• Energy Research

AbstractWe analyzed the magnitude, the trends and the uncertainties of fossil‐fuel CO2 emissions in the European Union 25 member states (hereafter EU‐25), based on emission inventories from energy‐use statistics. The stability of emissions during the past decade at EU‐25 scale masks decreasing trends in some regions, offset by increasing trends elsewhere. In the recent 4 years, the new Eastern EU‐25 member states have experienced an increase in emissions, reversing after a decade‐long decreasing trend. Mediterranean and Nordic countries have also experienced a strong acceleration in emissions. In Germany, France and United Kingdom, the stability of emissions is due to the decrease in the industry sector, offset by an increase in the transportation sector. When four different inventories models are compared, we show that the between‐models uncertainty is as large as 19% of the mean for EU‐25, and even bigger for individual countries. Accurate accounting for fossil CO2 emissions depends on a clear understanding of system boundaries, i.e. emitting activities included in the accounting. We found that the largest source of errors between inventories is the use of distinct systems boundaries (e.g. counting or not bunker fuels, cement manufacturing, nonenergy products). Once these inconsistencies are corrected, the between‐models uncertainty can be reduced down to 7% at EU‐25 scale. The uncertainty of emissions at smaller spatial scales than the country scale was analyzed by comparing two emission maps based upon distinct economic and demographic activities. A number of spatial and temporal biases have been found among the two maps, indicating a significant increase in uncertainties when increasing the resolution at scales finer than ≈200 km. At 100 km resolution, for example, the uncertainty of regional emissions is estimated to be 60 g C m−2 yr−1, up to 50% of the mean. The uncertainty on regional fossil‐fuel CO2 fluxes to the atmosphere could be reduced by making accurate 14C measurements in atmospheric CO2, and by combining them with transport models.

This is a response to the Editorial Commentary by Schulze et al

We investigated effects of plant species richness in experimental grassland plots on annual above‐ and belowground biomass production estimated from repeated harvests and ingrowth cores, respectively. Aboveground and total biomass production increased with increasing plant species richness while belowground production remained constant. Root to shoot biomass production ratios (R/S) in mixtures were lower than expected from monoculture performance of the species present in the mixtures, showing that interactions among species led to reduced biomass partitioning to belowground organs. This change in partitioning to belowground organs was not confined to mixtures with legumes, but also measured in mixtures without legumes, and correlated with aboveground overyielding in mixtures. It is suggested that species‐rich communities invest less in belowground biomass than do monocultures to extract soil resources, thus leading to increased investment into aboveground organs and overyielding.

Recent reports of local extinctions of arthropod species1, and of massive declines in arthropod biomass2, point to land-use intensification as a major driver of decreasing biodiversity. However, to our knowledge, there are no multisite time series of arthropod occurrences across gradients of land-use intensity with which to confirm causal relationships. Moreover, it remains unclear which land-use types and arthropod groups are affected, and whether the observed declines in biomass and diversity are linked to one another. Here we analyse data from more than 1 million individual arthropods (about 2,700 species), from standardized inventories taken between 2008 and 2017 at 150 grassland and 140 forest sites in 3 regions of Germany. Overall gamma diversity in grasslands and forests decreased over time, indicating loss of species across sites and regions. In annually sampled grasslands, biomass, abundance and number of species declined by 67%, 78% and 34%, respectively. The decline was consistent across trophic levels and mainly affected rare species; its magnitude was independent of local land-use intensity. However, sites embedded in landscapes with a higher cover of agricultural land showed a stronger temporal decline. In 30 forest sites with annual inventories, biomass and species number-but not abundance-decreased by 41% and 36%, respectively. This was supported by analyses of all forest sites sampled in three-year intervals. The decline affected rare and abundant species, and trends differed across trophic levels. Our results show that there are widespread declines in arthropod biomass, abundance and the number of species across trophic levels. Arthropod declines in forests demonstrate that loss is not restricted to open habitats. Our results suggest that major drivers of arthropod decline act at larger spatial scales, and are (at least for grasslands) associated with agriculture at the landscape level. This implies that policies need to address the landscape scale to mitigate the negative effects of land-use practices.

A canopy scale model is presented that utilises Lagrangian dispersal theory to describe the relationship between source distribution and concentration within the canopy. The present study differs from previous studies in three ways: (1) source/sink distributions are solved simultaneously for CO2, 13CO2, H2O and sensible heat to find a solution consistent with leaf-level constraints imposed by photosynthetic capacity, stomatal and boundary layer conductance, available energy and carbon isotopic discrimination during diffusion and carboxylation; (2) the model is used to solve for parameters controlling the nonlinear source interactions rather than the sources themselves; and (3) this study used plant physiological principles to allow the incorporation of within- and above-canopy measurements of the 13C/12C ratios of CO2 as an additional constraint. Source strengths of CO2, H2O, sensible heat and 13CO2 within a Siberian mixed-coniferous forest were constrained by biochemical and energy-balance principles applied to sun and shaded leaves throughout the canopy. Parameters relating to maximum photosynthetic capacity, stomatal conductance, radiation penetration and turbulence structure were determined by the optimisation procedure to match modelled and measured concentration profiles, effectively inverting the concentration data. Ground fluxes of CO2, H2O and sensible heat were also determined by the inversion. Total ecosystem fluxes predicted from the inversion were compared to hourly averaged above-canopy eddy covariance measurements over a ten-day period, with good agreement. Model results showed that stomatal conductance and maximum photosynthetic capacity were depressed due to the low temperatures experienced during snow melt; radiation penetrated further than simple theoretical predictions because of leaf clumping and penumbra, and stability effects were important in the morning and evening. The inversion was limited by little vertical structure in the concentration profiles, particularly of water vapour, and by co-dependence of canopy parameters.DOI: 10.1034/j.1600-0889.2002.01356.x