It is increasingly recognized that marine animals host microbes relevant to nitrogen cycling. Rocky shore tidepools host a phylogenetically diverse biota that inspired us to experimentally isolate their effects on microbial nitrogen processing. We found that mussels promote high rates and diverse types of microbial nitrogen metabolisms. We further developed a novel mathematical model that quantified these diverse processes and showed their significance to nitrogen processing.

The improved LPJ model was used to investigate plant functional type (PFT) changes in 1957–2009 and their responses to changes in root zone soil temperature, soil moisture, air temperature, precipitation, and CO₂ concentrations. The results show spatially heterogeneous changes in PFTs in the northern Tibetan Plateau in 1957–2009. Dominant driver for PFT change is precipitation. The implications of the study are on the regional fresh water resources, onset, and intensity of monsoon circulations.

The magnitude of N₂O emissions from managed grasslands depends on weather and on harvesting and fertilizer practices. Modelling provides a means to predict these emissions under diverse weather and management types. In this modelling study, we show that N₂O emissions depend on how weather affects temperatures and water contents of surface litter and near-surface soil. N₂O emissions modelled from the grassland were increased by suboptimal harvesting practices, fertilizer timing and soil properties.

This survey of an exceptional flood over Lake Geneva challenges the long-standing hypothesis that dense, particle-loaded and oxygenated rivers plunging into lakes necessarily contribute to deep-oxygen replenishment. We identified some river intrusions as hot spots for oxygen consumption, where inputs of fresh river-borne organic matter reactivate the respiration of more refractory lacustrine organic matter in a process referred to as "priming effect".

The ocean loses oxygen due to climate change. Addressing this issue in tropical ocean regions (off Peru and Mauritania), we aimed to understand the effects of oxygen depletion on various aspects of marine biogeochemistry, including primary production and export production, the nitrogen cycle, greenhouse gas production, organic matter fluxes and remineralization, and the role of zooplankton and viruses.

Reactive minerals are ubiquitous in soil and are proposed as a primary driver for carbon (C) retention. However, regulation of soil reactive minerals and direct evidence in sequestrating C by them are scarce. Here we show that, compared with chemical fertilization, inorganic and organic fertilization enhanced the C-binding loadings of Al and Fe minerals in soil colloids, suggesting that reactive mineral species and their associations with C are differentially affected by fertilization practices.

Discrepancies exist on the impact of tillage on soil CO₂ emissions and on the main soil and environmental controls. Results from a meta-analysis using 174 paired observations comparing CO₂ emissions over entire seasons or years from tilled (untilled) soils across different climates, crop types and soil conditions show that on average: (1) tilled soils emit 21 % more CO₂ than untilled soils; (2) the difference increase to 29 % in sandy soils from arid climates with low soil organic carbon content.

With a large-scale survey and sampling, results from this study provides strong evidence that increasing aridity would reduce the soil C and N storage in arid and semi-arid ecosystems due both to the changes of particle-sized fractions in soils (i.e. relatively more sand but less clay and silt in sites with higher aridity) and to the decline of C and N concentrations in each soil fraction.

Methane (CH₄) emissions from hydroelectric reservoirs could represent a significant fraction of global CH₄ emissions from inland waters. The monitoring of methane emissions every 2 weeks at nine stations in a subtropical hydroelectric reservoir revealed that emissions could occasionally be 1 to 2 orders of magnitude higher than expected for these man-made ecosystems. Upstream of the water intake, emissions are enhanced by the water column mixing that upwells CH₄-rich water to the surface.

This special issue showcases recent advancements on the impacts of disturbances and extreme events on the carbon (C) cycle. Notable advancements include quantifying harvest impacts on forest structure, recovery, and carbon stocks; observed dissolved organic C and methane increases in thermokarst lakes following summer warming; disentangling the roles of herbivores and fire on forest carbon dioxide flux; and improved atmospheric inversion of regional C flux by incorporating disturbances.

The Gippsland Lakes, Australia, have suffered from periodic blooms of cyanobacteria (blue green algae) since the mid 1980s. Prior to this, little is known about the history of cyanobacterial blooms in this system. We investigated the history of cyanobacterial blooms using a sediment core taken from the Gippsland Lakes which had each layer dated using lead isotopes. The results showed that surprising blooms of cyanobacteria were also prevalent prior to European settlement

The mineral composition, C / N ratios as well as ¹³C and ¹⁵N, of POC was firstly analyzed in suspended and surface sediments in the Wujiang River after the Three Gorges Dam began impounding sediment in 2004. A comparison of POC yield was made between karstic rivers and non-karstic rivers to evaluate the influence of carbonate distribution on POC transport. Considering the cascade reservoir and climate in the Wujiang River, the impacts of reservoirs and extreme drought were estimated in this study.

We assessed the progressive acidification (pH decrease) of the North Atlantic waters from direct observations between 1991 and 2015. The greatest pH decreases were observed in surface and intermediate waters. We conclude that the observed pH decreases are a consequence of the oceanic uptake of anthropogenic CO₂. In addition we find that they have been partially offset by alkalinity increases.

Landscape fires occur on a large scale in savannas and grasslands, affecting ecosystems and air quality. We combined two satellite-derived datasets to derive fuel consumption per unit of area burned for savannas and grasslands in the (sub)tropics. Fire return periods, vegetation productivity, vegetation type and human land management were all important drivers of its spatial distribution. The results can be used to improve fire emission modelling and management or to detect ecosystem degradation.

Accurately projecting future climate change requires a good methane modeling. However, how good the current models are and what are the key improvements needed remain unclear. This paper reviews the 40 published methane models to characterize the strengths and weakness of current methane models and further lay out the roadmap for future model improvements.

We derived the global maps of grassland management intensity of 1901–2012, including the minimum area of managed grassland with fraction of mown/grazed part. These maps, to our knowledge for the first time, provide global, time-dependent information for drawing up global estimates of management impact on biomass production and yields and for global vegetation models to enable simulations of carbon stocks and GHG budgets beyond simple tuning of grassland productivities to account for management.

Ponds associated with peatlands cover large areas in boreal regions and are potentially important sources of greenhouse gases to the atmosphere. At this point, little is known about the magnitude of these fluxes, where they are generated, and how they are controlled. We analyzed CH₄ and CO₂ summer exchange in a pond and bog located in Ontario and identified sources, mechanisms, and controls on gas exchange. The pond was a hot spot of gas release, with the shore being particularly important.

In the marine environment, sticky sugar-containing gels, termed transparent exopolymeric particles (TEP), are produced from biological sources and physical and chemical processes. These compounds are essential vectors enhancing downward flow of organic matter and its storage at depth. Spatial and temporal dynamics of TEPs were followed for 23 days during the VAHINE mesocosm experiment that investigated the fate of nitrogen and carbon derived from organisms fixing atmospheric N₂ (diazotrophs).

Grasslands hold 28 % of global soil organic carbon (SOC). We studied carbon-fluxes and -pools in subalpine grassland under atmospheric nitrogen (N) deposition (air pollution) treatment. Unlike plant yield, SOC and CO₂ gains were largest at intermediate, not maximum N deposition. Thus, N deposition driven plant yield increases may not be considered as a valid proxy for ecosystem C-pool increases and the biological sink for CO₂ greenhouse gas may be smaller under higher N deposition.

We used hemispherical photography to measure LAI values in three subtropical forests from April 2014 to January 2015. Spatial heterogeneity of LAI and its controlling factors were analysed using geostatistical methods and the generalised additive models (GAMs), respectively. Our results showed that LAI values differed greatly in three forests and their seasonal variations were consistent with plant phenology. Stand characters significantly affected the spatial variations in LAI values.

We use a novel ion chromatographic analysis that provides the first identification and quantification of major low-molecular-weight dissolved organic carbon (LMW-DOC) compounds in basal ice. LMW-DOC concentrations were dependent on the bioavailability of the overridden organic carbon, which in turn was influenced by the type of overridden material. The overridden material may thus act as a direct (abiotic leaching) and indirect (microbial cycling) source of DOC to the subglacial environment.