Author Correction: Mapping the world's free-flowing rivers.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Mapping the world's free-flowing rivers.

Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.

Effects of publication bias on conservation planning.

Conservation planners need reliable information on spatial patterns of biodiversity. However, existing data sets are skewed because some ecosystems, taxa, and locations are underrepresented. We determined how many articles have been published in recent decades on the biodiversity of different countries and their constituent provinces. We searched the Web of Science catalogues Science Citation Index (SCI) and Social Science Citation Index (SSCI) for biodiversity-related articles published from 1993 to 2016 that included country and province names. We combined data on research publication frequency with other provincial-scale factors hypothesized to affect the likelihood of research activity (i.e., economic development, human presence, infrastructure, and remoteness). Areas that appeared understudied relative to the biodiversity expected based on site climate likely have been inaccessible to researchers for reasons, notably armed conflict. Geographic publication bias is of most concern in the most remote areas of sub-Saharan Africa and South America. Our provincial-scale model may help compensate for publication biases in conservation planning by revealing the spatial extent of research needs and the low cost of redoing this analysis annually.

Efectos del Sesgo de Publicación sobre la Planeación de la Conservación Resumen Los planeadores de la conservación necesitan información confiable sobre los patrones espaciales de la biodiversidad. Sin embargo, los conjuntos de datos existentes están distorsionados porque algunos ecosistemas, taxones y localidades están subrepresentados. Determinamos cuántos artículos sobre la biodiversidad de diferentes países y sus provincias constituyentes han sido publicados en décadas recientes. Buscamos artículos relacionados con la biodiversidad publicados entre 1993 y 2016 que incluyeran el nombre de países y provincias en los catálogos SCI y SSCI de la Web of Science. Combinamos los datos de frecuencia de publicación de investigaciones con otros factores de escala provincial que creemos afectarían la probabilidad de la actividad de investigación (es decir, desarrollo económico, presencia humana, infraestructura y lejanía). Las áreas que aparentaron estar poco estudiadas en relación con la biodiversidad esperada basada en el clima del sitio probablemente han estado inaccesibles para los investigadores por diferentes razones, notablemente los conflictos armados. El sesgo geográfico en las publicaciones es un tema de importancia para las áreas más remotas del África subsahariana y América del Sur. Nuestro modelo de escala provincial puede ayudar a compensar los sesgos de publicación en la planeación de la conservación al revelar la extensión espacial de las necesidades de investigación y los bajos costos de repetir este análisis cada año.

Soil nitrogen dynamics in a river floodplain mosaic.

In their natural state, river floodplains are heterogeneous and dynamic ecosystems that may retain and remove large quantities of nitrogen from surface waters. We compared the soil nitrogen dynamics in different types of habitat patches in a restored and a channelized section of a Thur River floodplain (northeast Switzerland). Our objective was to relate the spatiotemporal variability of selected nitrogen pools (ammonium, nitrate, microbial nitrogen), nitrogen transformations (mineralization, nitrification, denitrification), and gaseous nitrogen emission (NO) to soil properties and hydrological processes. Our study showed that soil water content and carbon availability, which depend on sedimentation and inundation dynamics, were the key factors controlling nitrogen pools and processes. High nitrogen turnover rates were measured on gravel bars, characterized by both frequent inundation and high sediment deposition rates, as well as in low-lying alluvial forest patches with a fine-textured, nutrient-rich soil where anaerobic microsites probably facilitated coupled nitrification-denitrification. In contrast, soils of the embankment in the channelized section had comparatively small inorganic nitrogen pools and low transformation rates, particularly those related to nitrate production. Environmental heterogeneity, characteristic of the restored section, favors nitrogen removal by creating sites of high sedimentation and denitrification. Of concern, however, are the locally high NO efflux and the possibility that nitrate could leach from nitrification hotspots.