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Cover cropping is beneficial for reducing soil erosion and nutrient losses, but there are conflicting reports on how cover cropping affects emissions of nitrous oxide (N 2 O), a potent greenhouse gas. In this study, we measured N 2 O fluxes over a full year in Illinois corn plots with and without rye cover crop. We compared these year-round measurements to N 2 O emissions predicted by the Intergovernmental Panel on Climate Change (IPCC) Tier 1 equation and the Denitrification-Decomposition (DNDC) model. In addition, we measured potential denitrification and N 2 O production rates. The field measurements showed typical N 2 O peaks shortly after fertilizer application, as well as a significant late-winter peak. Cover cropping significantly reduced all peak N 2 O fluxes, with decreases ranging from 39 to 95%. Neither model was able to accurately predict annual N 2 O fluxes or the decrease in N 2 O emissions from cover-cropped fields. In contrast to field measurements, lab assays found that cover cropping significantly increased potential denitrification by 90-127% and potential N 2 O production by 54-106%. The rye cover-cropped plots had lower soil nitrate and higher soil carbon. When limiting nitrate and excess carbon were provided in lab assays, the proportion of N 2 O resulting from denitrification decreased. These results suggest that the discrepancy between the observed decrease in field N 2 O emissions and the increase in denitrification potential may be due to the difference in available nutrients between the field and laboratory measurements. Overall, these results suggest the importance of late-winter peaks in N 2 O emissions and the potential of rye cover cropping to reduce N 2 O emissions from agricultural fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Snake Fungal Disease (SFD), caused by Ophidiomyces ophiodiicola, is the most recently described fungal disease afflicting wildlife populations across North America and Europe. It has been proposed as a significant conservation threat yielding high mortality and yet much its ecology is unknown. We collected 144 skin swabs from Eastern Massasaugas (Sistrurus catenatus) in 2015 and 2016 to determine document ongoing prevalence and assess differences in microbial assemblages between positive and negative individuals. Alpha diversity of fungi was reduced in SFD positive animals, while beta diversity identified distinct assemblages of microbes between SFD-positive and -negative samples. Ophidiomyces was present on the skin of affected animals, even on body sites distant to lesions indicating that the microbiome on entire surface of the skin is altered. Ophidiomyces was not detected in any non-SFD snake. There were smaller, but significant, influences of year sampled. Bacterial genera Janthinobacterium and Serratia were significantly increased in SFD snakes, while Xylanimicrobium, Cellulosimicrobium, and Rhodococcus were the only bacterial taxa significantly reduced. The relative abundance of fungi within the orders Pleosporales and Canopdiales was reduced in SFD-positive samples, though Pyrenochaetopsis pratorum was the only species found to differ significantly. This is the first study to determine the impact that this fungal pathogen has on the skin microbiome.

Denitrifying bioreactors, consisting of water flow control structures and a woodchip-filled trench, are a promising approach for removing nitrate from agricultural subsurface or tile drainage systems. To better understand the seasonal dynamics and the ecological drivers of the microbial communities responsible for denitrification in these bioreactors, we employed microbial community "fingerprinting" techniques in a time-series examination of three denitrifying bioreactors over 2 years, looking at bacteria, fungi, and the denitrifier functional group responsible for the final step of complete denitrification. Our analysis revealed that microbial community composition responds to depth and seasonal variation in moisture content and inundation of the bioreactor media, as well as temperature. Using a geostatistical analysis approach, we observed recurring temporal patterns in bacterial and denitrifying bacterial community composition in these bioreactors, consistent with annual cycling. The fungal communities were more stable, having longer temporal autocorrelations, and did not show significant annual cycling. These results suggest a recurring seasonal cycle in the denitrifying bioreactor microbial community, likely due to seasonal variation in moisture content.

Gradients in abiotic parameters, such as soil moisture,can strongly influence microbial community structure and function. Denitrifying and ammonia-oxidizing microorganisms,in particular, have contrasting physiological responses to abiotic factors such as oxygen concentration and soil moisture. Identifying abiotic factors that govern the composition and activity of denitrifying and ammonia-oxidizing communities is critical for understanding the nitrogen cycle.The objectives of this study were to (i) examine denitrifier andarchaeal ammonia oxidizer community composition and (ii) assess the taxa occurring within each functional group related to soil conditions along an environmental gradient. Soil was sampled across four transects at four locations along a dry to saturated environmental gradient at a restored wetland. Soil pH and soil organic matter content increased from dry to saturated plots. Composition of soil denitrifier and ammonia oxidizer functional groups was assessed by terminal restriction fragment length polymorphism (T-RFLP) community analysis, and local soil factors were also characterized. Microbial community composition of denitrifiers and ammonia oxidizers differed along the moisture gradient (denitrifier:ANOSIM R = 0.739, P < 0.001; ammonia oxidizers: ANOSIMR = 0.760, P < 0.001). Individual denitrifier taxa were observed over a larger range of moisture levels than individual archaeal ammonia oxidizer taxa (Wilcoxon rank sum, W = 2413, P value = 0.0002). Together, our data suggest that variation in environmental tolerance of microbial taxa have potential to influence nitrogen cycling in terrestrial ecosystems.

Ecological restoration often involves only the manipulation of abiotic factors at the local scale. However, processes external to a restoration site determine the range of local conditions within the site, constraining the level of restoration progress that can be achieved by on-site manipulations. We examined the relationship of landscape and local explanatory variables to plant species composition in 28 restored wetlands in Illinois, USA. Using constrained ordination combined with variation partitioning, we determined the independent and joint effects of three spatially hierarchical sets of variables: (1) macroscale landscape features reflecting site setting within regional landscapes, (2) mesoscale landscape features reflecting nearby propagule sources and buffers from disturbances, and (3) local environmental factors. Because the relative influence of landscape- vs. local-scale factors on restoration success may depend on particular restoration goals, we repeated the analyses using three multivariate plant community responses that represented three frequently stated goals: (1) replicating species composition, (2) restoring a particular wetland community type, and (3) constructing sites with high value for plant conservation. Explanatory variables at landscape and local scales had independent and nearly equally strong relationships to plant species composition. In contrast, when species were aggregated based on plant traits, the independent contribution of local predictors was greater than the independent contributions of macroscale or mesoscale landscape predictors, reflecting convergence of plant trait composition in sites with similar local conditions. Local predictors explained a significant amount of variation in plant conservation value among sites, but much of the variation could be explained by large-scale landscape setting, indicating that landscape constraints on local environmental conditions limited the level of floristic conservation value achievable. The appropriate scale at which to focus restoration efforts will vary depending upon restoration objectives. Restoration of particular wetland community types might be successfully achieved through manipulation of local abiotic factors. In contrast, restoration of a particular species assemblage or reconstruction of wetlands with high value for conservation requires consideration of landscape processes and available species pools.