of temperatures allowed us to prepare a web-based simulation of the fires. Heat index and rate of spread estimates provided additional fire information. The TB units consistently burned cooler than the B units, perhaps because of uncured slash and a disrupted fuel bed in those units.

Abstract. By tracking oak-hickory (Quercus-Carya) regeneration for 13 yr across management-manipulated light and topographically driven moisture gradients after partial harvest and three prescribed fires, we document best-case conditions to promote advanced oak regeneration, and thereby provide a promising management tool to reverse the downward spiral in oak that plagues much of the Central Hardwoods within the eastern United States. This study was established in 2000 to assess regeneration following prescribed fire (spring of 2001, 2005, and 2010) in combination with partial harvest (late 2000) across two sites in southern Ohio. Each of the four 20+ ha treatment units (two partial harvest and burn, two controls) were modeled and mapped for long-term moisture regime using the Integrated Moisture Index (IMI) , and a 50-m grid of sampling points established throughout the units. Vegetation and light were sampled at each gridpoint before and after treatments, in 2000, 2001, 2004, 2006, 2009, and 2013. The partial harvest and burn treatments generally had more light which resulted in an increased number of oak stems. The fires promoted heterogeneity (pyrodiversity) in tree mortality and light availability, and consequently oakhickory regeneration, mostly following IMI patterns with the drier portions of the landscape having more fire, more light penetration, and greater regeneration compared to moist locations. Several other species also had marked variations in numbers and size throughout this period, depending on landscape variation in fire intensity and moisture regimes. These included Acer rubrum and Liriodendron tulipifera which expanded initially then collapsed after repeated fire, and Sassafras albidum which continued to flourish on dry sites. Based on this study, we recommend for topographically appropriate dry and intermediate sites, a partial harvest followed by two or three dormant-season fires (depending on fire intensity) allowing roughly 6-18% light to penetrate the forest floor. This will promote oak-hickory into the advanced oak regeneration status. Then, following a hiatus from burning for some years to further advance oak-hickory growth without topkill, some proportion of oaks and hickories can be expected to advance to the canopy following natural disturbance or harvest of current canopy. On mesic sites, though treatments demonstrated here do improve oak-hickory regeneration, the relative cost to benefit would be high.

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