Does organic grassland farming benefit plant and arthropod diversity at the expense of yield and soil fertility?

Organic management is one of the most popular strategies to reduce negative environmental impacts of intensive agriculture. However, little is known about benefits for biodiversity and potential worsening of yield under organic grasslands management across different grassland types, i.e. meadow, pasture and mown pasture. Therefore, we studied the diversity of vascular plants and foliage-living arthropods (Coleoptera, Araneae, Heteroptera, Auchenorrhyncha), yield, fodder quality, soil phosphorus concentrations and land-use intensity of organic and conventional grasslands across three study regions in Germany. Furthermore, all variables were related to the time since conversion to organic management in order to assess temporal developments reaching up to 18 years. Arthropod diversity was significantly higher under organic than conventional management, although this was not the case for Araneae, Heteroptera and Auchenorrhyncha when analyzed separately. On the contrary, arthropod abundance, vascular plant diversity and also yield and fodder quality did not considerably differ between organic and conventional grasslands. Analyses did not reveal differences in the effect of organic management among grassland types. None of the recorded abiotic and biotic parameters showed a significant trend with time since transition to organic management, except soil organic phosphorus concentrations which decreased with time. This implies that permanent grasslands respond slower and probably weaker to organic management than crop fields do. However, as land-use intensity and inorganic soil phosphorus concentrations were significantly lower in organic grasslands, overcoming seed and dispersal limitation by re-introducing plant species might be needed to exploit the full ecological potential of organic grassland management. We conclude that although organic management did not automatically increase the diversity of all studied taxa, it is a reasonable and useful way to support agro-biodiversity.

Concise Synthesis of Pyrrolidine and Indolizidine Alkaloids by a Highly Convergent Three-Component Reaction

The synthesis of pyrrolidine and indolizidine derivatives through radical carboazidation of alkenes with alpha-iodoketones, followed by reductive amination, is described. When properly substituted, further lactamization afforded pyrrolizidinones in good yield. This carboazidation/reductive amination sequence was efficiently applied to the total synthesis of three different simple alkaloids, including (+/-)-monomorine I.

Spatial isolation and genetic differentiation in naturally fragmented plant populations of the Swiss Alps

Aims The effect Of anthropogenic landscape fragmentation on the genetic diversity and adaptive potential of plant populations is a major issue in conservation biology. However, little is known about the partitioning of genetic diversity in alpine species, which occur in naturally fragmented habitats. Here, we, investigate molecular patterns of three alpine plants (Epilobium fleischeri, Geum reptans and Campanula thyrsoides) across Switzerland and ask whether Spatial isolation has led to high levels of populations differentiation, increasing over distance, and a decrease of within-population variability. We further hypothesize that file contrasting potential for long-distance dispersal (LDD) of Seed in these Species will considerably influence and explain diversity partitioning. Methods For each study species, we Sampled 20-23 individuals from each of 20-32 populations across entire Switzerland. We applied Random Amplified Polymorphic Dimorphism markers to assess genetic diversity within (Nei's expected heterozygosity, H-e; percentage of polymorphic hands, P-P) and among (analysis of molecular variance, Phi(st)) populations and correlated population size and altitude with within-populalion diversity. Spatial patterns of genetic relatedness were investigated using Mantel tests and standardized major axis regression as well as unweighted pair group method with arithmetic mean cluster analyses and Monmonier's algorithm. To avoid known biases, We standardized the numbers of populations, individuals and markers using multiple random reductions. We modelled LDD with a high alpine wind data set using the terminal velocity and height of seed release as key parameters. Additionally, we assessed a number of important life-history traits and factors that potentially influence genetic diversity partitioning (e.g. breeding system, longevity and population size). Important findings For all three species, We found a significant isolation-by-distance relationship but only a moderately high differentiation among populations (Phi(st): 22.7, 48 and 16.8%, for E. fleischeri, G. reptans and C. thyrsoides, respectively). Within-population diversity (H-c: 0.19-0.21, P-p: 62-75%) was not reduced in comparison to known results from lowland species and even small populations with < 50 reproductive individuals contained high levels of genetic diversity. We further found no indication that a high long-distance seed dispersal potential enhances genetic connectivity among populations. Gene flow seems to have a strong stochastic component causing large dissimilarity between population pairs irrespective of the spatial distance. Our results suggest that other life-history traits, especially the breeding System, may play an important role in genetic diversity partitioning. We conclude that spatial isolation in the alpine environment has a strong influence on population relatedness but that a number of factors can considerably influence the strength of this relationship.

Altered expression of the PTR/NRT1 homologue OsPTR9 affects nitrogen utilization efficiency, growth and grain yield in rice

The plant PTR/NRT1 (peptide transporter/nitrate transporter 1) gene family comprises di/tripeptide and low-affinity nitrate transporters; some members also recognize other substrates such as carboxylates, phytohormones (auxin and abscisic acid), or defence compounds (glucosinolates). Little is known about the members of this gene family in rice (Oryza sativa L.). Here, we report the influence of altered OsPTR9 expression on nitrogen utilization efficiency, growth, and grain yield. OsPTR9 expression is regulated by exogenous nitrogen and by the day-night cycle. Elevated expression of OsPTR9 in transgenic rice plants resulted in enhanced ammonium uptake, promotion of lateral root formation and increased grain yield. On the other hand, down-regulation of OsPTR9 in a T-DNA insertion line (osptr9) and in OsPTR9-RNAi rice plants had the opposite effect. These results suggest that OsPTR9 might hold potential for improving nitrogen utilization efficiency and grain yield in rice breeding.

On the evolution of the oceanic component of the IPSL climate models from CMIP3 to CMIP5: A mean state comparison

This study analyses the impact on the oceanic mean state of the evolution of the oceanic component (NEMO) of the climate model developed at Institut Pierre Simon Laplace (IPSL-CM), from the version IPSL-CM4, used for third phase of the Coupled Model Intercomparison Project (CMIP3), to IPSL-CM5A, used for CMIP5. Several modifications have been implemented between these two versions, in particular an interactive coupling with a biogeochemical module, a 3-band model for the penetration of the solar radiation, partial steps at the bottom of the ocean and a set of physical parameterisations to improve the representation of the impact of turbulent and tidal mixing. A set of forced and coupled experiments is used to single out the effect of each of these modifications and more generally the evolution of the oceanic component on the IPSL coupled models family. Major improvements are located in the Southern Ocean, where physical parameterisations such as partial steps and tidal mixing reinforce the barotropic transport of water mass, in particular in the Antarctic Circumpolar Current) and ensure a better representation of Antarctic bottom water masses. However, our analysis highlights that modifications, which substantially improve ocean dynamics in forced configuration, can yield or amplify biases in coupled configuration. In particular, the activation of radiative biophysical coupling between biogeochemical cycle and ocean dynamics results in a cooling of the ocean mean state. This illustrates the difficulty to improve and tune coupled climate models, given the large number of degrees of freedom and the potential compensating effects masking some biases.

Early responses of wild plant seedlings to arbuscular mycorrhizal fungi and pathogens

Abstract Many plants form associations with arbuscular mycorrhizal fungi (AMF) because they profit from improved phosphorus nutrition and from protection against pathogens. Whereas mycorrhiza-induced pathogen protection is well understood in agricultural plant species, it is rarely studied in wild plants. As many pathogens infest plants in the first days after germination, mycorrhiza-induced pathogen protection may be especially important in the first few weeks of plant establishment. Here, we investigated interacting effects of {AMF} and the seedling pathogen Pythium ultimum on the performance of six- to seven-week-old seedlings of six wild plant species of the family Asteraceae in a full factorial experiment. Plant species differed in their response to AMF, the pathogen and their interactions. {AMF} increased and the pathogen decreased plant biomass in one and three species, respectively. Two plant species were negatively affected by {AMF} in the absence, but positively or not affected in the presence of the pathogen, indicating protection by AMF. This mycorrhiza-induced pathogen protection is especially surprising as we could not detect mycorrhizal structure in the roots of any of the plants. Our results show that even seedlings without established intraradical hyphal network can profit from AMF, both in terms of growth promotion in the absence of a pathogen and pathogen protection. The function of {AMF} is highly species-specific, but tends to be similar for more closely related plant species, suggesting a phylogenetic component of mycorrhizal function. Further studies should test a wider range of plant species, as our study was restricted to one plant family, and investigate whether plants profit from early mycorrhizal benefits in the long term.

Geographic variation in floral allometry suggests repeated transitions between selfing and outcrossing in a mixed mating plant

• Premise of the study: Isometric and allometric scaling of a conserved floral plan could provide a parsimonious mechanism for rapid and reversible transitions between breeding systems. This scaling may occur during transitions between predominant autogamy and xenogamy, contributing to the maintenance of a stable mixed mating system. • Methods: We compared nine disjunct populations of the polytypic, mixed mating species Oenothera flava (Onagraceae) to two parapatric relatives, the obligately xenogamous species O. acutissima and the mixed mating species O. triloba. We compared floral morphology of all taxa using principal component analysis (PCA) and developmental trajectories of floral organs using ANCOVA homogeneity of slopes. • Key results: The PCA revealed both isometric and allometric scaling of a conserved floral plan. Three principal components (PCs) explained 92.5% of the variation in the three species. PC1 predominantly loaded on measures of floral size and accounts for 36% of the variation. PC2 accounted for 35% of the variation, predominantly in traits that influence pollinator handling. PC3 accounted for 22% of the variation, primarily in anther–stigma distance (herkogamy). During O. flava subsp. taraxacoides development, style elongation was accelerated relative to anthers, resulting in positive herkogamy. During O. flava subsp. flava development, style elongation was decelerated, resulting in zero or negative herkogamy. Of the two populations with intermediate morphology, style elongation was accelerated in one population and decelerated in the other. • Conclusions: Isometric and allometric scaling of floral organs in North American Oenothera section Lavauxia drive variation in breeding system. Multiple developmental paths to intermediate phenotypes support the likelihood of multiple mating system transitions.

Using plant functional traits and phylogenies to understand patterns of plant community assembly in a seasonal tropical forest in Lao PDR

Plant functional traits reflect different evolutionary responses to environmental variation, and among extant species determine the outcomes of interactions between plants and their environment, including other plant species. Thus, combining phylogenetic and trait-based information can be a powerful approach for understanding community assembly processes across a range of spatial scales. We used this approach to investigate tree community composition at Phou Khao Khouay National Park (18°14’-18°32’N; 102°38’- 102°59’E), Laos, where several distinct forest types occur in close proximity. The aim of our study was to examine patterns of plant community assembly across the strong environmental gradients evident at our site. We hypothesized that differences in tree community composition were being driven by an underlying gradient in soil conditions. Thus, we predicted that environmental filtering would predominate at the site and that the filtering would be strongest on sandier soil with low pH, as these are the conditions least favorable to plant growth. We surveyed eleven 0.25 ha (50x50 m) plots for all trees above 10 cm dbh (1221 individual trees, including 47 families, 70 genera and 123 species) and sampled soils in each plot. For each species in the community, we measured 11 commonly studied plant functional traits covering both the leaf and wood economic spectrum traits and we reconstructed a phylogenetic tree for 115 of the species in the community using rbcL and matK sequences downloaded from Genebank (other species were not available). Finally we compared the distribution of trait values and species at two scales (among plots and 10x10m subplots) to examine trait and phylogenetic community structures. Although there was strong evidence that an underlying soil gradient was determining patterns of species composition at the site, our results did not support the hypothesis that the environmental filtering dominated community assembly processes. For the measured plant functional traits there was no consistent pattern of trait dispersion across the site, either when traits were considered individually or when combined in a multivariate analysis. However, there was a significant correlation between the degree of phylogenetic dispersion and the first principle component axis (PCA1) for the soil parameters.Moreover, the more phylogenetically clustered plots were on sandier soils with lower pH. Hence, we suggest that the community assembly processes across our sitemay reflect the influence ofmore conserved traits that we did not measure. Nevertheless, our results are equivocal and other interpretations are possible. Our study illustrates some difficulties in combining trait and phylogenetic approaches that may result from the complexities of integrating spatial and evolutionary processes that vary at different scales.

Simple measures of climate, soil properties and plant traits predict national-scale grassland soil carbon stocks

Soil carbon (C) storage is a key ecosystem service. Soil C stocks play a vital role in soil fertility and climate regulation, but the factors that control these stocks at regional and national scales are unknown, particularly when their composition and stability are considered. As a result, their mapping relies on either unreliable proxy measures or laborious direct measurements. Using data from an extensive national survey of English grasslands, we show that surface soil (0–7 cm) C stocks in size fractions of varying stability can be predicted at both regional and national scales from plant traits and simple measures of soil and climatic conditions. Soil C stocks in the largest pool, of intermediate particle size (50–250 μm), were best explained by mean annual temperature (MAT), soil pH and soil moisture content. The second largest C pool, highly stable physically and biochemically protected particles (0·45–50 μm), was explained by soil pH and the community abundance-weighted mean (CWM) leaf nitrogen (N) content, with the highest soil C stocks under N-rich vegetation. The C stock in the small active fraction (250–4000 μm) was explained by a wide range of variables: MAT, mean annual precipitation, mean growing season length, soil pH and CWM specific leaf area; stocks were higher under vegetation with thick and/or dense leaves. Testing the models describing these fractions against data from an independent English region indicated moderately strong correlation between predicted and actual values and no systematic bias, with the exception of the active fraction, for which predictions were inaccurate. Synthesis and applications. Validation indicates that readily available climate, soils and plant survey data can be effective in making local- to landscape-scale (1–100 000 km2) soil C stock predictions. Such predictions are a crucial component of effective management strategies to protect C stocks and enhance soil C sequestration.

Search for Low-Molecular-Weight Biomarkers in Plant Tissues and Seeds Using Metabolomics: Tools, Strategies, and Applications

This chapter summarises the metabolomic strategies currently in force used in plant science and describes the methods used. The metabolite profiling and fingerprinting of plant tissues through MS- and/or NMR-based approaches and the subsequent identification of biomarkers is detailed. Strategies for the microisolation and de novo identification of unknown biomarkers are also discussed. The various approaches are illustrated by a metabolomic study of the maize response to herbivory. A review of recent metabolomic studies performed on seed and crop plant tissues involving various analytical strategies is provided.

Plant species decline due to abandonment of meadows cannot easily be reversed by mowing. A case study from the southern Alps

Abstract. We resumed mowing in two plots of ca. 100 m2 in an abandoned meadow dominated by Brachypodium pinnatum on the slope of Monte Generoso (Switzerland). We monitored species composition and hay yield using point quadrats and biomass samples. Species frequencies changed little during 10 yr (1988–1997) while hay yields showed large fluctuations according to mean relative humidity in April-June. We performed a seed-addition experiment to test whether the establishment of meadow species is limited by lack of diaspores or favourable microsites for germination and recruitment from the seed bank. We sowed ca. 12 000 seeds of 12 species originating from a nearby meadow individually in plots of a 4 × 6 unbalanced Latin square with four treatments, burning, mowing, mowing and removal of a layer of decayed organic matter, and a control. We monitored the fate of seedling individuals for 24 months. Seedlings of all species were established and survived for 12 months, 10 species survived during at least 24 months, some reached a reproductive stage. Species responded to different qualities of microsites provided by the different treatments thus required different regeneration niches. Spontaneous long-distance immigration was insignificant. We conclude that the former species composition of abandoned meadows cannot easily be restored by mowing alone because many plant species of meadows do not have persistent seed banks and immigration over distances of more than 25 m and successful establishment is very unlikely.