• Authors:
    • Tett, S. F. B.
    • Mineter, M. J.
    • Rivington, M.
    • Harding, A. E.
  • Source: CLIMATIC CHANGE
  • Volume: 128
  • Issue: 1-2
  • Year: 2015
  • Summary: Five stakeholder-relevant indices of agro-meteorological change were analysed for the UK, over past (1961-1990) and future (2061-2090) periods. Accumulated Frosts, Dry Days, Growing Season Length, Plant Heat Stress and Start of Field Operations were calculated from the E-Obs (European Observational) and HadRM3 (Hadley Regional Climate Model) PPE (perturbed physics ensemble) data sets. Indices were compared directly and examined for current and future uncertainty. Biases are quantified in terms of ensemble member climate sensitivity and regional aggregation. Maps of spatial change then provide an appropriate metric for end-users both in terms of their requirements and statistical robustness. A future UK is described with fewer frosts, fewer years with a large number of frosts, an earlier start to field operations (e.g., tillage), fewer occurrences of sporadic rainfall, more instances of high temperatures (in both the mean and upper range), and a much longer growing season.
  • Authors:
    • Dondini,M.
    • Jones,E. O.
    • Richards,M.
    • Pogson,M.
    • Rowe,R. L.
    • Keith,A. M.
    • Perks,M. P.
    • McNamara,N. P.
    • Smith,J. U.
    • Smith,P.
  • Source: Global Change Biology
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: Understanding and predicting the effects of land-use change to short rotation forestry (SRF) on soil carbon (C) is an important requirement for fully assessing the C mitigation potential of SRF as a bioenergy crop. There is little current knowledge of SRF in the UK and in particular a lack of consistent measured data sets on the direct impacts of land use change on soil C stocks. The ECOSSE model was developed to simulate soil C dynamics and greenhouse gas (GHG) emissions in mineral and organic soils. The ECOSSE model has already been applied spatially to simulate land-use change impacts on soil C and GHG emissions. However, it has not been extensively evaluated under SRF. Eleven sites comprising 29 transitions in Britain, representing land-use change from nonwoodland land uses to SRF, were selected to evaluate the performance of ECOSSE in predicting soil C and soil C change in SRF plantations. The modelled C under SRF showed a strong correlation with the soil C measurements at both 0-30 cm ( R=0.93) and 0-100 cm soil depth ( R=0.82). As for the SRF plots, the soil C at the reference sites have been accurately simulated by the model. The extremely high correlation for the reference fields ( R ≥0.99) shows a good performance of the model spin-up. The statistical analysis of the model performance to simulate soil C and soil C changes after land-use change to SRF highlighted the absence of significant error between modelled and measured values as well as the absence of significant bias in the model. Overall, this evaluation reinforces previous studies on the ability of ECOSSE to simulate soil C and emphasize its accuracy to simulate soil C under SRF plantations.
  • Authors:
    • Fernando,Ana Luisa
    • Duarte,Maria Paula
    • Vatsanidou,Anna
    • Alexopoulou,Efi
  • Source: Industrial Crops & Products
  • Volume: 68
  • Year: 2015
  • Summary: Bioenergy and biomaterials from fiber crops are regarded as promising substitutes for conventional ones, considering the growing concern about oil and other non-renewable resources depletion and the environmental impacts of the conventional systems. In this paper, the environmental aspects of fiber crops cultivation and use are reviewed. The analysis was based on the following categories: use of resources, emission of gases, effects on the quality of soil and water and biological and landscape diversity. As bioenergy and biomaterials carriers, fiber crops offer ecological advantages over conventional ones by contributing to carbon sequestration and energy savings, and to the reduction of greenhouse gases and non-renewable resources. However, other environmental outcomes, such as acidifying and eutrophication emissions, may limit the conversion and use of fiber crops. Even so, the low input requirements associated with this class of crops and its phytoremediation aptness for wastewaters or contaminated land, are some of the environmental advantages associated with fiber crops. Crop management options and processing choices can influence the outcomes, but site specific factors should be accurately assessed to evaluate the adequacy between crop and location. Opportunities for improvement are indicated, in order to provide new insights for the future development of these crops in a sustainable agro-industrial framework. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • Holland,R. A.
    • Eigenbrod,F.
    • Muggeridge,A.
    • Brown,G.
    • Clarke,D.
    • Taylor,G.
  • Source: Renewable and Sustainable Energy Reviews
  • Volume: 46
  • Year: 2015
  • Summary: The production of bioenergy from second generation (2G) feedstocks is being encouraged by legislation targeted at addressing a number of controversial issues including carbon emissions driven by land-use change and competition for crops used in food production. Here, we synthesise the implications of 2G feedstock production for a range of key ecosystem services beyond climate regulation. We consider feedstocks typical of temperate systems (Miscanthus; short-rotation coppice, short rotation forestry) and transitions from areas of forest, marginal land and first generation (1G) feedstock production. For transitions from 1G feedstocks, studies suggest significant benefits may arise for a number of ecosystem services, including hazard regulation, disease and pest control, water and soil quality. Although less evidence is available, the conversion of marginal land to 2G production will likely deliver benefits for some services while remaining broadly neutral for others. Conversion of forest to 2G production will likely reduce the provision of a range of services due to increased disturbance associated with shortening of the management cycle. Most importantly, further research is needed to broaden, and deepen, our understanding of the implications of transitions to 2G feedstocks on ecosystem services, providing empirical evidence for policy development, particularly for commercial deployment where landscape scale effects may emerge. A programme of research that mixes both the natural and social sciences based on an ecosystem service framework, and occurs concurrently with large scale commercial deployment of 2G feedstocks, would address this gap, providing evidence on the effectiveness of policies to promote production of 2G feedstocks on a wide range of ecosystem services. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Mangalassery,S.
    • Mooney,S. J.
    • Sparkes,D. L.
    • Fraser,W. T.
    • Sjoegersten,S.
  • Source: European Journal of Soil Biology
  • Volume: 68
  • Issue: 1
  • Year: 2015
  • Summary: Zero tillage management of agricultural soils has potential for enhancing soil carbon (C) storage and reducing greenhouse gas emissions. However, the mechanisms which control carbon (C) sequestration in soil in response to zero tillage are not well understood. The aim of this study was to investigate the links between zero tillage practices and the functioning of the soil microbial community with regards to C cycling, testing the hypothesis that zero tillage enhances biological functioning in soil with positive implications for C sequestration. Specifically, we determined microbial respiration rates, enzyme activities, carbon source utilization and the functional chemistry of the soil organic matter in temperate well drained soils that had been zero tilled for seven years against annually tilled soils. Zero tilled soils contained 9% more soil C, 30% higher microbial biomass C than tilled soil and an increased presence of aromatic functional groups indicating greater preservation of recalcitrant C. Greater CO2 emission and higher respirational quotients were observed from tilled soils compared to zero tilled soils while microbial biomass was 30% greater in zero tilled soils indicating a more efficient functioning of the microbial community under zero tillage practice. Furthermore, microbial enzyme activities of dehydrogenase, cellulase, xylanase, beta-glucosidase, phenol oxidase and peroxidase were higher in zero tilled soils. Considering zero tillage enhanced both microbial functioning and C storage in soil, we suggest that it offers significant promise to improve soil health and support mitigation measures against climate change. (C) 2015 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Fu,Y. H.
    • Piao ShiLong
    • Vitasse,Y.
    • Zhao HongFang
    • Boeck,H. J. de
    • Liu Qiang
    • Yang Hui
    • Weber,U.
    • Hanninen,H.
    • Janssens,I. A.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: Recent studies have revealed large unexplained variation in heat requirement-based phenology models, resulting in large uncertainty when predicting ecosystem carbon and water balance responses to climate variability. Improving our understanding of the heat requirement for spring phenology is thus urgently needed. In this study, we estimated the species-specific heat requirement for leaf flushing of 13 temperate woody species using long-term phenological observations from Europe and North America. The species were defined as early and late flushing species according to the mean date of leaf flushing across all sites. Partial correlation analyses were applied to determine the temporal correlations between heat requirement and chilling accumulation, precipitation and insolation sum during dormancy. We found that the heat requirement for leaf flushing increased by almost 50% over the study period 1980-2012, with an average of 30 heat units per decade. This temporal increase in heat requirement was observed in all species, but was much larger for late than for early flushing species. Consistent with previous studies, we found that the heat requirement negatively correlates with chilling accumulation. Interestingly, after removing the variation induced by chilling accumulation, a predominantly positive partial correlation exists between heat requirement and precipitation sum, and a predominantly negative correlation between heat requirement and insolation sum. This suggests that besides the well-known effect of chilling, the heat requirement for leaf flushing is also influenced by precipitation and insolation sum during dormancy. However, we hypothesize that the observed precipitation and insolation effects might be artefacts attributable to the inappropriate use of air temperature in the heat requirement quantification. Rather than air temperature, meristem temperature is probably the prominent driver of the leaf flushing process, but these data are not available. Further experimental research is thus needed to verify whether insolation and precipitation sums directly affect the heat requirement for leaf flushing.
  • Authors:
    • Michalsky,M.
    • Hooda,P. S.
  • Source: Environmental Science and Policy
  • Volume: 48
  • Year: 2015
  • Summary: Today considerable efforts are being made in identifying means of further energy efficiencies within the UK food system. Current air importation of fruit and vegetables (FVs) generates large amounts of greenhouse gas (GHG) emissions part of which could be avoided. Local food production has been recognized as an environmentally feasible alternative production option and could help reduce GHG emissions, as required under the legally binding emissions targets stipulated by the UK Climate Change Act 2008. Climate change impacts of FVs importation were determined for a selection of five indigenous FV commodities, namely: apples, cherries, strawberries, garlic and peas. Carbon dioxide equivalents (CO 2e) emissions associated with the production and transport stages were calculated using the sample of selected fruit and vegetables (SFVs). The latter stage includes three diverse geographic locations/regions for emissions comparison, namely the UK, Europe and non-European (NE) countries. On average (across the five SFVs), NE commodities, all in fresh/chilled state, were found to contain embedded (arising from production, air freighting and distribution within the UK) GHG emissions of 10.16 kg CO 2e/kg. This is 9.66 kg more CO 2e emissions compared to a kilogram of these commodities produced and supplied locally. A scenario-based approach determined the level of emissions savings that could be achieved by local FVs production in the UK. The least dramatic change of SCENARIO-1 (25% reduction in NE SFVs imports by increasing their local production by the same amount) could save 28.9 kt CO 2e/year, while SCENARIO-2 (50% reduction in NE SFVs imports) and SCENARIO-3 (75% reduction in NE SFVs imports) could result in saving of 57.8 kt and 86.7 kt, respectively.
  • Authors:
    • Mangalassery,S.
    • Sjoegersten,S.
    • Sparkes,D. L.
    • Mooney,S. J.
  • Source: The Journal of Agricultural Science
  • Volume: 153
  • Issue: 7
  • Year: 2015
  • Summary: The benefits of reduced and zero-tillage systems have been presented as reducing runoff, enhancing water retention and preventing soil erosion. There is also general agreement that the practice can conserve and enhance soil organic carbon (C) levels to some extent. However, their applicability in mitigating climate change has been debated extensively, especially when the whole profile of C in the soil is considered, along with a reported risk of enhanced nitrous oxide (N2O) emissions. The current paper presents a meta-analysis of existing literature to ascertain the climate change mitigation opportunities offered by minimizing tillage operations. Research suggests zero tillage is effective in sequestering C in both soil surface and sub-soil layers in tropical and temperate conditions. The C sequestration rate in tropical soils can be about five times higher than in temperate soils. In tropical soils, C accumulation is generally correlated with the duration of tillage. Reduced N2O emissions under long-term zero tillage have been reported in the literature but significant variability exists in the N2O flux information. Long-term, location-specific studies are needed urgently to determine the precise role of zero tillage in driving N2O fluxes. Considering the wide variety of crops utilized in zero-tillage studies, for example maize, barley, soybean and winter wheat, only soybean has been reported to show an increase in yield with zero tillage (77% over 10 years). In several cases yield reductions have been recorded e.g. c. 1-8% over 10 years under winter wheat and barley, respectively, suggesting zero tillage does not bring appreciable changes in yield but that the difference between the two approaches may be small. A key question that remains to be answered is: are any potential reductions in yield acceptable in the quest to mitigate climate change, given the importance of global food security?
  • Authors:
    • McCabe,Gregory J.
    • Wolock,David M.
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: A monthly water-balance model is used with CRUTS3.1 gridded monthly precipitation and potential evapotranspiration (PET) data to examine changes in global water deficit (PET minus actual evapotranspiration) for the Northern Hemisphere (NH) for the years 1905 through 2009. Results show that NH deficit increased dramatically near the year 2000 during both the cool (October through March) and warm (April through September) seasons. The increase in water deficit near 2000 coincides with a substantial increase in NH temperature and PET. The most pronounced increases in deficit occurred for the latitudinal band from 0 to 40A degrees N. These results indicate that global warming has increased the water deficit in the NH and that the increase since 2000 is unprecedented for the 1905 through 2009 period. Additionally, coincident with the increase in deficit near 2000, mean NH runoff also increased due to increases in P. We explain the apparent contradiction of concurrent increases in deficit and increases in runoff.
  • Authors:
    • Fenner, R.
    • McMahon, R.
    • Kopec, G.
    • Richards, K.
    • Allwood, J.
    • Mourão, Z.
    • Konadu, D.
  • Source: Energy Policy
  • Volume: 86
  • Year: 2015
  • Summary: The UK's 2008 Climate Change Act sets a legally binding target for reducing territorial greenhouse gas emissions by 80% by 2050, relative to 1990 levels. Four pathways to achieve this target have been developed by the Department of Energy and Climate Change, with all pathways requiring increased us of bioenergy. A significant amount of this could be indigenously sourced from crops, but will increased domestic production of energy crops conflict with other agricultural priorities?To address this question, a coupled analysis of the UK energy system and land use has been developed. The two systems are connected by the production of bioenergy, and are projected forwards in time under the energy pathways, accounting for various constraints on land use for agriculture and ecosystem services. The results show different combinations of crop yield and compositions for the pathways lead to the appropriation of between 7% and 61% of UK's agricultural land for bioenergy production. This could result in competition for land for food production and other land uses, as well as indirect land use change in other countries due to an increase in bioenergy imports. Consequently, the potential role of bioenergy in achieving UK emissions reduction targets may face significant deployment challenges. © 2015 The Authors.