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Abstract Seedling recruitment is an important mode of establishment utilized by many invasive plants. In widespread invasive plants, regional variation in the rates of seedling recruitment can contribute to differences in invasion intensity across regions. In this study, we examined regional variation in reproductive traits and seedling performance in a cosmopolitan invasive wetland grass,Phragmites australis. We tested whether nitrogen levels and regions with different histories and intensities of invasion would affect reproductive traits and seedling performance. We sampled invasivePhragmitesinflorescences from 34 populations across three regions in North America: The Northeast (old, most intense invasion), the Midwest (recent, intense invasion), and Southeast (recent, sparse invasion). We hypothesized that NortheastPhragmitespopulations would have the highest reproductive output and seedling performance, and that populations experiencing high nitrogen pollution would have higher reproductive output and seedling performance under high nitrogen conditions. We found that populations in the Northeast had the highest inflorescence mass, as expected. We also found that despite sparse distribution ofPhragmitesin the Southeast, populations from the Southeast displayed a high potential for sexual reproduction. However, increasing watershed-level nitrogen (kg/km²) decreased percent seed germination in Southeastern populations, suggesting that Southeastern populations are sensitive to rising nitrogen levels. While elevated nitrogen improved seedling performance through increased belowground growth in SoutheasternPhragmitesseedlings, elevated nitrogen decreased belowground growth in Midwestern seedlings. These results suggest that the southeastern region of North America may be primed to become an emergent invasion front ofPhragmites, warranting more research into the possible management ofPhragmitesspread in the region. 

Abstract Nearly all plants are colonized by fungal endophytes, and a growing body of work shows that both environment and host species shape plant-associated fungal communities. However, few studies place their work in a phylogenetic context to understand endophyte community assembly through an evolutionary lens. Here, we investigated environmental and host effects on root endophyte assemblages in coastal Louisiana marshes. We isolated and sequenced culturable fungal endophytes from roots of three to four dominant plant species from each of three sites of varying salinity. We assessed taxonomic diversity and composition as well as phylogenetic diversity (mean phylogenetic distance, MPD) and phylogenetic composition (based on MPD). When we analyzed plant hosts present across the entire gradient, we found that the effect of the environment on phylogenetic diversity (as measured by MPD) was host dependent and suggested phylogenetic clustering in some circumstances. We found that both environment and host plant affected taxonomic composition of fungal endophytes, but only host plant affected phylogenetic composition, suggesting different host plants selected for fungal taxa drawn from distinct phylogenetic clades, whereas environmental assemblages were drawn from similar clades. Our study demonstrates that including phylogenetic, as well as taxonomic, community metrics can provide a deeper understanding of community assembly in endophytes. 

Sand made from recycled glass cullet could supplement limited dredged river sand (dredge) in coastal wetland restorations; however, its suitability for wetland plants is unknown. In two experiments, we compared the biomass of several wetland plants in recycled glass sand to growth in dredge. First, we grewSalix nigra,Zizaniopsis miliacea, andSporobolus alterniflorusin fine‐ and coarse‐glass sands, dredge, and a coarse‐glass/dredge mixture. Second, we grewTaxodium distichumandSchoenoplectus californicusin a revised coarse‐glass blend, dredge, and a mix. We characterized the substrate porosity, particle density, and bulk density for both experiments and tested how substrate nutrients, metals, and pH impactedS. californicusleaf contents. We found species‐specific responses to substrates: herbaceous species grew better in the mix and dredge than in glass alone, whereas trees grew equally well in the coarse glass, mix, and dredge. Glass sand was less dense than dredge. When saturated and compressed, finer‐grained glass sand and mixes had lower estimated porosities than coarser glass sand and dredge.S. californicusleaf chemistry resembled that of the plant's substrate. This study demonstrated that wetland plants can grow in glass sand, that mixtures of glass and dredge have species‐specific effects, and that substrate structure and chemistry could help explain these differences. Thus, it opens the door for broader field studies on how glass sand can best be used in coastal restoration efforts. 

Abstract Disturbance response and recovery are increasingly important in microbial ecology, as microbes may recover from disturbances differently than macro communities. Past disturbances can alter microbial community structure and their response to subsequent disturbance events, but it remains unclear if the same recovery patterns persist after long‐term exposure to stress. Here, we compare bacterial community composition in a community that experienced 2 years of monthly salinity addition disturbances with a community that has not experienced salinity additions. We then track the response and recovery to an additional salinity addition based on past disturbance exposure. We tested the following hypotheses: first, communities with a repeated disturbance history will have a different community composition than communities without a disturbance history; second, communities exposed to repeated disturbances will undergo a different recovery trajectory than communities experiencing a novel disturbance. We find that repeated disturbances alter community composition and affect community response and recovery to a subsequent disturbance after 2 years, primarily through increased resistance. This work enhances our understanding of microbial temporal dynamics and suggests that novel disturbances may pose a threat to microbial community structure and function.