Long-term research catchments to investigate shrub encroachment in the Sonoran and Chihuahuan deserts: Santa Rita and Jornada experimental ranges     

Enrique R. Vivoni  Eli R. Pérez-Ruiz  Zachary T. Keller  Eric A. Escoto  Ryan C. Templeton  Nolie P. Templeton  Cody A. Anderson  Adam P. Schreiner-McGraw  Luis A. Méndez-Barroso  Agustin Robles-Morua  Russell L. Scott  Steven R. Archer  Debra P. C. Peters 《水文研究》2021,35(2):e14031

Woody plant encroachment is a global phenomenon whereby shrubs or trees replace grasses. The hydrological consequences of this ecological shift are of broad interest in ecohydrology, yet little is known of how plant and intercanopy patch dynamics, distributions, and connectivity influence catchment-scale responses. To address this gap, we established research catchments in the Sonoran and Chihuahuan Deserts (near Green Valley, Arizona and near Las Cruces, New Mexico, respectively) that represent shrub encroachment in contrasting arid climates. Our main goals in the coordinated observations were to: (a) independently measure the components of the catchment water balance, (b) deploy sensors to quantify the spatial patterns of ecohydrological processes, (c) use novel methods for characterizing catchment properties, and (d) assess shrub encroachment impacts on ecohydrological processes through modelling studies. Datasets on meteorological variables; energy, radiation, and CO₂ fluxes; evapotranspiration; soil moisture and temperature; and runoff at various scales now extend to nearly 10 years of observations at each site, including both wet and dry periods. Here, we provide a brief overview of data collection efforts and offer suggestions for how the coordinated datasets can be exploited for ecohydrological inferences and modelling studies. Given the representative nature of the catchments, the available databases can be used to generalize findings to other catchments in desert landscapes.  相似文献   

Elsterian‐Holsteinian deposits at Kås Hoved,northern Denmark: sediments,foraminifera, ostracods,and stable isotopes     

Karen Luise Knudsen  Claus Ditlefsen  David N. Penney  Peter Kristensen  Christian Kronborg  Jón Eiríksson 《Boreas: An International Journal of Quaternary Research》2014,43(1):251-271

The coastal cliff section at Kås Hoved in northern Denmark represents one of the largest exposures of marine interglacial deposits in Europe. High‐resolution analyses of sediments, foraminifera, ostracods, and stable isotopes (oxygen and carbon) in glacial‐interglacial marine sediments from this section, as well as from two adjacent boreholes, are the basis for an interpretation of marine environmental and climatic change through the Late Elsterian‐Holsteinian glacial‐interglacial cycle. The overlying glacial deposits show two ice advances during the Saalian and Weichselian glaciations. The assemblages in the initial glacier‐proximal part of the marine Late Elsterian succession reveal fluctuations in the inflow of sediment‐loaded meltwater to the area. This is followed by faunal indication of glacier‐distal, open marine conditions, coinciding with a gradual climatic change from arctic to subarctic environments. Continuous marine sedimentation during the glacial‐interglacial transition is presumably a result of a large‐scale isostatic subsidence caused by the preceding extended Elsterian glaciation. The similarity of the climatic signature of the interglacial Holsteinian and Holocene assemblages in this region indicates that the Atlantic Ocean circulation was similar during these two interglacials, whereas Eemian interglacial assemblages indicate a comparatively high water temperature associated with an enhanced North Atlantic Current. The foraminiferal zones are correlated with other Elsterian‐Holsteinian sites in Denmark, as well as those in the type area for the Holsteinian interglacial in northern Germany and the southern North Sea. Correlation of the NW European Holsteinian succession with the marine isotope stages MIS 7, 9 or 11 is still unresolved.  相似文献   

Quantifying household social resilience: a place-based approach in a rapidly transforming community     

Sarah Henly-Shepard  Cheryl Anderson  Kimberly Burnett  Linda J. Cox  John N. Kittinger  Maka‘ala Ka‘aumoana 《Natural Hazards》2015,75(1):343-363

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Oceanographic observations on the Scotian Shelf during CASP     

Carl Anderson  Peter C. Smith 《大气与海洋》2013,51(1):130-156

Abstract

Winter‐time (1985–86) observations of sea‐level, surface waves, currents, bottom pressure, and water properties were made on the Scotian Shelf as part of the Canadian Atlantic Storms Program (CASP). The purpose of the field program and the locations, instrument systems, and sampling schemes are described.

Statistics on the observed currents are presented, and monthly estimates of the longshore transport of the Nova Scotian Current are given for four months spanning the winter season (December to March). The 1985–86 transports are compared with previous estimates of the baroclinic transport made using the dynamic method.

Cross‐shelf temperature and salinity distributions corresponding to the beginning and end of the field program are described and compared with the climatological means.

The autospectra of the observed currents exhibit energy concentrations at frequencies of 0.2–0.5, 1.0, 1.4 and 2.0 cycles per day (cpd). Coastal‐trapped wave motions account for significant portions of the energy in the two lowest frequency bands, forced by wind stress and the diurnal tide, respectively. Inertial oscillations generated by wind stress events predominate at 1.4 cpd, and the semidiurnal tide, at 2 cpd. These motions are described separately, and references to more detailed discussions are given.  相似文献   

A rose by any other name ...?: What members of the general public prefer to call “climate change”     

Karen Akerlof  Edward W. Maibach 《Climatic change》2011,106(4):699-710

Unlike many other environmental problems, the terms used to describe the phenomenon of increasing atmospheric concentrations of anthropogenic greenhouse gases are many, with multiple and sometimes conflicting meanings. Whether there are meaningful distinctions in public perceptions of “global warming,” “climate change,” and “global climate change” has been a topic of research over the past decade. This study examines public preferences for these terms based on respondent characteristics, including climate change beliefs, political affiliation, and audience segment status derived from the “Global Warming’s Six Americas” classification. Certainty of belief in global warming, political affiliation and audience segment status were found to be the strongest predictors of preference, although “I have no preference” was the modal response. Global warming appears to be a more polarizing term than climate change, preferred most by people already concerned about the issue, and least by people who don’t believe climate change is occurring. Further research is needed to identify which of these two names promotes the engagement of people across the spectrum of climate change beliefs in constructive dialogue about the issue.  相似文献   

Building resilience to climate change through development assistance: USAID’s climate adaptation program     

John Furlow  Joel B. Smith  Glen Anderson  William Breed  Jon Padgham 《Climatic change》2011,108(3):411-421

The topics of climate change and of what to do about it have been the subject of discussion for over two decades. Much of the focus has been on mitigating greenhouse gas emissions to reduce the rate and magnitude of changes. Adapting to the impacts of those changes has received much less attention. In recent years, the development assistance community has recognized that climate change poses a stress on economic and social development in poor countries and has turned its attention to addressing climate stress. The US Agency for International Development developed a methodology of working with stakeholders to identify sources of climate related vulnerability and approaches to reducing that vulnerability. The methodology was developed iteratively with several pilot studies looking at vulnerability and adaptation in different sectors and settings.  相似文献   

Spatial variability and temporal stability of throughfall in a eucalyptus plantation in the hilly lowlands of southeastern Brazil   总被引：2，自引：0，他引：2  

Anderson Mululo Sato  André de Souza Avelar  Ana Luiza Coelho Netto 《水文研究》2011,25(12):1910-1923

Throughfall has been widely studied in forests but there is a scarcity of studies that focus on the spatial variability and temporal stability of throughfall in eucalyptus plantations. We examined throughfall in a daily basis in a 2·5‐year eucalyptus plantation in southeastern Brazil using three sample arrangements: (1) close to tree trunks (CT) and in the central point between trunks (BT), (2) four‐radial layout centred in tree trunk and (3) eight‐radial layout. Throughfall was spatially non‐uniform and varied according to the spatial monitoring arrangement: accumulated throughfall/precipitation ratio of 146% (CT) and 85% (BT) in arrangement 1, mean throughfall of 88% in arrangement 2, 84% (hilltop) and 85% (side slope) in arrangement 3. The highest throughfall values, spatial variability and persistence of dry and wet conditions were found close to eucalyptus trunks. Often accumulated throughfall close to trunks exceeded rainfall, especially for long‐duration rainfall > 5 mm. The ‘funnel effect’ was consistently observed in all three arrangements and we speculate that the high throughfall concentration and temporal stability are related to canopy structures of eucalyptus. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

C 1s K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy for characterizing functional group chemistry of black carbon     

Karen Heymann  Johannes Lehmann  Dawit Solomon  Michael W.I. Schmidt  Thomas Regier 《Organic Geochemistry》2011,42(9):1055-1064

Black carbon (BC) is considered ubiquitous in soil organic matter (OM) and therefore plays an important role in soil biogeochemistry. Its complexity, particularly within environmental matrices, presents a challenge for research, primarily as a result of techniques which may favor detection of certain functional group types rather than capturing total sample C. The objective of this study was to utilize carbon (C) 1s near edge X-ray absorption fine edge structure (NEXAFS) spectroscopy to characterize the C chemistry of a broad range of BC materials. Characteristic resonances in the NEXAFS spectra allowed direct molecular speciation of the total C chemistry of the reference materials, environmental matrices and potentially interfering materials, obtained from an earlier BC ring trial. Spectral deconvolution was used to further identify the functional group distribution of the materials. BC reference materials and soils were characterized by a large aromatic C region comprising around 40% of total absorption intensity. We were able to distinguish shale and melanoidin from BC reference materials on the basis of their unique spectral characteristics. However, bituminous coal shared chemical characteristics with BC reference materials, namely high aromaticity of more than 40% identified by way of a broad peak. Lignite also shared similar spectra and functional group distributions to BC reference materials and bituminous coal. We compared the results of spectral deconvolution with the functional group distributions obtained by way of direct polarization magic angle spinning (DPMAS) ¹³C nuclear magnetic resonance (NMR) spectroscopy. Correlations between aromatic type C values for DPMAS ¹³C NMR and NEXAFS gave r² = 0.633 (p < 0.05) and the values for NEXAFS were around 30–40% lower than for ¹³C NMR. Correlations were also drawn between the aromatic C/O-alkyl C ratio values for the two methods (r² = 0.49, p < 0.05). Overall, NEXAFS was applicable for a wide range of environmental materials, such as those measured, although some limitations for the technique were addressed.  相似文献   

Exploring links between vadose zone hydrology and chemical weathering in the Boulder Creek critical zone observatory     

Abigail L. Langston  Gregory E. Tucker  Robert S. Anderson  Suzanne P. Anderson 《Applied Geochemistry》2011

Understanding the relationship between subsurface flow paths on hillslopes and chemical weathering of bedrock is fundamental to understanding the timing and mechanisms that weather bedrock to saprolite. The link between chemical weathering of bedrock and contact time with reactive water along flow paths motivates this study. Water drives the chemical alteration of rock into saprolite, yet connected porosity generally declines with depth into the weathered profile. Saprolite formation, therefore, reflects coupled weathering and permeability development over time. This study uses numerical modeling and soil-moisture monitoring to explore the hydrology of the unsaturated zone and the influence of fracture density, hillslope gradient, and permeability contrasts within the saprolite development horizon on saprolite development.  相似文献   

Web 2.0 collaborations address uncertainty in climate reconstructions of the past millennium     

David Morrill Anderson  Bruce A. Bauer  Charles R. Buckner  Edward Gille  Wendy S. Gross  Michael Hartman  Carrie Morrill  Anju M. Shah  Eugene R. Wahl 《Earth Science Informatics》2011,4(4):161-167

Reducing uncertainty in global temperature reconstructions of the past millennium remains the key issue in applying this record to society’s pressing climate change problem. Reconstructions are collaborative, built on the research of hundreds of scientists who apply their diverse scientific expertise and field and laboratory skill to create the individual proxy reconstructions that underlie the multi-proxy, global average temperature time series. Web 2.0 features have enabled collaborative efforts that improve the characterization of uncertainty. Raw data shared via a repository (the World Data Center for Paleoclimatology) enable new reconstructions from the collection of user-generated data. Standards propagated by expert communities facilitate quality control and interoperability. Open access to data and computer code promote transparency and make the science accessible to a broader audience. Blogs, wikis, and listservs share background information and highlight contentious as well as unique aspects of paleo science. A novel approach now underway, titled the Paleoclimate Reconstruction Challenge, and based on the sharing of simulated data (pseudo-proxies) and reconstruction results, seeks to facilitate method development, further reducing uncertainty. Broadly-useful aspects of the Challenge may find application in other fields.  相似文献