The impact of spatial scale: exploring urban butterfly abundance and richness patterns using multi-criteria decision analysis and principal component analysis     

Emily C. Hazell  Claus Rinner 《International journal of geographical information science》2020,34(8):1648-1681

ABSTRACT

Modelling changes in biodiversity have become a necessary component of smart urban planning practices. However, concepts such as biodiversity are often evaluated using area-based composite indices, the results of which are heavily reliant on specific parameters chosen. This paper explores the design and implementation of a butterfly biodiversity index by comparing two widely accepted modelling techniques: principal component analysis and spatial multi-criteria decision analysis (MCDA). A high degree of scale dependency has been demonstrated in previous studies exploring the use of area-based composite measures. To evaluate the impact of scale, each model was assessed at two different spatial resolutions. The outcomes were analyzed, mapped and compared using ordinary least squares, geographically weighted regression and global Moran’s I to evaluate relative biodiversity patterns across the City of Toronto, Canada. Findings indicate that the impact of spatial scale was significant, whereby the coarser resolution models were found to be more highly correlated with biodiversity, compared to the finer resolution models. The results of this study contribute to a growing body of literature that explores key conceptual questions regarding the robustness of GIS-based MCDA, the impact of scale in urban ecology studies, and the use of composite indices to manage spatial ecological data.  相似文献   

Fifty years of runoff response to conversion of old-growth forest to planted forest in the H. J. Andrews Forest,Oregon, USA     

Emily A. Crampe  Catalina Segura  Julia A. Jones 《水文研究》2021,35(5):e14168

Long-term watershed experiments provide the opportunity to understand forest hydrology responses to past logging, road construction, forest regrowth, and their interactions with climate and geomorphic processes such as road-related landslides. We examined a 50-year record from paired-watershed experiments in the H. J. Andrews Experimental Forest, Oregon, USA in which 125 to 450-year-old conifer forests were harvested in the 1960s and 1970s and converted to planted conifer forests. We evaluated how quickflow and delayed flow for 1222 events in treated and reference watersheds changed by season after clearcutting and road construction, including 50 years of growth of planted forest, major floods, and multi-decade reductions in snowpack. Quickflow runoff early in the water year (fall) increased by up to +99% in the first decade, declining to below pre-harvest levels (−1% to −15%) by the third to fifth decade after clearcutting. Fall delayed flow responded more dramatically than quickflow and fell below pre-treatment levels in all watersheds by the fifth decade, consistent with increased transpiration in the planted forests. Quickflow increased less (+12% to 70%) during the winter and spring but remained higher than pre-treatment levels throughout the fourth or fifth decade, potentially impacted by post-harvest burning, roads, and landslides. Quickflow remained high throughout the 50-year period of study, and much higher than delayed flow in the last two decades in a watershed in which road-related changes in flow routing and debris flows after the flood of record increased network connectivity. A long-term decline in regional snowpack was not clearly associated with responses of treated vs. reference watersheds. Hydrologic processes altered by harvest of old-growth conifer forest more than 50 years ago (transpiration, interception, snowmelt, and flow routing) continued to modify streamflow, with no clear evidence of hydrologic recovery. These findings underscore the importance of continued long-term watershed experiments.  相似文献   

The Community Economic Impacts of Large Wildfires: A Case Study from Trinity County,California     

Emily Jane Davis  Cassandra Moseley  Max Nielsen-Pincus  Pamela J. Jakes 《社会与自然资源》2014,27(9):983-993

Wildfires are increasing in severity and frequency in the American West, but there is limited understanding of their economic effects at the community level. We conducted a case study of the impacts of large wildfires in 2008 in Trinity County, California, by examining labor market, suppression spending, and qualitative interview data. We found that the 2008 fires had interrelated effects on several economic sectors in the county. Labor market data indicated a decrease in total private-sector employment and wages and an increase in public-sector employment and wages during the summer of 2008 compared to the previous year, while interviews captured more nuanced impacts for individual businesses.  相似文献   

Stability of YREE complexes with the trihydroxamate siderophore desferrioxamine B at seawater ionic strength     

Emily A. Christenson 《Geochimica et cosmochimica acta》2011,75(22):7047-7062

Organic complexation of yttrium and the rare earth elements (YREEs), although generally believed to be important, is an understudied aspect of YREE solution speciation in the open ocean. We report the first series of stability constants for complexes of YREEs (except Ce and Pm) with the trihydroxamate siderophore desferrioxamine B (DFOB), representing a class of small organic ligands that have an extraordinary selectivity for Fe(III) and are found in surface seawater at low-picomolar concentrations. Constants were measured by potentiometric titration of DFOB (pH 3-10) in the presence of single YREEs, in simple media at seawater ionic strength (NaClO₄ or NaCl, I = 0.7 M). Under these circumstances, the terminal amine of DFOB does not deprotonate. The four acid dissociation constants of the siderophore were determined separately by potentiometric titration of DFOB alone.Values for the bidentate (log β₁), tetradentate (log β₂), and hexadentate (log β₃) complexes of La-Lu range from 4.88 to 6.53, 7.70 to 11.27, and 10.09 to 15.19, respectively, while Y falls between Gd and Tb in each case. Linear free-energy relations of the three stability constants with the first YREE hydrolysis constant, log , yield regression coefficients of >0.97. On the other hand, plots of the constants vs. the radius of the inner hydration sphere display an increasing deviation from linearity for the lightest REEs (La > Pr > Nd). This may signify steric constraints in DFOB folding around bulkier cations, a larger mismatch in coordination number, or a substantial degree of covalence in the YREE-hydroxamate bond.Complexes of the YREEs with DFOB are many orders of magnitude more stable than those with carbonate, the dominant inorganic YREE ligand in seawater. Speciation modeling with MINEQL indicates that, for an average seawater composition, the hexadentate complex could constitute as much as 28% of dissolved Lu at free DFOB concentrations as low as 10⁻¹³ M. Such conditions might occur when DFOB or other siderophores are present in excess over metals for which they have high affinity, like Fe(III) and Co(III), for example during plankton blooms. Even if it turns out that trihydroxamate siderophores are not the dominant organic YREE ligand in seawater, our results establish a benchmark for producing effects on YREE solution speciation comparable to that of DFOB: the free concentration of any weaker organic ligand L must exceed that of DFOB by a factor β₃/_Lβ₁, assuming its first order complex is formed in greatest abundance.  相似文献   

Is denitrification kinetically-limited or transport-limited in tidal freshwater marshes?     

Emily Seldomridge  Karen Prestegaard 《Applied Geochemistry》2011

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Isotopic Determination of Food Web Origins in Restoring and Ancient Estuarine Wetlands of the San Francisco Bay and Delta   总被引：1，自引：0，他引：1  

Emily R. Howe  Charles A. Simenstad 《Estuaries and Coasts》2011,34(3):597-617

We compared the extent to which ancient and restoring wetlands in three estuary regions of San Francisco Bay support estuarine ecosystems through food web contributions. In comparison to mature marshes, we hypothesized that food webs of increasingly younger restoration sites would display increased dependency upon allochthonous subsidies due to nominal internal production. Using multiple stable isotopes (δ¹³C, δ¹⁵N, δ³⁴S) in a mixing model, we traced links among primary producers and estuarine consumers. Results indicate that food webs of estuarine marshes are heavily dependent upon autochthonous marsh materials (76 ± 17%), even within the youngest restoration marshes (11 years). Nearly all sampled organisms relied upon autochthonous marsh materials, with the exception of Neomysis kadiakensis, a mysid shrimp, which derived the majority of its support from freshwater-produced phytoplankton. Marsh-derived organic matter (OM) support was consistent both temporally throughout the year and spatially along the three estuary regions, but evidence suggests that the specific type of OM supporting estuarine consumers depends on position along the estuarine gradient and on seasonal shifts in freshwater flow. These results indicate that wetland restoration rapidly provides important contributions to marsh consumers and potentially bolsters food web linkages in shallow-water ecosystems.  相似文献   

CFSv2 ensemble prediction of the wintertime Arctic Oscillation     

Emily E. Riddle  Amy H. Butler  Jason C. Furtado  Judah L. Cohen  Arun Kumar 《Climate Dynamics》2013,41(3-4):1099-1116

Lagged ensembles from the operational Climate Forecast System version 2 (CFSv2) seasonal hindcast dataset are used to assess skill in forecasting interannual variability of the December–February Arctic Oscillation (AO). We find that a small but statistically significant portion of the interannual variance (>20 %) of the wintertime AO can be predicted at leads up to 2 months using lagged ensemble averages. As far as we are aware, this is the first study to demonstrate that an operational model has discernible skill in predicting AO variability on seasonal timescales. We find that the CFS forecast skill is slightly higher when a weighted ensemble is used that rewards forecast runs with the most accurate representations of October Eurasian snow cover extent (SCE), hinting that a stratospheric pathway linking October Eurasian SCE with the AO may be responsible for the model skill. However, further analysis reveals that the CFS is unable to capture many important aspects of this stratospheric mechanism. Model deficiencies identified include: (1) the CFS significantly underestimates the observed variance in October Eurasian SCE, (2) the CFS fails to translate surface pressure anomalies associated with SCE anomalies into vertically propagating waves, and (3) stratospheric AO patterns in the CFS fail to propagate downward through the tropopause to the surface. Thus, alternate boundary forcings are likely contributing to model skill. Improving model deficiencies identified in this study may lead to even more skillful predictions of wintertime AO variability in future versions of the CFS.  相似文献   

Multi-object near-infrared Hα spectroscopy of z∼ 1 star-forming galaxies in the Hubble Deep Field North     

Michelle Doherty  rew Bunker  Robert Sharp  Gavin Dalton  Ian Parry  Ian Lewis  Emily MacDonald  Christian Wolf  Hans Hippelein 《Monthly notices of the Royal Astronomical Society》2004,354(1):L7-L12

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Reduction of Manganese Oxides: Thermodynamic,Kinetic and Mechanistic Considerations for One- Versus Two-Electron Transfer Steps     

George W. LutherIII  Aubin Thibault de Chanvalon  Véronique E. Oldham  Emily R. Estes  Bradley M. Tebo  Andrew S. Madison 《Aquatic Geochemistry》2018,24(4):257-277

Manganese oxides, typically similar to δ-MnO₂, form in the aquatic environment at near neutral pH via bacterially promoted oxidation of Mn(II) species by O₂, as the reaction of [Mn(H₂O)₆]²⁺ with O₂ alone is not thermodynamically favorable below pH of ~?9. As manganese oxide species are reduced by the triphenylmethane compound leucoberbelein blue (LBB) to form the colored oxidized form of LBB (λ_max?=?623 nm), their concentration in the aquatic environment can be determined in aqueous environmental samples (e.g., across the oxic–anoxic interface of the Chesapeake Bay, the hemipelagic St. Lawrence Estuary and the Broadkill River estuary surrounded by salt marsh wetlands), and their reaction progress can be followed in kinetic studies. The LBB reaction with oxidized Mn solids can occur via a hydrogen atom transfer (HAT) reaction, which is a one-electron transfer process, but is unfavorable with oxidized Fe solids. HAT thermodynamics are also favorable for nitrite with LBB and MnO₂ with ammonia (NH₃). Reactions are unfavorable for NH₄⁺ and sulfide with oxidized Fe and Mn solids, and NH₃ with oxidized Fe solids. In laboratory studies and aquatic environments, the reduction of manganese oxides leads to the formation of Mn(III)-ligand complexes [Mn(III)L] at significant concentrations even when two-electron reductants react with MnO₂. Key reductants are hydrogen sulfide, Fe(II) and organic ligands, including the siderophore desferioxamine-B. We present laboratory data on the reaction of colloidal MnO₂ solutions (λ_max?~?370 nm) with these reductants. In marine waters, colloidal forms of Mn oxides (<?0.2 µm) have not been detected as Mn oxides are quantitatively trapped on 0.2-µm filters. Thus, the reactivity of Mn oxides with reductants depends on surface reactions and possible surface defects. In the case of MnO₂, Mn(IV) is an inert cation in octahedral coordination; thus, an inner-sphere process is likely for electrons to go into the empty e _g ^* conduction band of its orbitals. Using frontier molecular orbital theory and band theory, we discuss aspects of these surface reactions and possible surface defects that may promote MnO₂ reduction using laboratory and field data for the reaction of MnO₂ with hydrogen sulfide and other reductants.  相似文献   

Seasonal-Scale and Decadal-Scale Sediment-Vegetation Interactions on the Subaqueous Susquehanna River Delta,Upper Chesapeake Bay     

Emily R. Russ  Cindy M. Palinkas 《Estuaries and Coasts》2018,41(7):2092-2104

Submersed aquatic vegetation (SAV) have been a prominent feature on the Susquehanna Flats, the shallow, subaqueous delta of the Susquehanna River, Maryland. SAV were absent from the Flats between 1972 and 2000, but have since recovered. While it is well established that SAV can improve water quality by promoting sediment and nutrient retention, it is not well understood how SAV on the Flats modulate sediment input from the Susquehanna River into the Upper Chesapeake Bay over different timescales. This study evaluates sedimentation on the Flats over seasonal to decadal timescales, using naturally occurring radioisotopes (⁷Be, ²¹⁰Pb) within the context of SAV biomass and Flats geomorphology. Results indicate that sedimentation on the Flats is both spatially and temporally variable. Although this variability cannot be explained by relationships with grain size and SAV biomass, river discharge, sediment supply, and geometry over the SAV bed likely control sedimentation in this system. Decadal-scale sedimentation is influenced by both flood events and changes in SAV biomass abundance. Average annual sediment accumulation was higher when SAV were present than when SAV were absent. SAV bed area was strongly correlated with average annual accumulation rate. These results suggest that a positive feedback between SAV abundance and accumulation rate exists; however, sediment supply and transport pathways are also important factors.  相似文献