In oak (Quercus) savannas in the Midwest region of the United States, fire continues to play a significant role in its persistence within the landscape; however, in southeastern Wisconsin, quantified fire history records are limited. This study documented occurrences of fire for the last 200 y using 16 cross-dated oak sections from an oak savanna remnant in Kenosha County, Wisconsin. Fire history was reconstructed by: (1) obtaining fire-scarred cross sections from cut down oaks in an area planned for an industrial park, (2) preparing sample surfaces to count rings, (3) creating skeleton plots to crossdate samples, (4) dating fire scars, (5) calculating intervals between fires and (6) determining seasonality of the fire. In addition, a master chronology was constructed for the oak savanna using the cross sections to correlate with precipitation. Throughout the entire time series, only 50% of the fire dates were associated with significantly dry years. Although the overall Weibull median interval was 4.59 y, fire frequency fluctuations and gaps reflected specific time periods of human activities. Although some studies report a high fire frequency during Euro-American settlement, in this study the mean fire interval (MFI) was 19.5 y in the early settlement years in 1840–1872 and 4.77 y in the post settlement years in 1873–1979. From 1980 to the present, MFI was 6.7 y. In addition, the data revealed time periods with no fire events: (1) during early Euro-American settlement (1840–1872), (2) land fragmentation and deforestation (1904–1920) and (3) increased industrial zoning (1989–present). Although lightning strikes occur most often during the summer months, the majority of fires that occurred during the dormant season (53%) were set by humans. These data are essential in understanding oak dynamics and in developing management programs for restoration and preservation of remnant areas of oak savanna.

Climate, specifically moisture and temperature, influences plant growth and nutrient cycling; thus, climate also influences prairie development. Relatively little research has been conducted in the ecological transition zone between the Great Plains and the more humid forests. Since moisture and temperature affect many ecosystem processes, the wetter climate of the southern forest region should influence soil biogeochemical cycling quite differently from that in grassland soils. The objective of this study was to evaluate soil quality and the relationships between selected soil properties across a climosequence in a transition zone between tallgrass prairie in humid-temperate (Ozark Highlands) and humid-subtropical (Grand Prairie) climate regimes in Arkansas. Soil physical, chemical and biological properties of the upper 10 cm differed significantly between physiographic regions. Linear relationships between total soil nitrogen (N) and carbon (C), extractable phosphorus and manganese, electrical conductivity and soil organic matter concentration differed significantly between physiographic regions. Total soil N and C decreased with increasing soil bulk density in both physiographic regions. The relationship between total C and bulk density differed by physiographic region, while the relationship between total N and bulk density did not. Soil organic matter concentration, C:N ratio, and many extractable nutrients, were higher and relationships between selected soil properties differed under native tallgrass prairie in a relatively warm and wet climate than that in a relatively cooler and drier climate. The results of this study suggest that prairie preservation, restoration and management practices should differ depending on climate regimes.

We calculated relative growth rates of all species over 10 cm circumference at breast height from 1997–1999, 1999–2001 and 2001–2003 in a 70 by 100 m plot in an oak forest in southeastern Michigan. Red maple and black cherry represented most of the understory species while white and black oaks dominated the canopy. During the summer of 1999, outbreak levels of gypsy moths preferentially defoliated oaks on the plot, often resulting in 100% defoliation. The relative growth rates (RGR) of red maple and black cherry were significantly higher during the time period where gypsy moths were at outbreak levels. Oaks had lower RGR during the gypsy moth attack than in the subsequent time period. Consequently, the preference gypsy moths exhibited towards oak species indirectly resulted in a higher growth rate for understory tree species, possibly due to increased light availability and the decreased competitive capacity of the defoliated oaks. This indirect effect could accelerate the succession at which oak dominated communities become red maple forests.

We examined the effects of fire regime and bison activity on the plant communities of active bison wallows and the surrounding grazing lawns at Konza Prairie Biological Station in northeastern Kansas, USA. In both mid-June and late July the grazed sites had higher species richness and more vegetation cover than the wallow edges regardless of fire regime. The percent cover of most dominant perennial species was significantly higher on grazing lawns than in wallows. Annual species and exotic species had significantly higher cover in wallows than in grazing lawns and in annually burned sites compared to those burned at a 4-y interval. Overall, treatment effects on community structure and individual species abundance were stronger in the June. However, in July there was significantly more bare ground wallows around sites burned at a 4-y interval, suggesting increased wallowing activity at these sites. This finding suggests a strong effect of fire regime on seasonal bison activity, which further indicates the importance of multiple interacting disturbances for generating local- and landscape-level vegetation patterns in tall grass prairie.

Goodyear Swamp Sanctuary, a wetland adjacent to Otsego Lake, Otsego County, New York, has been dominated by the invasive nonnative plant purple loosestrife (Lythrum salicaria L.) since 1975. In June 1997 a combined total of 100 adult Galerucella calmariensis (L.) and G. pusilla (Duft) were introduced into the Sanctuary in an attempt to control loosestrife. Since then, annual spring and fall monitoring has been conducted on 5/m² quadrats with the intention of evaluating the abundance of Galerucella spp. and their impact on loosestrife over time. Through 2000 Galerucella spp. populations increased, as did damage to loosestrife, though not to the extent of controlling its growth or seed production. During the summers of 2001 and 2002 loosestrife was decimated. Following those periods, ephemeral non-target feeding by Galerucella spp. was documented primarily on red osier (Cornus stolonifera) in 2001 and speckled alder (Alnus rugosa) in 2002 with three other species being grazed to a lesser degree. No non-target species were substantially impacted during these brief periods (<1 wk). Temporal variation in the population distribution suggests that a shortage of appropriate food may have initiated early aestivation. During the summer of 2002 Galerucella spp. were found 9 km off-site, believed to result from a single-season dispersal, suggesting a mobility of a greater extent than previously recorded.

Increased abundance and distribution of eastern redcedar (Juniperus virginianus), a native species in the Great Plains, has been associated with changes in ecosystem functioning and landscape cover. Knowledge of the main consumers and dispersal agents of eastern red cedar cones is essential to understanding the invasive spread of the species. We examined animal removal of cedar cones in three habitats (tallgrass prairie, eastern red cedar and woodland-prairie margins) in the Cross Timbers ecoregion using three exclosure treatments during autumn and winter. Exclosure treatments excluded study trees from ungulates, from terrestrial rodents and ungulates or from neither (control). Loss of cones from branches varied by a habitat-time interaction, but was not affected by exclosure type. Loss of cones from containers located under experimental trees varied by a habitat-treatment-time interaction. In December and January, cone consumption from containers in no-exclosure treatments was highest in margins, followed by tallgrass prairie and eastern red cedar habitats. We conclude birds consumed the majority of cones from branches and small- and medium-sized mammals consumed cones on the ground. Both birds and mammals likely contribute to the spread of eastern red cedar but at different scales. Limiting invasion of eastern red cedar in forests may require early detection and selective removal of pioneer seedlings in cross timbers and other habitats that attract a high diversity or density of frugivores.

As a result of game management practices and alterations in habitat, white-tailed deer populations (Odocoileus virginianus Z.) have increased to all time highs within the last century. Large herd numbers are having negative impacts at multiple levels in forest ecosystems, although there are many aspects that have not yet been investigated. One of the least understood impacts is the effect of deer browsing on the fate of valuable harvested understory species such as American ginseng (Panax quinquefolius L.). The objectives of this study were to quantify the natural frequency at which fruit-bearing ginseng plants are browsed by deer, to determine the amount of ginseng seeds consumed by deer and with feeding trials, to determine if white-tailed deer are seed dispersers or seed predators of American ginseng. Our results showed that fruits are frequently browsed in natural populations and that browsed seeds are most likely destroyed during the digestive process. The loss of ginseng seeds to deer browsing can negatively impact the seed bank and ultimately affect long term population growth and viability. Although white-tailed deer and American ginseng are managed species, effective growth of deer populations is adversely affecting ginseng, as well as other valuable forest species.

Population estimations and indices based on roadside or spotlight counts typically require investigators to determine the route with maximum viewing area and calculate area visible from the census route. Viewshed analysis may provide a simpler and more accurate method for determining route, area and population estimate. From September 2000 to August 2001 we observed adult bison from a driving route at The Nature Conservancy's Tallgrass Prairie Preserve. We recorded group locations to field test the ability of viewshed analysis to predict the area where bison were visible. We developed viewsheds based on digitized layers of the driving route and for high, low and random points within the Preserve to determine the viewshed with maximum visible area. We developed a population estimate based on number of bison observed and visible area calculated from our driving route. We compared population estimates to known bison populations before and after 1 May 2001 and for our entire study period. Ninety-nine percent (P < 0.001) of bison locations occurred within the viewshed. Our driving route provided the most visible area (81%), followed by viewsheds of high (77%), random (61%) and low (31%) points. Estimated adult bison populations before 1 May 2001 were different (P < 0.001), but similar on and after 1 May 2001 (P = 0.10) to known populations. The estimated population for the entire study was different (P < 0.001) from the mean population size. Viewshed analysis is an efficient method to predict locations of easily observed ungulates and has utility in planning census routes with maximum visible area a priori. We suggest that viewshed analysis provides a more accurate estimation of area visible from census routes and resulting population estimations than conventional surveys.

Debris flows are mass movements of sediment, wood and water down stream channels that profoundly impact streams and adjacent riparian areas and are a major erosion process in many steep mountainous terrains. Their impact on aquatic ecosystems, however, is poorly understood. In this report, we describe the ecological effects of a debris flow on a headwater stream in old-growth temperate forest that occurred in December 1999. This geomorphic disturbance scoured our study reach to bedrock and removed live trees 5 to 15 m into the adjacent riparian forest. Summer water temperature was higher in the affected reach after the debris flow than before; these changes have persisted through 2002. Algal biomass after the debris flow was similar to before; however, we speculate that algal growth was constrained by herbivory, as the abundance of two insect herbivores Chironomidae and Baetis spp. increased 380 and 9300%, respectively, within the first year after the debris flow. Overall, these data show that a rare disturbance event can mediate the population dynamics of stream herbivores in small, headwater streams such as those found in Olympic National Park likely via increased primary production and water temperature.

Basic ignorance about the ecology and life history of the endangered Mitchell's satyr butterfly, Neonympha mitchellii mitchellii, is impeding conservation efforts. To assist with recovery, we examined Mitchell's satyr butterfly population structure using mark-release-recapture techniques at two sites in southwestern Michigan in 1997 and 1998. During the single annual flight period spanning 2 to 3 wk from mid June to late July, the sex ratio changed over time, with males predominating early in the flight period and females in the latter half of the season. Scott's Method 1 and recapture decay plotting showed average residence times of 1.4 to 5.3 d. Males were more catchable than females, a probable consequence of behavioral differences between the sexes. Males were commonly found patrolling through the vegetation in search of mates, whereas females were rarely observed in undisturbed flight. Daily population estimates were obtained by the Jolly stochastic method and total brood size and flight area population densities were calculated using estimated residence rates. All population size estimates were low. Total brood size estimates ranged from 164 to 372. Peak daily flight area density ranged between 70 and 159 butterflies per ha. Adult movement was limited. Maximum range estimates were 290 m and 420 m at the two sites. Average movement distances were 37 m and 33 m. Male butterflies moved significantly greater distances than females. Remnants of a metapopulation structure are apparent, but the data are insufficient to differentiate between an extinction—recolonization structure and a source—sink structure. Butterfly movements between habitat patches within occupied sites occur, albeit rarely. Short residence times, low density and sedentary behavior make extant populations vulnerable to environmental stochasticity and human disturbance. Conservation actions need to consider the implications of these important life history traits if we are to reduce local extinction probabilities and recover Mitchell's satyr butterfly.

Temporal and spatial variability in herbivory can be influenced by plant genotype, environmental conditions and their interactions. However, few studies correctly control for the relative influence of these factors. Here, I report results from a reciprocal common garden experiment designed to tease apart the effect of local environmental variation and plant genotype on the abundance of four insect species: Dasineura lupini (Felt), D. lupinorum (Gagne), Epinotia infuscana (Walsingham) and Orgyia vetusta (Boisduval). Full-sib/half-sib families of Lupinus arboreus Sims were made within three different natal populations; replicates from each lupine family then were transplanted back into common gardens located in each of the three parental populations. In two separate years I measured how insect density varied between local environments, within a population of related lupine and among the three populations of lupine. For each insect species, local environment influenced density substantially and microsite variation within environments explained a significant amount of variation. Two insect species (E. infuscana and O. vetusta) congregated on plants originating from the same parental population more than lupine from other populations, while the other two insect species showed this pattern only in specific environments. Even though these insects were differentially abundant on lupine from the three natal populations, they rarely discriminated among individual genotypes within a population. Thus, insect density was affected by environmental factors unique to each site and partly by genotypes originating from the same natal origin, but rarely by fine-scale differences among genotypes from within one parental population.

The Poteau River, a major tributary of the Arkansas River, flows through the Ouachita Uplands of eastern Oklahoma and western Arkansas. The river has been harvested for mussels, historically by the Caddo Indians and recently for the pearl industry. We documented the current distribution and abundance of mussels in the river, compared this with historical distributions and examined whether the river can sustain current levels of commercial harvest. The Poteau River retains a rich mussel fauna of 35 species. However, mussel abundance is much lower than in surrounding rivers. Mean total mussel densities in the largest beds in the river are 3.8 individuals/m². Densities of the two commercially harvested species, Megalonaias nervosa (washboard) and Amblema plicata (threeridge), are only 0.15 and 1.25 individuals/m², respectively. Mussel size distributions indicate very low recent recruitment of both M. nervosa and A. plicata. The majority of M. nervosa exceed the shell height limit of 4 inches established by the state of Oklahoma and, thus, are not protected by this regulation. Our data indicate that the Poteau River cannot sustain commercial mussel harvest. A recently established mussel sanctuary should be retained and further commercial harvest of mussels should be avoided.

We compared freshwater mussel assemblages (Bivalvia: Unionidae) in a developing oxbow (old channel) and a newly-cut (new) channel of the Neosho River, Kansas, during 2001. We sampled mussels at approximately 1.5 km intervals, totaling 19 sites in the old channel and seven in the new, by groping substrate from bank to bank in a zigzag fashion along a 100 m reach. We found 1239 live individuals of 20 mussel species in the old channel and 20 live individuals of six species in the new channel. Mussel abundance, diversity and current species richness were greater in the old channel than in the new. Abundance, diversity and historic and current species richness all declined significantly from upstream to downstream in the old channel. Historic richness was greater than current richness in the old channel, but both decreased from upstream to downstream at the same rate. The loss of historic species from the old channel was no different from that in the rest of the Neosho River in Kansas; however, a further decrease in lotic species will likely occur as the channel continues to evolve into an oxbow lake. Canonical correspondence analysis illustrated a substrate compaction, substrate composition and depth gradient in the old channel, with three species in flowing waters with sand and gravel substrate and all other species in still waters with silt substrate. Information regarding habitat use by freshwater mussels is important in designing surveys and recovery plans for rare species (Strayer, 1993).

Because prey acquisition in young organisms often has profound effects later in life, understanding the foraging ecology of early age classes is important. We examined diet and prey preference of neonate Eastern Massasaugas (Sistrurus c. catenatus) at Carlyle Lake, Clinton County, Illinois. Prey recovered from free-ranging neonates consisted primarily of southern short-tailed shrews (Blarina carolinensis). In feeding trials, neonates demonstrated a preference for snake prey, disinterest in anuran and insect prey and indifference toward mammal prey. Because of gape limitations, neonates may have difficulty ingesting small mammals, but snakes are comparably easier to ingest and are the most common prey item of young S. c. catenatus in other parts of their range. Blarina carolinensis has not been reported previously from the diet of S. c. catenatus as their ranges overlap only in southwestern Illinois. Blarina carolinensis is considerably smaller than most mammals preyed upon by older age classes and would be easier for neonates to ingest. Thus, at Carlyle Lake, snakes may not be as important a prey resource for neonate massasaugas as in other parts of their range due to the availability of B. carolinensis.

We investigated variation of fish assemblages in response to environmental factors using Long Term Resource Monitoring Program data. Data were collected from 1993 to 2000 from five physical habitats in the unimpounded upper Mississippi River. We captured 89 species composing 18 families. Of these, 26% were fluvial specialists, 25% were fluvial dependent and 49% were generalists. The numerically dominant component of the adult fish assemblage (species accounting for >10% of total catch) accounted for 50% of the assemblage and was comprised of only three species: gizzard shad (Dorosoma cepedianum; 25%), common carp (Cyprinus carpio; 15%) and channel catfish (Ictalurus punctatus; 10%). The dominant component of the YOY fish assemblage was comprised of only two species, which accounted for 76% of the total catch: freshwater drum (Aplodinotus grunniens; 39%) and gizzard shad (37%). We used a cross-validation multivariate approach to explore how adult and young-of-the-year (YOY) assemblages varied with respect to physical habitat and environmental gradients. Furthermore, we were interested how the fish assemblages changed over time. Partial canonical correspondence analyses (pCCA) demonstrated significant effects of physical habitats. Such effects differed between young-of-the-year and adult fishes. The four main environmental gradients influencing overall assemblage structure for both age groups were river elevation, water velocity, conductivity and depth of gear deployment. Morisita's index revealed similar adult assemblage structure over time. However, the YOY assemblage present in 1995 was dissimilar from assemblages present during the other years. We speculate this is a lag effect from the backwater spawning episodes (floodpulse) that occurred with the 500-y flood in 1993. Shannon-Weiner diversity and Camargo's evenness indices were low, but stable across years for the adult assemblage, but varied across years for the YOY assemblage.

Intersexual social segregation at small spatial scales is prevalent in ruminants that are sexually dimorphic in body size. Explaining social segregation, however, from hypotheses of how intersexual size differences affects the foraging process of males and females has had mixed results. We studied whether body size influences on forage behavior, intersexual social incompatibility or both might influence social segregation in a population of Roosevelt elk (Cervus elaphus roosevelti) that declined 40% over 5 y. Most males and females in the population occurred in the same forage patches, meadows, but occupied different parts of meadows and most groups were overwhelming comprised of one sex. The extent of segregation varied slightly with changing elk density. Cropping rate, our surrogate of forage ingestion, of males in mixed-sex groups differed from males in male-only groups at high, but not low, elk density. In a prior study of intersexual social interactions it was shown that females avoided groups containing ≥6 males. Therefore, we predicted that females should avoid parts of meadows where groups of males ≥6 were prevalent. Across the 5 y of study this prediction held because ≤5% of all females were found in parts of meadows where median aggregation sizes of males were ≥6. Social segregation was coupled to body size influences on forage ingestion at high density and social incompatibility was coupled to social segregation regardless of elk density.

Fecal corticosteroid levels were monitored in free-living populations of deer mice (Peromyscus maniculatus) and southern red-backed voles (Clethrionomys gapperi) in North-Central Idaho. Sex, reproductive condition and age had no significant effect on fecal corticosteroid level in either species, but fecal corticosteroid levels were significantly higher in deer mice than red-backed voles regardless of sex or age. These data are consistent with the plasma corticosterone level profile exhibited by wild-caught individuals of both species maintained in captivity. In addition, for deer mice estimated population size was significantly correlated with fecal corticosteroid levels. Overall, these data clearly indicate the utility of fecal corticosteroid measures in assessing the adrenal status of wild populations of rodents.

Chinese tallow (Sapium sebiferum) is an invasive tree in the southeastern United States that has been a management concern in Florida. We used observational and experimental approaches to explore factors influencing Chinese tallow invasion around the perimeter of Lake Jackson, Leon County, Florida. Twenty-one transect sites were randomly chosen, 12 with, and 9 without Chinese tallow. We used abundances of co-occurring species and abiotic environmental data to study factors associated with Chinese tallow abundance among and within transects. Canonical correspondence analysis indicated that soil moisture availability and other soil characteristics correlated with Chinese tallow invasion, but that Chinese tallow was not associated with other species distributions. A seeding experiment demonstrated that higher elevations with lower soil moisture have higher germination and seedling survival. This experiment predicts specific elevations around the lake that are most vulnerable to Chinese tallow invasion. Presence or absence of Chinese tallow among transects was not a significant predictor of germination success, suggesting that not all sites suitable for invasion have been invaded. In addition, controlled burning decreased germination probability and may therefore be useful for invasion control.

I studied microgeographic and size-related variation in the diet composition of the Northern Watersnake Nerodia sipedon sipedon in the Beaver Archipelago of Lake Michigan. Snakes from Lake Michigan shoreline sites were piscivorous whereas snakes from interior sites on Beaver Island ate mostly amphibians. Sculpin (Cottus sp.) were the dominant prey of all size classes, but a gradual size-related shift in diet may be occurring in archipelago snakes. Large snakes tended to eat larger prey than small snakes and to drop the smallest prey from their diets, but overlap in prey size occurred among all size classes of snakes. The diet composition of snakes from different sites is likely a reflection of local differences in prey abundance, as found in several previous studies. The overlap in prey size and prey type among snake size classes contradicts the results of some previous studies of Nerodia sp. and merits further investigation.

Florida largemouth bass (Micropterus salmoides floridanus) have been intensively stocked throughout the southern United States for the past three to four decades due to perceived superior growth characteristics. As a result, introgression of Florida largemouth bass with native stocks of northern largemouth bass (M. s. salmoides) has been prevalent. Lakes Ashbaugh and SWEPCO, located in northern Arkansas, were both constructed near 1980 and initially stocked with Florida largemouth bass (LMB). Allele frequencies of three discriminant allozyme loci (sAAT-B, sIDH-B, sMDH-B) between Florida and northern largemouth bass were determined for LMB collected between 1994–1996. Florida largemouth bass alleles were common within each reservoir, yet more common in SWEPCO Lake, a cooling pond for a coal powered electric plant. FLMB allele frequencies in Lake Ashbaugh bass were 0.20 for sAAT-B*3–4 alleles, to 0.24 for sIDHP-B*2 and 0.27 for sMDH-B*2; SWEPCO Lake FLMB allele frequencies were highly variable, with 0.58 for sIDHP-B*2 alleles, 0.64 for sAAT-B*3–4 and 0.92 for sMDH-B*2. High incidence of Hardy- Weinberg disequilibrium was observed, indicative of genetic change within both populations. LMB alleles within the sMDH-B locus may be under selective pressure in SWEPCO Lake. Caution should prevail when introducing non- native stock into native gene complexes, as introduced genes persist through many generations.

We compared 11 ecological variables thought to be important for assessing the habitat of the endangered Virginia northern flying squirrel (Glaucomys sabrinus fuscus) at 11 occupied and 9 unoccupied sites within northern hardwood-montane conifer forests in the central Appalachians of West Virginia. Forest stands at sites occupied by G. s. fuscus had significantly higher relative importance values of montane conifers such as red spruce (Picea rubens) and little or no presence of northern red oak (Quercus rubra) than did sites that were believed unoccupied. Probabilities derived from logistic regression analyses indicated that sites were considered occupied when relative importance values of montane conifers in forest stands exceeded approximately 35%. Conversely, we detected no differences in elevation, absolute forest basal area, overstory tree species richness, total shrub density, percent coarse woody debris cover, percent herbaceous cover, percent emergent rock cover and percent soil organic matter (humus) between occupied and unoccupied sites. We observed low levels hypogeal fungi across all sites and fungi presence did not differ between occupied and unoccupied sites. Patchily distributed fungi combined with the much reduced and altered forest habitat in the region provide additional insights into the rarity of G. s. fuscus in the central Appalachians.