We demonstrate the potential of spaceborne data for integrating forest height and density to assess forest structure for patches in the taiga–tundra ecotone. We map forest patches at sites in northern Siberia with spaceborne data and examine the uncertainty of forest patch height estimates across these ecotone sites. Results demonstrate the opportunities for improving patch-based spaceborne estimates of forest height and forest structure patterns in the circumpolar domain.

It is important to be able to assess whether changes in land use or management affect soil properties, but testing differences between soil profiles can be challenging. We developed a straightforward approach that makes use of soil core data (which are not spatially independent) to compare soil properties at specific locations down a depth profile. We hope that this approach can be used more widely, based on new or existing data, to examine the impacts of land use and management on soils.

Records of stable oxygen isotope ratios in tree rings are valuable tools for reconstructing past climatic conditions. So far, they have not been used in global dynamic vegetation models. Here we present a model that simulates oxygen isotope ratios in tree rings. Our results compare well with measurements performed in European forests. The model is useful for studying oxygen isotope patterns of tree ring cellulose at large spatial and temporal scales.

Iron is an essential nutrient for plankton growth. One important source of iron is wind-blown dust. The polar oceans are remote from dust sources but melting icebergs supply sediment that contains iron which is potentially available to plankton. We show that iceberg sediments contain more potentially bioavailable iron than wind-blown dust. Iceberg sources will become increasingly important with climate change and increased plankton growth can remove more carbon dioxide from the atmosphere.

Spray- and marble-type equilibrators and a membrane-enclosed CO₂ sensor were compared to assess their suitability for continuous pCO₂ measurements in inland waters. The results suggest that the fast response of the equilibration systems facilitates capturing large spatial variations in pCO₂ during short underway measurements. The membrane-enclosed sensor would be suitable for long-term continuous measurements if biofouling could be overcome by antifouling measures such as copper mesh coverings.

Temporal variability in the apparent quantum yield of photochemical CDOM mineralisation in a boreal brown water lake was severalfold smaller than previously reported across different lakes. Simulated DIC photoproduction (2012–2014) averaged 2.0 ± 0.1 to 10.3 ± 0.7 g C m⁻² yr⁻¹ using the least and most reactive sample, which represented 1 to 8 % of the total mean CO₂ emissions. Thus, direct CDOM photomineralisation makes only a minor contribution to mean CO₂ emissions from Swedish brown water lakes.

We studied GHG emissions along water-level gradients of two inundated cutover fens with closed chambers. N₂O fluxes were negligible. CO₂ and CH₄ fluxes were controlled by vegetation composition and plant productivity, which in turn depended on water level and nutrient conditions. CH₄ fluxes from mesotrophic sites were low and largely compensated for by CO₂ uptake. Eutrophic sites were strong CH₄ sources, and GHG balances depended on the plant's net C sink, which strongly differed between species.

Predicting the effects of changing climate on microbial community shifts on longer timescales can be challenging. This study exploits the power of combining organic geochemistry, molecular microbial ecology, and geochemistry to unravel trends in microbial community induced by climatic variability. Our results show that climate-induced variability on decadal timescales can trigger changes in both lake trophic status and phytoplankton communities.

Understanding controls of air–sea gas exchange is necessary for predicting regional- and global-scale trace gas fluxes and feedbacks. Recent studies demonstrated the importance of surfactants, which occur naturally in the uppermost layer of coastal water bodies, to suppress the gas transfer velocity (kw). Here we present data for seawater samples collected from the North Sea. Using a novel analytical approach we show a strong seasonal and spatial relationship between natural surfactants and kw.

The fusion of ground-based forest inventory data with satellite observations achieved with HASM-S provided much more accurate estimates of forest carbon stocks, comparing with either the remote sensing descriptions or the forest inventory data. The HASM-S results show that the forest carbon stocks of China have increased by 2.24 Pg during the period 1984–2008 to a new high of 7.08 Pg C in 2008.

We compare future projections in marine export production, generated by four ecosystem models under IPCC's high-emission scenario RCP8.5. While all models project decreases in export, they differ strongly regarding the drivers. The formation of sinking particles of organic matter is the most uncertain process with models not agreeing on either magnitude or the direction of change. Changes in diatom concentration are a strong driver for export in some models but of low significance in others.

Changes in Arctic vegetation composition and structure feed back to climate and permafrost. Using field observations at a Siberian tundra site, we find that dwarf shrubs absorb more solar radiation than wet sedges and thus amplify surface warming, especially during snow melt. On the other hand, permafrost thaw was enhanced below sedges as a consequence of high soil moisture. Standing dead sedge leaves affected the radiation budget strongly and deserve more scientific attention.