Open ocean phytoplankton include coccolithophore algae, a key element in carbon cycle regulation with important feedbacks to the climate system. We document latitudinal variability in both coccolithophore assemblage and the mass variation in one particular species, Emiliania huxleyi, for a transect across the Drake Passage (in the Southern Ocean). Coccolithophore abundance, diversity and maximum depth habitat decrease southwards, coinciding with changes in the predominant E. huxleyi morphotypes.

We measured greenhouse gas and energy fluxes for 2 years after clear-cutting in a peatland forest. We found high carbon dioxide and nitrous oxide emissions. However, in the second year after clear-cutting, the carbon dioxide emissions had already decreased by 33 % from the first year. Also, clear-cutting turned the site from a methane sink into a methane source. We conclude that clear-cutting peatland forests exerts a strong climatic warming effect through accelerated emission of greenhouse gas.

Key findings are the nearly optimal response of T to atmospheric water vapor pressure deficits across methods and scales. Additionally, the notion that T / ET intermittently approaches 1, which is a basis for many partitioning methods, does not hold for certain methods and ecosystems. To better constrain estimates of E and T from combined ET measurements, we propose a combination of independent measurement techniques to better constrain E and T at the ecosystem scale.

Phytoplankton sustain important fisheries along the coast of Greenland. However, climate change is causing severe melting of the Greenland Ice Sheet, and continued melting has the potential to alter fjord ecosystems. We investigate how freshwater from the ice sheet is impacting the environment of one fjord in northeast Greenland, causing a low production of phytoplankton. This fjord may be a model for how some fjord ecosystems will be altered following increased melting and glacial retreat.

Around half of the global primary production (PP) is produced in the ocean. Here we quantified how much oceanic PP estimates would increase if we included the dark DIC fixation rates (which are usually excluded in the carbon-14 method) into the PP estimation. We found that the inclusion of dark DIC fixation would increase PP estimates by 5–22 %. This represents ca. 1.2 to 11 Pg C yr⁻¹ of newly synthesized organic carbon available for the marine food web.

Tropical rivers might be strong sources of CO₂ and CH₄ to the atmosphere, although there is an enormous data gap. The origin of CO₂ in lowland tropical rivers is not well characterized and can be from terra firme or from wetlands (flooded forests and aquatic macrophytes). We obtained a large field dataset of CO₂, CH₄ and N₂O in the Congo, the second-largest river in the world, which allows us to quantity the emission of these greenhouse gases to the atmosphere and investigate their origin.

We reconstructed environmental changes in the Öresund during the last 200 years, using foraminifera (microfossils), sediment, and climate data. Five zones were identified, reflecting oxygen, salinity, food content, and pollution levels for each period. The largest changes occurred ~ 1950, towards stronger currents. The foraminifera responded quickly (< 10 years) to the changes. Moreover, they did not rebound when the system returned to the previous pattern, but displayed a new equilibrium state.

The Zambezi teak forests are a source of raw material for the timber industry. Through application of the LPJ-GUESS vegetation model, we determined the forests' response to climate change at the wetter Kabompo, drier Sesheke, and intermediate Namwala sites in Zambia. While increased CO₂ concentration enhances forests' productivity at Kabompo and Namwala, the decreased rainfall will reduce forests' productivity at Sesheke by the year 2099, resulting in reduced raw material for saw millers.

We investigate whether soil organic compounds preserve information about nitrogen availability to plants. We isolate chlorophyll degradation products in leaves, litter, and soil and explore possible species and climate effects on preservation and interpretation. We find that compound-specific nitrogen isotope measurements in soil have potential as a new tool to reconstruct changes in nitrogen cycling on a landscape over time, avoiding issues that have limited other proxies.

This study compares simulated burned area of seven global vegetation models provided by the Fire Model Intercomparison Project (FireMIP) since 1900. We investigate the influence of five forcing factors: atmospheric CO₂, population density, land–use change, lightning and climate. We find that the anthropogenic factors lead to the largest spread between models. Trends due to climate are mostly not significant but climate strongly influences the inter-annual variability of burned area.

Coastal terrestrial–aquatic interfaces represent dynamic yet poorly understood zones of biogeochemical cycles. We evaluated associations between the soil salinity gradient, molecular-level soil-C chemistry, and microbial community assembly processes in a coastal watershed on the Olympic Peninsula in Washington, USA. Results revealed salinity-driven gradients in molecular-level C chemistry, with little evidence of an association between C chemistry and microbial community assembly processes.

Decaying animals perturb soil biogeochemical cycles. Stable δ¹⁵N composition, which reflects the sum of all biogeochemical processes, increases during decay and persists for years. Enrichment following beaver decay persisted after at least 1 year, and was evident up to 10 cm depth and 60 cm from the decaying animals, beyond where soils were visibly impacted by decomposition. Nutrients sourced from decaying animals represent an integral and long–lived component of nitrogen cycling in soils.

Permafrost temperatures increased substantially at a global scale, potentially altering microbial assemblages involved in carbon mobilization before permafrost thaws. We used Arctic Shelf submarine permafrost as a natural laboratory to investigate the microbial response to long-term permafrost warming. Our work shows that millennia after permafrost warming by > 10 °C, microbial community composition and population size reflect the paleoenvironment rather than a direct effect through warming.