Highlight articles

Microbial community composition and abundance after millennia of submarine permafrost warming

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.

The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 1: Model description

Our paper describes the Ecosystem Demography model. This computer program calculates how plants and ground exchange heat, water, and carbon with the air, and how plants grow, reproduce and die in different climates. Most models simplify forests to an average big tree. We consider that tall, deep-rooted trees get more light and water than small plants, and that some plants can with shade and drought. This diversity helps us to better explain how plants live and interact with the atmosphere.

The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 2: Model evaluation for tropical South America

The Ecosystem Demography model calculates the fluxes of heat, water, and carbon between plants and ground and the air, and the life cycle of plants in different climates. To test if our calculations were reasonable, we compared our results with field and satellite measurements. Our model predicts well the extent of the Amazon forest, how much light forests absorb, and how much water forests release to the air. However, it must improve the tree growth rates and how fast dead plants decompose.

Physical constraints for respiration in microbial hotspots in soil and their importance for denitrification

Biogeosciences
DOI 10.5194/bg-16-3665-2019
27 September 2019

A combination of gas chromatography and X-ray CT reveals the microscale processes that govern soil respiration. Aerobic and anaerobic respiration in microbial hotspots depends not only on the quality and quantity of soil organic matter, but also on the spatial distribution of hotspots. Denitrification kinetics are mainly governed by hotspot architecture due to local competition for oxygen during growth. Cumulative behavior is mainly governed by water saturation due to the overall supply with O₂.

Improved methodologies for Earth system modelling of atmospheric soluble iron and observation comparisons using the Mechanism of Intermediate complexity for Modelling Iron (MIMI v1.0)

MIMI v1.0 was designed for use within Earth system models to simulate the 3-D emission, atmospheric processing, and deposition of iron and its soluble fraction. Understanding the iron cycle is important due to its role as an essential micronutrient for ocean phytoplankton; its supply limits primary productivity in many of the world’s oceans. Human activity has perturbed the iron cycle, and MIMI is capable of diagnosing many of these impacts; hence, it is important for future climate studies.

Ideas and perspectives: is shale gas a major driver of recent increase in global atmospheric methane?

Atmospheric methane has risen rapidly since 2008 and has become more depleted in ¹³C, in contrast to the trend towards more ¹³C enrichment in the late 20th century. Many have used this isotopic evidence to infer an increased biogenic source. Here I analyze the ¹³C trend with the consideration that methane from shale gas is somewhat depleted in ¹³C compared to other fossil fuels. I conclude that shale gas may be responsible for a third of the global increase from all sources.

Global soil–climate–biome diagram: linking surface soil properties to climate and biota

Surface soils interact strongly with both climate and biota and provide fundamental ecosystem services. However, the quantitative linkages between soil, climate, and biota remain unclear at a global scale. By compiling a large global soil database, we mapped eight major soil properties based on machine learning algorithms and developed a global soil–climate–biome diagram. Our results suggest shifts in soil properties under global climate and land cover change.

Dissolved organic matter at the fluvial–marine transition in the Laptev Sea using in situ data and ocean colour remote sensing

In this article, we present the variability and characteristics of dissolved organic matter at the fluvial–marine transition in the Laptev Sea from a unique dataset collected during 11 Arctic expeditions. We develop a new relationship between dissolved organic carbon (DOC) and coloured dissolved organic matter absorption, which is used to estimate surface water DOC concentration from space. We believe that our findings help current efforts to monitor ongoing changes in the Arctic carbon cycle.

Responses of an abyssal meiobenthic community to short-term burial with crushed nodule particles in the south-east Pacific

To elucidate the potential effects of crushed nodule particle deposition on abyssal meiobenthos, we covered abyssal soft sediment in the Peru Basin (4200 m depth) with approximately 2 cm of this nodule material for 11 d. About half of the meiobenthos migrated from the sediment into the added material, and nematode feeding type proportions in that added layer were altered. These results considerably contribute to our understanding of the short-term responses of deep-sea meiobenthos to burial.

Reciprocal bias compensation and ensuing uncertainties in model-based climate projections: pelagic biogeochemistry versus ocean mixing

Anthropogenic greenhouse gas emissions trigger complex climate feedbacks. Output form Earth system models provides a basis for related political decision-making. One challenge is to arrive at reliable model parameter estimates for the ocean biogeochemistry module. We illustrate pitfalls through which flaws in the ocean module are masked by wrongly tuning the biogeochemistry and discuss ensuing uncertainties in climate projections.

BG Biogeosciences Highlight articles

Highlight articles

Microbial community composition and abundance after millennia of submarine permafrost warming

The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 1: Model description

The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 2: Model evaluation for tropical South America

Physical constraints for respiration in microbial hotspots in soil and their importance for denitrification

Improved methodologies for Earth system modelling of atmospheric soluble iron and observation comparisons using the Mechanism of Intermediate complexity for Modelling Iron (MIMI v1.0)

Ideas and perspectives: is shale gas a major driver of recent increase in global atmospheric methane?

Global soil–climate–biome diagram: linking surface soil properties to climate and biota

Dissolved organic matter at the fluvial–marine transition in the Laptev Sea using in situ data and ocean colour remote sensing

Responses of an abyssal meiobenthic community to short-term burial with crushed nodule particles in the south-east Pacific

Reciprocal bias compensation and ensuing uncertainties in model-based climate projections: pelagic biogeochemistry versus ocean mixing

Information for

External links