We distinguished particulate organic carbon (POC) export fluxes out of the nutrient-depleted layer (NDL) and the euphotic zone. The amount of POC export flux at the NDL base suggests that the NDL could be a hotspot of particle export. The substantial POC export flux at the NDL base challenges traditional concepts that the NDL was limited in terms of POC export. The dominant nutrient source for POC export fluxes should be subsurface nutrients, which was determined by ¹⁵N isotopic mass balance.

We measured the land–atmosphere exchange of CO₂ and water vapor in alpine Norway over 3 years. The extremely snow-rich conditions in 2020 reduced the total annual evapotranspiration to 50 % and reduced the growing-season carbon assimilation to turn the ecosystem from a moderate annual carbon sink to an even stronger source. Our analysis suggests that snow cover anomalies are driving the most consequential short-term responses in this ecosystem’s functioning.

In this study we investigated the effect of different parameters (temperature, landscape position) on the production of greenhouse gases during a 1-year permafrost thaw experiment. For very similar carbon and nitrogen contents, our results show a strong heterogeneity in CH₄ production, as well as in microbial abundance. According to our study, these differences are mainly due to the landscape position and the hydrological conditions established as a result of the topography.

Bacteriohopanepolyols (BHPs) are a diverse class of lipids produced by bacteria across a wide range of environments. This study characterizes the diversity of BHPs in lakes and coastal lagoons in the Azores Archipelago, as well as a co-culture enriched for methanotrophs. We highlight the potential of BHPs as taxonomic markers for bacteria associated with certain ecological niches, which can be preserved in sedimentary records.

Drained peatlands (peat areas where ditches have been excavated to enhance crop productivity) are one of the main sources of carbon dioxide emissions globally. Blocking the ditches by building dams is a common strategy to raise the water table and to mitigate carbon dioxide emissions. But how effective is ditch blocking in raising the overall water table over a large area? Our work tackles this question by making use of the available data and physics-based hydrological modeling.

Unprecedented climate extremes (UCEs) are expected to have dramatic impacts on ecosystems. We present a road map of how dynamic vegetation models can explore extreme drought and climate change and assess ecological processes to measure and reduce model uncertainties. The models predict strong nonlinear responses to UCEs. Due to different model representations, the models differ in magnitude and trajectory of forest loss. Therefore, we explore specific plant responses that reflect knowledge gaps.

To study whether nutrient availability controls tropical dry forest responses to reductions in soil moisture, we established the first troughfall exclusion experiment in a tropical dry forest plantation system crossed with a fertilization scheme. We found that the effects of fertilization on net primary productivity are larger than the effects of a ~15 % reduction in soil moisture, although in many cases we observed an interaction between drought and nutrient additions, suggesting colimitation.

Data on past relative humidity (RH) ARE needed to improve its representation in Earth system models. A novel isotope parameter (¹⁷O-excess) of plant silica has been developed to quantify past RH. Using comprehensive monitoring and novel methods, we show how environmental and plant physiological parameters influence the ¹⁷O-excess of plant silica and leaf water, i.e. its source water. The insights gained from this study will help to improve estimates of RH from fossil plant silica deposits.

Dissolved organic matter (DOM) mobilized from surface soils is a source of carbon (C) for deeper mineral horizons but also a mechanism of C loss. Composition of DOM mobilized in boreal forests varied more by season than as a result of forest harvesting. Results suggest reduced snowmelt and increased fall precipitation enhance DOM properties promoting mineral soil C stores. These findings, coupled with hydrology, can inform on soil C fate and boreal forest C balance in response to climate change.

The decomposition of soil organic matter and flux of carbon dioxide are expected to increase as temperatures rise. However, soil organic matter decomposition is a two-step process whereby large molecules are first broken down outside microbial cells and then respired within microbial cells. We show here that these two steps are not equally sensitive to increases in soil temperature and that global warming may cause a shift in the rate-limiting step from outside to inside the microbial cell.