The response of ecosystems to elevated atmospheric CO₂ is affected by nitrogen (N) availability. It has been hypothesized that N limitation becomes progressively stronger (progressive N limitation, PNL). Most long-term free air CO₂ enrichment studies did not see a PNL. This paper shows that enhanced biological N₂ fixation only prevents PNL in plant communities with symbiotic N₂ fixation. In most ecosystems a stimulation of gross N mineralization prevents the development of a PNL.

Aquatic macrophytes can be used for wastewater polishing but not for purification. At a low nutrient loading M. spicatum and A. filiculoides performed equally well for P removal, whereas at loads ≥ 22 mg P m⁻² d⁻¹, A. filiculoides removes P more efficiently. We provide an easily applicable method to select efficient macrophytes species for wastewater polishing, which is essential for decision support in water management using constructed wetlands for nutrient removal by plant harvesting.

Although India has the third highest number of dams globally, there is a knowledge gap on the cycling of bioessential elements in such systems. This study (first of its kind) investigates the stable isotopes of nitrate and particulate organic matter in a pristine Indian reservoir. Nitrogen transformations in the anaerobic bottom waters were isotopically characterised. Overall, solar intensity, water depth and redox conditions are the major controls on the biogeochemical cycling in this system.

In this study HAMOCC2.0 is used to address how mechanisms of oxygen minimum zone (OMZ) expansion respond to changes in CO₂ radiative forcing within the model. Atmospheric pCO₂ is increased at a rate of 1 % annually until stabilized. Our study suggests that expansion in the Pacific Ocean within the model is controlled largely by changes in particulate organic carbon export (POC). The vertical expansion of the OMZs in the Atlantic and Indian oceans is linked to reduced oxygen solubility.

Release of greenhouse gases from northern soils contributes significantly to the global atmosphere and plays an important role in regulating climate. This study, based in N. Finland, aimed to measure and understand release of CH₄ and N₂O, and using satellite imagery, upscale our results to a 2 × 2 km area. Wetlands released large amounts of CH₄, with emissions linked to temperature and the presence of Sphagnum; landscape emissions were 2.05 mg C m⁻² hr⁻¹. N₂O fluxes were consistently near-zero.

The 2015–2016 El Niño was the strongest on record and has generated significant coral bleaching and mortality worldwide. In Indonesia, first signs of bleaching were reported in April 2016. However, we show that this El Niño has impacted Indonesian reefs since 2015 through a different process than temperature-induced bleaching. Another El Niño-induced process, sea level fall, is responsible for significant coral mortality on North Sulawesi shallow reefs, and probably throughout Indonesia.

Planktonic foraminifera species depth habitat remains poorly constrained and the existing conceptual models are not sufficiently tested by observational data. Here we present a synthesis of living planktonic foraminifera abundance data in the subtropical eastern North Atlantic from vertical plankton tows. We also test potential environmental factors influencing the species depth habitat and investigate yearly or lunar migration cycles. These findings may impact paleoceanographic studies.

This paper describes operational methods to achieve whole-ecosystem warming (WEW) for tall-stature, high-carbon, boreal forest peatlands. The methods enable scientists to study immediate and longer-term (1 decade) responses of organisms (microbes to trees) and ecosystem functions (carbon, water and nutrient cycles). The WEW technology allows researchers to have a plausible glimpse of future environmental conditions for study that are not available in the current observational record.

The Cretaceous–Paleogene boundary, ~ 66 Ma, is characterized by a mass extinction. We studied groups of both surface-dwelling and bottom-dwelling organisms to unravel the oceanographic consequences of these extinctions. Our integrated records indicate that a reduction of the transport of organic matter to the sea floor resulted in enhanced recycling of nutrients in the upper water column and decreased food supply at the sea floor in the first tens of thousands of years after the extinctions.

Accurate ecological data on planktic foraminifera (calcifying microbes that play an important role in the carbon cycle) are important for modelling their response to climate change. We studied the species G. bulloides. A lack of algal symbionts and unusual shell chemistry suggest a different life history compared to other spinose species. We demonstrate that G. bulloides hosts cyanobacterial endobionts. This has implications for modelling this species and for understanding its shell chemistry.

Root systems are essential in nutrient uptake and translocation, but are difficult to characterize non-invasively with existing methods. We propose electrical impedance tomography (EIT) as a new tool for the imaging and monitoring of crop root systems. In a laboratory experiment we demonstrate the capability of the method to capture physiological responses of root systems with high spatial and temporal resolution. We conclude that EIT is a promising functional imaging technique for crop roots.

The surface sediments of the Ulleung Basin (UB) in the East Sea are characterized by high organic carbon contents (> 2.5 %, dry wt.) and very high concentrations of Mn oxides (> 200 μmol cm⁻³) and Fe oxides (up to 100 μmol cm⁻³). For the first time in deep offshore sediments on the Asian margin with water depth over 2000 m, we report that Mn reduction and Fe reduction were the dominant organic carbon (C_org) oxidation pathways, comprising 45 % and 20 % of total C_org oxidation, respectively.

Coastal lagoons are extremely rich, diverse, and dynamic but very fragile ecosystems subject to anthropogenic pressures. A joint France–Mexico biogeochemical study was conducted in the Términos Lagoon under severe drought related to an El Niño Modoki episode. In short, the water column of the Términos Lagoon functioned as a nitrogen sink, but variation in mineral stoichiometry across the lagoon mainly accounted for the heterogeneity in microbial distribution and activity.

Lianas (woody vines) tend to respond positively to disturbance and show high densities in secondary forests. Lianas are a key component of tropical forests because they may reduce carbon potential. Identifying tools for liana detection is therefore essential for monitoring changes in tropical forests. In this study, we describe how terrestrial laser scanning can be used to detect the presence of lianas in forest stands of different ages in secondary tropical dry forests at a regional scale.

The use of ¹⁵N natural abundance of soil ammonium and nitrate demonstrates a clear shifting contribution from abiotic to biotic controls on N cycling along a 3200 km dryland transect in northern China, with a threshold at mean annual precipitation of 100 mm. Abiotic factors were the main driver below threshold, shown by the accumulation of atmospheric N and NH₃ losses. In the area above threshold, soil N cycling was controlled mainly by biological factors, e.g., plant uptake and denitrification.

We present a suitable and reliable method to detect short-term and small-scale soil organic carbon stock dynamics (ΔSOC). Spatiotemporal dynamics of ΔSOC are determined for a 5-year study period at the experimental field trial CarboZALF using automatic chamber measurements of NEE and modeled NPP_shoot. Results were compared against ΔSOC observed from repeated soil inventories. Both ∆SOC data sets corresponded well regarding their magnitude and spatial tendency.

To resolve multiple N transformation rates, we proposed an innovative “isotope matrix method” to simultaneously derive rates for multiple transformations. This method was designed specifically for incubations in the euphotic zone under simulated in situ light conditions and minimized potential biases caused by non-targeted processes. The method facilitates simple post hoc analysis of data and can be used to probe specific effects of environmental factors on the rates of interactive N processes.