• Authors:
    • Xiao, C. Y.
    • Dunlap, R. E.
    • McCright, A. M.
  • Source: CLIMATIC CHANGE
  • Volume: 119
  • Issue: 2
  • Year: 2013
  • Summary: Given the well-documented campaign in the USA to deny the reality and seriousness of anthropogenic climate change (a major goal of which is to "manufacture uncertainty" in the minds of policy-makers and the general public), we examine the influence that perception of the scientific agreement on global warming has on the public's beliefs about global warming and support for government action to reduce emissions. A recent study by Ding et al. (Nat Clim Chang 1:462-466, 2011) using nationally representative survey data from 2010 finds that misperception of scientific agreement among climate scientists is associated with lower levels of support for climate policy and beliefs that action should be taken to deal with global warming. Our study replicates and extends Ding et al. (Nat Clim Chang 1:462-466, 2011) using nationally representative survey data from March 2012. We generally confirm their findings, suggesting that the crucial role of perceived scientific agreement on views of global warming and support for climate policy is robust. Further, we show that political orientation has a significant influence on perceived scientific agreement, global warming beliefs, and support for government action to reduce emissions. Our results suggest the importance of improving public perception of the scientific agreement on global warming, but in ways that do not trigger or aggravate ideological or partisan divisions.
  • Authors:
    • Don, A.
    • Poeplau, C.
  • Source: GEODERMA
  • Volume: 192
  • Year: 2013
  • Summary: Land-use changes (WC) influence the balance of soil organic carbon (SOC) and hence may cause CO2 emissions or sequestration. In Europe there is a side by side of LUC types that lead to SOC loss or SOC accumulation. However, there is a lack of studies covering all major LUC types to investigate qualitative and quantitative LUC effects on SOC. In this study we sampled 24 paired sites in Europe to a depth of 80 cm, covering a wide range of pedo-climatic conditions and comprising the major European LUC types cropland to grassland, grassland to cropland, cropland to forest and grassland to forest To assess qualitative changes and the sensitivity of different functional SOC pools with distinct turnover times, we conducted a fractionation to isolate five different fractions of SOC. The mean SOC stock changes after LUC were 18 +/- 11 Mg ha(-1) (cropland to grassland), 21 +/- 13 Mg ha(-1) (cropland to forest), -19 +/- 7 Mg ha(-1) (grassland to cropland) and 10 +/- 7 Mg ha(-1) (grassland to forest) with the main changes occurring in the topsoil (0-30 cm depth). However, subsoil carbon stocks ( >30 cm depth) were also affected by LUC, at 19 out of 24 sites in the same direction as the topsoil. LUC promoting subsoil SOC accumulation might be a sustainable C sink Particulate organic matter (POM) was found to be most sensitive to LUC After cropland afforestation. POM accounted for 50% (9.1 +/- 2.3 Mg ha(-1)) of the sequestered carbon in 0-30 cm: after grassland afforestation POM increased on average by 5 +/- 23 Mg ha(-1), while all other fractions depleted. Thus, afforestations shift SOC from stable to labile pools. The resistant fraction comprising the so-called inert carbon was found to be only slightly less sensitive than the total SOC pool, suggesting that an inert carbon pool was not chemically extracted with NaOCl oxidation, if there is any inert carbon.
  • Authors:
    • Arbuckle,J. Gordon, Jr.
    • Morton,Lois Wright
    • Hobbs,Jon
  • Source: Climatic Change
  • Volume: 118
  • Issue: 3-4
  • Year: 2013
  • Summary: Agriculture is both vulnerable to climate change impacts and a significant source of greenhouse gases. Increasing agriculture's resilience and reducing its contribution to climate change are societal priorities. Survey data collected from Iowa farmers are analyzed to answer the related research questions: (1) do farmers support adaptation and mitigation actions, and (2) do beliefs and concerns about climate change influence those attitudes. Results indicate that farmers who were concerned about the impacts of climate change on agriculture and attributed it to human activities had more positive attitudes toward both adaptive and mitigative management strategies. Farmers who believed that climate change is not a problem because human ingenuity will enable adaptations and who did not believe climate change is occurring or believed it is a natural phenomenon-a substantial percentage of farmers-tended not to support mitigation.
  • Authors:
    • Maynard, N. G.
    • Huntington, H. P.
    • Chapin, F. S.
    • Tom, S.
    • Pungowiyi, C.
    • Huntington, O. H.
    • Cochran, P.
    • Trainor, S. F.
  • Source: Research Article
  • Volume: 120
  • Issue: 3
  • Year: 2013
  • Summary: Despite a keen awareness of climate change, northern Indigenous Peoples have had limited participation in climate-change science due to limited access, power imbalances, and differences in worldview. A western science emphasis on facts and an indigenous emphasis on relationships to spiritual and biophysical components indicate important but distinct contributions that each knowledge system can make. Indigenous communities are experiencing widespread thawing of permafrost and coastal erosion exacerbated by loss of protective sea ice. These climate-induced changes threaten village infrastructure, water supplies, health, and safety. Climate-induced habitat changes associated with loss of sea ice and with landscape drying and extensive wildfires interact with northern development to bring both economic opportunities and environmental impacts. A multi-pronged approach to broadening indigenous participation in climate-change research should: 1) engage communities in designing climate-change solutions; 2) create an environment of mutual respect for multiple ways of knowing; 3) directly assist communities in achieving their adaptation goals; 4) promote partnerships that foster effective climate solutions from both western and indigenous perspectives; and 5) foster regional and international networking to share climate solutions.
  • Authors:
    • Iqbal,Javed
    • Nelson,Jim A.
    • McCulley,Rebecca L.
  • Source: Plant and Soil
  • Volume: 364
  • Issue: 1-2
  • Year: 2013
  • Summary: Novel fungal endophyte (Neotyphodium coenophialum; Latch, Christensen and Samuels; Glenn, Bacon, and Hanlin) genotypes in symbiosis with tall fescue (Lolium arundinaceum; Schreb. Darbysh.) have been recently introduced to agricultural seed markets. These novel endophytes do not produce the full suite of toxins that the 'common toxic' form does, and therefore, may not have the same consequences on plant and soil processes. Here, we evaluated the effects of endophyte presence and genotype on ecosystem processes of tall fescue stands. We quantified the effects of the presence of the common toxic endophyte (CT), two novel endophyte genotypes (AR-542, AR-584), no endophyte (endophyte free, E-), and a mixture of all endophyte statuses (mix) within a single genotype of tall fescue (PDF) on various soil and plant parameters. Endophyte presence and genotype affected tall fescue cover and plant species diversity: cover-CT, AR-542, AR -584, mix > E- and species diversity-E- > AR-542, AR -584 > CT, mix. Most measured soil parameters had significant endophyte effects. For example, higher fluxes of soil CO2 and N2O were measured from stands of AR-542 than from the other endophyte treatments. These results indicate that endophyte presence and genetic identity are important in understanding the ecosystem-scale effects of this agronomically important grass-fungal symbiosis.
  • Authors:
    • Mano,Yoshiro
    • Omori,Fumie
  • Source: Plant and Soil
  • Volume: 370
  • Issue: 1-2
  • Year: 2013
  • Summary: The teosinte Zea nicaraguensis, which is adapted to frequently flooded lowlands, is considered a valuable germplasm resource for the development of flooding-tolerant maize. This species can form constitutive root aerenchyma under well-drained conditions. The objectives of this study were to screen Z. nicaraguensis accessions for the capacity to form constitutive aerenchyma, to obtain progeny with differing degrees of aerenchyma formation, and to compare the flooding tolerance of these progeny. We evaluated constitutive aerenchyma formation in the root cortex of seedlings of eight accessions and several segregating populations of Z. nicaraguensis. We also evaluated flooding tolerance in lines selected for high or low degrees of constitutive aerenchyma formation. Seedlings of the eight accessions showed an extremely wide and continuous range of variation in aerenchyma formation. By phenotypic selection within two accessions, we obtained lines with either high or low degrees of constitutive aerenchyma formation. The lines selected for a higher degree of formation showed relatively high flooding tolerance evaluated by shoot dry weight ratio (flooded:control) than those with a lower degree of formation. A greater capacity to form constitutive aerenchyma can enhance flooding tolerance.
  • Authors:
    • Fierer,Noah
    • Ladau,Joshua
    • Clemente,Jose C.
    • Leff,Jonathan W.
    • Owens,Sarah M.
    • Pollard,Katherine S.
    • Knight,Rob
    • Gilbert,Jack A.
    • McCulley,Rebecca L.
  • Source: Science
  • Volume: 342
  • Issue: 6158
  • Year: 2013
  • Summary: Native tallgrass prairie once dominated much of the midwestern United States, but this biome and the soil microbial diversity that once sustained this highly productive system have been almost completely eradicated by decades of agricultural practices. We reconstructed the soil microbial diversity that once existed in this biome by analyzing relict prairie soils and found that the biogeographical patterns were largely driven by changes in the relative abundance of Verrucomicrobia, a poorly studied bacterial phylum that appears to dominate many prairie soils. Shotgun metagenomic data suggested that these spatial patterns were associated with strong shifts in carbon dynamics. We show that metagenomic approaches can be used to reconstruct below-ground biogeochemical and diversity gradients in endangered ecosystems; such information could be used to improve restoration efforts, given that even small changes in below-ground microbial diversity can have important impacts on ecosystem processes.
  • Authors:
    • Kelley, J. J.
    • Tans, P. P.
    • Sweeney, C.
    • Welp, L. R.
    • Wofsy, S. C.
    • Stephens, B. B.
    • Patra, P. K.
    • Piper, S. C.
    • Keeling, R. F.
    • Graven, H. D.
    • Daube, B. C.
    • Kort, E. A.
    • Santoni, G. W.
    • Bent, J. D.
  • Source: Report
  • Volume: 341
  • Issue: 6150
  • Year: 2013
  • Summary: Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45 degrees to 90 degrees N but by less than 25% for 10 degrees to 45 degrees N. An increase of 30 to 60% in the seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear to signal large ecological changes in northern forests and a major shift in the global carbon cycle.
  • Authors:
    • Holden, Z. A.
    • Abatzoglou, J. T.
    • Luce, C. H.
  • Source: Article
  • Volume: 342
  • Issue: 6164
  • Year: 2013
  • Summary: Trends in streamflow timing and volume in the Pacific Northwest United States have been attributed to increased temperatures, because trends in precipitation at lower-elevation stations were negligible. We demonstrate that observed streamflow declines are probably associated with declines in mountain precipitation, revealing previously unexplored differential trends. Lower-troposphere winter (November to March) westerlies are strongly correlated with high-elevation precipitation but weakly correlated with low-elevation precipitation. Decreases in lower-tropospheric winter westerlies across the region from 1950 to 2012 are hypothesized to have reduced orographic precipitation enhancement, yielding differential trends in precipitation across elevations and contributing to the decline in annual streamflow. Climate projections show weakened lower-troposphere zonal flow across the region under enhanced greenhouse forcing, highlighting an additional stressor that is relevant for climate change impacts on hydrology.
  • Authors:
    • Hussain, I.
    • Olson, K. R.
  • Source: Pakistan Journal of Botany
  • Volume: 44
  • Issue: 2
  • Year: 2012
  • Summary: Adoption of conservation tillage resulted in changes in soil properties, soil organic matter, soil nutrients. These soil variables were strongly correlated and could not be explained independently by the univariate analysis. The objectives of the study were to use the factor analysis for the identification of the factor pattern in soil properties and to examine the changes in factor scores in no-till (NT), chisel plow (CP) and moldboard plow (MP) tillage systems at different depths after 8 years of the tillage application and planting of corn and soybean on a sloping and previously eroded with a root restricting fragipan Grantsburg soil. The soil samples from the 0 to -5 and -5 to -15 cm soil depths were analyzed for the Ca, Mg, K, P, aggregate stability, particulate organic C, N and humified organic C and N. With factor analysis, 13 highly correlated soil variables were grouped into three different uncorrelated factors, which accounted for the 78% total variance of the data. The soil organic factor had high variable loading on aggregate stability, soil organic C and N contents in soil, POM and humified organic fractions. This factor varied between tillage and represented the accumulation of soil organic matter and its effect on aggregation because of the adoption of tillage. The soil exchange factor had high variable loading for the extractable Ca, Mg and CEC, and varied with tillage and depth because of mixing due to plowing and stratification due to use of no-till treatment. The soil nutrient factor had high variable loading on soil K and P and soil pH and varied between tillage treatments. The nutrient factor scores were also affected by fertilizer application and its mixing by plowing in CP and MP. No-till, which lacks mixing, resulted in decrease in availability of nutrients. This technique enables us to combine the correlated soil variables into three different groups and assess the impact of soil management systems, soil depths and sampling years on these factors. In the NT, lack of tillage, resulted in stratification of exchangeable bases, reduced availability of nutrients. However, it contributed to the maintenance of soil organic matter and soil aggregation. The mixing of soil with plowing resulted in the uniform nutrient availability and exchange capacity of soil in plow layer with the CP and MP systems. The plowing affected soil aggregation adversely due to decomposition of soil organic matter and making soil more susceptible to erosion. The crop yield of maize and soybean were higher with NT system than with CP and MP systems.