Filetype
The global terrestrial carbon cycle plays a pivotal role in regulating the atmospheric composition of greenhouse gases. It has recently been suggested that the upward trend in net primary production (NPP) seen during the 1980's and 90's has been replaced by a negative trend since 2000 induced by severe droughts mainly on the southern hemisphere. Here we compare results from an individual-based glo
We evaluated the seasonality of CO2 fluxes simulated by nine terrestrial ecosystem models of the TRENDY project against (1) the seasonal cycle of gross primary production (GPP) and net ecosystem exchange (NEE) measured at flux tower sites over different biomes, (2) gridded monthly Model Tree Ensembles-estimated GPP (MTE-GPP) and MTE-NEE obtained by interpolating many flux tower measurements with a
Past, present, and possible future changes in the Baltic Sea acid-base and oxygen balances were studied using different numerical experiments and a catchment-sea model system in several scenarios including business as usual, medium scenario, and the Baltic Sea Action Plan. New CO2 partial pressure data provided guidance for improving the marine biogeochemical model. Continuous CO2 and nutrient mea
It is over three decades since a large terrestrial carbon sink (S-T) was first reported. The magnitude of the net sink is now relatively well known, and its importance for dampening atmospheric CO2 accumulation, and hence climate change, widely recognised. But the contributions of underlying processes are not well defined, particularly the role of emissions from land-use change (E-LUC) versus the
Isoprene emission from Sphagnum species naturally growing at different positions above the water table were measured in a subarctic peatland and at monoliths from a temperate bog. Our objectives were to investigate (1) whether emission rates were species and/or moisture dependent, and (2) whether short-term temperature history had an influence on emission capacity. We expected greater emission cap
Herbivory is an important part of most ecosystems and affects the ecosystems' carbon balance both directly and indirectly. Little is known about herbivory and its impact on the carbon balance in high arctic mire ecosystems. We hypothesized that trampling and grazing by large herbivores influences the vegetation density and composition and thereby also the carbon balance. In 2010, we established fe
We present a network of sites across Fennoscandia for optical sampling of vegetation properties relevant for phenology monitoring and satellite data calibration. The network currently consists of five sites, distributed along an N-S gradient through Sweden and Finland. Two sites are located in coniferous forests, one in a deciduous forest, and two on peatland. The instrumentation consists of dual-
Terrestrial ecosystems currently sequester about one third of anthropogenic CO 2 emissions each year, an important ecosystem service that dampens climate change. The future fate of this net uptake of CO 2 by land based ecosystems is highly uncertain. Most ecosystem models used to predict the future terrestrial carbon cycle share a common architecture, whereby carbon that enters the system as net p
The maximum light use efficiency (LUE = gross primary production (GPP)/absorbed photosynthetic photon flux density (aPPFD)) of plant canopies has been reported to vary spatially and some of this variation has previously been attributed to plant species differences. The canopy nitrogen concentration [N] can potentially explain some of this spatial variation. However, the current paradigm of the N-e
The aim of the study was to estimate the range of climate variability during the Ferdynandovian climatostratigraphic unit (MIS 13-15). The studied pollen sequences encompass two interglacials (Ferdynandovian I and II - FI and F II), the glaciation separating them (FI/II), the late glacial of the Sanian I (= Elsterian 1) and the early glacial of the Sanian II (=Elsterian 2) and are correlated with
Treeline encroachments and retractions can provide global-scale feedbacks to the climate system, and treeline dynamics are therefore of great relevance for understanding global climate variability. To assess the accuracy of long-term treeline simulations based on the generalized dynamic vegetation model LPJ-GUESS, we simulate European Arctic treeline dynamics over the past 9000 years and compare t
Holocene summer temperature reconstructions from northern Europe based on sedimentary pollen records suggest an onset of peak summer warmth around 9,000 years ago. However, pollen-based temperature reconstructions are largely driven by changes in the proportions of tree taxa, and thus the early-Holocene warming signal may be delayed due to the geographical disequilibrium between climate and tree p
Carbon assimilation defined as the overall rate of fixation of carbon through the process of photosynthesis is central to the climate change research. The present study compares the two well-known algorithms in satellite based carbon assimilation estimation, the Vegetation Photosynthesis Model (VPM) and the MOD 17A2 GPP Model, over the tropical forest types in India for a period of two years (Sept
Values among individuals having client-related jobs and organisations in client related sectors might differ from values in their counterparts in jobs and sectors that are not client-related. It is possible that jobs that include interactions with other people demand more developed moral thinking. This report is a description of differences that has been found in a comparison between a ward in the
En redogörelse för och diskussion av debattklimatet (olika positioner) i Saudiarabien mot bakgrund av terrorvågen i början av 2000-talet.
Denna uppsats jämför de lagstiftningstekniker som valdes av Sverige respektive Storbritannien för att implementera den del av Postdirektivet som omfattar de samhällsomfattande posttjänsterna och vilka resultat respektive land har uppnått. Den utvärderar även EU:s val av regleringsmetod. Motivet bakom Postdirektivet, som trädde ikraft 1997, var EU:s vilja att försäkra invånarna tillgång till samhäThis essay compares the different ways that Sweden and Great Britain respectively chose to implement the part of the Postal Directive that include the universal services and the results that have been achieved by each country. It also evaluates the EU's choice of regulatory approach. The motive behind the Postal Directive, which came into force in 1997, was the EU's desire to assure resid
Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and te
We propose and demonstrate a new approach for the simulation of woody ecosystem stand dynamics, demography, and disturbance-mediated heterogeneity suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any earth system model. The approach is encoded in a model called Populations-Order-Physiology (POP). We demonstrate the behavior and per
