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For the prairie-forest ecotone of central North America, research of the effects of climate and fire on the annual growth of nonwoody plant types is currently needed to compliment dendrochronological research used for predicting the stability of this ecotone in the future. Using cores of Quercus stellata Wangenh. and collars of taproots of Asclepias viridis Walter from central Oklahoma, as well as cores from Quercus macrocarpa Michx. and Lespedeza capitata Michx. collars in central Minnesota, we aimed to distinguish the response towards annual precipitation and temperature, as well as fire regime, between these co-existing plant types through patterns in annual ring growth. The effect of spring fire on the annual growth increment was only consistently significant for one of the forbs, with a positive relationship. The strong negative effect of summer temperature was consistent between forbs and Q. stellata, while the positive effect of either growing season precipitation was consistent between plant types. Furthermore, we found stronger patch-specific annual ring patterns in forbs in comparison with trees when patches are separated based on unique fire histories. Overall, such efforts could be used in further studies to better predict growth rates of dominant plant types in landscapes susceptible to significant environmental change. [ABSTRACT FROM AUTHOR]

We surveyed a 5948-ha study site on the north slope of Winding Stair Mountain, entirely within the Ouachita National Forest in LeFlore County, Oklahoma, U.S.A. The area is jointly managed by the National Forest Service and the Oklahoma Department of Wildlife Conservation. We made 261 collections of bryophytes from spring 2012 to early spring 2014. We found 50 families and 75 genera represented by 87 moss, 1 hornwort, and 29 liverwort species. This includes 22 state records and 34 county records. Two species (Plagiochila dubia and Frullania appalachiana) were discovered far from their previously reported ranges. The large number (18%) of species newly reported for the state of Oklahoma demonstrates the need for more bryophyte surveys to be conducted on these understudied organisms. [ABSTRACT FROM AUTHOR]

The relatively new field of herbaceous root chronology ('herb chronology') uses the annual rings of secondary xylem in roots of perennial forbs to analyze belowground secondary growth as a function of annual growth environment. By using three tallgrass forb species from long-term experiments within Konza prairie of northeastern Kansas (USA), we aimed to find the effects of fertilization, growing season temperature, and precipitation on annual secondary growth. For two of the three species, we found annual rings were significantly larger among plots that were fertilized annually with phosphorus or nitrogen + phosphorus in contrast to unfertilized control plots. Rings also had significant variation with climatic variables. We found a consistent negative correlation with early season temperature for each species. However, early growing season precipitation proved to be far less consistent, with positive correlations only found in a few cases between species. Overall, we conclude that annual rings in these select tallgrass prairie species may not carry reliable climatic signatures; rather site-specific ecological factors, such as aboveground competition with neighbors, may be more important for annual ring patterns. In our discussion we propose a framework to help better disentangle the effects of site or climatic factors that may affect herbaceous annual ring variation. [ABSTRACT FROM AUTHOR]

Background: Plant endophytic bacteria play an important role benefiting plant growth or being pathogenic to plants or organisms that consume those plants. Multiple species of bacteria have been found co-inhabiting plants, both cultivated and wild, with viruses and fungi. For these reasons, a general understanding of plant endophytic microbial communities and their diversity is necessary. A key issue is how the distributions of these bacteria vary with location, with plant species, with individual plants and with plant growing season. Results: Five common plant species were collected monthly for four months in the summer of 2010, with replicates from four different sampling sites in the Tallgrass Prairie Preserve in Osage County, Oklahoma, USA. Metagenomic DNA was extracted from ground, washed plant leaf samples, and fragments of the bacterial 16S rDNA genes were amplified for analysis of terminal restriction fragment length polymorphism (T-RFLP). We performed mono-digestion T-RFLP with restriction endonuclease DdeI, to reveal the structures of leaf endophytic bacterial communities, to identify the differences between plant-associated bacterial communities in different plant species or environments, and to explore factors affecting the bacterial distribution. We tested the impacts of three major factors on the leaf endophytic bacterial communities, including host plant species, sampling dates and sampling locations. Conclusions: Results indicated that all of the three factors were significantly related (α = 0.05) to the distribution of leaf endophytic bacteria, with host species being the most important, followed by sampling dates and sampling locations. [ABSTRACT FROM AUTHOR]

Floras, or documented lists of vascular plant species in a defined area, are widely used in biodiversity research and conservation, and represent a common type of publication in regional botanical and natural history journals. Although all floras present common types of information, there has not yet been a formal attempt to develop community standards for floristic data. As a consequence, published floras often lack basic data describing the study area, taxonomic sources, and criteria for inclusion of species. Here, we develop a grading scheme for floras and apply it to 145 articles in 5 leading journals (Castanea, Rhodora, Sida/Journal of the Botanical Research Institute of Texas, Journal of the Torrey Botanical Club, and Southeastern Naturalist) published from 2000 through 2009. We found that the average 'grade' was 80%, and did not vary among journals. We also list common mistakes and confusions. We urge authors, editors, and reviewers to adopt (and adhere to) a set of standards that we provide, or to develop similar comprehensive standards of their own. [ABSTRACT FROM AUTHOR]

Questions: Most modern fire-prone landscapes have experienced disruptions of their historic fire regimes. Are the primary tallgrass prairies of the Flint Hills reflective of a history of continuous fire occurrence? Did fire frequency, severity, size and seasonality change in connection with changes in land use? Has fire occurrence been related to drought conditions? Location: Edges of Cross Timbers forest stands at the Tallgrass Prairie Preserve (TGPP) in the Flint Hills of Osage County, Oklahoma, USA. Methods: Cross-sections of 76 Quercus stellata were collected from Cross Timbers stands at or near the grassland edge in the TGPP. Dendrochronological methods were used to identify years of formation for tree rings and fire scars. Superposed epoch analysis was used to evaluate the effect of drought conditions on fire occurrence. Results: Fires were recorded in 46.6% of the years between 1729 and 2005. In 41 cross-sections at one site, the mean fire interval between 1759 and 2003 was 2.59 years, with fire interval decreasing from a mean fire interval of 3.76 years in the early part of the record to 2.13 years in modern times. No extended periods without fire were recorded in the study area. Drought conditions had no significant effect on fire occurrence. Conclusions: In contrast with many fire-prone landscapes worldwide, the prairies of the Flint Hills have experienced no recent fire suppression or exclusion. Changes in fire frequency mark transitions in land use, primarily from being traditionally used by Native Americans to being managed for cattle production. [ABSTRACT FROM AUTHOR]

Vascular plant checklists (floras) supply key information for biodiversity studies by providing a comprehensive picture of the floristic composition of a specific study area. A bibliography of floras conducted within the state of North Carolina was compiled. Eighty-six floras were completed within North Carolina between the years 1834 and 2009. Floras conducted in North Carolina cover areas of varying size, from small islands and state parks to entire counties. These studies include journal articles, government publications, technical reports and Master's theses. More than half of the flora citations were not published in scientific journals and were often difficult to discover or obtain. [ABSTRACT FROM AUTHOR]

Asthma increased dramatically in the last decades of the 20th century and is representative of chronic diseases that have been linked to altered microbial exposure and immune responses. Here we evaluate the effects of environmental exposures typically associated with asthma protection or risk on the microbial community structure of household dust (dogs, cats, and day care). PCR-denaturing gradient gel analysis (PCR-DGGE) demonstrated that the bacterial community structure in house dust is significantly impacted by the presence of dogs or cats in the home (P = 0.0190 and 0.0029, respectively) and by whether or not children attend day care (P = 0.0037). In addition, significant differences in the dust bacterial community were associated with asthma outcomes in young children, including wheezing (P = 0.0103) and specific IgE (P = 0.0184). Our findings suggest that specific bacterial populations within the community are associated with either risk or protection from asthma. [ABSTRACT FROM AUTHOR]

Variation in individual density may explain the unimodal richness-biomass relationship in which species richness peaks at an intermediate level of total biomass. However, it is unclear how individual density is regulated by community thinning (i.e., mortality due to competition with neighbors) as total above-ground biomass increases. We developed a simulation model which demonstrates that the spatial structure of a population can influence the initiation and rate of community thinning and thus the shape of the richness-biomass relationship. Specifically, we found that more clustered populations resulted in a more abrupt initiation and rapid rate of thinning and thus a sharper unimodal richness-biomass relationship. Our simulation also demonstrated that a wide diversity of richness-biomass relationships can be produced by community-thinning. [ABSTRACT FROM AUTHOR]

Abstract: Recent studies have indicated that plant growth-promoting bacteria (PGPB) can improve revegetation of arid mine tailings as measured by increased biomass production. The goals of the present study were first to evaluate how mode of application of known PGPB affects plant growth, and second to evaluate the effect of this inoculation on rhizosphere microbial community structure. PGPB application strategies investigated include preliminary surface sterilization of seeds (a common practice in phytoremediation trials) followed by a comparison of two application methods; immersion and alginate encapsulation. Results with two native desert plant species, Atriplex lentiformis and Buchloe dactyloides, suggest that seed surface sterilization prior to inoculation is not necessary to achieve beneficial effects of introduced PGPB. Both PGPB application techniques generally enhanced plant growth although results were both plant and PGPB specific. These results demonstrate that alginate encapsulation, which allows for long-term storage and easier application to seeds, is an effective way to inoculate PGPB. In addition, the influence of PGPB application on B. dactyloides rhizosphere community structure was evaluated using PCR-DGGE (denaturing gradient gel electrophoresis) analysis of bacterial DNA extracted from rhizosphere samples collected 75 d following planting. A comparative analysis of DGGE profiles was performed using canonical correspondence analysis (CCA). DGGE-CCA showed that rhizosphere community profiles from PGPB-inoculated treatments are significantly different from both uninoculated tailings rhizosphere profiles and profiles from the compost used to amend the tailings. Further, community profiles from B. dactyloides inoculated with the best performing PGPB (Arthro Mix) were significantly different from two other PGPB tested. These results suggest that introduced PGPB have the potential to influence the development of the rhizosphere community structure found in plants grown in mine tailings. [Copyright &y& Elsevier]

Recent empirical work in numerous systems has demonstrated the interdependence of spatial and temporal accumulation of species in the species-time-area relationship (STAR). The purpose of this study was to develop a process-based stochastic model for the STAR that assumes species neutrality and to compare the model's expectations to data collected on plant species in a tallgrass prairie. We varied two important aspects of the neutral species assemblage: evenness in the species pool and individual replacement rate (R). When R is larger than ∼0.5 and evenness is intermediate to high, the neutral STAR generates patterns qualitatively similar to the empirical STAR. Our model also indicates that space and time were not symmetrical in their effects on species accumulation, except in the special case of R = 1.0. We observed both positive and negative time-by-area interactions in the sampling model, which indicates that nonzero interactions are not necessarily evidence of ecological processes. Furthermore, as accumulated richness approaches the size of the species pool, the time-by- area interaction becomes increasingly negative in our model. This suggests that negative time- by-area interactions should be expected a priori in empirical systems if rates of species accumulation decrease due to increasing rarity of unique species. Given the wide range of STARs that the sampling model generated, the difficulty in estimating key parameters, arid the complexity of assessing the relative abundance distribution and scale of the species pool, we cannot refute the sampling effect, and we suggest caution in accepting ecologically oriented explanations of empirical STARs. [ABSTRACT FROM AUTHOR]

The biodiversity crisis demands that scientists be careful in their application of quantitative methods, because misuse of biodiversity statistics can lead to trivial but real patterns (artifacts) or to false patterns (artifictions). While misuses such as biases in taxonomic ratios, standardization by dividing by area or individuals, and the rarefaction effect have been repeatedly recognized in the literature, they continue to appear regularly in the scientific literature. Here, we illustrate (using data from North American floras and the Tallgrass Prairie Preserve in Oklahoma, USA) examples of how artifacts and artifictions can lead to misinterpretation of biodiversity patterns. We urge biogeographers and ecologists to be vigilant when using biodiversity statistics, to avoid false interpretations. [ABSTRACT FROM AUTHOR]

The 15,410 ha Tallgrass Prairie Preserve (Osage County, Oklahoma), managed by The Nature Conservancy, consists of a variety of grassland, forested, wetland, and disturbed habitats. 1,612 specimens of vascular plants collected between 1992 and 2007 were examined to obtain a vouchered flora of the preserve. The known flora consists of 763 species in 411 genera and 109 families. 12.1% of the species are not native to North America. [ABSTRACT FROM AUTHOR]

Despite the common geographic occurrence of inland (athalassic) saline habitats, their biota has not been extensively studied. Diatoms have been estimated to contribute as much as 25% to the earth's primary production (Werner, 1977). However, in hypersaline systems the proportion of in situ carbon fixation by diatoms is likely to be higher. We used substrate samples taken from the Salt Plains National Wildlife Refuge, an athalassic hypersaline ecosystem, to investigate the relationship between diatom genus diversity, composition and salinity. These samples range in salinity from 14 to 306 ppt and contain 21 genera. Six genera ( Cymbella, Mastogloia, Psammodictyon, Amphora, Navicula and Nitzschia) comprise 97% of the diatoms counted in all samples. Diatom genus diversity shows an inverse relationship with salinity, while genus richness shows no clear relationship with salinity. Hence, loss in diversity is the result of dominance by fewer taxa at higher salinities. The relative abundance of the genus Navicula is positively correlated with salinity, with it dominating the highest salinity sites. We used a canonical correspondence analysis (CCA) to explore the relationship between salinity and relative abundance of diatom genera. The primary variables influencing diatom genus composition at the Salt Plains were found to be the variability of salinity within a site and the overall magnitude of salinity. [ABSTRACT FROM AUTHOR]

Questions: Does distance decay exist in an old-growth neotropical forest? Is this distance decay stronger than expected due to environmental heterogeneity alone? At what spatial scales are distance decay manifested? Location: La Selva Biological Station, Costa Rica, Central America. Methods: An index of distance decay is applied appropriate for small quadrats (the probability of encountering a conspecific tree) to a grid of 11700.01-ha plots. A null model is provided that accounts for environmental heterogeneity. Results: Significant, but weak, distance decay is found. After correcting for known patterns of environmental heterogeneity, the distance decay almost disappears, except for fine spatial scales. Conclusions: These results are inconsistent with models that predict distance decay at all spatial scales. However, biological processes leading to distance decay may be more relevant and detectable at scales broader than this study. Research utilizing objectively-located samples over much broader scales is necessary to evaluate the generality and magnitude of distance decay. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Although the relationship between soil reaction and species richness is of great theoretical interest, and has been relatively well studied in temperate latitudes, the southern Great Plains of North America have not received much attention. We analyzed the relationship between species richness and measures of soil reaction (pH, cation exchange capacity, Ca) in 418 10 m x 10 m samples (with nested smaller quadrats) in the Tallgrass Prairie Preserve, Osage County, Oklahoma. We found a negative correlation of richness with soil reaction that is consistent across scales and years in grasslands, with soil calcium exhibiting the strongest relationships. The relationship in woodlands is weakly positive. The proportion of (primarily Eurasian) exotic species is positively related to calcium concentrations in both woodlands and grasslands. Although our results are not inconsistent with species pool hypotheses, critical tests of such hypotheses are operationally difficult. [ABSTRACT FROM AUTHOR]

Feeding habits and food choice of anurans found on two islands in the lower Danube floodplain were studied for two years. The five most abundant anuran species included in this study were Bombina bombina, Hyla arborea, Pelobates fuscus, Rana esculenta and R. ridibunda. In B. bombina the niche breadths of young and adults were of similar magnitude and the degree of overlap between these size classes was high. In Rana esculenta complex young individuals had a much broader trophic niche than adults. A low degree of overlap existed between young and adults, suggesting that the various size classes exploit different segments of the prey resource. Overall, species with a larger size range consumed a higher prey diversity. Prey occurrence was sampled throughout the study on a regular basis. The analysis of selectivity in feeding using Ivlev's index showed that the prey taxa that appeared to be preferred were generally rare in the environment. Detrended Correspondence Analysis revealed that the composition of anuran diets were highly overlapping but differed from the composition of the resource base. The trophic resource was highly partitioned in space and time and thus allowed the coexistence of large populations with similar diets. [ABSTRACT FROM AUTHOR]

In caricature, the equilibrium paradigm of community ecology states that plant communities are stable entities consisting of competing specks - and that such specks coexist because each has its "niche". This paradigm, in its extreme, has been dead for some time. Nevertheless, it has yet to be replaced by a credible "non" - equilibrium paradigm. The quasi-neutral concept of plant communities, proposed by Kristjan Zobel, Folia Geobot. 36: 3-8, 2001, possesses some of the key ingredients of a nonequilibrium theory of diversity. It recognizes that there are inescapable relationships between diversity at different scales, that similarity can influence the rate of competitive exclusion, that successional change is typically associated with changes in life form, and that rarefaction (i.e. "sampling artifacts") can have strong effects on fine-scale diversity. However, the current formulation of the quasi-neutral concept is incomplete in that it relies on an unrealistic definition of community, it assumes that random sampling means that specks richness at one scale will be linearly related to richness at finer scales, it ignores the possibility of fine-scale processes producing broader-scale patterns, and it avows the subject of fine-scale environmental heterogeneity. But the most serious limitation of the quasi-neutral concept is that similarity of species alone is not sufficient to allow indefinite coexistence. I present the results of a simple simulation to demonstrate that: (1) identical species will eventually be lost from communities due to stochastic "drift", (2) slight variations in reproductive rates accelerate this loss, but (3) adding a miniscule "cost of commonness" to the modal allows the indefinite coexistence of species. I conclude that the quasi-neutral model cannot work without some kind of trade-off. [ABSTRACT FROM AUTHOR]

Presents information on a study which demonstrated the utility of cross-validation of gradient analysis for uncovering the processes structuring communities. Materials and methods; Results and discussion; Conclusion.

Examines the prevalence of nonrandom distribution of trees and palms in relation to soil type and topographic position in the tropical rain forest of Costa Rica. Classification of topographic position of plots; Measurement of slope; Relationship of tree species to soil types and topographic position; Rate of tree species in the dominant soil type.

Outlines the essential features of the Canonical Correspondence Analysis (CCA) family of ordination methods. CCA as one of the most widely used gradient analysis technique in ecology; CCA algorithm's basis on the Correspondence Analysis (CA); Testing of whether CCA suffers from defects; CCA's performance with skewed species distributions.

Evaluates the scale dependence of species richness in a forest that is sampled at a series of different grains and extents. Species-area curves; Influence of grain versus extent versus number of quadrants of the degree of species-area relationship; Random expectation; Spatial variation.

Proposes standards for writing of floras or listings of all plants in a given area aimed at making floristic research widely applicable. Various definitions for `flora'; Use of floristic data; Limitations of floras; Description of proposed minimal standards; Evaluation of existing floras' conformation to criteria; Prospects for floristic research.

We provide algebraic simplifications for the redundancy analysis (RDA) eigenvalue and the canonical correspondence analysis (CCA) eigenvalue in the special case of permanent plots sampled twice. The indices for RDA and CCA are interrelated and are intuitively interpretable. These simplifications also apply to simple split-plot designs and to a balanced design with two independent samples. [ABSTRACT FROM AUTHOR]

Premise of the Study: Herb chronology, the study of belowground annual growth rings in perennial forbs, has much potential as a tool for monitoring plant growth as a function of environment. To harness this potential, understanding of the coordination between ring ontogeny, aboveground phenology, and the temporal allocation of carbon products belowground in herbaceous forbs must be improved. Methods: We investigated these relationships in two southern United States tallgrass prairie perennial forb species, Asclepias viridis and Lespedeza stuevei, making monthly excavations for a year. Key Results: Belowground xylogenesis began when starch reserves were at their seasonal low in the spring as shoots reached maximum height. The highest relative radial growth of the ring occurred concurrently with replenishment of root starch reserves in early summer. Xylogenesis concluded with leaf senescence in late summer and belowground starch reserves near saturation. Conclusions: By demonstrating that ring ontogeny is tied to early summer starch replenishment, our results illustrate the mechanisms behind previous findings where ring width was highly correlated with summer climatic conditions for these two species. This study provides a new physiological link between how ring chronologies in herbs often accord with growing‐season environment; further dissecting this phenomenon is vital in unlocking the potential of herb chronology. [ABSTRACT FROM AUTHOR]

The study of habitat selection has long been influenced by the ideal free model, which maintains that young adults settle in habitat according to its inherent quality and the density of conspecifics within it. The model has gained support in recent years from the finding that conspecifics produce cues inadvertently that help prebreeders locate good habitat. Yet abundant evidence shows that animals often fail to occupy habitats that ecologists have identified as those of highest quality, leading to the conclusion that young animals settle on breeding spaces by means not widely understood. Here, we report that a phenomenon virtually unknown in nature, natal habitat preference induction (NHPI), is a strong predictor of territory settlement in both male and female common loons (Gavia immer). NHPI causes young animals to settle on natal-like breeding spaces, but not necessarily those that maximize reproductive success. If widespread, NHPI might explain apparently maladaptive habitat settlement. [ABSTRACT FROM AUTHOR]

Fossil plants are often used to infer the paleoclimates in which they occurred by applying methods that match fossils to their nearest living relatives and, in turn, use the climatic preferences of the living species to infer paleoclimate. These methods of paleoclimatic reconstruction are termed taxon-based and are ideally accomplished using pairs of fossil and extant species. However, in practice, they are often performed using higher taxonomic ranks, such as genera, families, or even orders. The use of higher taxonomic ranks has largely unknown effects on the performance of the taxon-based methods. In this study, we tested the effects of using species, genera, families and orders on the accuracy and precision of climatic predictions from the taxon-based method known as taxonomic calibration. We performed taxonomic calibration using the extant floras of US counties and compared our predictions with the reported values for the counties. We made predictions for mean annual temperature, minimum temperature during the coldest month, average temperature during the coldest quarter, and mean annual precipitation for the US counties. We evaluated our results from taxonomic calibration for accuracy and precision using several measures of differences between reported and predicted values and r 2 , respectively. Our results showed that genera performed as well as or better than species for all climatic variables according to our measures of accuracy and precision, and families performed only slightly less well. Orders performed relatively poorly, but still showed an unexpectedly high percentage of accurate predictions for annual temperature and average temperature during the coldest month. Our results validate the use of taxonomic calibration for inferring climates using taxonomic data at the ranks of species, genus, and family and suggest that orders may be used cautiously in some cases. We discuss the applicability of our findings to studies of paleoclimates. [ABSTRACT FROM AUTHOR]

We present a data set collected in 1989 of vascular plant occurrences in overlapping grids of nested plots in the Oosting Natural Area of the Duke Forest, Orange County, North Carolina, USA. The purpose of these data is to allow the study of vascular plant biodiversity at multiple spatial scales, in terms of both grain and extent. There are eight distinct plot sizes (grains), with size four times that of the next smallest, from 0.015625 m2 to 256 m2. Larger grains are possible by aggregating adjacent plots. Extents (linear distances between plots) range from 1 m to 362 m. In addition, trees were mapped over the entire 256 m x 256 m study site in 1990, and again in 1998 to assess the effects of Hurricane Fran in September 1996. Tree species, diameters, and damage descriptors (1998 only) were also recorded. Soils were gathered from the entire grid in 1990 and analyzed for nutrients, pH, and organic matter. These data have already been used to assess scale dependence of plant diversity, to evaluate new methods for the study of spatial scale, and to study the importance of spatial scale on the interpretation of hurricane damage to forests. They are presented as a case study for future scale research. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "The Biofuels Conundrum," by Donald Kennedy in the April 27, 2007 issue.

Several letters to the editor are presented including "The Path Forward for Biofuels and Biomaterials," by A. J. Ragauskas et al., "Ethanol can Contribute to Energy and Environmental Goals," by A. E. Farrell et al., and "Getting Serious About Biofuels," by Steven E. Koonin.

Presents information on an additional feature in the April 2002 issue of 'Journal of Vegetation Science.'

Question: Does understory vegetation cover and richness decline along a gradient of increasing Juniperus virginiana midstory canopy cover and is that decline best correlated with litter accumulation? Location: Cross Timbers Forest in Payne County, OK, USA. Methods: We measured vegetation in forest gaps as well as forest areas without J. virginiana, at the inner and outer edge of J. virginiana canopies and near J. virginiana trunks (200 plots) and compared vegetation differences among location to light, litter, soil and microclimate variables. Results: Species richness (11 spp m−2 to 6 spp m−2) and summer vegetation cover (53.3% to 12.7%) declined with proximity to trunks. Regression indicated that richness declines ( R2=0.08) and cover ( R2=0.18) were best correlated with J. virginiana litter accumulation. Partial canonical correspondence analysis (pCCA) revealed two strong canonical axes, one related to litter/light and another to cover of Quercus spp. versus J. virginiana. Tree seedlings and woody vines dominated near J. virginiana. Forbs, graminoids and Quercus spp. seedlings were more common in areas without J. virginiana. Conclusions: Increasing J. virginiana and consequent litter additions alter understory biomass and composition and, through inhibiting Quercus spp. recruitment, may lead to changes in overstory composition. Decreases in herbaceous litter, which historically contributed to fuel accumulation, may have positive feedback effects on midstory encroachment by reducing the potential for prescribed burning. [ABSTRACT FROM AUTHOR]

Past studies on changes in species distribution have mainly been based on analysis of range boundaries. In contrast, the method used here evaluates shifts in species' geographic centroids within a predefined area. We used presence/absence data on epiphytic lichens collected 1986 and 2003 from 64 sites in southern Sweden. A centroid was calculated each year, for each lichen species and substrate. The distance of centroid movement was evaluated in a permutation procedure. In total, 56 lichen species on 22 tree species were involved in the analyses, yielding 30 cases that had sufficient sample sizes both years to be evaluated. Out of these, three exhibited a significant movement of their centroid. The shift of lichen centroids of Hypogymnia physodes (L.) Nyl. and Vulpicida pinastri (Scop.) J.-E. Mattsson & M. J. Lai on the tree species Juniperus communis L. was 50 and 151 km with the direction 27° and 48°, respectively. For Hypogymnia physodes on Pinus sylvestris L., corresponding values were 41 km and 30°. The northnortheast shifts of these species in Sweden could be a response to a warming climate. [ABSTRACT FROM AUTHOR]

The species-area relationship (SAR), describing the increase in species richness with increasing area, and the latitudinal diversity gradient (LDG), describing the decrease in species richness with increasing latitude, are the oldest and most robust patterns in biogeography, yet connections between them remain poorly understood. Here, using 1,742 floras covering the entirety of North America north of Mexico (NAM) and including all of NAM's native species of vascular plants, we show that the slope of the SAR consistently decreases with increasing latitude. This trend is general and holds for subsets of the floras in eastern and western NAM. The southernmost latitudinal quarter of NAM exhibits SARs more than twice as steep as those of the northernmost quarter for both eastern and western regions. This decrease in SAR slope with increasing latitude is consistent with the environmental texture hypothesis and Rapoport's rule, and it suggests that more detailed studies of species endemism in relation to environmental and historical factors will yield significant insights into the underlying causes of SAR and LDG patterns. [ABSTRACT FROM AUTHOR]

Maize samples were obtained at two depths [0–30 cm (top sample) and 30–60 cm (bottom sample) from the maize surface] at 19–28 locations from a naturally infested maize storage facility in Wisconsin, USA. Based on identification of insects in stored-maize samples from 13 weekly sampling events, four topics were addressed: (i) the seasonal fluctuation in the insect community; (ii) ordination analysis was conducted to examine the association among insect taxa and to determine their distribution along abiotic and geographic gradients; (iii) the demographic characteristics of insect communities in maize samples with high abundance of either Plodia interpunctella ( Plodia samples) or Sitophilus zeamais ( Sitophilus samples); and (iv) to what extent natural enemies were spatially associated with their prey species. We identified a total of 18 different taxa, composed of adults and larvae of 14 determined species, and others identified to genus, family or order. Insect density was significantly higher in top samples compared to bottom samples, and the insect taxa occurred more frequently in top samples compared to bottom samples. In the ordination analysis, the three explanatory variables accounting for eastern, northern and vertical position of maize samples explained the largest part of the total variance. There was a gradual time trend with some of the insect species mainly occurring early or late in the monitoring period. Moisture content of the maize was the weakest of the significant explanatory variables, while temperature in the grain mass did not explain a significant part of the total variance. Plodia samples and Sitophilus samples had significantly different spatial distribution patterns and had markedly different insect species composition. Plodia samples were characterized by low abundance of all granivores and fungivores, except P. interpunctella. Conversely, Sitophilus samples had high abundance of T. castaneum, A. advena, and C. ferrugineus. Consequently, Sitophilus samples seemed to comprise more diverse insect communities than Plodia samples. Natural enemies were not significantly associated with their most common hosts. In a highly homogeneous habitat (stored maize), we demonstrated that stored-product insect species had significantly different distribution patterns mainly along geographic gradients. Stochasticity of the initial infestation process or interspecific competition are two of the possible explanations for the spatial segregation of stored-product insects, and the spatial segregation of insects on the same trophic level may have profound implications for the understanding of how these ecosystems develop over time and thereby how integrated pest management strategies are implemented to control insect pest populations. [ABSTRACT FROM AUTHOR]

We studied trophic resource use and availability in three populations of the common frog (Rana temporaria): one from the subarctic (Kilpisjärvi, Finland), and two (alpine and low-altitude valley populations) from the Retezat Mountains (Southern Carpathians, Romania). We used stomach flushing to sample consumed prey, and estimated prey availability using pitfall traps and netting. In addition, we analyzed the geographical pattern of feeding based on published records covering the entire range of the species. Feeding intensity varied, both spatially and according to frog size. Adults consumed prey of higher richness and more prey items than juveniles. There was latitudinal variation in prey consumption, with populations from extreme habitats (alpine and arctic) having the highest prey richness. This high feeding plasticity partly explains why Rana temporaria is widespread and reaches high altitudes and latitudes in Europe. [ABSTRACT FROM AUTHOR]

Recently, methods for constructing Spatially Explicit Rarefaction (SER) curves have been introduced in the scientific literature to describe the relation between the recorded species richness and sampling effort and taking into account for the spatial autocorrelation in the data. Despite these methodological advances, the use of SERs has not become routine and ecologists continue to use rarefaction methods that are not spatially explicit. Using two study cases from Italian vegetation surveys, we demonstrate that classic rarefaction methods that do not account for spatial structure can produce inaccurate results. Furthermore, our goal in this paper is to demonstrate how SERs can overcome the problem of spatial autocorrelation in the analysis of plant or animal communities. Our analyses demonstrate that using a spatially-explicit method for constructing rarefaction curves can substantially alter estimates of relative species richness. For both analyzed data sets, we found that the rank ordering of standardized species richness estimates was reversed between the two methods. We strongly advise the use of Spatially Explicit Rarefaction methods when analyzing biodiversity: the inclusion of spatial autocorrelation into rarefaction analyses can substantially alter conclusions and change the way we might prioritize or manage nature reserves. [ABSTRACT FROM AUTHOR]

Questions While mowing is a viable management tool for the maintenance of diversity in grasslands, the suitability of mowing in grasslands with invasion by exotic plants is poorly understood. In this 18-yr study, we investigate the effects of long-term mowing on a tallgrass prairie community invaded by exotic yellow bluestem ( Bothriochloa ischaemum; BOIS). We explore the influence of BOIS on species richness and composition in the face of different mowing treatments as well as monitoring any post-treatment legacy effects. Location Northeast central Oklahoma, US. Methods A total of 144 permanent plots were laid out comprising eight treatments (i.e. all combinations of Mar, Jun and Sept, mows resulting in three single mows, three double mows, one triple mow and an un-mowed control). Plots were mowed 1996-2011 and recovery was monitored through 2014. Repeated mixed model ANOVA, PERMANOVA and principal response curves were employed to analyse species richness and compositional changes from mowing. Correlation was used to explore the effects of BOIS on species richness. Results Mowing resulted in higher species richness relative to the absence of mowing, with the highest levels being sustained in the late season mown plots throughout the study. Once mowing had ceased, early season mown plots declined in species richness down to the same levels as the un-mown plots, concomitant with the sharpest increased cover of BOIS in these plots relative to all other treatments. Overall, we found a strong negative correlation between BOIS cover and species richness. Species dissimilarity was highest between any plot that was mowed and the un-mown controls, as well as between March and September only treatments. Conclusions Our study highlights the potential of mowing in maintaining high species richness. However, the positive response to early season mowing of the exotic yellow bluestem and ensuing negative effect on species richness suggests that BOIS can confound the favourable effects of mowing. We found only minor post-treatment legacy effects, since BOIS strongly re-established in the absence of mowing in all previously mown plots, especially the early season mown plots. Thus, we recommend sustained late season mowing to help control the spread of BOIS and maintain species-rich grasslands. [ABSTRACT FROM AUTHOR]

Question How does the interaction between silicon ( Si) and vegetation affect local and global ecological processes, higher levels of ecological organization, and terrestrial- and watershed-scale Si fluxes? Location We selected several ecosystems throughout the world, from river headwaters to estuaries, being examples of (i) terrestrial vegetation, (ii) aquatic and floodplain vegetation, and (iii) tidal wetland vegetation. Methods We provide examples of the importance of linking Si use by terrestrial and aquatic vegetation, to larger-scale Si flux consequences towards and through rivers. Cross-disciplinary studies achieve the best understanding of vegetation effects on the global Si cycle, and the role of Si as a plant functional trait. Conclusion Si use by plants has not always received the research attention of other elements. Yet, today the importance of Si for plant functioning is slowly becoming better understood. Silicon is a crucial element for many plant species, being important for decomposition processes, plant competitiveness and stress tolerance. The inclusion by vegetation scientists of Si uptake as a plant functional trait is important to assess links between plant physiology, plant distribution and plant tolerance to environmental changes, but also to understand the role of vegetation on Si fluxes through the watershed. However, lack of knowledge regarding the biological control of the Si cycle hinders accurate quantification. Only a concerted effort bringing scientists together from a broad array of disciplines will provide this new direction for research on vegetation- Si cycling. [ABSTRACT FROM AUTHOR]

Abstract: Upland oak forests in the ecotone between the eastern deciduous forest and the southern Great Plains are threatened by encroachment of eastern redcedar (Juniperus virginiana) due to fire suppression. The rapid rate of encroachment caused concern about concomitant alterations of site characteristics including nutrient cycling and the soil microbial communities (SMC) that could lead to positive feedbacks reinforcing eastern redcedar encroachment. We studied eight upland oak forests across central and western Oklahoma with stands representing three levels of encroachment: oak-dominated, eastern redcedar-dominated, and an intermediate mixture of both species. We analyzed litter chemistry (carbon, lignin, and nitrogen), soil chemistry (soil organic matter, NH4N, NO3-N, PO4, K, and pH), and profiled soil microbial communities using phospholipid fatty acid analysis (PLFA). Eastern redcedar encroachment was accompanied by reduced litter carbon along with higher levels of arbuscular mycorrhizal (AM) fungi while litter N was lower in mixed stands. However, we detected no change in soil chemistry. Our results indicate eastern redcedar encroachment in these upland oak forests reduced litter quality and altered the SMC through increases in AM fungi, a symbiont associated with eastern redcedar. These alterations may create positive soil–microbial feedbacks by reducing the fitness of the dominant oak species and facilitating rapid increase in eastern redcedar in this threatened, oak-dominated ecosystem. [Copyright &y& Elsevier]

Abstract: Viruses are most frequently discovered because they cause disease. To expand knowledge of plant-associated viruses beyond these narrow constraints, non-cultivated plants of the Tallgrass Prairie of the United States were systematically surveyed for evidence of viruses. This report discusses putative viruses of the family Secoviridae identified by the survey. Sequence analysis suggests the presence of at least six viruses in the study site, including Bean pod mottle virus, Maize chlorotic dwarf virus, three previously undescribed viruses within the subfamily Comovirinae and one unclassifiable virus. [Copyright &y& Elsevier]

Native virus-plant interactions require more understanding and their study will provide a basis from which to identify potential sources of emerging destructive viruses in crops. A novel tymovirus sequence was detected in Asclepias viridis (green milkweed), a perennial growing in a natural setting in the Tallgrass Prairie Preserve (TGPP) of Oklahoma. It was abundant within and frequent among A. viridis plants and, to varying extents, within other dicotyledonous and one grass (Panicum virgatum) species obtained from the TGPP. Extracts from A. viridis containing the sequence were infectious to a limited number of species. The virus genome was cloned and determined to be closely related to Kennedya yellow mosaic virus. The persistence of the virus within the Oklahoma A. viridis population was monitored for five successive years. Virus was present in a high percentage of plants within representative areas of the TGPP in all years and was spreading to additional plants. Virus was present in regions adjacent to the TGPP but not in plants sampled from central and south-central Oklahoma. Virus was present in the underground caudex of the plant during the winter, suggesting overwintering in this tissue. The RNA sequence encoding the virus coat protein varied considerably between individual plants (≈3%), likely due to drift rather than selection. An infectious clone was constructed and the virus was named Asclepius asymptomatic virus (AsAV) due to the absence of obvious symptoms on A. viridis. [ABSTRACT FROM AUTHOR]

The Fostering African American Improvement in Total Health! (FAITH!) Nutrition Education Program is a theory-based, multicomponent health intervention developed and operated in partnership with an East Baltimore church. The program aims to improve eating habits, as well as knowledge and beliefs about healthy eating, among African American adults in order to prevent diseases related to dietary choices. This article addresses the development, design, and formative research that informed the FAITH! program. The main program components are also discussed. Program design used a framework for strategic intervention planning (PRECEDE-PROCEED), and health education theories informed the evaluation process. Formative research was conducted to incorporate the needs and assets of the priority population. The main program components are culturally tailored educational materials, lectures and discussions on diet and related diseases, video presentations on healthy eating, healthy cooking demonstrations/food samples, evaluation, and a church-run healthy food pantry. [ABSTRACT FROM AUTHOR]

Abstract: Viruses are most frequently discovered because they cause disease in organisms of importance to humans. To expand knowledge of plant-associated viruses beyond these narrow constraints, non-cultivated plants of the Tallgrass Prairie Preserve, Osage County, Oklahoma, USA were systematically surveyed for evidence of the presence of viruses. This report discusses viruses of the family Tombusviridae putatively identified by the survey. Evidence of two carmoviruses, a tombusvirus, a panicovirus and an unclassifiable tombusvirid was found. The complete genome sequence was obtained for putative TGP carmovirus 1 from the legume Lespedeza procumbens, and the virus was detected in several other plant species including the fern Pellaea atropurpurea. Phylogenetic analysis of the sequence and partial sequence of a related virus supported strongly the placement of these viruses in the genus Carmovirus. Polymorphisms in the sequences suggested existence of two populations of TGP carmovirus 1 in the study area and year-to-year variations in infection by TGP carmovirus 3. [Copyright &y& Elsevier]

Abstract: This study investigates stable carbon isotopes (δ 13C), opal phytolith assemblages, burnt phytoliths, microscopic charcoal and Sporormiella spores from modern soils and paleosols in Kansas and Oklahoma. Grass and dicot phytoliths in combination with δ 13C are used as proxies for reconstructing the structure of grasslands and woodlands. Burnt grass phytoliths and microscopic charcoal are evaluated as proxies for reconstructing paleofire incidence. Concentrations of the fungal spore Sporormiella are used as a proxy for assessing large herbivore activity. These proxies were tested on various modern grassland communities of the central and southern Great Plains, including areas with bison, cattle, and small herbivores, and areas under different fire frequencies. Opal phytolith assemblages and δ 13C values show that before cal 11ka, C3 grasses and woody plants predominated in areas that today are dominated by C4 grasses. The origin of the shortgrass prairie dates back to about cal 10ka. The origin of the tallgrass prairie, however, is not clear as phytolith data show variable assemblages throughout the Holocene (mixed-grass, tallgrass, and tallgrass–woodland mosaic). Different proxies (burnt phytoliths vs. charcoal) reveal different fire frequencies, but it is apparent that microfossil evidence for fire incidence is closely related to the abundance of woody plants in the landscape. Before cal 12ka, soils show somewhat elevated concentration of Sporormiella, but lower concentrations than the modern high-density bison and cattle grazing areas. Throughout the Holocene, Sporormiella frequencies are low, which suggests lower large ungulate densities and perhaps high mobility. [Copyright &y& Elsevier]

Questions: (1) How have the composition and structure of undisturbed upland Quercus forests changed over 50 years across a large region and moisture gradient; (2) What factors are associated with long-term and broad-scale changes in these forests? Location: Oklahoma, USA. Methods: We re-sampled 30 forest stands originally sampled in the 1950s across a large geographical area and compared basal area, tree density, and sapling density between the sampling periods using paired t-tests, CCA, and DCA. We examined vegetation dynamics in the context of drought indices compiled for the sample period. Results: Total and Quercus stellata basal area and tree density increased, but Q. stellata and Q. marilandica sapling density decreased. Juniperus virginiana and woody species richness increased for all measures. DCA indicated that re-sampled stands generally changed from Q. stellata-Q. marilandica-dominated forests to forests with greater woody species richness and more J. virginiana. Q. stellata remained a dominant tree species; otherwise, composition shifted towards mesophytic and invasive woody species. Measurements taken in the 1950s immediately followed a major drought; whereas subsequent decades were significantly moister. Conclusions: Fire exclusion and drought may have played an important role in driving changes towards lower dominance by Quercus, increased importance of mesophytic and invasive species, and greater woody species richness. These phenomena are similar to those found in Quercus-dominated forests throughout the northern hemisphere. [ABSTRACT FROM AUTHOR]