Biology subjects

Dorrepaal, E.

Publications and source records attributed to Dorrepaal, E..

4 recordsLinked to original sources

bioRxiv2026

Dynamic winter microbial communities shape nitrogen cycling potential in Arctic tundra soils

Arctic winters are long and cold and have traditionally been considered a period of limited biological activity. However, the seasonal dynamics of microbial community composition and functional potential during winter remain poorly understood. Here, we investigated taxonomic (bacteria, fungi, archaea) and functional (fungal guilds and nitrogen cycling genes) dynamics throughout a full year at two Arctic tundra heath sites with contrasting snow regimes. A steep drop in microbial abundances in early to mid-winter, likely linked to freeze-thaw events, coincided with shifts in soil pH and elevated community turnover. Saprotrophic and root-associated fungi were more abundant in the cold-season, while inorganic nitrogen cycling groups were more abundant in summer and declined toward winter despite high bacterial abundance. This indicates sustained organic matter cycling during the winter and expanded inorganic nitrogen cycling in the summer. Functional gene ratios further suggested a higher early-winter nitrogen loss potential via nitrous oxide and greater late-winter nitrogen retention. Site-specific differences in snow regime altered the timing and magnitude of these dynamics. Together, our results demonstrate that winter represents a critical and dynamic period for microbial community restructuring with important implications for nitrogen turnover in Arctic tundra soils.

microbiology↗

bioRxiv2025

Diversity, abundance, and biogeography of CO2 fixing microorganisms in peatlands

Microbial communities play a crucial role in the carbon (C) dynamic of peatlands-- a major terrestrial C reservoir. While heterotrophic microorganisms attracted much attention over the past decades due to their role in peatland greenhouse gases emissions, CO2 fixing microorganisms (CFMs) remained particularly overlooked. Here, by leveraging metabarcoding and digital droplet PCR (ddPCR), we provide a comprehensive survey of CFM communities, including oxygenic phototrophs, chemoautotrophs and aerobic anoxygenic phototrophic bacteria (AAnPBs), in different peatland types. We demonstrate that CFMs are very abundant and diverse in peatlands, with on average 1021 CFMs contributing up to 40% of the total bacterial abundance. In particular, we show that oxygenic phototrophs (mostly Cyanophyceae and Palmophylloceae) are the most abundant CFMs, closely followed by chemoautotrophs (Proteobacteria) and AAnPBs (Vulcanimicrobiia). Using a joint-species distribution model, we further find that CFMs aggregate into six major clusters with different niche size. These clusters constitute the core and specific CFM microbiome. The core microbiome, which the occurrence is strongly influenced by temperature and nutrients, directly modulate the diversity and abundance of CFMs. Our findings highlight the importance of CFM diversity and abundance in peatlands, further reveal their complex structuration in link with environmental conditions and suggest that changes in environmental conditions could shift CFMs communities. These results are the foundation to better understand the role of CFMs for the peatland C cycle inputs.

microbiology↗

bioRxiv2024

Macro-environment strongly interacts with warming in a global analysis of decomposition

Empirical studies worldwide show substantial variability in plant litter decomposition responses to warming, leaving the overall impact of climate change on this process uncertain. We conducted a meta-analysis of 109 experimental warming studies across seven continents, utilizing natural and standardized plant material, to assess the overarching effect of warming on decomposition and identify potential moderating factors. Warming influences decomposition differently across macro-environmental gradients of moisture and temperature. Negative warming effects on decomposition in warmer, low-moisture areas were counterbalanced by the positive, though not significant, warming effects in colder areas, resulting in an overall non-significant effect. We determine that at least 5.2 degrees of warming is required for a significant increase in decomposition. This is particularly relevant given the past decades global warmth in higher latitudes, holding a significant proportion of terrestrial carbon. Low-quality plant litter was more sensitive to warming. Therefore, future vegetation changes toward low-quality, temperature-sensitive plants could increase carbon release and reduce the net supply of stored organic matter in the soil by increasing the decomposition of low-quality litter with warming. Our findings emphasize the connection between warming responses, macro-environment, and litter characteristics, refining predictions of climate changes consequences on key ecosystem processes and its contextual dependencies.

ecology↗

bioRxiv2020

Morphological and biochemical responses of Sphagnum mosses to environmental changes

* Background and AimsSphagnum mosses are vital for peatland carbon (C) sequestration, although vulnerable to environmental changes. For averting environmental stresses such as hydrological changes, Sphagnum mosses developed an array of morphological and anatomical peculiarities maximizing their water holding capacity. They also produce plethora of biochemicals that could prevent stresses-induced cell-damages but these chemicals remain poorly studied. We aimed to study how various anatomical, metabolites, and antioxidant enzymes vary according to Sphagnum taxonomy, phylogeny and environmental conditions. * MethodsWe conducted our study in five Sphagnum-dominated peatlands distributed along a latitudinal gradient in Europe, representing a range of local environmental and climate conditions. We examined the direct and indirect effects of latitudinal changes in climate and vegetation species turnover on Sphagnum anatomical (cellular and morphological characteristics) and biochemical (spectroscopical identification of primary and specialized metabolites, pigments and enzymatic activities) traits. * Key resultsWe show that Sphagnum traits were not driven by phylogeny, suggesting that taxonomy and/or environmental conditions prevail on phylogeny in driving Sphagnum traits variability. We found that moisture conditions were important determinants of Sphagnum anatomical traits, especially those related to water holding capacity. However, the species with the highest water holding capacity also exhibited the highest antioxidant capacity, as showed by the high flavonoid and enzymatic activities in their tissues. Our study further highlighted the importance of vascular plants in driving Sphagnum biochemical traits. More particularly, we found that Sphagnum mosses raises the production of specific compounds such as tannins and polyphenols known to reduce vascular plant capacity when herbaceous cover increases. * ConclusionsOur findings show that Sphagnum anatomical and biochemical traits underpin Sphagnum niche differentiation through their role in specialization towards biotic stressors, such as plant competitors, and abiotic stressors, such as hydrological changes, which are important factors governing Sphagnum growth.

ecology↗