• Authors:
    • Fox, T. R.
    • Seiler, J. R.
    • Stovall, J. P.
  • Source: Plant and Soil
  • Volume: 363
  • Issue: 1-2
  • Year: 2013
  • Summary: We investigated whether changes in respiratory C fluxes, soil CO2 efflux, or root exudate quantity or quality explained differences in growth rates between closely related clones of Pinus taeda (L.). A factorial design with two clones, fertilized and control treatments, and four sequential harvests was installed in a greenhouse for 121 days. The two clones did show significant differences in respiratory C fluxes, soil CO2 efflux, and root exudation quantity and quality. While the clones also differed in growth rates, the C fluxes assessed in this paper did not explain how seedlings were able to allocate more C to stem growth in the months following fertilizer application. Changes in root exudation were not consistent with reduced heterotrophic soil CO2 efflux, which does not appear to be a plant-mediated process. These results indicate that if single genotypes are deployed over large land areas in plantations, dramatic differences between clonal plant-soil interactions may require consideration in ecosystem C budgets. Further, the range of belowground fluxes observed implies that genotype-specific C allocation may make some clones better able to exploit a given resource environment than others.
  • Authors:
    • Zhang, Z.
    • Tao, F.
  • Source: Agricultural and Forest Meteorology
  • Volume: 170
  • Year: 2013
  • Summary: Ensemble-based probabilistic projection is an effective approach to deal with the uncertainties in climate change impact assessments and to inform adaptations. Here, the crop model MCWLA-Wheat was firstly developed by adapting the process-based general crop model, MCWLA [Tao, F., Yokozawa, M., Zhang, Z., 2009a. Modelling the impacts of weather and climate variability on crop productivity over a large area: a new process-based model development, optimization, and uncertainties analysis. Agric. For. Meteorol. 149, 831-850], to winter wheat. Then the Bayesian probability inversion and a Markov chain Monte Carlo (MCMC) technique were applied to the MCWLA-Wheat to analyse uncertainties in parameters estimations, and to optimize parameters. Ensemble hindcasts showed that the MCWLA-Wheat could capture the interannual variability of detrended historical yield series fairly well, especially over a large area. Finally, based on the MCWLA-Wheat, a super-ensemble-based probabilistic projection system was developed and applied to project the probabilistic responses of wheat productivity and water use in the North China Plain (NCP) to future climate change. The system used 10 climate scenarios consisting of the combinations of five global climate models and two greenhouse gases emission scenarios (A1FI and B1), the corresponding atmospheric CO2 concentration range, and multiple sets of crop model parameters representing the biophysical uncertainties from crop models. The results showed that winter wheat yields in the NCP could increase with high probability in future due to climate change. During 2020s, 2050s, and 2080s, with (without) CO2 fertilization effects, relative to 1961-1990 level, simulated wheat yields would increase averagely by up to 37.7% (18.6%), 67.8% (23.1%), and 87.2% (34.4%), respectively, across 80% of the study area; simulated changes in evaportranspiration during wheat growing period would range generally from -6% to 6% (-0.6% to 10%), from -10% to 8% (-1.0% to 17%), and from -17% to 4% (7-12%), respectively, across the study area. Further analyses suggested that the improvements in heat and water resources and rising atmospheric CO2 concentration ([CO2]) could contribute notably to wheat productivity increase in future. Climate change could enhance the development and photosynthesis rate; however the duration of reproductive period could be less affected than that of vegetative period, and wheat productivity could benefit from enhanced photosynthesis due to climate change and rising [CO2]. Furthermore, wheat could become mature earlier, which could prevent it from severe high temperature stress. Our study parameterized explicitly the effects of high temperature stress on productivity, accounted for a wide range of crop cultivars with contrasting phenological and thermal characteristics, and presented new findings on the probabilistic responses of wheat productivity and water use to climate change in the NCP.
  • Authors:
    • Thomas,Amy R. C.
    • Bond,Alan J.
    • Hiscock,Kevin M.
  • Source: Global Change Biology Bioenergy
  • Volume: 5
  • Issue: 3
  • Year: 2013
  • Summary: Reduction in energy sector greenhouse gas GHG emissions is a key aim of European Commission plans to expand cultivation of bioenergy crops. Since agriculture makes up 1012% of anthropogenic GHG emissions, impacts of land-use change must be considered, which requires detailed understanding of specific changes to agroecosystems. The greenhouse gas (GHG) balance of perennials may differ significantly from the previous ecosystem. Net change in GHG emissions with land-use change for bioenergy may exceed avoided fossil fuel emissions, meaning that actual GHG mitigation benefits are variable. Carbon (C) and nitrogen (N) cycling are complex interlinked systems, and a change in land management may affect both differently at different sites, depending on other variables. Change in evapotranspiration with land-use change may also have significant environmental or water resource impacts at some locations. This article derives a multi-criteria based decision analysis approach to objectively identify the most appropriate assessment method of the environmental impacts of land-use change for perennial energy crops. Based on a literature review and conceptual model in support of this approach, the potential impacts of land-use change for perennial energy crops on GHG emissions and evapotranspiration were identified, as well as likely controlling variables. These findings were used to structure the decision problem and to outline model requirements. A process-based model representing the complete agroecosystem was identified as the best predictive tool, where adequate data are available. Nineteen models were assessed according to suitability criteria, to identify current model capability, based on the conceptual model, and explicit representation of processes at appropriate resolution. FASSET, ECOSSE, ANIMO, DNDC, DayCent, Expert-N, Ecosys, WNMM and CERES-NOE were identified as appropriate models, with factors such as crop, location and data availability dictating the final decision for a given project. A database to inform such decisions is included.
  • Authors:
    • Venkateswarlu, B.
    • Rao,V. U. M.
  • Source: Climate Change Modeling, Mitigation, and Adaptation
  • Year: 2013
  • Authors:
    • Zhao, Y-C.
    • Sun, W-X.
    • Tan, M-Z.
    • Xu, S-X.
    • Yu, D-S.
    • Shi, X-Z.
    • Wang, M-Y.
  • Source: Pedosphere
  • Volume: 23
  • Issue: 6
  • Year: 2013
  • Summary: The agricultural soil carbon pool plays an important role in mitigating greenhouse gas emission and understanding the soil organic carbon-climate-soil texture relationship is of great significance for estimating cropland soil carbon pool responses to climate change. Using data from 900 soil profiles, obtained from the Second National Soil Survey of China, we investigated the soil organic carbon (SOC) depth distribution in relation to climate and soil texture under various climate regimes of the cold northeast region (NER) and the warmer Huang-Huai-Hai region (HHHR) of China. The results demonstrated that the SOC content was higher in NER than in HHHR. For both regions, the SOC content at all soil depths had significant negative relationships with mean annual temperature (MAT), but was related to mean annual precipitation (MAP) just at the surface 0-20 cm. The climate effect on SOC content was more pronounced in NER than in HHHR. Regional differences in the effect of soil texture on SOC content were not found. However, the dominant texture factors were different. The effect of sand content on SOC was more pronounced than that of clay content in NER. Conversely, the effect of clay on SOC was more pronounced than sand in HHHR. Climate and soil texture jointly explained the greatest SOC variability of 49.0% (0-20 cm) and 33.5% (20-30 cm) in NER and HHHR, respectively. Moreover, regional differences occurred in the importance of climate vs. soil texture in explaining SOC variability. In NER, the SOC content of the shallow layers (0-30 cm) was mainly determined by climate factor, specifically MAT, but the SOC content of the deeper soil layers (30-100 cm) was more affected by texture factor, specifically sand content. In HHHR, all the SOC variability in all soil layers was predominantly best explained by clay content. Therefore, when temperature was colder, the climate effect became stronger and this trend was restricted by soil depth. The regional differences and soil depth influence underscored the importance of explicitly considering them in modeling long-term soil responses to climate change and predicting potential soil carbon sequestration.
  • Authors:
    • Mahmood, K.
    • Awan, A. R.
    • Singh, R. K.
    • Stille, L.
    • Akanda, R.
    • Smeets, E. M. W.
    • Wicke, B.
    • Faaij, A. P. C.
  • Source: Journal of Environmental Management
  • Volume: 127
  • Issue: September
  • Year: 2013
  • Summary: This study explores the greenhouse gas balance and the economic performance (i.e. net present value (NPV) and production costs) of agroforestry and forestry systems on salt-affected soils (biosaline (agro) forestry) based on three case studies in South Asia. The economic impact of trading carbon credits generated by biosaline (agro)forestry is also assessed as a potential additional source of income. The greenhouse gas balance shows carbon sequestration over the plantation lifetime of 24 Mg CO2-eq. ha(-1) in a rice-Eucalyptus camaldulensis agroforestry system on moderately saline soils in coastal Bangladesh (case study 1), 6 Mg CO2-eq. ha(-1) in the rice-wheat- Eucalyptus tereticornis agroforestry system on sodic/saline-sodic soils in Haryana state, India (case study 2), and 96 Mg CO2-eq. ha(-1) in the compact tree (Acacia nilotica) plantation on saline-sodic soils in Punjab province of Pakistan. The NPV at a discount rate of 10% is 1.1 k(sic) ha(-1) for case study 1, 4.8 k(sic) ha(-1) for case study 2, and 2.8 k(sic) ha(-1) for case study 3. Carbon sequestration translates into economic values that increase the NPV by 1-12% in case study 1, 0.1 -1% in case study 2, and 2-24% in case study 3 depending on the carbon credit price (1-15 (sic) Mg-1 CO2-eq.). The analysis of the three cases indicates that the economic performance strongly depends on the type and severity of salt-affectedness (which affect the type and setup of the agroforestry system, the tree species and the biomass yield), markets for wood products, possibility of trading carbon credits, and discount rate. (C) 2013 Elsevier Ltd. All rights reserved.
  • Authors:
    • Kitano, M.
    • Yasunaga, E.
    • Setoyama, S.
    • Araki, T.
    • Tamanoi, A.
    • Matsubara, K.
    • Ohara, M.
    • Yano, T.
  • Source: Environmental Control in Biology
  • Volume: 51
  • Issue: 1
  • Year: 2013
  • Summary: Light condition is a fundamental environmental factor for high-quality plant production. In this paper, we discuss how light condition affects fruit development in the long and short term, and attempt to clarify management methods for active fruit development under conditions of low solar radiation, by using quantitative research on fruit water and carbon balance during greenhouse cultivation of Satsuma mandarin (Citrus unshiu Marc.). A significant decrease in yield due to shading was not detected, but we confirmed that shading treatment affected the dry weights of source-sink units, fruit volume, increase in volume of the fruits, and fruit quality parameters, such as sugar accumulation, acid content, and rind color. Qualitatively, the carbon balance of Satsuma mandarin fruit is comparable to that of tomato fruit or rice panicle, but quantitatively, the carbon balance of Satsuma mandarin fruit may differ, as shown by low sink relative growth rate. In addition, fruit growth parameters such as translocation rate for a fruit and fruit relative growth rate showed significant positive correlations with dark respiration, despite the shading treatment. The fruit carbon demand may be simply described by fruit dark respiration as the sum of new photosynthetic carbon and stored carbon translocation for a fruit.
  • Authors:
    • Malemela, M. P.
    • Chen, F.
    • Wang, F.
    • Zhang, M.
    • Zhang, H.
  • Source: Journal of Cleaner Production
  • Volume: 54
  • Year: 2013
  • Summary: Whether farmland serves as a carbon (C) source or sink depends on the balance of soil organic carbon (SOC) sequestration and greenhouse gas (GHG) emissions. Tillage practices critically affect the SOC concentration, SOC sequestration rate and soil carbon storage (SCS). The objective of this paper is to assess the tillage effects on SOC sequestration, SCS and C footprint. Tillage experiments were established on a double cropping system of winter wheat (Triticum aestivum L) and summer corn (Zea mays L) in the North China Plain since 2001 with three treatments: no tillage (NT), rotary tillage (RT) and conventional tillage (CT). In order to assess SOC sequestration efficiency under different tillage systems, SCS, SOC sequestration rate, hidden carbon cost (HCC), indexes of sustainability (I-s) and C productivity (CP) were computed in this study. Results showed that the SCS increased with years of residue retention. The SCS attained the highest degree in 2007, which was about 25%-30% higher than that in 2004. The net SOC sequestration rate was the highest in NT and lowest in cc, while HCC was lowest under NT and highest under CT. The value of Is for CT, RT and NT treatments was 1.46, 1.79 and 1.88, respectively, and that of CP was 11.02, 12.79 and 10.57, respectively. Therefore, it can be concluded that NT provides a good option for increasing SOC sequestration for agriculture in the North China Plain.
  • Authors:
    • Cheng,Xiaoli
    • Yang,Yuanhe
    • Li,Ming
    • Dou,Xiaolin
    • Zhang,Quanfa
  • Source: Plant and Soil
  • Volume: 366
  • Issue: 1-2
  • Year: 2013
  • Summary: Over recent decades, a large uncultivated area has been converted to woodland and shrubland plantations to protect and restore riparian ecosystems in the Danjiangkou Reservoir area, a water source area of China's Middle Route of the South-to-North Water Transfer Project. Besides water quality, afforestation may alter soil organic carbon (SOC) dynamics and stock in terrestrial ecosystems, but its effects remain poorly quantified and understood. We investigated soil organic C and nitrogen (N) content, and delta C-13 and delta N-15 values of organic soil in plant root-spheres and open areas in an afforested, shrubland and adjacent cropped soil. Soil C and N recalcitrance indexes (RIC and RIN) were calculated as the ratio of unhydrolyzable C and N to total C and N. Afforestation significantly increased SOC levels in plant root-spheres with the largest accumulation of C in the afforested soil. Afforestation also increased belowground biomass. The C:N ratios in organic soil changed from low to high in the order the cropped, the shrubland and the afforested soil. The RIC in the afforested and shrubland were higher than that in cropped soil, but the RIN increased from the afforested to shrubland to cropped soil. The delta N-15 values of the organic soil was enriched from the afforested to shrubland to cropped soil, indicating an increased N loss from the cropped soil compared to afforested or shrubland soil. Changes in the delta C-13 ratio further revealed that the decay rate of C in the three land use types was the highest in the cropped soil. Afforestation increased the SOC stocks resulted from a combination of large C input from belowground and low C losses because of decreasing soil C decomposition. Shifts in vegetation due to land use change could alter both the quantity and quality of the soil C and thus, have potential effects on ecosystem function and recovery.
  • Authors:
    • Liu,Zhijuan
    • Yang,Xiaoguang
    • Chen,Fu
    • Wang,Enli
  • Source: Climatic Change
  • Volume: 117
  • Issue: 4
  • Year: 2013
  • Summary: Northeast China (NEC) is one of the major agricultural production areas in China and also an obvious region of climate warming. We were motivated to investigate the impacts of climate warming on the northern limits of maize planting. Additionally, we wanted to assess how spatial shifts in the cropping system impact the maize yields in NEC. To understand these impacts, we used the daily average air temperature data in 72 weather stations and regional experiment yield data from Jilin Province. Averaged across NEC, the annual air temperature increased by 0.38 A degrees C per decade. The annual accumulated temperature above 10 A degrees C (AAT10) followed a similar trend, increased 66 A degrees C d per decade from 1961 to 2007, which caused a northward expansion of the northern limits of maize. The warming enabled early-maturing maize hybrids to be sown in the northern areas of Heilongjiang Province where it was not suitable for growing maize before the warming. In the southern areas of Heilongjiang Province and the eastern areas of Jilin Province, the early-maturing maize hybrids could be replaced by the middle-maturing hybrids with a longer growing season. The maize in the northern areas of Liaoning Province was expected to change from middle-maturing to late-maturing hybrids. Changing the hybrids led to increase the maize yield. When the early-maturing hybrids were replaced by middle-maturing hybrids in Jilin Province, the maize yields would increase by 9.8 %. Similarly, maize yields would increase by 7.1 % when the middle-maturing hybrids were replaced by late-maturing hybrids.