Rapid Natural Decline of Upper Montane Forests in the Swedish Scandes

Unprecedented needle loss of mature forest stands occurred in natural Swedish montane forests during 1987. Pine (Pinus sylvestris L.) and spruce (Picea abies [L.] Karst.) needles turned reddish-brown during the spring and early summer. An intensive study within a severely damaged pine population indicated that damage was primarily due to a coincidence of shallow snow cover and severe cold from mid-December 1986 to mid-January 1987. This resulted in unusually cold soils and late thawing of the soils. Acute drought stress then developed in late winter during a period of sunny weather and great diurnal temperature ranges. Thus, the study supports the classical theory of winter desiccation as an important component in population ecology of cold marginal forests in this part of the world. Historical data indicate that the present kind of damage was more frequent prior to the present century. It is suggested that cold-induced dieback is an important, but often overlooked, disturbance process in northern boreal forests relevant to Holocene forest history.Key words: forest damage, montane forests, Pinus sylvestris L., winter desiccation, disturbance, Holocene forest history, SwedenMots clés: dommages àla forêt, forêts montagneuses, Pinus sylvestris L., dessèchement hivernal, perturbation, histoire de la forêt de l’holocène, Suèd

Niche differentiation and evolution of the wood decay machinery in the invasive fungus Serpula lacrymans

Abstract Ecological niche breadth and the mechanisms facilitating its evolution are fundamental to understanding adaptation to changing environments, persistence of generalist and specialist lineages and the formation of new species. Woody substrates are structurally complex resources utilized by organisms with specialized decay machinery. Wood-decaying fungi represent ideal model systems to study evolution of niche breadth, as they vary greatly in their host range and preferred decay stage of the substrate. In order to dissect the genetic basis for niche specialization in the invasive brown rot fungus Serpula lacrymans , we used phenotyping and integrative analysis of phylogenomic and transcriptomic data to compare this species to wild relatives in the Serpulaceae with a range of specialist to generalist decay strategies. Our results indicate specialist species have rewired regulatory networks active during wood decay towards decreased reliance on enzymatic machinery, and therefore nitrogen-intensive decay components. This shift was likely accompanied with adaptation to a narrow tree line habitat and switch to a pioneer decomposer strategy, both requiring rapid colonization of a nitrogen-limited substrate. Among substrate specialists with narrow niches, we also found evidence for pathways facilitating reversal to generalism, highlighting how evolution may move along different axes of niche space

Editorial: The Use and Understanding of Style Differences to Enhance Learning

Comparison of Molecular Function annotations of R. solani genes between the induced (log2FPKM > 0) and repressed (log2FPKM < 0) genes when challenged with S4 Serratia proteamaculans. (FPMK = fragments per kilobase of exon per million fragments mapped

Contrasting demographic histories revealed in two invasive populations of the dry rot fungus Serpula lacrymans

Globalization and international trade have impacted organisms around the world leading to a considerable number of species establishing in new geographic areas. Many organisms have taken advantage of human-made environments, including buildings. One such species is the dry rot fungus Serpula lacrymans, which is the most aggressive wood-decay fungus in indoor environments in temperate regions. Using population genomic analyses of 36 full genome sequenced isolates, we demonstrated that European and Japanese isolates are highly divergent and the populations split 3000–19,000 generations ago, probably predating human influence. Approximately 250 generations ago, the European population went through a tight bottleneck, probably corresponding to the fungus colonization of the built environment in Europe. The demographic history of these populations, probably lead to low adaptive potential. Only two loci under selection were identified using a Fst outlier approach, and selective sweep analyses identified three loci with extended haplotype homozygosity. The selective sweep analyses found signals in genes possibly related to decay of various substrates in Japan and in genes involved DNA replication and protein modification in Europe. Our results suggest that the dry rot fungus independently established in indoor environments in Europe and Japan and that invasive species can potentially establish large populations in new habitats based on a few colonizing individuals

Complete genome sequence of Serratia plymuthica strain AS12

A plant-associated member of the family Enterobacteriaceae, Serratia plymuthica strain AS12 was isolated from rapeseed roots. It is of scientific interest because it promotes plant growth and inhibits plant pathogens. The genome of S. plymuthica AS12 comprises a 5,443,009 bp long circular chromosome, which consists of 4,952 protein-coding genes, 87 tRNA genes and 7 rRNA operons. This genome was sequenced within the 2010 DOE-JGI Community Sequencing Program (CSP2010) as part of the project entitled “Genomics of four rapeseed plant growth promoting bacteria with antagonistic effect on plant pathogens”

Insight into trade‐off between wood decay and parasitism from the genome of a fungal forest pathogen

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91191/1/j.1469-8137.2012.04128.x.pd

Building a Pipeline for Gathering and Rendering With Spatially Variant Incident Illumination Using Real Time Video Light Probes

Lighting plays an important part in computer graphics. When making photo realistic renderings the ultimate goal is to generate an image that would be indistinguishable from a real photograph or to seamlessly integrate a synthetic object into a photo. One of the key elements is to get correct lighting and shading in the rendering since the human vision is very well attuned to subtile variations of the lighting. Recent image based techniques has been developed that uses high dynamic range omni directional images, light probes, from the real world as light information to illuminate synthetic objects. Such images are capturing the incident light information in the point it was taken. By using these images as lighting information the objects illuminated will integrate seamlessly into a background photography of the scene. However these techniques assumes that the lighting is spatially constant throughout the scene. By using more light probes spatial variations in the scene can be captured. We will here present a pipeline for capturing and rendering with spatially variant light probes using a device that can capture light probes at very high dynamic range. Using this pipeline we have captured high frequency variations in a scene and scenes with complex real world lighting and used this information to render objects representing these variations

Re-examining the evidence for the mother tree hypothesis - resource sharing among trees via ectomycorrhizal networks

Seminal scientific papers positing that mycorrhizal fungal networks can distribute carbon (C) among plants have stimulated a popular narrative that overstory trees, or 'mother trees', support the growth of seedlings in this way. This narrative has far-reaching implications for our understanding of forest ecology and has been controversial in the scientific community. We review the current understanding of ectomycorrhizal C metabolism and observations on forest regeneration that make the mother tree narrative debatable. We then re-examine data and conclusions from publications that underlie the mother tree hypothesis. Isotopic labeling methods are uniquely suited for studying element fluxes through ecosystems, but the complexity of mycorrhizal symbiosis, low detection limits, and small carbon discrimination in biological processes can cause researchers to make important inferences based on miniscule shifts in isotopic abundance, which can be misleading. We conclude that evidence of a significant net C transfer via common mycorrhizal networks that benefits the recipients is still lacking. Furthermore, a role for fungi as a C pipeline between trees is difficult to reconcile with any adaptive advantages for the fungi. Finally, the hypothesis is neither supported by boreal forest regeneration patterns nor consistent with the understanding of physiological mechanisms controlling mycorrhizal symbiosis