Managing the impact of grassland management on nitrous oxide emissions through an improved understanding of soil microbial communities

Nitrous oxide (N2O) plays an important role in the atmospheric radiative balance and in stratospheric ozone chemistry and has a global warming potential 298 times higher than CO2. Grasslands occupy two thirds of the agricultural land in the UK. have been estimated to emit up to 0.54 – 0.58 Gg of N2O per year. N2O is produced as a result of nitrifying and denitrifying soil microbial communties. Both microbial groups are strongly influenced by soil physical factors such as oxygen availability, with decreases in soil oxygen increasing N2O production from the soil. Grasslands are subject to a range of managment treatments that enhance the production of N2O, such as cattle traffic and the movement of heavy agricultural machinery, which increases soil bulk density, resulting in a reduction in available air-filled pore space. This in combination with the use of fertilisers, such as urea and cattle slurry and also the deposition of urine, lead to the ideal conditions for N2O production to proceed. Mitigation techniques, such as the use of nitrification inhibitors, such as Dicyandiamide (DCD) are used to reduce these emissions, however, even with the use of these nitrification inhibitors N2O emissions still proceed. An improved understanding of the effect of bulk density and soil water-filled pore space (WFPS), as well as the movement of gas through compacted soils is elucidated. The importance of soil heterotrophic nitrification was observed in compacted grassland soils and a crucial pathway of the effect of a commonly used eukaryotic protein synthesis inhibitor (cylcoheximide) used to distinguish between soil bacterial and fungal activity was highlighted and the implication for its use in soil nitrogen cycling studies is discussed. Limitations of DCD were also highlighted, with indications of alternative pathways of microbial N2O production in grassland soils treated with this nitrification inhibitor

Biochar alteration of the sorption of substrates and products in Soil Enzyme Assays

Pine wood and barley straw biochar amendments to Kettering and Cameroon sandy silt loam soils (15, 30, or 150 mg biochar g−1 soil) caused significant reductions (up to 80%

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Long-term thermal sensitivity of Earth’s tropical forests

The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate