We investigated the light response of field Trichodesmium N₂ fixation and net dissolved nitrogen release behavior. Our results suggest that N₂ fixation was a function of light intensity, and the light requirement of Trichodesmium nitrogen fixation was high relative to its photosynthetic light demand. Meanwhile, light is a crucial parameter driving the physiological state of Trichodesmium, which subsequently determined the C / N metabolism and net dissolved nitrogen release.

This study suggests that soil moisture significantly affects soil organic matter dynamics along a salinity gradient in semiarid steppe soils. The covarying moisture gradient along the salinity gradient serves as an explanatory factor for (i) the increasing soil organic carbon (OC) stocks with increasing salinity, (ii) the constant proportion and stability of particulate OC along the transect, and (iii) a similar fungi : bacteria ratio in the topsoils along the studied gradient.

We present the first large-scale survey of planktonic biogenic carbonate concentrations south of Australia, accompanied by biogenic silica and particulate organic carbon. These suggest that coccolithophores are largely restricted to subantarctic waters and are present in much lower abundance than in Northern Hemisphere polar waters. Comparison to upper ocean properties suggests that thermal tolerance and competition with diatoms for limiting iron may be as influential as ocean acidification.

On long timescales, the inventory of total dissolved inorganic carbon in the ocean is mainly driven by the increase in anthropogenic CO₂ emitted to the atmosphere due to human activities. On short timescales, however, the anthropogenic signal can be masked by the variability in natural inorganic carbon, shown in this study based on Irminger Sea cruise data from 1991 to 2015. In order to estimate oceanic carbon budgets, we suggest jointly assessing natural, anthropogenic and total carbon.

Computer simulations of the highly variable phytoplankton in the Ross Sea demonstrated how incorporating data from different sources (satellite, ship, or glider) results in different system interpretations. For example, simulations assimilating satellite-based data produced lower carbon export estimates. Combining observations with models in this remote, harsh, and biologically variable environment should include consideration of the potential impacts of data frequency, duration, and coverage.

We compared the biomass recovery curves from a recent field-based study with those used in bookkeeping models and demonstrated the importance of considering gross forest changes rather than net forest changes. We also derived a critical gross-to-net forest area change ratio, beyond which the sign of carbon flux will be reversed. This critical ratio was further applied to the high-resolution satellite data in the Amazon to distinguish the sensitive regions.

Soil solution phosphorus (P) turnover is essential for describing the bioavailability of this important nutrient. Here, we provide a derivation of calculating soil solution P turnover using parameters obtained from isotope exchange kinetic experiments. We then calculated and analyzed soil solution P turnover for 217 soils and for 18 long-term P fertilizer field experiments worldwide. Our study thus provides important insights on P dynamics in soils.

By modelling soil CO₂ production, transport and surface exchange processes (e.g. biocrust photosynthesis, respiration and photodegradation), we simulated the large variation of soil CO₂ emissions from sparsely vegetated dryland ecosystem. Based on the model, we studied the roles of different processes in regulating soil C emissions. The complexity of regulation processes implied possibly high non-linearity of C responses to climatic variation, climate change and extreme climate events.

The activity and environmental controls of methanogenesis (MG) within the sulfate-reducing zone (0–30 cm below the seafloor) were investigated in organic-rich sediments of the seasonally hypoxic Eckernförde Bay, SW Baltic Sea. MG activity was mostly linked to non-competitive substrates. The major controls identified were organic matter availability, C / N, temperature, and O₂ in the water column, revealing higher rates in warm, stratified, hypoxic seasons compared to colder, oxygenated seasons.

This study provides a new contribution to our understanding of the coupling between the oxygen minimum zones (OMZs) and climate. It explores how idealized changes in summer and winter Indian monsoon winds affect the productivity of the Arabian Sea and the size and intensity of its OMZ. We find that intensification of Indian monsoon winds can amplify climate warming on decadal to centennial timescales.

Estimated values of selected key CLM4.5-BGC parameters obtained with the Markov chain Monte Carlo (MCMC) approach DREAM_(zs) strongly altered catchment-scale NEE predictions in comparison to global default parameter values. The effect of perturbed meteorological input data on the uncertainty of the predicted carbon fluxes was notably higher for C₃-grass and C₃-crop than for coniferous and deciduous forest. A future distinction of different crop types including management is considered essential.

We combined productivity and photophysiology measurements to investigate the effects of ocean acidification on a natural Antarctic marine microbial community. Our study identifies a threshold for CO₂ tolerance in the phytoplankton community between 953 and 1140 μatm of CO₂, above which productivity declines. Bacteria were tolerant to CO₂ up to 1641 μatm. We identify physiological changes in the phytoplankton at high CO₂ that allowed them to acclimate to the high CO₂ treatment.

Tree fire tolerance strategies may significantly impact woody carbon stability and the existence of tropical savannas under global climate change. We used a numerical ecosystem model to test the impacts of fire survival strategy under differing fire and rainfall regimes. We found that the high survival rate of large fire-tolerant trees reduced carbon losses with increasing fire frequency, and reduced the range of conditions leading to either complete tree loss or complete grass loss.

A systematic investigation of the coccolithophore ecology was performed for the first time in the NW Iberian Margin to broaden our knowledge on the use of fossil coccoliths in marine sediment records to infer environmental conditions in the past. Coccolithophores proved to be significant primary producers and their abundance and distribution was favoured by warmer and nutrient–depleted waters during the upwelling regime, seasonally controlled offshore and influenced by coastal processes onshore.

Amazonia is highly biodiverse and of global importance for regulating the climate system. Because soils are highly weathered, phosphorus (P) is suggested to limit ecosystem productivity. Here, we evaluate the importance of P redistribution by animals using a simple mathematical model synthesizing the major processes of the Amazon P cycle. Our findings suggest that food web complexity plays an important role for sustaining the productivity of terra firme forests.

The introduction of trees in an agricultural field modifies organic matter (OM) inputs to the soil (litterfall, root litter), the microclimate, and the stabilization and decomposition processes of OM. These changes could affect soil organic carbon (SOC) storage, but the importance of each process is not well known. In a long-term agroforestry trial, we showed that SOC storage could be explained by high OM inputs to the soil but that enhanced decomposition could also have reduced this potential.

In Lake Grevelingen, a coastal ecosystem, foraminifera experience important temporal variations in oxygen concentration and in pore water manganese. The high resolution of LA-ICP-MS allows us to analyse the chambers of foraminiferal shells separately and to obtain signals from a series of calcification events. We estimate the variability in Mn/Ca observed within single shells due to biomineralization and show that a substantial part of the signal is related to environmental variability.

In this study we measured phytoplankton use of nitrogen from wastewater treatment plant effluent in a river. The project was designed to test a new technique for isolating phytoplankton from river water prior to isotopic analysis in order to use trace nitrogen source use under environmental conditions. This study helps us understand the fate of anthropogenic nitrogen in aquatic ecosystems, which is essential to establishing effective nutrient management plans.

The south slope of Tian Shan differs from the north slope in environment. The study showed that leaf δ¹⁵N, soil δ¹⁵N and △δ¹⁵N_leaf-soil on the south slope were greater than those on the north slope. The significant influential factors of leaf and soil δ¹⁵N on the south slope were different from those on the north slope. The results suggested that the south slope has higher soil N transformation rates than the north slope and relationships between leaf and soil δ¹⁵N and environment are localized.

Salt marshes have high rates of plant productivity and carbon accumulation. For this study, we found that differences in environmental conditions between estuary types were important in determining the source and stability of soil organic carbon. Specifically, sediment availability was extremely important in promoting high plant productivity and carbon accumulation in an estuary which was sediment-limited. In a sediment-rich estuary vegetation–soil-carbon relationships were weaker.