The gut mucosal environment is key in host health; protecting against pathogens and providing a niche for beneficial bacteria, thereby facilitating a mutualistic balance between host and microbiome. Lack of dietary fiber results in erosion of the mucosal layer, suggested to be a result of increased mucus-degrading gut bacteria. This study aimed to use quantitative analyses to investigate the diet-induced imbalance of mucosal homeostasis. Seven days of fiber-deficiency affected intestinal anatomy and physiology, seen by reduced intestinal length and loss of the colonic crypt-structure. Moreover, the mucus layer was diminished, muc2 expression decreased, and impaired mucus secretion was detected by stable isotope probing. Quantitative microbiome profiling of the gut microbiota showed a diet-induced reduction in bacterial load and decreased diversity across the intestinal tract, including taxa with fiber-degrading and butyrate-producing capabilities. Most importantly, there was little change in the absolute abundance of known mucus-degrading bacteria, although, due to the general loss of taxa, relative abundance would erroneously indicate an increase in mucus degraders. These findings underscore the importance of using quantitative methods in microbiome research, suggesting erosion of the mucus layer during fiber deprivation is due to diminished mucus production rather than overgrowth of mucus degraders. View Full-Text

Soils in the northern high latitudes are a key component in the global carbon cycle; the northern permafrost region covers 22 % of the Northern Hemisphere land surface area and holds almost twice as much carbon as the atmosphere. Permafrost soil organic matter stocks represent an enormous long-term carbon sink which is in risk of switching to a net source in the future. Detailed knowledge about the quantity and the mechanisms controlling organic carbon storage is of utmost importance for our understanding of potential impacts of and feedbacks on climate change. Here we present a geospatial dataset of physical and chemical soil properties calculated from 651 soil pedons encompassing more than 6500 samples from 16 different study areas across the northern permafrost region. The aim of our dataset is to provide a basis to describe spatial patterns in soil properties, including quantifying carbon and nitrogen stocks. There is a particular need for spatially distributed datasets of soil properties, including vertical and horizontal distribution patterns, for modeling at local, regional, or global scales. This paper presents this dataset, describes in detail soil sampling; laboratory analysis, and derived soil geochemical parameters; calculations; and data clustering. Moreover, we use this dataset to estimate soil organic carbon and total nitrogen storage estimates in soils in the northern circumpolar permafrost region (17.9×106 km2) using the European Space Agency's (ESA's) Climate Change Initiative (CCI) global land cover dataset at 300 m pixel resolution. We estimate organic carbon and total nitrogen stocks on a circumpolar scale (excluding Tibet) for the 0–100 and 0–300 cm soil depth to be 380 and 813 Pg for carbon, and 21 and 55 Pg for nitrogen, respectively. Our organic carbon estimates agree with previous studies, with most recent estimates of 1000 Pg (−170 to +186 Pg) to 300 cm depth. Two separate datasets are freely available on the Bolin Centre Database repository (https://doi.org/10.17043/palmtag-2022-pedon-1, Palmtag et al., 2022a; and https://doi.org/10.17043/palmtag-2022-spatial-1, Palmtag et al., 2002b).

Carbon dioxide removal (CDR) that increases the area of forest cover or bio-energy crops inherently competes for land with crop and livestock systems, compromising food security, or will encroach natural lands, compromising biodiversity. Mass deployment of these terrestrial CDR technologies to reverse climate change therefore cannot be achieved without a substantial intensification of agricultural output, i.e., producing more food on less land. This poses a major challenge, particularly in regions where arable land is little available or severely degraded and where agriculture is crucial to sustain people's livelihoods, such as the Global South. Enhanced silicate weathering, biochar amendment, and soil carbon sequestration are CDR techniques that avoid this competition for land and may even bring about multiple co-benefits for food production. This paper elaborates on the idea to take these latter CDR technologies a step further and use them not only to drawdown CO2 from the atmosphere, but also to rebuild fertile soils (negative erosion) in areas that suffer from pervasive land degradation and have enough water available for agriculture. This way of engineering topsoil could contribute to the fight against malnutrition in areas where crop and livestock production currently is hampered by surface erosion and nutrient depletion, and thereby alleviate pressure on intact ecosystems. The thrust of this perspective is that synergistically applying multiple soil-related CDR strategies could restore previously degraded soil, allowing it to come back into food production (or become more productive), potentially alleviating pressure on intact ecosystems. In addition to removing CO2 from the atmosphere, this practice could thus contribute to reducing poverty and hunger and to protection of biodiversity.