Lightning- and human-ignited fires have shaped many of Florida's natural communities. Plant persistence in these habitats requires adaptation to survive high temperatures, ability to respond to aboveground tissue loss, or avoidance of these conditions through survival in unburned patches or in the soil seed bank. Limited distribution of many rare species in increasingly fragmented habitats and uncertainty of whether rare species tolerate, require, or persist through avoidance of fire hampers fire management when it is possible and threatens long-term viability of plants. We review up to 14 years of monitoring data for 18 rare plant species from 14 families occurring on sandhill, scrub, pine rockland, and mixed deciduous hardwood communities across Florida. For a number of variables measured, including density, frequency, flowering, and recruitment, 50% of the species showed significant positive responses to burning and 50% of the species showed a neutral or no response. None of the species were unable to recover post-burn. These results suggest that prescribed fire in these pyrogenic habitats need not be delayed until species-specific responses to fire are understood.

Large woody debris (LWD) in the form of standing dead trees and down logs is an important structural and functional component of forest ecosystems and is a key factor linking riparian forests and streams. We examined the influence of forest seral stage (old-growth vs. second-growth forest) on terrestrial (snags and down logs) and in-stream LWD abundance in a riparian forest-stream system in Cook Forest State Park, Pennsylvania. Snag density, but not basal area, was significantly greater in second-growth forest due to elevated mortality of eastern white pine (Pinus strobus L.). Abundance of both terrestrial and in-stream LWD was significantly greater in the old-growth forest-stream system than in second-growth. Eastern hemlock, Tsuga canadensis (L.) Carr., strongly dominated the volume of both terrestrial and in-stream LWD in the old-growth stand and adjacent stream reaches. Terrestrial and in-stream LWD loadings that we recorded are similar to loadings occurring in forest-stream systems elsewhere in the eastern United States, especially the Appalachian region, suggesting that these values may be useful targets for LWD enhancement projects for Allegheny High Plateau forest-stream systems.

A Geographic Information System was used to assess the representation of ecological land units (ELUs) both within and external to the current preserve network of the Lower Twin Creek Watershed (LTCW), southwestern Ohio. ELUs were classified using multivariate and cluster analyses on forest canopy tree species and seven physiographic and soil variables derived from digital elevation models and a soil series map. Cluster analysis of the five most significant variables (landform, soil drainage, hillshade, curvature, and percent slope) influencing vegetation distribution resulted in nine discrete ELUs. They included uplands dominated by Fagus grandifolia-Acer saccharum, dry slopes dominated by Quercus spp.-Carya ovata, mesic slopes dominated by a mixed mesophytic community, and wet floodplains dominated by Platanus occidentalis-Populus deltoldes. The area of forest in each ELU in the preserve network was compared to the area of forest in each ELU in the watershed as a whole and the potential natural area of forest cover determined by topographic position. Well-drained upland and poorly-drained upland ELUs were most underrepresented in the preserve network followed by wet broad floodplains. Results of the gap analysis based on current vegetation distribution were influenced by the pattern of deforestation in the LTCW, which was, in turn, related to topographic position: slopes were more likely to be forested and incorporated into a preserve system than more level lands suitable for agriculture. Protecting and restoring forest in upland ELUs will be necessary to capture a full range of ecosystem diversity in the LTCW.

Mature and diverse floodplain forests are among the world's most diminished ecosystems and conservationists need a rapid method to identify the best remaining examples of these systems. Because large rivers and their dynamics bind the floodplain together, the method must go beyond simple inventory of remnant patches to evaluate flood processes and identify constraints in the surrounding watersheds. We develop such a method for a three million hectare watershed in New England using a combination of data types to evaluate key attributes of floodplain systems. Riparian and floodplain communities were modeled using a GIS analysis of river valley topography and riverine processes, and floodplain forest occurrences were identified in a classification and regression (CART) analysis. Current flooding was verified using overlays of remotely sensed imagery of spring and fall water levels. We evaluated the intactness of the floodplain occurrences using ratios of upstream dam storage to annual runoff, the length of the connected stream network, and the naturalness of surrounding land cover. Field-assigned ranks of forest quality were correlated with the occurrence size, percent verified flooding, and percent natural cover. Predicted quality ranks reinforced the importance of these factors. Results indicate that the twenty top-ranking streams collectively contain 75 high quality areas suitable for floodplain forest restoration and conservation. Independent verification of these areas strongly corroborated our results.

Fire is a common disturbance in savanna ecosystems that may either facilitate or impede non-native plant invasions. Although fire can create recruitment opportunities for non-native plants, it can also prevent their invasion if it exerts strong negative effects on their demographic processes. Some savannas may, therefore, be able to resist invasion provided the natural, frequent-fire regime remains intact. We examined the effects of fire on the demography of the invasive shrub Brazilian pepper, Schinus terebinthifolius Raddi., which is invading fire-prone slash pine savannas of southern Florida. We studied survivorship, growth, and reproduction of low-density populations of Brazilian pepper in a pine savanna within Everglades National Park to investigate whether fire might suppress Brazilian pepper in the early stages of invasion. We found a significant decrease in Brazilian pepper survivorship following fire, particularly among small individuals. We further found that fire reduced fecundity of surviving Brazilian pepper individuals for at least two years. However, resprouting individuals that survived fire had high relative growth rates the following year, which could facilitate population recovery during inter-fire periods. We used a simple population simulation to show that a low-density cohort of Brazilian pepper may be rapidly eliminated from pine savannas with fire-return intervals of four years or less, but individuals may persist for > 50 years with fire-return intervals of eight years or more. Our study suggests the need to maintain the historical frequent-fire regime in pine savannas in order to prevent their invasion by fire-intolerant shrubs such as Brazilian pepper.

Cathedral State Park (CSP) is a 54-ha, old-growth, eastern hemlock-hardwood forest located in the central Appalachian Mountains of West Virginia. Hemlock woolly adelgid (HWA) (Adelges tsugae Annand) is an exotic insect that currently threatens eastern hemlock (Tsuga canadensis (L.) Carr.) in its native range, and was found in CSP in 2002. In 2006, field plots established in 2000 were re-measured to assess adelgid-induced changes to forest structure and species composition. The herbaceous plant community was also measured during the 2006 growing season to describe how the ground flora has changed since it was originally surveyed in 1965. In addition, characteristics of snags and downed dead wood in CSP were compared to published data on 25 old-growth hemlock-hardwood stands in the eastern United States. From 2000 to 2006, little HWA-induced change occurred in CSP. Density and basal area of overstory hemlock did not change, while snag density and basal area decreased over time. However, more than 10% of measured overstory hemlock trees were infested with HWA, with plot infestations ranging from 0 to 93% of stems. CSP had 1.5 times the volume of downed dead logs compared to other old-growth hemlock-hardwood stands. This study serves as a reference of forest structure and species composition in CSP prior to HWA-induced mortality.

The identification and inventory of remnant-dependent or conservative species is an essential prerequisite to sound reserve selection and management in severely fragmented regions. We expanded an ongoing study of insect conservatism to include approximately 1200 additional species on 50 prairie and savanna remnants in the Chicago Wilderness Region (CW). Approximately 700 surveys were conducted from 1995 to 2006, with special emphasis placed on 15 high quality reserves. Our objectives were to: (1) gauge the prevalence of conservatism among remnant-inhabiting insects; (2) determine the status of each conservative species; and (3) gauge the extent that small, isolated sites contribute to the preservation of biodiversity in this landscape. Seventeen percent of 2424 species considered were determined to be narrowly associated with remnant habitats, suggesting that the overall prevalence of conservatism among CW insects is low. One hundred and seventy nine (44%) of these species were rarely or never encountered and are considered to be of conservation concern. Species richness for 15 high quality sites of 2 to 600 ha in area ranged from 39 to 167 species, demonstrating that small, isolated sites contribute appreciably to the preservation of biodiversity in this fragmented landscape. A comparison of vulnerable insect, plant, and vertebrate species richness suggests that conservative insect species far outnumber conservative plant and special-concern vertebrate species, and given their apparent rarity, should play a pivotal role in the establishment of conservation priorities within the CW and probably throughout much of the midcontinental United States.

We quantified fire-driven loss and post-fire recovery of understory and soil carbon (C) and nutrient pools for one to three years following a single prescribed fire in a naturally regenerated longleaf (Pinus palustris Mill.) and slash pine (Pinus elliottii Engelm. var. elliottii) forest located in north central Florida. Fire immediately reduced total aboveground understory C and nitrogen (N) pools, but these pools recovered to pre-fire levels after three years. Our results also showed that the effect of fire on the understory composition and structure was only short-lived. Prescribed fire significantly reduced total C and N pools in the forest floor (F and H horizons), and this effect persisted for at least one year postfire. Available NH₄ , PO₄^3-, Ca² , Mg², and K concentrations in the forest floor decreased immediately after fire, but increased in the surface mineral soil (O to 5 cm depth); Ca² , Mg² , and K remained elevated for the first year after fire. Fire immediately reduced total ecosystem C and N pools by 40% and 27%, respectively, emitting 3860 g C m^-2 and 170 g N m^-2 to the atmosphere. The pools recovered to 67% and 76% of pre-fire C and N pools, respectively, after one year. Of the pools measured, C and N recovery in forest floor materials was the slowest, and projections of initial recovery rates suggest that it will take more than six years, the previous fire interval, to reach pre-fire levels. This slow recovery may indicate variation in past rates of forest floor accumulation due to management practices as well as effects of the severity of this or previous fires.

Little is known about the distribution and relative abundance of leaf beetles (Coleoptera: Chrysomelidae) within the United States. However, recent extensive collecting efforts within Kentucky, as well as the compilation and digitization of label data from seven museum collections, have resulted in distribution data for 11,079 beetles collected between 1884 and 2007. We used an integrated approach to assign abundance classifications of rare, local, infrequent, frequent, and abundant to the 253 known leaf beetle species recorded, incorporating both specimen data and our knowledge of the dataset. We initially selected a recently collected subset of 149 species, which were assigned preliminary subjective classifications. Possible index calculations were applied to all 253 species, and the calculation whose order was most aligned with the subjective classifications was chosen. Cutoffs between categories (e.g., abundant to frequent) were identified using subjective classifications as well as natural breaks in data or index values. Final classifications resulted in 132 rare, 38 local, 44 infrequent, 20 frequent, and 19 abundant species. These categories were 81.9% consistent with those given an initial subjective classification. In order to assess the ability of our abundance classifications to differentiate habitat types and quality, we used contingency analysis to compare leaf beetle species composition from two habitats (a native grassland nature preserve and a research farm). Species composition between these two habitats was significantly different (Pearson's χ²=11.4, P = 0.023). Our results indicate that quantitative data can be used to establish consistent abundance classifications, which can then be used to compare species composition of different habitats or communities.