Metabarcoding Inventory of an Arctic Tundra Soil Ecosystem Reveals Highly Endemic Communities

Abstract

Biodiversity surveys of Arctic soil ecosystems are limited. Here, we provide a sequence-based inventory of soil fauna from an Arctic tundra ecosystem near Iqaluktuutiaq (Cambridge Bay), Nunavut. Invertebrate communities were extracted from soil at three sites with vegetation cover and three non-vegetated sites and inventoried using 18S metabarcode sequencing. A total of 361 Amplicon Sequence Variants (ASV) were identified and assigned to the closest matching taxonomic orders, most of which belonged to the Nematoda and Arthropoda. Vegetated soils showed no significantly higher ASV richness relative to non-vegetated soils although they contained a significantly higher diversity of arthropod taxa including insects, mites and springtails. The majority of taxa were found only at a single location and communities were distinct between soils even for sites with vegetation cover, suggesting that belowground species richness in Arctic tundra habitats is highly endemic and heterogeneous. Preserving endemicity is essential for Inuit communities who rely on intact tundra ecosystems for their health and wellbeing.

Summer litter decomposition is moderated by scale‐dependent microenvironmental variation in tundra ecosystems

“…Our results support the idea that large-scale variation in litter decomposition can be explained by macro-scale temperature conditions (Swift et al 1979, Davidson and Janssens 2006, Keuskamp et al 2013 https://www.zotero.org/google-docs/?broken=xgn2Za, but indicated that variation in soil moisture and active layer thickness play a greater role at the landscape scale. While we detected no significant interactions between soil moisture and thermal sum at this location, as the tundra continues to change under warming climates and shifting weather regimes, examining relationships between temperature, soil moisture and active layer depth and decomposition remains an important step in further research (Tao et al 2019, Jorna et al 2022.…”

“…We did not investigate soil fauna or microbial activity in this study, but soil fauna presence, which increases litter decomposition, is globally driven by both soil moisture content (Thakur et al 2018) and global temperature patterns (Wall et al 2008). Tundra soil fauna populations can be spatially heterogeneous and linked to microhabitats and vegetation (Tao et al 2019, Jorna et al 2022). We did however, observe fungal biomass in soils during the extraction of our tea bags in some locations, suggesting that the below‐ground biotic environment could be an important factor explaining litter decomposition across this study system.…”

“…Taking the below‐ground heterogeneity of both biotic and abiotic factors into consideration along with projections of environmental change such as increasing precipitation will be key for generating robust estimates of decomposition rates across the tundra (Filser et al 2016). (Jorna et al 2022, Tao et al 2019)…”

“…Taking the below-ground heterogeneity of both biotic and abiotic factors into consideration along with projections of environmental change such as increasing precipitation will be key for generating robust estimates of decomposition rates across the tundra (Filser et al 2016). (Jorna et al 2022, Tao et al 2019 We initially predicted that decomposition would decrease with elevation due to more exposed microclimates and greater drainage of soils. We found slight decreases in mass loss with increasing elevation in our data, and surprisingly we found slightly greater decomposition on north-facing slopes, which despite not receiving as much sunlight as south-facing slopes, may have been wetter due to delayed snowmelt (Fig.…”