Pan-Arctic soil moisture control on tundra carbon sequestration and plant productivity.

Long-term atmospheric CO concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength.

Vegetation type is an important predictor of the arctic summer land surface energy budget.

Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994-2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics.

Mismatch of N release from the permafrost and vegetative uptake opens pathways of increasing nitrous oxide emissions in the high Arctic.

Biogeochemical cycling in permafrost-affected ecosystems remains associated with large uncertainties, which could impact the Earth's greenhouse gas budget and future climate policies. In particular, increased nutrient availability following permafrost thaw could perturb the greenhouse gas exchange in these systems, an effect largely unexplored until now. Here, we enhance the terrestrial ecosystem model QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system), which simulates fully coupled carbon (C), nitrogen (N) and phosphorus (P) cycles in vegetation and soil, with processes relevant in high latitudes (e.

Large loss of CO in winter observed across the northern permafrost region.

Recent warming in the Arctic, which has been amplified during the winter, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO). However, the amount of CO released in winter is highly uncertain and has not been well represented by ecosystem models or by empirically-based estimates. Here we synthesize regional observations of CO flux from arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain.

Hydrology-driven ecosystem respiration determines the carbon balance of a boreal peatland.

The carbon (C) balance of boreal peatlands is mainly the sum of three different C fluxes: carbon dioxide (CO2), methane (CH4) and dissolved organic carbon (DOC). Intra- and inter-annual dynamics of these fluxes are differentially controlled by similar factors, such as temperature and water-table. Different climatic conditions within and between years might thus result in varying absolute and relative contributions of each flux to net ecosystem productivity (NEP).