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Communities of arbuscular mycorrhizal (AM) fungi in Mongolian grassland were characterized under gradients of grazing intensity at three study sites of different aridity: mountain forest steppe at Hustai National Park (Hustai), and desert steppe at Mandalgovi and Bulgan. Grazing intensity was classified into three categories: lightly grazed (LG), moderately grazed (MG), and heavily grazed (HG). With regard to floristic composition, grazing decreased the shoot biomass of Poaceae species, especially Stipa spp. Distinctness of the AM fungal communities was observed among the three study sites, but most of the AM fungal operational taxonomic units (OTUs) that comprised over 1.0% of the total reads were ubiquitous. This result indicates that the AM fungal communities may be derived from similar AM fungal floras in correspondence with environmental factors. The composition of AM fungal communities differed significantly among the grazing intensities at all study sites. The relative abundance of the most dominant AM fungal OTU of the LG plots decreased with an increase in grazing intensity at all study sites. The mean proportions of the most dominant AM fungal OTUs also decreased with increased grazing intensity at Hustai. Dominance by a single AM fungal taxon may be a typical ecological feature of the AM fungal symbiosis, and grazing disturbs AM fungal community structure.

IntroductionHighly pathogenic avian influenza (HPAI) viruses of subtype H5N8 were re-introduced into the Netherlands by late 2016, after detections in south-east Asia and Russia. This second H5N8 wave resulted in a large number of outbreaks in poultry farms and the deaths of large numbers of wild birds in multiple European countries. Methods : Here we report on the detection of HPAI H5N8 virus in 57 wild birds of 12 species sampled during active (32/5,167) and passive (25/36) surveillance activities, i.e. in healthy and dead animals respectively, in the Netherlands between 8 November 2016 and 31 March 2017. Moreover, we further investigate the experimental approach of wild bird serology as a contributing tool in HPAI outbreak investigations. Results : In contrast to the first H5N8 wave, local virus amplification with associated wild bird mortality has occurred in the Netherlands in 2016/17, with evidence for occasional gene exchange with low pathogenic avian influenza (LPAI) viruses. Discussion : These apparent differences between outbreaks and the continuing detections of HPAI viruses in Europe are a cause of concern. With the current circulation of zoonotic HPAI and LPAI virus strains in Asia, increased understanding of the drivers responsible for the global spread of Asian poultry viruses via wild birds is needed.

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant abundance and quality. Here, we investigate whether generalist bumblebee species, with stable population trends over the past years, adapted their diets in response to changes in the distribution and chemical quality of their pollen resources. We selected five common species of bumblebee in NW Europe for which we had a precise description of their pollen diet through two time periods ('prior to 1950' and '2004-2005'). For each species, we assessed whether the shift in their pollen diet was related with the changes in the suitable area of their pollen resources. Concurrently, we evaluated whether the chemical composition of pollen resources changed over time and experimentally tested the impact of new major pollen species on the development of B. terrestris microcolonies. Only one species (i.e. B. lapidarius) significantly included more pollen from resources whose suitable area expanded. This opportunist pattern could partly explain the expansion of B. lapidarius in Europe. Regarding the temporal variation in the chemical composition of the pollen diet, total and essential amino acid contents did not differ significantly between the two time periods while we found significant differences among plant species. This result is driven by the great diversity of resources used by bumblebee species in both periods. Our bioassay revealed that the shift to new major pollen resources allowed microcolonies to develop, bringing new evidence on the opportunist feature of bumblebee in their diets. Overall, this study shows that the response to pollen resource drift varies among closely related pollinators, and a species-rich plant community ensures generalist species to select a nutrient-rich pollen diet., (© 2016 John Wiley & Sons Ltd.)

There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost-effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost-effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.

Microsatellite (or simple sequence repeat, SSR) markers are highly informative DNA markers often used in conservation genetic research. Next-generation sequencing enables efficient development of large numbers of SSR markers at lower costs. Boswellia papyrifera is an economically important tree species used for frankincense production, an aromatic resinous gum exudate from bark. It grows in dry tropical forests in Africa and is threatened by a lack of rejuvenation. To help guide conservation efforts for this endangered species, we conducted an analysis of its genomic DNA sequences using Illumina paired-end sequencing. The genome size was estimated at 705 Mb per haploid genome. The reads contained one microsatellite repeat per 5.7 kb. Based on a subset of these repeats, we developed 46 polymorphic SSR markers that amplified 2-12 alleles in 10 genotypes. This set included 30 trinucleotide repeat markers, four tetranucleotide repeat markers, six pentanucleotide markers and six hexanucleotide repeat markers. Several markers were cross-transferable to Boswellia pirrotae and B. popoviana. In addition, retrotransposons were identified, the reads were assembled and several contigs were identified with similarity to genes of the terpene and terpenoid backbone synthesis pathways, which form the major constituents of the bark resin., (Published by Oxford University Press on behalf of the Annals of Botany Company.)

The South-to-North Water Transfer (SNWT) Project of China is the largest of its kind ever implemented. Of its three routes (i.e., East, Middle and West), the middle one will transfer 14 billion m(3) of water annually from the Han River, a tributary of the Yangtze and the water supplying area, to Beijing by 2030. Thus water quality in the 95,000 km(2) upper Han River basin is of great concern. A watershed management initiative has been implemented in the basin, and the ultimate objectives are to quantify basin's ecosystem functioning and to develop an integrated management system with respect to water resources conservation. Specifically, the program includes five activities: characterization of riparian ecosystems, detection of land use and land cover change, quantification of nutrient cycling of representative ecosystems, determination of spatial and temporal variations of water quality, and finally development of a watershed management system for water conservation. This article provides the justifications of the watershed management initiative and the initial results are comprehended with respect to the water conservation in the Han River basin.

Trees forage for light through optimal leaf display. Effective leaf display is determined by metamer traits (i.e., the internode, petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage in a light-limited environment. We examined 11 metamer traits of sun and shade trees of 38 coexisting moist forest tree species and determined the relative strengths of intra- and interspecific variation. Species-specific metamer traits were related to two variables that represent important life history variation; the regeneration light requirements and average leaf size of the species. Metamer traits varied strongly across species and, in contrast to our expectation, showed only modest changes in response to light. Intra- and interspecific responses to light were only congruent for a third of the traits evaluated. Four traits, amongst which leaf size, specific leaf area (SLA), and leaf area ratio at the metamer level (LAR) showed even opposite intra- and interspecific responses to light. Strikingly, these are classic traits that are thought to be of paramount importance for plant performance but that have completely different consequences within and across species. Sun trees of a given species had small leaves to reduce the heat load, but light-demanding species had large leaves compared to shade-tolerants, probably to outcompete their neighbors. Shade trees of a given species had a high SLA and LAR to capture more light in a light-limited environment, whereas shade-tolerant species have well-protected leaves with a low SLA compared to light-demanding species, probably to deter herbivores and enhance leaf lifespan. There was a leaf-size-mediated trade-off between biomechanical and hydraulic safety, and the efficiency with which species can space their leaves and forage for light. Unexpectedly, metamer traits were more closely linked to leaf size than to regeneration light requirements, probably because leaf-size-related biomechanical and vascular constraints limit the trait combinations that are physically possible. This suggests that the leaf size spectrum overrules more subtle variation caused by the leaf economics spectrum, and that leaf size represents a more important strategy axis than previously thought.

Background and Aims: The volume of tree stems is made up of three components: solid wood, gas and water. These components have important consequences for the construction costs, strength and stability of trees. Here, the importance of stem components for sapling growth and survival in the field was investigated, and then these stem components were related to two important life history axes of variation: the light requirements for regeneration and the adult stature of the species., Methods: Stem fractions of wood, gas and water were determined for saplings and adults of respectively 30 and 58 Bolivian tropical moist-forest species. Sapling height growth and survival were monitored for 2 years in the field as indicators of sapling performance., Key Results: Sapling stems consisted of 26 % wood (range 7-36 % for species), 59 % water (range 49-88 %), and 15 % gas (range 0-38 %) per unit volume. The wood fraction was the only determinant of sapling performance and was correlated with increased survival and decreased growth rate across species. The wood fraction decreased with light requirements of the species, probably because a high wood fraction protects shade-tolerant species against pathogens and falling debris. The gas fraction increased with the light requirements and adult stature of the species; probably as an aid in realizing a rapid height growth and accessing the canopy in the case of light-demanding species, and for rapidly attaining stability and a large reproductive size in the case of tall species. The water fraction was not correlated with the life history variation of tree species, probably because it leads to increased stem loading and decreased stability., Conclusions: The wood fraction might partially explain the growth-survival trade-off that has been found across tropical tree species. The wood and gas fractions are closely related to the regeneration light requirements of the species. Tall species have a high gas fraction, probably not only because gas is a cheap filler, but also because it might lead to an increased stability of these tall trees.