1,298 publications from this institution
Summary 1. Plant–soil interactions play a central role in the biogeochemical carbon (C), nitrogen (N) and hydrological cycles. In the context of global environmental change, they are important both in modulating the impact of climate change and in regulating the feedback of greenhouse gas emissions (CO 2 , CH 4 and N 2 O) to the climate system. 2. Dynamic global vegetation models (DGVMs) represent the most advanced tools available to predict the impacts of global change on terrestrial ecosystem functions and to examine their feedbacks to climate change. The accurate representation of plant–soil interactions in these models is crucial to improving predictions of the effects of climate change on a global scale. 3. In this paper, we describe the general structure of DGVMs that use plant functional types (PFTs) classifications as a means to integrate plant–soil interactions and illustrate how models have been developed to improve the simulation of: (a) soil carbon dynamics, (b) nitrogen cycling, (c) drought impacts and (d) vegetation dynamics. For each of these, we discuss some recent advances and identify knowledge gaps. 4. We identify three ongoing challenges, requiring collaboration between the global modelling community and process ecologists. First, the need for a critical evaluation of the representation of plant–soil processes in global models; second, the need to supply and integrate knowledge into global models; third, the testing of global model simulations against large‐scale multifactor experiments and data from observatory gradients. 5. Synthesis . This paper reviews how plant–soil interactions are represented in DGVMs that use PFTs and illustrates some model developments. We also identify areas of ecological understanding and experimentation needed to reduce uncertainty in future carbon coupled climate change predictions.
Following publication in The Antiquaries Journal volume 96 (2016) of ‘Moor Park in the Seventeenth Century’, by Drury, Jeffery and Wrightson, this article presents the results of research by the present four authors on another house by Hugh May – Eltham Lodge, Kent – which survives rather better. Its exterior is often referred to as being relatively unaltered, but analysis of the surviving fabric and much new documentary evidence have nevertheless revealed many interventions, both inside and out, permitting a clearer understanding of the original appearance, layout and setting of this important Restoration house.
Abstract. Field margins are a valuable resource in the farmed landscape, providing numerous environmental benefits. We present a preliminary analysis of the carbon mitigation potential of different field margin management options for Great Britain, calculated using data from long‐term experiments and literature estimates. The carbon sequestration potential of the individual options investigated here varies from 0.1 to 2.4% of 1990 UK CO 2 ‐C emissions, or 0.7–20% of the Quantified Emission Limitation Reduction Commitment (QELRC). The scenarios investigated covered three possible margin widths and options for the management of margins at each width (viz. grass strips, hedgerows and tree strips). Scenarios involving margin widths of 2, 6 or 20 m would require approximately 2.3, 6.7 or 21.3% of the total arable area of Great Britain, respectively. Scenarios including tree strips offered the greatest potential for carbon sequestration, since large amounts would be accumulated in above‐ground biomass in addition to that in soil. We also accounted for the possible impacts of changed land management on trace gas fluxes, which indicated that any scenario involving a change from arable to grass strip, hedgerow or tree strip would significantly reduce N 2 O emissions, and thus further increase carbon mitigation potential. There would also be considerable potential for including the scenarios investigated here with other strategies for the alternative management of UK arable land to identify optimal combinations. We assumed that it would take 50–100 years for soil carbon to reach a new equilibrium following a land use change. More detailed analyses need to be conducted to include environmental benefits, socioeconomic factors and the full system carbon balance.
Abstract We present the most comprehensive pan‐European assessment of future changes in cropland and grassland soil organic carbon (SOC) stocks to date, using a dedicated process‐based SOC model and state‐of‐the‐art databases of soil, climate change, land‐use change and technology change. Soil carbon change was calculated using the Rothamsted carbon model on a European 10 × 10′ grid using climate data from four global climate models implementing four Intergovernmental Panel on Climate Change (IPCC) emissions scenarios (SRES). Changes in net primary production (NPP) were calculated by the Lund–Potsdam–Jena model. Land‐use change scenarios, interpreted from the narratives of the IPCC SRES story lines, were used to project changes in cropland and grassland areas. Projections for 1990–2080 are presented for mineral soil only. Climate effects (soil temperature and moisture) will tend to speed decomposition and cause soil carbon stocks to decrease, whereas increases in carbon input because of increasing NPP will slow the loss. Technological improvement may further increase carbon inputs to the soil. Changes in cropland and grassland areas will further affect the total soil carbon stock of European croplands and grasslands. While climate change will be a key driver of change in soil carbon over the 21st Century, changes in technology and land‐use change are estimated to have very significant effects. When incorporating all factors, cropland and grassland soils show a small increase in soil carbon on a per area basis under future climate (1–7 t C ha −1 for cropland and 3–6 t C ha −1 for grassland), but when the greatly decreasing area of cropland and grassland are accounted for, total European cropland stocks decline in all scenarios, and grassland stocks decline in all but one scenario. Different trends are seen in different regions. For Europe (the EU25 plus Norway and Switzerland), the cropland SOC stock decreases from 11 Pg in 1990 by 4–6 Pg (39–54%) by 2080, and the grassland SOC stock increases from 6 Pg in 1990 to 1.5 Pg (25%) under the B1 scenario, but decreases to 1–3 Pg (20–44%) under the other scenarios. Uncertainty associated with the land‐use and technology scenarios remains unquantified, but worst‐case quantified uncertainties are 22.5% for croplands and 16% for grasslands, equivalent to potential errors of 2.5 and 1 Pg SOC, respectively. This is equivalent to 42–63% of the predicted SOC stock change for croplands and 33–100% of the predicted SOC stock change for grasslands. Implications for accounting for SOC changes under the Kyoto Protocol are discussed.
In this Special Issue, we present a series of papers arising from two related research projects funded by the UK Energy Research Centre (UKERC), ‘Spatial Mapping and Evaluation of Energy Crop Distribution in Great Britain (GB) to 2050’ and ‘The Disaggregated Scenarios for Demand Studies (DS4DS) project’, conducted by a team from the University of Aberdeen, University of East Anglia, Forest Research, University of Southampton, Centre for Ecology and Hydrology, Scotland's Rural College, University of Portsmouth and Loughborough University. Despite considerable interest in second generation, nonfood bioenergy crops, such as the giant grass Miscanthus, and short rotation coppice (SRC) species like willow or poplar, to date no attempt has been made to match potential supply with demand. In this project, we have attempted to do this. Currently, energy crops are cofired with fuels like coal in traditional power stations, but the most carbon- and cost-efficient way to use biomass energy is to generate heat and power at the same time through Combined Heat and Power (CHP) plants. To make the best use of bioenergy crops, a future infrastructure of small and medium-sized CHP plants using locally sourced biomass would be required. To see where heat and electricity are most needed, and where bioenergy crops are best grown to meet that demand, the papers collected in this special issue describe how the team have generated high resolution (1 km) maps of demand, potential bioenergy supply, and the size and location of the CHP plants that would be required to exploit the resource for energy. The final papers then examine the economics of using bioenergy to supply heat and electricity – i.e. whether it makes sense from an energy price and from a grower's perspective, and consider the cost of greenhouse gas abatement provided by bioenergy. The first paper (Lovett et al., 2014) examines the land available to grow bioenergy crops. Not all areas are suitable for energy crop production; for example protected areas and peatlands will be unsuitable, and these areas are mapped at high resolution. By applying different constraints, the available area for energy crops is found to be between 8.5 and 9 M ha (37–40% of GB), and the location of current energy crops is compared to these available areas. In Hastings et al. (2014), state-of-the-art, process-based models of Miscanthus, SRC and short rotation forestry are used to simulate potential yield under current conditions, and under future climate (to 2050). These models identify which crop produces the most biomass on land suitable for bioenergy crops. This paper defined the potential supply of biomass at high resolution (1 km) now and in the future, and shows significant technical biomass potential in GB. Having defined potential biomass supply, Taylor et al. (2014), used detailed energy and census statistics to map demand for heat and electricity at 1 km resolution for Great Britain, both now and, using UKERC scenarios, to project these demand surfaces out to 2050. These high resolution demand estimates are the first of their kind in GB, and provide the first opportunity to make a detailed comparison between supply and demand. With high resolution datasets of potential supply of biomass feedstock and electricity and heat demand, an economic optimization model is used in Wang et al. (2014) to determine how much demand could be met by the available supply at competitive energy prices, and where and what size the CHP plant would be needed to make use of the bioenergy efficiently. The optimization model was used by Wang et al. (2014) to map optimal supply and demand for GB now and to 2050 from an energy price perspective. In Alexander et al. (2014a), a farm-scale economic model is used to examine the farm level optimization problem, that is, at what price farmers might consider growing energy crops, taking account of the costs and returns associated with competing crops. In this paper, maps of bioenergy crops that match supply and demand are derived, avoiding unsuitable areas, and that make economic sense from an energy price and a grower's perspective. The areas for future growth of bioenergy crops are different to where they are currently grown because energy crops are currently grown to cofire in large conventional power plants, rather than in smaller CHP plants, which would be a more appropriate infrastructure for bioenergy use in the future. In the final paper in the special feature, Alexander et al. (2014b) use an agent-based model to investigate the behavior of the GB energy crop market and to examine the cost of emission abatement that the market might provide. The paper poses the question: do existing policies for perennial energy crops make this a more or less cost effective mitigation option if we consider how these policies are likely to affect market evolution? The paper considers the relative merits of providing incentives to farmers relative to energy producers. It also examines the trade-offs between increased or decreased subsidy levels and the rate and level of market uptake, and hence abatement cost. The analysis suggests that maintaining the energy crop scheme, which provides farmers' establishment grants, can increase both the emissions abatement potential and cost-effectiveness. A minimum carbon equivalent abatement cost is seen at intermediate subsidy levels for energy generation. The paper identifies an optimum level to cost-effectively stimulate the market to achieve emissions reduction. Alexander et al. (2014a) suggest (in table 2 of their paper) that, at a Miscanthus price of £60 odt−1 and an SRC price of £48 odt−1, energy crops could supply around 50 Pj yr−1 (=1.6 Gw yr−1) in GB, but the profitability of bioenergy crops is very sensitive to the price paid for the biomass. With relatively small increases in price, the area (and thereby the potential energy supplied by biomass) increases dramatically. The location of the nearest power plant is critical in decisions to grow bioenergy crops, so a bioenergy market may not thrive in Britain until a more distributed power generation infrastructure is developed. In addition, growers need a market and a good price to convert to growing bioenergy crops. To convert the potential for energy cropping outlined in the papers presented here into reality, biomass prices or productivity will need to increase, and a new power generation infrastructure (more, distributed CHP plants) would need to be developed in GB in the coming years.
