I.Introduction: continuing to face up to root ecology's challenges 975 II.Semantics: defining concepts for better understanding and communication 977III. Species-level vs ecosystem-level measurements 978

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Metabolomics and biochemical assays were employed to identify physiological perturbations induced by a commercial formulation of glyphosate in susceptible (S) and resistant (R) biotypes of Amaranthus palmeri. At 8 h after treatment (HAT), compared to the respective water-treated control, cellular metabolism of both biotypes were similarly perturbed by glyphosate, resulting in abundance of most metabolites including shikimic acid, amino acids, organic acids and sugars. However, by 80 HAT the metabolite pool of glyphosate-treated R-biotype was similar to that of the control S- and R-biotypes, indicating a potential physiological recovery. Furthermore, the glyphosate-treated R-biotype had lower reactive oxygen species (ROS) damage, higher ROS scavenging activity, and higher levels of potential antioxidant compounds derived from the phenylpropanoid pathway. Thus, metabolomics, in conjunction with biochemical assays, indicate that glyphosate-induced metabolic perturbations are not limited to the shikimate pathway, and the oxidant quenching efficiency could potentially complement the glyphosate resistance in this R-biotype.

(Houtt.) Ronse Decr.]. Can. J. Plant Sci. 86: 887-905. Polygonum cuspidatum (Japanese knotweed) is an introduced perennial geophyte in the buckwheat family (Polygonaceae). The phytogeographic distribution of P. cuspidatum in North America suggests a large number of intentional introductions via ornamental plantings from 1870 to 2000, followed by secondary spread from these foci. This species is most pernicious along riparian corridors and road and railroad rights-of-way, reducing visibility, displacing native species, negatively affecting native wildlife, and causing alterations in natural hydrologic processes. Although non-hybrid seed recruitment has not been observed in Europe because of the presence of male-sterile clones only, dispersal of seeds and stem and rhizome fragments by flowing water does occur in North America and populations are readily established from these sources. The primary means of local and regional range expansion is human-mediated transport of rhizome-infested soil. Hybridization is common with the congener P. sachalinense in the introduced ranges of North America and Europe resulting in the equally noxious P. × bohemicum.

SummarySoil carbon (C) sequestration, as an ecosystem property, may be strongly influenced by invasive plants capable of depositing disproportionately high quantities of chemically distinct litter that disrupt ecosystem processes. However, a mechanistic understanding of the processes that regulate soil C storage in invaded ecosystems remains surprisingly elusive.Here, we studied the impact of the invasion of two noxious nonnative species, Polygonum cuspidatum, which produces recalcitrant litter, and Pueraria lobata, which produces labile litter, on the quantity, molecular composition, and stability of C in the soils they invade.Compared with an adjacent noninvaded old-field, P. cuspidatum-invaded soils exhibited a 26% increase in C, partially through selective preservation of plant polymers. Despite receiving a 22% higher litter input, P. lobata-invaded Pinus stands exhibited a 28% decrease in soil C and a twofold decrease in plant biomarkers, indicating microbial priming of native soil C. The stability of C exhibited an opposite trend: the proportion of C that was resistant to oxidation was 21% lower in P. cuspidatum-invaded soils and 50% higher in P. lobata-invaded soils.Our results highlight the capacity of invasive plants to feed back to climate change by destabilizing native soil C stocks and indicate that environments that promote the biochemical decomposition of plant litter would enhance the long-term storage of soil C. Further, our study highlights the concurrent influence of dominant plant species on both selective preservation and humification of soil organic matter.

Summary1 Unlike non-clonal plants, clonal plants can develop a division of labour in which connected ramets specialize to acquire different, locally abundant resources. This occurs as a plastic response to a patchy environment where two resources tend not to occur together and different ramets experience high availabilities of different resources. We hypothesized that if division of labour is an important advantage of clonal growth in such environments in nature, then clones from habitats where resource availabilities are negatively associated should show a greater capacity for division of labour than clones from habitats where resource availabilities are more uniform. 2 To test this, we collected clones of Fragaria chiloensis from sand dune and grassland sites in each of three regions of the central coast of California, grew pairs of connected or severed ramets under low light and high N or under high light and low N, and measured leaf area, chlorophyll content and final dry mass. Given that previous work has indicated that high availabilities of light and N show a stronger tendency not to occur together in the dune than in the grassland sites, we expected that clones from dunes would show greater capacity for division of labour than clones from grasslands. 3 Clones from dunes showed a greater capacity than clones from grasslands to specialize for acquisition of abundant N via high proportional mass of roots. Clones from the two types of habitats showed similar capacity to specialize for acquisition of abundant light via high leaf area and chlorophyll content of leaves. Specialization via leaf area and chlorophyll content took place mainly within the first half of the 60-day experiment. 4 These results provide evidence that division of labour in a clonal plant has been selected for in natural habitats where high levels of different resources tend to be spatially separated. Results also show that division of labour can occur, not just via allocation of mass, but also via physiological traits, and that both morphological and physiological specialization can take place within a few weeks. 5 Clonal plants dominate many habitats and include many highly invasive species. Division of labour is one of the most striking potential advantages of clonal growth, and is a remarkable instance of phenotypic plasticity in plants. This study further suggests that division of labour in clonal plants is an instance of adaptive plasticity and could therefore play a part in their widespread ecological success.

Summary Climate change could increase the frequency with which plants experience abiotic stresses, leading to changes in their metabolic pathways. These stresses may induce the production of compounds that are structurally and biologically different from constitutive compounds. We studied how warming and altered precipitation affected the composition, structure, and biological reactivity of leaf litter tannins in Acer rubrum at the Boston‐Area Climate Experiment, in Massachusetts, USA. Warmer and drier climatic conditions led to higher concentrations of protective compounds, including flavonoids and cutin. The abundance and structure of leaf tannins also responded consistently to climatic treatments. Drought and warming in combination doubled the concentration of total tannins, which reached 30% of leaf‐litter DW. This treatment also produced condensed tannins with lower polymerization and a greater proportion of procyanidin units, which in turn reduced sequestration of tannins by litter fiber. Furthermore, because of the structural flexibility of these tannins, litter from this treatment exhibited five times more enzyme (β‐glucosidase) complexation capacity on a per‐weight basis. Warmer and wetter conditions decreased the amount of foliar condensed tannins. Our finding that warming and drought result in the production of highly reactive tannins is novel, and highly relevant to climate change research as these tannins, by immobilizing microbial enzymes, could slow litter decomposition and thus carbon and nutrient cycling in a warmer, drier world.

Per-and polyfluoroalkyl substances (PFAS) are ubiquitous in many consumer products and present serious environmental challenges due to their persistent nature. Currently, conventional water treatment methods fail to remove PFAS, and other newly proposed materials/techniques face challenges when employed under realistic conditions. This study reports on poly(ethylenimine)-functionalized cellulose microcrystals (PEI-f-CMC) that showed a near-instant and high removal of PFAS under concentrations relevant to their actual occurrence in the natural environment (i.e., <1000 ng/L). The selective removal efficiency of 22 PFAS from different classes (i.e., legacy carboxylic and sulfonated PFAS, emerging carboxylic and sulfonated PFAS, and PFAS-precursors) using PEI-f-CMC was confirmed in lake water as well as solutions codosed with two additional types of natural organic matter. The performance of PEI-f-CMC was maintained in eight consecutive adsorption/regeneration cycles to remove PFAS. The PEI-f-CMC with its unique fast kinetics and high adsorption activity toward PFAS exhibits a great potential for being a promising alternative adsorbent for PFAS control.