Mixed Land Use and Obesity: An Empirical Comparison of Alternative Land Use Measures and Geographic Scales

Obesity is a growing epidemic in the United States. Walkable neighborhoods, characterized as having the three Ds of walkability (population Density, land use Diversity, and pedestrian-friendly Design), have been identified as a potentially promising factor to prevent obesity for residents. Past studies examining the relationship between obesity and walkability vary in geographic scales of neighborhood definitions and methods of measuring the three Ds. To better understand potential influences of these sometimes arbitrary choices, we test how four types of alternative measures of land use diversity measured at three geographic scales relate to body mass index for 4,960 Salt Lake County adults. Generalized estimation equation models demonstrate that optimal diversity measures differed by gender and geographic scale and that integrating walkability measures at different scales improved the overall performance of models.     

A land-use-based modelling chain to assess the impacts of Natural Water Retention Measures on Europe’s Green Infrastructure

This article details the process of integrating models to answer a specific policy-driven question: ‘What could be the impact of proposed Natural Water Retention Measures (NWRMs) on Europe’s Green Infrastructure (GI)?’ It describes the new Land Use Modelling Platform (LUMP), now enabling a high spatial scale (100-m) and large coverage (pan-European), whereby several sector-specific models contribute to assessing the impact of regional-level policy on a given spatial topic of concern. The configuration (land claims and land allocations modules) and calibration (accessibility and biophysical suitability) of the LUMP are explained. Four NWRM scenarios (riparian areas, afforestation, grassland and baseline scenario) are configured to run the simulations. For the reference: year 2006, the spatial representation of GI is based on land-use features of a refined version of the CORINE Land Cover (CLC), and resumed as connected components made of nodes and links.

Mathematical morphological image processing and network graph theory model, available from the free software package GUIDOS (the Joint Research Center of the European Commission), enabled the measurement of the GI connectivity and identified most critical links. Results show that the competition for land claimed by different economic sectors, combined with policy-driven rule-sets for the implementation of different NWRMs, yields very different results for the 2030 land-use projections, and subsequently for the morphology of GI. Three indicators associated with the morphology of GI are computed in order to assess the model outputs for 2030. The indicators are computed to answer the following questions: (1) How is the quantity of GI affected by each of the NWRM, and what proportion of that GI is most valuable? (2) What is the location of the most critical nodes and connectors of GI, and what land-use conversions occur under these? (3) Are the average components getting larger or smaller?

Whereas the grassland measure results in the largest net increase of GI, the afforestation measure results in the overall largest number of hectares of key nodes and links within the network. Land conversions occur under the critical GI nodes and links, with a large increase in agricultural areas, especially for the riparian measure under critical nodes and the grassland measure under critical links. Also predominant is the swapping of land from pasture to forest under critical links with the afforestation measure. The riparian measure most increases the average size of GI components, and all three measures contribute to bridging two large components which were divided in the 2006 land-use map, thus increasing the size of the largest component by more than 50%.     

Shifts in isotopic signatures of animals with complex life-cycles can complicate conclusions on cross-boundary trophic links

Stable isotopes (¹³C and ¹⁵N) are widely applied in studies of trophic links. We used this method to investigate the contribution of aquatic and terrestrial prey to the diet of riparian predatory arthropods in two mountain headwater streams in Colorado, USA. Aquatic and terrestrial prey and riparian predators were collected during summer 2009. To evaluate the reliability of conclusions based on stable isotope ratios, we compared the isotopic signatures of aquatic larval and terrestrial adult stages of three abundant stream insect species and assessed variation in mixing model estimates for spider diet composition under varying assumptions for trophic fractionation. Adult isotopic signatures of some aquatic prey species were indistinguishable from those of prey species with exclusively terrestrial life histories (stoneflies: ¹³C and ¹⁵N, chironomids: ¹³C). Other prey had distinctly aquatic isotopic signatures as both larvae and adults (a mayfly and a caddisfly). There was no evidence that prey with aquatic isotopic signatures contributed to the diet of the spiders near one stream. For the other stream, mixing model analysis suggested that chironomids were included in the diets of lycosid, linyphiid and liocranid spiders. Reliable estimates of the contributions of prey sources were compromised by the sensitivity of mixing models to assumptions on trophic fractionation and the presence of “isotopically cryptic” prey. This study emphasizes the importance of supporting isotope-based studies on cross-boundary trophic links with data on isotopic shifts in prey with complex life cycles and assessment of fractionation rates specific to the study system.     

Environmental changes in southeastern Amazonia during the last 25,000 yr revealed from a paleoecological record

New pollen, micro-charcoal, sediment and mineral analyses of a radiocarbon-dated sediment core from the Serra Sul dos Carajás (southeast Amazonia) indicate changes between drier and wetter climatic conditions during the past 25,000 yr, reflected by fire events, expansion of savanna vegetation and no-analog Amazonian forest communities. A cool and dry last glacial maximum (LGM) and late glacial were followed by a wet phase in the early Holocene lasting for ca. 1200 yr, when tropical forest occurred under stable humid conditions. Subsequently, an increasingly warm, seasonal climate established. The onset of seasonality falls within the early Holocene warm period, with possibly longer dry seasons from 10,200 to 3400 cal yr BP, and an explicitly drier phase from 9000 to 3700 cal yr BP. Modern conditions with shorter dry seasons became established after 3400 cal yr BP. Taken together with paleoenvironmental evidence from elsewhere in the Amazon Basin, the observed changes in late Pleistocene and Holocene vegetation in the Serra Sul dos Carajás likely reflect large-scale shifts in precipitation patterns driven by the latitudinal displacement of the Inter-Tropical Convergence Zone and changes in sea-surface temperatures in the tropical Atlantic.     

Oxygen isotopes from Chinese caves: records not of monsoon rainfall but of circulation regime

Oxygen isotope variations in Chinese stalagmites have been widely interpreted as a record of the amount of East Asian summer monsoonal rainfall. This interpretation infers decreasing monsoonal rainfall from the mid‐Holocene and large, dipolar rainfall oscillations within glaciations. However, the speleothem δ¹⁸O variations conflict with independent palaeoclimate proxies (cave δ¹³C, loess/palaeosol magnetic properties, δ¹³C alkanes), which indicate no systematic decline in rainfall from the mid‐Holocene, and no glacial rainfall maxima. Using mass balance calculations (which incorporate seasonality effects in both δ¹⁸O concentration and amount of precipitation), we demonstrate that the cave δ¹⁸O variations cannot be accounted for by summer rainfall changes, or rainfall seasonality or winter cooling, but instead reflect changes in moisture source. A possible driver of the δ¹⁸O variations in Chinese stalagmites is precessional forcing of inter‐hemispheric temperature gradients, and resultant shifts in the position and intensity of the subtropical pressure cells. Through such forcing, Indian monsoon‐sourced δ¹⁸O may have dominated at times of high boreal summer insolation, and local Pacific‐sourced moisture at low insolation. Suppression of summer monsoonal rainfall during glacial stages may reflect diminished sea and land surface temperatures and the radiative impacts of increased regional dust fluxes. Copyright © 2012 John Wiley & Sons, Ltd.     

Depositional history of the Tyne valley associated with retreat and stagnation of Late Devensian Ice Streams

This paper provides sedimentological and morphological data from an investigation of the Late Devensian glacigenic deposits along the Tyne valley, northeast England. The area lies in the central sector of the British-Irish Ice Sheet, with the lowlands influenced by both the Tyne Gap and Tweed-Cheviot ice streams. The sequences here provide insights into the existence of complex, multi-phase activity within the British-Irish Ice Sheet. Field mapping of the area reveals kamiform topography in the Tyne lowlands and lower South Tyne valley, whilst the mid Tyne is characterised by high-level sandur terraces. Inset below the glacial features are river terraces. The sedimentary sequence comprises diamicton overlain by gravel and sandy gravels; sands, muddy sands and gravels; laminated silty sands and muds; and well sorted sands and gravel. The depositional environments indicate ice-contact, subaqueous and terrestrial sedimentation, with supraglacial, proglacial, subaquatic and paraglacial landsystems. Following the onset of deglaciation, westward retreat of Tyne Gap ice resulted in land to the east and southeast of its margin becoming ice-free. Continued/renewed southward flow of ice along the North Sea coast formed a persistent barrier to sediment-charged meltwaters draining the Tyne Gap ice margin. The separation of these two ice masses allowed a glacial lake to develop in the lower Tyne fed by a large proglacial sandur system, which with ice marginal retreat subsequently merged with Glacial Lake Wear. The sediment sequences record the final waning of the Tyne Gap ice stream, and are contiguous with sediments that extend west through the Tyne Gap and into the Cumbrian lowlands.     

Monitoring and Modeling of Syringodium filiforme (Manatee Grass) in Southern Indian River Lagoon

Decreased salinity and submarine light associated with hurricanes of 2004?C2005 impacted seagrass habitats in the Florida coastal zone. A combination of salinities ??20 and light attenuation ??1.5?m^?1 resulting from the freshwater discharge in 2005 were among the drivers for a widespread decrease in the coverage and biomass of Syringodium filiforme (manatee grass) in 2006. These observations provided an opportunity to develop and apply a modeling framework to simulate responses of S. filiforme to variable water quality. The framework connects water column variables to field monitoring of seagrass abundance and salinity growth response experiments. The base model was calibrated with macrophyte abundance observed in southern Indian River Lagoon (IRL) from 2002 to 2007 and tested against shoot data from a different time (1997?C2002) and nearby location in the IRL. Model shoot biomass (gC?m^?2) was similar to field observations (r ²?=?0.70) while responding to monthly seasonal fluctuations in salinity and light throughout the 6-year simulations. Field and model results indicated that S. filiforme growth and survival were sensitive to, and increased with, rising salinity throughout 2007. This modeling study emphasizes that discharge, salinity, and submarine light are inter-dependent variables affecting South Florida seagrass habitats on seasonal to inter-annual time scales.     

Evolution of anthropogenic and biomass burning emissions of air pollutants at global and regional scales during the 1980�C2010 period

Several different inventories of global and regional anthropogenic and biomass burning emissions are assessed for the 1980?C2010 period. The species considered in this study are carbon monoxide, nitrogen oxides, sulfur dioxide and black carbon. The inventories considered include the ACCMIP historical emissions developed in support of the simulations for the IPCC AR5 assessment. Emissions for 2005 and 2010 from the Representative Concentration Pathways (RCPs) are also included. Large discrepancies between the global and regional emissions are identified, which shows that there is still no consensus on the best estimates for surface emissions of atmospheric compounds. At the global scale, anthropogenic emissions of CO, NO_x and SO₂ show the best agreement for most years, although agreement does not necessarily mean that uncertainty is low. The agreement is low for BC emissions, particularly in the period prior to 2000. The best consensus is for NO_x emissions for all periods and all regions, except for China, where emissions in 1980 and 1990 need to be better defined. Emissions of CO need better quantification in the USA and India for all periods; in Central Europe, the evolution of emissions during the past two decades needs to be better determined. The agreement between the different SO₂ emissions datasets is rather good for the USA, but better quantification is needed elsewhere, particularly for Central Europe, India and China. The comparisons performed in this study show that the use of RCP8.5 for the extension of the ACCMIP inventory beyond 2000 is reasonable, until more global or regional estimates become available. Concerning biomass burning emissions, most inventories agree within 50?C80%, depending on the year and season. The large differences between biomass burning inventories are due to differences in the estimates of burned areas from the different available products, as well as in the amount of biomass burned.     

Landscape response to tipping points in granite weathering: The case of stepped topography in the Southern Sierra Critical Zone Observatory

The dynamics of granitic landscapes are modulated by bimodal weathering, which produces patchy granular soils and expanses of bare rock ranging from meter-scale boulders to mountain-scale domes. We used terrain analysis and with cosmogenic nuclide measurements of erosion rates to quantitatively explore Wahrhaftig’s decades-old hypothesis for the development of “stepped topography” by differential weathering of bare and soil-mantled granite. According to Wahrhaftig’s hypothesis, bare granite weathers slower than soil-mantled granite; thus random erosional exposure of bare rock leads to an alternating sequence of steep, slowly weathering bedrock “steps” and gently sloped, but rapidly weathering, soil-mantled “treads.” Our investigation focused on the terrain surrounding the Southern Sierra Critical Zone Observatory (CZO), which is underlain by granitic bedrock and lies outside the limits of recent glaciation, in the heart of the stepped topography described by Wahrhaftig. Our digital terrain analysis confirms that steep steps often grade into gentle treads, consistent with Wahrhaftig’s hypothesis. However, we observe a mix-and-match of soil and bare rock on treads and steps, contrary to one of the hypothesis’ major underpinnings – that bare rock should be much more common on steps than on treads. Moreover, the data show that bare rock is not as common as expected at step tops; Wahrhaftig’s hypothesis dictates that step tops should act as slowly eroding base levels for the treads above them. The data indicate that, within each landscape class (i.e., the steps and treads), bare rock erodes more slowly than surrounding soil. This suggests that the coupling between soil production and denudation in granitic landscapes harbors a tipping point wherein erosion rates decrease when soils are stripped to bedrock. Although broadly consistent with the differential weathering invoked by Wahrhaftig, the data also show that steps are eroding faster than treads, undermining Wahrhaftig’s explanation for the origins of the steps. The revised interpretation proposed here is that the landscape evolves by back-wearing of steps in addition to differential erosion due to differences in weathering of bare and soil-mantled granite.     

On the use of IPCC-class models to assess the impact of climate on Living Marine Resources

The study of climate impacts on Living Marine Resources (LMRs) has increased rapidly in recent years with the availability of climate model simulations contributed to the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Collaboration between climate and LMR scientists and shared understanding of critical challenges for such applications are essential for developing robust projections of climate impacts on LMRs. This paper assesses present approaches for generating projections of climate impacts on LMRs using IPCC-class climate models, recommends practices that should be followed for these applications, and identifies priority developments that could improve current projections. Understanding of the climate system and its representation within climate models has progressed to a point where many climate model outputs can now be used effectively to make LMR projections. However, uncertainty in climate model projections (particularly biases and inter-model spread at regional to local scales), coarse climate model resolution, and the uncertainty and potential complexity of the mechanisms underlying the response of LMRs to climate limit the robustness and precision of LMR projections. A variety of techniques including the analysis of multi-model ensembles, bias corrections, and statistical and dynamical downscaling can ameliorate some limitations, though the assumptions underlying these approaches and the sensitivity of results to their application must be assessed for each application. Developments in LMR science that could improve current projections of climate impacts on LMRs include improved understanding of the multi-scale mechanisms that link climate and LMRs and better representations of these mechanisms within more holistic LMR models. These developments require a strong baseline of field and laboratory observations including long time series and measurements over the broad range of spatial and temporal scales over which LMRs and climate interact. Priority developments for IPCC-class climate models include improved model accuracy (particularly at regional and local scales), inter-annual to decadal-scale predictions, and the continued development of earth system models capable of simulating the evolution of both the physical climate system and biosphere. Efforts to address these issues should occur in parallel and be informed by the continued application of existing climate and LMR models.