Stream channelization results in modifications to the natural meandering of stream channels. Channelized streams experience higher rates of drying in late summer and early fall because of efficient water movement and higher water temperatures. Approximately 70% of east-central Indiana landuse is rowcrop agriculture with widespread stream channelization. We sampled fishes and invertebrates at 14 sites in seven headwater streams in the Buck Creek watershed. We defined streams that dry in late summer and early fall as seasonal, and those that maintain flow throughout the year as perennial streams. Our predictions were that alterations to the natural channel structure, which change the seasonal drying patterns of the streams, would also cause changes in fish and invertebrate assemblages. Detrended Correspondence Analyses (DCA) of fish and invertebrate assemblages produced significant correlations for resulting axes with habitat and water quality variables. No significant differences in fish and invertebrate assemblages were found in our comparisons of seasonal vs. perennial streams.

We investigated the spatial variation in the Kansas River (USA) fish assemblage to determine how fish community structure changes with habitat complexity in a large river. Fishes were collected at ten sites throughout the Kansas River for assessing assemblage structure in summer 2007. Aerial imagery indicated riparian land use within 200 m from the river edge was dominated by agriculture in the upper river reaches (>35%) and tended to increase in urban land use in the lower reaches (>58%). Instream habitat complexity (number of braided channels, islands) also decreased with increased urban area (<25%). Canonical correspondence analysis indicated that species that prefer high-velocity flows and sandy substrate (e.g., blue sucker Cycleptus elongatus and shovelnose sturgeon Scaphirhynchus platorynchus) were associated with the upper river reaches. Abundance of omnivorous and planktivorous fish species were also higher in the lower river. The presence of fluvial dependent and fluvial specialist species was associated with sites with higher water flows, more sand bars, and log jams. Our results suggest that conserving intolerant, native species in the Kansas River may require maintaining suitable habitat for these species and restoration of impacted areas of the river.

This study investigated the location and diel habitat preferences (at 100 m reach scale) of fish in a small tributary stream in late spring, early summer. During the day, coho (Oncorhynchus kisutch) preferred areas with more cover (deeper, greater extent of undercut banks) vs. night when LWD was preferred (Pearson correlation and step-wise MLR). Chinook (O. tshawytscha) exhibited an opposite pattern, preferring LWD during the day vs. higher velocity at night. This suggests these two potadromous species may be partitioning resources. Pooling coho, chinook and rainbow trout (O. mykiss) indicated reaches with more LWD were selected at night (r²  =  0.86, p  =  0.005) vs. deeper reaches during the day (r²  =  0.62, p  =  0.04). Although not measured specifically, we believe LWD supports more macroinvertebrate production vs. the predominantly sandy substrate. Thus, a potential mechanism behind the observed patterns in reach selection may be the tradeoff between food resource abundance vs. predation risk. The majority of captured fish were juveniles supporting the premise first order tributaries can serve as important nursery habitats, especially if they exhibit stable flow and thermal regimes.

Floodplain forests are among the most threatened habitats in North America. We used the richness, abundance and diversity of amphibians and reptiles to assess the effects of habitat modifications at the Old Sabine Bottom Wildlife Management Area (OSBWMA) in Smith County, Texas, USA. Amphibians and reptiles were surveyed using artificial cover objects and minnow traps at nine ephemeral pools: three in undisturbed bottomland forest, three in deer food plots and three near active oil pumps. A total of 627 amphibians and reptiles representing 31 species was captured. Undisturbed forest plots sustained a higher amphibian richness compared to food and oil pump plots. Amphibian abundance differed significantly among habitats with food plots having the highest and oil pump plots the lowest. Reptile abundance was not significantly different among habitat types neither was reptile richness following rarefaction correction. Overall, each habitat type had similar Simpson's diversity indices, ranging from 0.852–0.894 for total amphibians and reptiles. The community compositions in the three habitat types were significantly different. In general, the food plots had little impact on the amphibians and reptiles in this floodplain however oil pump plots appeared to be avoided. Overall, species presence varied according to the type of habitat modification which should be considered before implementing management plans.

Red imported fire ants (Solenopsis invicta) have negative impacts on a broad array of invertebrate species. We investigated the impacts of fire ants on the upland arthropod community on 20∼40 ha study sites in southern Mississippi. Study sites were sampled from 1997–2000 before, during, and after fire ant bait treatments to reduce fire ant populations. Fire ant abundance was assessed with bait transects on all sites, and fire ant population indices were estimated on a subset of study sites. Species richness and diversity of other ant species was also assessed from bait transects. Insect biomass and diversity was determined from light trap samples. Following treatments, fire ant abundance and population indices were significantly reduced, and ant species diversity and richness were greater on treated sites. Arthropod biomass, species diversity and species richness estimated from light trap samples were negatively correlated with fire ant abundance, but there were no observable treatment effects. Solenopsis invicta has the potential to negatively impact native arthropod communities resulting in a potential loss of both species and function.

Several aspects of the reproductive ecology of the hibiscus seed beetle were investigated during summer 2003 and the succeeding winter and spring. Throughout the flowering period that extended from late Jul. to early Sept., aggregations of adult hibiscus seed beetles (Althaeus hibisci Olivier) were collected from swamp rose mallow (Hibiscus moscheutos L.) flowers at 5 d intervals and counted separately by sex. The occurrence of strongly male-biased sex ratios that decreased progressively during the flowering season, accompanied mid-season by slightly male-biased ratios on incipient fruits, suggests that both the flowers and developing fruits serve as sites frequented by the males to acquire mates. During the apparent peak of beetle activity, a cohort of incipient fruits was examined at 3 d intervals for the presence of beetle eggs. Oviposition began <3 d after corolla abscission and had occurred on nearly 100% of the fruits by day 6. Egg density reached an asymptote at day 12. Adult beetle emergence was monitored from seeds originating from flowers that bloomed during separate dates 5 d apart. The seeds were maintained until spring under weather conditions similar to those at the marsh where they were obtained. From seeds produced by fruits derived from flowers that bloomed early in the season (late Jul.–mid Aug.), beetles emerged in autumn of the same year. However, late-season fruits were colonized by beetles that emerged after mid-winter and thus effectively overwintered in the seed. This corrects previous reports indicating that beetles overwinter exclusively as emerged adults.

Caves are unique habitats and important components of their ecosystems. Caves are also vital to local economies because they serve as tourist attractions. Cave habitats appear to host diverse communities of fungi. In this study we explore associations between levels of human disturbance and the diversity of fungi in four caves in Kentucky and Tennessee. Species isolated from cave soils were cultured at 10 C (cave temperature) and room temperature. The results show that fungal diversity is low in heavily trafficked sites, increases in moderately visited sites and peaks at low disturbance levels. No fungi were cultured from sites that had very rarely or never been entered before we sampled. Species were counted using the morphological species concept. Fungi from the most diverse site were also characterized using sequence data of the ITS locus. Using this method the fungi were identified as species of Bionectria, Cadophora, Fusarium, Hypocrea, Mortierella, Paraconiothyrium, Penicillium and Podospora.

Ecologists have long studied extrinsic factors to explain intraspecific variation in phenotypic expression, yet assessment of intrinsic factors may also be important in understanding intraspecific phenotypic variation. Resources are allocated among the competing life history traits of growth, reproduction and storage. Thus, assessment of the suite of these traits may be critical to better understand phenotypic expression of life history traits. We examined growth (body size), reproduction (reproductive frequency) and storage (tail fat) of museum specimens of Red-backed Salamanders, Plethodon cinereus, at low and high elevations to test how altitudinal differences affected resource allocation among these life history traits. Based on the findings from previous studies, we hypothesized that animals at high elevations would be smaller in body size, reproduce less frequently and have less fat storage. We found that adult animals at high elevations were smaller in body size, reproduced less frequently (only females), but had greater tail fat storage relative to their body size than their counterparts at low elevations. The stored fat on tails can be used when salamanders are short of food. It may be more crucial for animals at high elevations to store more fuel for survival because longer and colder winters prevent them from actively foraging for longer periods. Our results suggest that resource allocation to growth and reproduction may be more constrained at high elevations because of the shorter growing season and greater allocation of energy into storage.

Eastern red-backed salamander (Plethodon cinereus; RBS), known to be one of the most common vertebrates within its geographical range, is an amphibian species commonly used as indicator of forest ecosystem health. Its suitability in this role is based in part on previous studies showing that it is sensitive to changes in habitat such as increased acidity. The occurrence and body sizes of RBS were examined under coverboards, over a 5 y period, in a northern hardwood forest of Québec (Canada) having a highly acidic forest floor (pH  =  3.7 ± 0.4). During this period, 565 RBS were captured. Encounter rate (29%) of salamanders under coverboards was considered very high, as compared to similar studies. Also, 87% of youngs of the year and 83% of adults were found under coverboards that had a forest floor pH ≤ 3.8, representing 79% of all coverboards. Weight and length of RBS measured in this forest ecosystem are among the highest values reported in the scientific literature for this species. Both the relatively high body parameter values and occurrence of RBS in this acidic environment contradict previous studies that demonstrated the negative influence of soil pH on the occurrence and health of RBS. These observations indicate that a highly acidic habitat may support a healthy RBS population. Moreover, the studied forest seems to have the lowest pH yet reported for a habitat known to support this salamander species. Given that RBS has been widely used as an indicator for monitoring forest ecosystems in recent years, this new information on microhabitat tolerance should be considered for correctly using this species as indicator of forest health and soil acidity.

Herbivores can affect the composition of grassland communities. We examined seedling herbivory by the introduced snail, Helix aspersa, on four grass species common in California grasslands. To assess preference, standardized tests using equal amounts of seedlings of the same age were conducted in addition to tests in which live seedlings were exposed to snail herbivory. Helix aspersa exhibited the greatest preference for native Bromus carinatus, while native Nassella pulchra and exotic B. hordeaceus were moderately preferred. Exotic Avena fatua was least preferred. Assessment of preference using both standardized and live seedling trials yielded consistent results, suggesting that preference is due to variation in seedling quality rather than differences in per-seedling biomass that are likely to exist under field conditions. Avena fatua is very common in California grasslands while B. carinatus is relatively rare. Our results suggest that the high level of snail preference for B. carinatus and aversion to A. fatua, coupled with severe effects on future growth due to complete defoliation of live seedlings, may reinforce patterns of establishment of these grasses observed in natural communities.

Roosts are an integral habitat component for species of bats and may affect their survival and fitness. Conversion of forests to agricultural and urban areas may decrease available roosting habitat for the endangered Indiana bat (Myotis sodalis). Furthermore, the effects of habitat loss could be exacerbated if sympatric species favor and compete for similar roost-sites. We used radio-telemetry to study roosting habits of two species of Myotis in northeastern Missouri. We did not directly test for competition between these species for maternity roosts; rather, our goal was to determine if similarities in roost site characteristics were strong enough to warrant further investigation into competition for maternity roosts. Of 118 roosts located throughout the study, 79 were used by Indiana bats and 39 by northern bats (M. septentrionalis). Differences in roost structure (natural vs. manmade), tree status (live vs. snag), roost type (bark vs. cavity/crevice) and canopy coverage indicate that subtle, but biologically important differences exist in roost selection. Northern and Indiana bats both relied heavily on trees as roosts sites; however, Indiana bats roosted in trees with lower canopy cover and less often in cavities and live trees than northern bats. Our results suggest that niche separation in roost selection exists between northern and Indiana bats.

Mycorrhizal fungi are ubiquitous components of terrestrial ecosystems that can influence plant performance, abundance and diversity. Patterns of allocation to specific mycorrhizal fungal structures could provide a useful context for understanding belowground dynamics in response to changing resources. Specifically, increased soil nutrient availability has been predicted to favor plants with lower rates of mycorrhizal association. In addition, fertilization has been predicted to favor mycorrhizae with higher investment in storage structures relative to uptake and exchange structures.

A 3 y field experiment was conducted in coastal tallgrass prairie to examine how fertilization affects mycorrhizal abundance and investment patterns. Fertilization significantly increased total mycorrhizal abundance. Specifically, mycorrhizal investment in hyphae, coils and vesicles were significantly increased 53%, 252% and 440% in fertilized plots, respectively. Together these results suggest that mycorrhizae in high fertility soils allocate more to internal fungal storage at a potential cost to plant hosts. Thus, fertilization could have important indirect effects on the aboveground plant community by potentially altering the costs and benefits of mycorrhizae to host plants.

The objective of this study was to track changes in growth and dendroclimatic response of white oak (Quercus alba) trees that established in the forest interior and, following the creation of an artificial lake, continued living along the lake edge. Twenty-one white oaks from the lake edge were cored and 91% of the trees exhibited a growth response to the creation of the lake – most commonly a suppression. Two 32 y segments (pre-lake and post-lake) were compared for differences in dendroclimatic response. The tree-ring chronology from the pre-lake time period had significant negative correlations between ring width index (RWI) and temperature in Jun.; significant positive correlations between RWI and precipitation from Jun. of the previous year; significant positive correlations between RWI and precipitation in Mar. of the current year; and significant positive correlations between RWI and Palmer Drought Severity Index (PDSI) in Jul. After lake construction, the same trees exhibited significant positive correlations between RWI and Jul. temperature from the previous year; significant negative correlations between RWI and temperature in Feb. and May; significant positive correlations between RWI and precipitation in Sep.; and significant positive correlations between RWI and PDSI in Jun., Jul., Aug. and Sep. Most trees that experienced transitions from interior to edge positions responded with a decline in growth rate and a moderate change in dendroclimatic responsiveness.

Trillium recurvatum Beck is a long lived perennial with its northernmost distributional range in southern Wisconsin and is listed as Special Concern. The breeding system and reproductive ecology of this purple sessile flowered Trillium have not been previously studied. To test the hypothesis that pollen limitation is a primary contributing factor to the rarity of T. recurvatum, its breeding system and reproductive ecology were studied. Pollinator activities, pollen to ovule ratios, fruit and seed set and breeding system dynamics via field crossing studies were assessed. Observations of insect visitations revealed a single effective pollinator Coleomegilla maculata De Greer. The estimated pollen to ovule ratio was 3255 to 1 suggesting strongly obligate outcrossing. Seeds were small weighing less than any species in the genus. Fruit set in hand pollinated, outcrossed flowers was significantly greater than in open pollinated controls, demonstrating pollen limitation. Autogamous crosses yielded less than 2% fruit set, indicating self incompatibility. Seed set was greater in open pollinated controls than in manipulated flowers, indicating high pollen load depositions. This study demonstrates that pollen limitation is present in T. recurvatum but loss of habitat, habitat fragmentation and effects of distributional range limitation may not be discounted as forces influencing its rarity.

While goldenrod species are often found to be allelopathic in laboratory settings, its importance in controlling plant community dynamics has been much more difficult to assess. We designed a study to determine whether allelopathy is related to the success of goldenrods in abandoned agricultural land. To accomplish this, we conducted laboratory bioassays for six co-occurring goldenrod species and compared these results to the cover and impacts of these species in the field. We determined the germination responses of two target species to a gradient of leaf extract concentrations to assess the allelopathic potential of these goldenrods. We also used long-term successional data to determine the influence of each goldenrod species on community turnover. Germination percentages in the lab were reduced by leaf extracts for most goldenrod species and varied dramatically among species. In the field, influences of goldenrods on their associated communities were weak and opposite expected allelopathic effects, as the number of associated species generally increased with goldenrod cover. The relative strength of allelopathy among goldenrods was not related to the abundance achieved during succession. In this system, we documented the potential for goldenrods to exhibit allelopathic interactions in a controlled situation. However, these effects were not strong enough to alter community structure and turnover.

Flowers are expected to be under strong selection pressure to be attractive to pollinators. Yet, floral traits that serve in pollinator attraction may inadvertently attract animals that consume flowers. We expected animals to utilize floral cues in targeting plants to attack so for three field seasons we examined florivory in four sympatric Ipomoea species that differed in their pollination syndrome (flower color and shape) as well as their geographic origin (native vs. introduced). Most of the damage to Ipomoea flowers was caused by larval Spodoptera spp. that consumed all or parts of the corolla, pistil and stamens. There was no overall difference in damage levels to flowers of the bee or hummingbird-pollinated plants. However, florivores exhibited a strong preference for the native, bumble bee-pollinated I. cordatotriloba relative to the remaining three non-native Ipomoea species. The non-native, hummingbird-pollinated I. hederifolia and I. quamoclit consistently experienced the lowest florivory rates. There were reproductive consequences to florivory as damaged flowers had reduced fruit set. Seed set was not influenced by corolla damage, but was reduced when flowers suffered damage to reproductive organs. The results of our study suggest that flower-eating insects are not focusing in on traits associated with different pollination syndromes, but are preferentially visiting the native Ipomoea species, and this may contribute to the successful invasion of introduced Ipomoea plants that suffer reduced damage levels.

Ecologists have come to appreciate that plant genotype can affect the success of restoration efforts, but the role of plant symbionts has received less attention. Epichloë-type endophytic fungi (EF) grow in the aboveground tissues of most plants and occur systemically in 20–30% of all grass species. Despite the potential for EF to alter plant competitive hierarchies and to be lost under improper seed storage, they have yet to be considered as an important factor in plant restoration ecology. We surveyed EF infection frequency in 42 native and restored populations of the dominant Great Lakes dune grass Ammophila breviligulata. We also conducted a greenhouse experiment to compare effects of herbivory and drought on an uninfected Michigan population of A. breviligulata and the commercially available ‘Cape’ variety, which is commonly planted for restoration. Surveys revealed low levels of EF infection in natural populations in the Great Lakes region. ‘Cape’ nursery stock was 100% infected. In the greenhouse, the Michigan plants were more sensitive to grasshopper herbivory and drought than the ‘Cape’ plants. Our results suggest that the variety of A. breviligulata used in dune restorations possibly could alter plant and insect community dynamics due to differences in EF status, though further tests under field conditions are needed.

Past management practices have changed much of the native mixed pine-hardwood forests on upland alluvial terraces of the western Gulf Coastal Plain to either pine monocultures or hardwood (angiosperm) stands. Changes in dominant tree species can alter soil chemical, biological, and physical properties and processes, thereby changing soil attributes, and ultimately, soil functions. Restoring these forests may be slow or difficult if soil function is altered appreciably. We studied the soil properties and processes in pine or hardwood-dominated stands after 35 y since conversion from a mixed pine-hardwood stand. The pine forest floor biomass was about twice as great as that of the oak stands, the oak soils were 20–30% wetter than the pine soils throughout the sampling period, the oak soils released more CO₂ through respiration and had higher rates of N mineralization in the summer. We observed few differences between pine and oak stands in soil chemistry or microbial biomass. Since the difference in forest floor depth and soil biological activity may confer competitive advantages or disadvantages to some species, this study supports the hypothesis that pine- or hardwood-only stands create functionally different soils on these site types after 35 y.

Disturbances may add or remove resources from communities and can facilitate the spread of some invaders. Differential successes of exotic plants to spread into different communities suggest that some habitats are more invasible than others. Hesperis matronalis (dame's rocket) is widespread across the continent and has potential to become a major problem in natural communities owing to its ability to exploit excess resources and its negative effect on native species. We grew H. matronalis seedlings in a Colorado foothill community at various levels of nitrogen and water with and without neighbors. We expected H. matronalis to maximize its growth under high resource conditions especially without neighbors because ruderal species are able to take advantage of excess resources. Our results reveal that presence or absence of neighbors was the main decisive factor for H. matronalis (aboveground biomass and relative growth rate) success, though seedlings particularly suffered under low resource conditions. Early determination of the potential invasiveness of a widespread exotic species such as H. matronalis in natural communities may promote effective management.

Impacts of biological invasions on recipient plant communities vary enormously, depending on both the traits of the introduced species and those of its new ecosystem. The trajectories of many introduced plant species in invaded ecosystems seem very similar to those taken by native plants as part of secondary succession. It is likely that studying them in the framework of modern succession ecology would be fruitful. Other introduced species of plants, animals and pathogens cause massive, rapid and often irreversible changes in the recipient communities, of a magnitude rarely produced by native species. Understanding such invasions, and the great range of impacts caused by introduced species, will probably require at least some approaches different from those of other sciences of vegetation change. Although invasion biology has been somewhat dissociated from other research on vegetation change, at least a partial rapprochement is underway, and, in any event, it is not evident that understanding of invasions has been retarded by the dissociation. Research on plant invasions has already contributed greatly to recent progress in understanding the determinants of community structure and function, as well as to many other areas of ecology. The rapidly increasing number of communities composed wholly or largely of introduced species would seem to be an ideal probe into questions about the nature of plant communities and the forces molding them, but they have barely been exploited in this regard. Invasion biology has not produced powerful general laws, but neither has community ecology as a whole. This fact does not indicate that they are weak sciences, only that any laws in these fields will probably be local, contingent patterns because of the complexity and idiosyncrasies of biological communities.

Herbivory and inflorescence size can influence floral visitors. Damaged inflorescences have been shown to have fewer floral visitors due to changes in floral appearance/chemistry, whereas larger inflorescences attract more pollinators because of greater pollen/nectar reward. This study examined whether floral herbivory by a moth, Coleotechnites eryngiella Bottimer (Gelechiidae), and inflorescence size have any effect on the attractiveness of Eryngium yuccifolium Michaux (Apiaceae) to floral visitors. In particular, the study seeks to determine how combined effects of inflorescence size and herbivory affect overall and main composition of floral visitors groups. Twelve plants, six with one inflorescence stalk (three with and three without herbivory) and six with three inflorescence stalks (three with and three without herbivory) were observed for floral visitors in 2004 and 2007 at four remnant tallgrass prairies located in east-central Illinois, USA. Damaged inflorescences had lower flower visitation than undamaged inflorescences. Larger floral displays attracted more floral visitors. Differences between the numbers of flies, bees and beetles visiting the flowers were not independent of herbivory and inflorescence size. This study provides additional evidence that herbivory and inflorescence size can influence insect visitation. In addition, this study provides further support to recent publications regarding the more sophisticated nature of the pollinator guild associated with members of Apiaceae. Finally, it also provides the foundation for future studies to determine how differences in the composition of floral visitors are associated with the male and female inflorescence phases of E. yuccifolium and their relation to male and female fitness.

Breeding pair and brood surveys suggest that duck production in the Southern High Plains can be substantial in some years, particularly for Mallards (Anas platyrynchos). Management of habitats used by nesting ducks and brood surveys could be improved with knowledge of hatching chronology. We studied hatching chronology and brood abundance of waterfowl using playa wetlands in the Southern High Plains of Texas in 2005 and 2007 (playas were dry in 2006). Broods were found on 67% (n  =  36) and 79% (n  =  19) of wet playas in 2005 and 2007, respectively. Broods per playa averaged 1.9 (±0.4 se) in 2005 and 3.2 (±1.0 se) in 2007. Hatching peaked during 1–15 Jun. and by 15 Jul. about 90% of broods had hatched. Delaying haying, mowing and other manipulations of upland nesting habitats until 15 Jul. should give 90% of broods a chance to reach playas. Brood abundance peaked during the two Jul. periods; production surveys conducted during Jul. should capture >70% of broods.