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1. Nativity and seed dispersal mode influence species’ responses to habitat connectivity and urban environments

   https://doi.org/10.1111/geb.12760  

   Lopez, Bianca E. ; Urban, Dean ; White, Peter S. ( July 2018 , Global Ecology and Biogeography)

   Urbanization alters local environmental conditions and the ability of species to disperse between remnant habitat patches within the urban matrix. Nonetheless, despite the ongoing growth of urban areas worldwide, few studies have investigated the relative importance of dispersal and local environmental conditions for influencing species composition within urban and suburban landscapes. Here, we explore this question using spatial patterns of plant species composition.

   The Research Triangle area, which includes the cities of Raleigh, Durham, Chapel Hill and Cary, in central North Carolina, USA.

   2012–2014.

   Vascular plants.

   We sampled riparian forest plant communities along an urban‐to‐rural gradient and used redundancy analysis to identify predictors of species composition patterns for groups of species categorized by nativity and seed dispersal mode. We first compared the ability of different models of habitat connectivity (least‐cost paths that avoided urban land cover versus Euclidean and along‐stream distance) to explain spatial patterns of species composition. We then partitioned the variation in species composition explained by habitat connectivity models, local environmental conditions and measures of urbanization in the surrounding landscape.

   We found that several groups of native species were best explained by least‐cost path models that avoided urban development, suggesting that urbanization impedes dispersalmore »within this landscape, particularly for short‐dispersed species. Environmental variables related to urbanization (e.g., temperature, stream incision) were important predictors of species composition for many species groups, but measures of urbanization in the surrounding landscape were more important for exotic than for native species.

   Our results demonstrate that urbanization influences plant species composition via its effects on both habitat connectivity and environmental conditions. However, the strength of these effects varies somewhat predictably across seed dispersal modes and between native and exotic species. These results highlight the importance of landscape‐scale planning for urban conservation.

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2. Influence of infrastructure on water quality and greenhouse gas dynamics in urban streams

   https://doi.org/10.5194/bg-14-2831-2017  

   Smith, Rose M. ; Kaushal, Sujay S. ; Beaulieu, Jake J. ; Pennino, Michael J. ; Welty, Claire ( January 2017 , Biogeosciences)

   Streams and rivers are significant sources of nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) globally, and watershed management can alter greenhouse gas (GHG) emissions from streams. We hypothesized that urban infrastructure significantly alters downstream water quality and contributes to variability in GHG saturation and emissions. We measured gas saturation and estimated emission rates in headwaters of two urban stream networks (Red Run and Dead Run) of the Baltimore Ecosystem Study Long-Term Ecological Research project. We identified four combinations of stormwater and sanitary infrastructure present in these watersheds, including: (1) stream burial, (2) inline stormwater wetlands, (3) riparian/floodplain preservation, and (4) septic systems. We selected two first-order catchments in each of these categories and measured GHG concentrations, emissions, and dissolved inorganic and organic carbon (DIC and DOC) and nutrient concentrations biweekly for 1 year. From a water quality perspective, the DOC : NO₃⁻ ratio of streamwater was significantly different across infrastructure categories. Multiple linear regressions including DOC : NO₃⁻ and other variables (dissolved oxygen, DO; total dissolved nitrogen, TDN; and temperature) explained much of the statistical variation in nitrous oxide (N₂O, r² =  0.78), carbon dioxide (CO₂, r² =  0.78), and methane (CH₄, r² =  0.50) saturation in stream water. We measured N₂O saturation ratios, which were among the highest reported in the literaturemore »for streams, ranging from 1.1 to 47 across all sites and dates. N₂O saturation ratios were highest in streams draining watersheds with septic systems and strongly correlated with TDN. The CO₂ saturation ratio was highly correlated with the N₂O saturation ratio across all sites and dates, and the CO₂ saturation ratio ranged from 1.1 to 73. CH₄ was always supersaturated, with saturation ratios ranging from 3.0 to 2157. Longitudinal surveys extending form headwaters to third-order outlets of Red Run and Dead Run took place in spring and fall. Linear regressions of these data yielded significant negative relationships between each gas with increasing watershed size as well as consistent relationships between solutes (TDN or DOC, and DOC : TDN ratio) and gas saturation. Despite a decline in gas saturation between the headwaters and stream outlet, streams remained saturated with GHGs throughout the drainage network, suggesting that urban streams are continuous sources of CO₂, CH₄, and N₂O. Our results suggest that infrastructure decisions can have significant effects on downstream water quality and greenhouse gases, and watershed management strategies may need to consider coupled impacts on urban water and air quality.« less
3. The Wasatch Environmental Observatory: A mountain to urban research network in the semi‐arid western US

   https://doi.org/10.1002/hyp.14352  

   Follstad Shah, Jennifer J. ; Bares, Ryan ; Bowen, Brenda B. ; Bowen, Gabriel J. ; Bowling, David R. ; Eiriksson, David P. ; Fasoli, Benjamin ; Fiorella, Richard P. ; Hallar, Anna Gannet ; Hinners, Sarah J. ; et al ( September 2021 , Hydrological Processes)

   The 2085 km²Jordan River Basin, and its seven sub‐catchments draining the Central Wasatch Range immediately east of Salt Lake City, UT, are home to an array of hydrologic, atmospheric, climatic and chemical research infrastructure that collectively forms the Wasatch Environmental Observatory (WEO). WEO is geographically nested within a wildland to urban land‐use gradient and built upon a strong foundation of over a century of discharge and climate records. A 2200 m gradient in elevation results in variable precipitation, temperature and vegetation patterns. Soil and subsurface structure reflect systematic variation in geology from granitic, intrusive to mixed sedimentary clastic across headwater catchments, all draining to the alluvial or colluvial sediments of the former Lake Bonneville. Winter snowfall and spring snowmelt control annual hydroclimate, rapid population growth dominates geographic change in lower elevations and urban gas and particle emissions contribute to episodes of severe air pollution in this closed‐basin. Long‐term hydroclimate observations across this diverse landscape provide the foundation for an expanding network of infrastructure in both montane and urban landscapes. Current infrastructure supports both basic and applied research in atmospheric chemistry, biogeochemistry, climate, ecology, hydrology, meteorology, resource management and urban redesign that is augmented through strong partnerships with cooperating agencies. These featuresmore »allow WEO to serve as a unique natural laboratory for addressing research questions facing seasonally snow‐covered, semi‐arid regions in a rapidly changing world and an excellent facility for providing student education and research training.

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4. Geospatial Modeling Approaches to Historical Settlement and Landscape Analysis

   https://doi.org/10.3390/ijgi11020075  

   Herold, Hendrik ; Behnisch, Martin ; Hecht, Robert ; Leyk, Stefan ( February 2022 , ISPRS International Journal of Geo-Information)

   Landscapes and human settlements evolve over long periods of time. Land change, as one of the drivers of the ecological crisis in the Anthropocene, therefore, needs to be studied with a long-term perspective. Over the past decades, a substantial body of research has accumulated in the field of land change science. The quantitative geospatial analysis of land change, however, still faces many challenges; be that methodological or data accessibility related. This editorial introduces several scientific contributions to an open-access Special Issue on historical settlement and landscape analysis. The featured articles cover all phases of the analysis process in this field: from the exploration and geocoding of data sources and the acquisition and processing of data to the adequate visualization and application of the retrieved historical geoinformation for knowledge generation. The data used in this research include archival maps, cadastral and master plans, crowdsourced data, airborne LiDAR and satellite-based data products. From a geographical perspective, the issue covers urban and rural regions in Central Europe and North America as well as regions subject to highly dynamic urbanization in East Asia. In the view of global environmental challenges, both the need for long-term studies on land change within Earth system research andmore »the current advancement in AI methods for the retrieval, processing and integration of historical geoinformation will further fuel this field of research.« less
5. Effects of instream processes, discharge, and land cover on nitrogen export from southern Appalachian Mountain catchments

   https://doi.org/10.1002/hyp.13325  

   Webster, Jackson R. ; Stewart, Rebecca M. ; Knoepp, Jennifer D. ; Jackson, C. Rhett ( November 2018 , Hydrological Processes)

   Catchments with minimal disturbance usually have low dissolved inorganic nitrogen (DIN) export, but disturbances and anthropogenic inputs result in elevated DIN concentration and export and eutrophication of downstream ecosystems. We studied streams in the southern Appalachian Mountains, USA, an area dominated by hardwood deciduous forest but with areas of valley agriculture and increasing residential development. We collected weekly grab samples and storm samples from nine small catchments and three river sites. Most discharge occurred at baseflow, with baseflow indices ranging from 69% to 95%. We identified three seasonal patterns of baseflow DIN concentration. Streams in mostly forested catchments had low DIN with bimodal peaks, and summer peaks were greater than winter peaks. Streams with more agriculture and development also had bimodal peaks; however, winter peaks were the highest. In streams draining catchments with more residential development, DIN concentration had a single peak, greatest in winter and lowest in summer. Three methods for estimating DIN export produced consistent results. Annual DIN export ranged from less than 200 g ha⁻¹ year⁻¹for the less disturbed catchments to over 2,000 g ha⁻¹ year⁻¹in the catchments with the least forest area. Land cover was a strong predictor of DIN concentration but less significant for predicting DIN export. The two forestedmore »reference catchments appeared supply limited, the most residential catchment appeared transport limited, and export for the other catchments was significantly related to discharge. In all streams, baseflow DIN export exceeded stormflow export. Morphological and climatological variation among watersheds created complexities unexplainable by land cover. Nevertheless, regression models developed using land cover data from the small catchments reasonably predicted concentration and export for receiving rivers. Our results illustrate the complexity of mechanisms involved in DIN export in a region with a mosaic of climate, geology, topography, soils, vegetation, and past and present land use.

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