We tested the hypothesis that diffuse radiation from cloudy and overcast skies penetrates the canopy more effectively than direct radiation from clear skies. We compared the flux density and spectral properties of direct and diffuse radiation above, within and below a forest stand under sunny, cloudy and overcast conditions in a thinned Sitka spruce forest. We recorded vertical (1m resolution) and horizontal (2.5m resolution) profiles of radiation penetration at 1nm resolution.

Climate change may not affect phytoplankton species as such, but may lead to changes in population structure of a species, with strains exhibiting high phenotypic plasticity dominating the population. Simulated climate scenarios showed that combined effects of increased temperature and acidification counterbalanced each other in the ecologically important model organism Fragilariopsis cylindrus. The variation among strains was larger than the variation observed due to the changes in parameters.

We found that energy partitioning to latent and sensible heat and surface resistance was dramatically responsive to climatological drought. All physiological and bioclimatological metrics (Bowen ratio, surface resistance, and Priestley-Taylor coefficient) indicated that the water demands of the poplar plantation were greater than the amount available through precipitation, highlighting the poor match of a water-intensive species like poplar to a water-limited region in northern China.

We investigated an unusual ice type, called hair ice. It grows on the surface of dead wood of broad-leaf trees at temperatures slightly below 0°C. We describe this phenomenon and present our biological, physical, and chemical investigations to gain insight in the properties and processes related to hair ice: we found, that a winter-acive fungus in the wood is required. Ice segregation is the common mechanism. Chemical analyses show a complex mixture of several thousand lignin/tannin compounds.

This study provides a new approach to estimate both anthropogenic non-point source and point source nitrogen (N) inputs to the landscape, and determines their impacts on riverine ammonia-nitrogen (AN) flux, providing a foundation for further exploration of anthropogenic effects on N pollution. Our findings highlight the importance of anthropogenic N inputs from both point sources and non-point sources in heavily polluted watersheds, and provide some implications for N prediction and management.

Studying century-scale ecological processes and their legacy effects requires taking forest management into account. In this study we produce spatially and temporally explicit maps of European forest management from 1600 to 2010. The most important changes between 1600 and 2010 are an increase of 593 000km2 in conifers at the expense of deciduous forest, a 612 000km2 decrease in unmanaged forest, a 152 000km2 decrease in coppice management and a 818 000km2 increase in high stand management.

The relative magnitude of thermokarst lake CH4 production in surface sediments vs. deeper-thawed permafrost is not well understood. We assessed CH4 production potentials from a lake sediment core and adjacent permafrost tunnel in interior Alaska. CH4 production was highest in the organic-rich surface lake sediments and recently thawed permafrost at the bottom of the talik, implying CH4 production is highly variable and that both modern and ancient OM are important to lake CH4 production.

The origin of stream dissolved organic matter (DOM) in a lowland headwater catchment was investigated using high-frequency sampling combined with chemical biomarker analysis. Inter-storm stream DOM corresponds to the flushing of soil DOM reservoirs, while storm stream DOM would also result from three additional mechanisms: biofilm destabilization, surface and sub-surface erosion.

Dams impact river reaches. Upstream of dams, reservoirs transform terrestrial organic carbon and produce autochthonously derived organic carbon. In addition, tailwater reaches below dams may produce and export similar amounts of organic carbon to that stored behind dams. Our work demonstrates that not only do reservoirs need to be considered for their capacity to store and transform organic carbon but also the combined impact of their tailwater ecosystems should to be considered as well.

Soil carbon models are primary tools for projecting soil carbon balance under changing environment and management. This study shows that the carbon model produces divergent projections but accurate reproduction of measured soil carbon. This projection uncertainty is mainly due to an insufficient understanding of microbial processes and soil carbon composition. Climate conditions and land management in terms of carbon input also have significant effects.

We used outputs from nine models to better understand land-atmosphere CO2 exchanges across Northern Eurasia over the period 1960-1990. Model estimates were assessed against independent ground and satellite measurements. We find that the models show a weakening of the CO2 sink over time; the models tend to overestimate respiration, causing an underestimate in NEP; the model range in regional NEP is twice the multimodel mean. Residence time for soil carbon decreased, amid a gain in carbon storage.

Limitations of satellite-based normalized difference vegetation index (NDVI) for monitoring vegetation trends are investigated using observations from the Widou Thiengoly test site in northern Senegal. NDVI do not reflect the large differences found in biomass production and species composition between grazed and ungrazed plots. This is problematic for vegetation trend analysis in the context of drastically increasing numbers of Sahelian livestock in recent decades.

Iron biogeochemical budgets during the natural ocean fertilisation experiment KEOPS-2 showed that complex circulation and transport pathways were responsible for differences in the mode and strength of iron supply, with vertical supply dominant on the plateau and lateral supply dominant in the plume. The exchange of iron between dissolved, biogenic and lithogenic pools was highly dynamic, resulting in a decoupling of iron supply and carbon export and controlling the efficiency of fertilization.

A numerical model is presented that explicitly includes spectral irradiance and optically important water constituents. The model captures 3-D biogeochemical, ecosystem, and optical observations, including surface reflectance analogous to ocean colour satellite observations. Sensitivity experiments demonstrate the relative importance of each of the water constituents, and the feedbacks between the light field, fitness of phytoplankton types, and the biogeochemistry of the ocean.

The study characterizes the microbial community composition of a cold-water coral mound. Roche GS-FLX amplicon sequencing was carried out targeting Bacteria and Archaea. Water is well-mixed at 400m depth, less so at 5 mab, where composition of communities differed among summit, slope and off-mound. Near-bottom water differed from 5 mab, showing that waters in between frameworks represent a separate microbial habitat. Patterns of microbial distribution are coupled to topo- and hydrography.

The oceans currently take up around a quarter of the carbon dioxide (CO2) emitted by human activity. While stored in the ocean, this CO2 is not causing global warming. Here we explore high latitude North Atlantic CO2 uptake across a set of climate model simulations, and find that the models show a peak in ocean CO2 uptake around the middle of the century after which time CO2 uptake begins to decline. We identify the causes of this long-term change and interannual variability in the models.

Optical sampling expands our understanding of the "breathing" of terrestrial ecosystems beyond what is possible by eddy covariance alone. The light-use efficiency (LUE) model provides a useful conceptual framework for integrating optical and CO2 flux measurements. Contrasting optical and flux behavior can reveal distinct optical types that provide key information on flux controls. Practical applications include assessment of ecosystem health, productivity, and biospheric carbon sequestration.