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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.

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]

A response by the authors to a letter to the editor about their article on the ecological advantage of low-input high-diversity biofuels over many alternative biofuel systems is presented.

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.

The article speculates whether low-input high diversity (LIHD) biofuels could lead the way for the creation of a sustainable system. It is explained how LIHD cultivation of biofuel feedstocks can become an alternative to high-input low-diversity (HILD) agricultural systems. The benefits of LIHD which include large reductions in agrichemical inputs, soil tillage, and water demand; and conservation and maintenance of ecosystem services, is highlighted.

We studied the effects of windthrow on the understory plant species composition of a pine forest (dominated by Pinus strobus) and an oak forest (dominated by Quercus ellipsoidalis). We recorded the presenceof vascular plant species in randomly located quadrats in the two forests, and in three microsite types associated with tipup mounds (pit, old soil and new soil) in the pine forest at irregular intervals over the course of 14 years. The understories of the two forests remained distinct throughout the study. The frequency of occurrence of a number of forest floor species considerably increased; few species decreased. The disturbance specialists Rubus idaeus and Polygonum cilinode increased in frequency throughout the study in the pine forest, butare beginning to decline in the less disturbed oak forest. Annuals and biennials preferentially colonized the disturbed soil of microsites on tipups, and declined in frequency after about 7 yr. Both forestshave increased in understory species richness, but have not changed substantially in the distribution of growth forms. Despite early differences in species composition, microsite types associated with tipupmounds became more similar through time. Although small in magnitude, there was a directional change in understory composition at both forests, with no apparent sign of a return to pre-disturbance conditions. [ABSTRACT FROM AUTHOR]

We measured tree damage and mortality following a catastrophic windthrow in permanent plots in an oak forest and a pine forest in centralMinnesota. We monitored changes in forest structure and composition over the next fourteen years. Prior to the storm, the oak forest was dominated by Quercus ellipsoidalis, and the pine forest by Pinus strobus. The immediate impacts of the storm were to differentially damageand kill large, early-successional hardwoods and pines. Subsequent recovery was characterized by the growth of late-successional hardwoods. In both forests the disturbance acted to accelerate succession. Ordination of tree species composition confirmed the trend of accelerated succession, and suggested a convergence of composition between thetwo forests. [ABSTRACT FROM AUTHOR]

The study of vegetation dynamics in tallgrass prairie in response tofire has focused on dormant season fire in late successional prairies. Our objective was to determine if late season fire of varying frequency results in divergent successional patterns in an early successional tallgrass prairie disturbed by grazing and cultivation. Specifically, we evaluated the influence of late-summer fires of varying frequency on community composition and species richness. We collected vegetation and environmental data on two sites burned in the late growing-season at varying frequencies. These communities differed in composition depending primarily on edaphic factors, time since the last burn, and year-to-year variation. We interpret the time effect as related to changes in species composition accompanying plant succession that followed disturbance either from cropping and heavy grazing on the loamy site or heavy grazing on the shallow site. Other unidentified factors also have a role in vegetation dynamics on this prairie. Community composition and species richness were not consistently responsive to frequency of growing-season fires. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

The article provides insight on the importance of a sustainable system for biofuel production. It provides an overview on the sustainability issues faced by cellulosic biofuels industry and hobble grain-based biofuels. It cites that although cellulosic biofuels have many positive impact in social and environmental sector, the realization of its benefit still depends on which, where, and how cellulosic biofuels are produced. It discusses several factors that are needed to be considered in the cellulosic biofuels production including marginal lands, crop choices, and harvesting strategy. Furthermore, it points out the importance of implementing a science-based policy and comprehensive and collaborative research agenda in order to establish a sustainable biofuel production systems.

In this study, we describe Metriocnemus erythranthei sp. nov. and Limnophyes viribus sp. nov., leafminers of herbaceous wetland plants. The M. erythranthei larva is a true miner entering fresh leaves and excavating the tunnels, and the L. viribus larva inhabits vacated mines of M. erythranthei. M. erythranthei is widespread in North America, with collections from the Pacific coast to Pennsylvania, and L. viribus has been collected from Iowa and Oregon. We also describe the larva of a possible new species associated with these plants, which we refer to as Metriocnemus sp. "Oregon". A key to the known larval stages of North American Metriocnemus is also provided. Along with providing a detailed account of the mining ecology of these new species, we discuss additional observations of mostly Orthocladiinae midges associated with aquatic and terrestrial plants. These include documenting the rearing of Metriocnemus eurynotus (Holmgren, 1883) from larvae feeding on Impatiens (Balsaminaceae) cotyledons, initially as leafminers and later externally. Larvae of M. eurynotus also were found feeding within mines of M. erythranthei on Veronica (Plantaginaceae) and were collected along with M. erythranthei larvae on leaves of Petasites (Asteraceae).

The Plant Virus Biodiversity and Ecology project was undertaken to better understand the nature of plant-viral interactions and the occurrence of non-pathogenic viruses. Plants from the Tallgrass Prairie Preserve (TPP), Osage County, Oklahoma, were surveyed from 2005 to 2008 for the presence of viruses, resulting in the detection, using a virus-like particle enrichment method, of the genome a novel virus, Ambrosia asymptomatic virus 1 (AAV1), from Ambrosia psilostachya DC (western ragweed). Here, we present the genomic organization and genetic variability of AAV1. The virus has a single-stranded RNA genome of about 7408 nt, which has six open reading frames (ORFs). Phylogenetic analysis of the replicase and coat protein ORFs of the virus indicates strongly that the virus should be placed in the genus Mandarivirus. No evidence of recombination was detected. We also report the detection in the TPP of two known viruses and seven other putative viruses, members of the order Tymovirales.

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.