https://repository.kopri.re.kr/handle/201206/14812 2026-03-05T09:23:18Z https://repository.kopri.re.kr/handle/201206/15068 Title: Responses of soil micro-eukaryotic communities to decadal drainage in a Siberian wet tussock tundra Authors: Myeong, Nu Ri; 권민정; Mathias Gockede; Binu M. Tripathi; Kim, Mincheol Abstract: Climate warming holds the potential to cause extensive drying of wetlands in the Arctic, but the warming-drying effects on belowground ecosystems, particularly micro-eukaryotes, remain poorly understood. We investigated the responses of soil micro-eukaryotic communities, including fungi, protists, and microbial metazoa, to decadal drainage manipulation in a Siberian wet tundra using both amplicon and shotgun metagenomic sequencing. Our results indicate that drainage treatment increased the abundance of both fungal and non-fungal micro-eukaryotic communities, with key groups such as Ascomycota (mostly order Helotiales), Nematoda, and Tardigrada being notably abundant in drained sites. Functional traits analysis showed an increase in litter saprotrophic fungi and protistan consumers, indicating their increased activities in drained sites. The effects of drainage were more pronounced in the surface soil layer than the deeper layer, as soils dry and warm from the surface. Marked compositional shifts were observed for both communities, with fungal communities being more strongly influenced by drainage-induced vegetation change than the lowered water table itself, while the vegetation effect on non-fungal micro-eukaryotes was moderate. These findings provide insights into how belowground micro-eukaryotic communities respond to the widespread drying of wetlands in the Arctic and improve our predictive understanding of future ecosystem changes. 2024-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/14915 Title: Responses of dissolved organic carbon to freeze-thaw cycles associated with the changes in microbial activity and soil structure Authors: 김유진; 김진현; Jung, Ji Young Abstract: Arctic warming accelerates snowmelt, exposing soil surfaces with shallow or no snow cover to freeze-thaw cycles (FTCs) more frequently in early spring and late autumn. FTCs influence Arctic soil C dynamics by increasing or decreasing the amount of dissolved organic carbon (DOC); however, mechanism-based explanations of DOC changes that consider other soil biogeochemical properties are limited. To understand the effects of FTCs on Arctic soil responses, we designed microcosms with surface organic soils from Alaska and investigated several soil biogeochemical changes for seven successive temperature fluctuations of freezing at 9.0 +/- 0.3 degrees C and thawing at 6.2 +/- 0.3 degrees C for 12 h each. FTCs significantly changed the following soil variables: soil CO2 production (CO2), DOC and total dissolved nitrogen (TDN) contents, two DOC quality indices (SUVA(254) and A(365) = A(254)), microaggregate (53-250 mu m) distribution, and small-sized mesopore (0.2-10 mu m) proportion. Multivariate statistical analyses indicated that the FTCs improved soil structure at the scale of microaggregates and small-sized mesopores, facilitating DOC decomposition by soil microbes and changes in DOC quantity and quality by FTCs. This study showed that FTCs increased soil CO2 production, indicating that FTCs affected DOC characteristics without negatively impacting microbial activity. Soil microaggregation enhanced by FTCs and the subsequent increase in microbial activity and small-sized pore proportion could promote DOC decomposition, decreasing the DOC quantity. This study provides a mechanism-based interpretation of how FTCs alter DOC characteristics of the organic soil in the active layer by incorporating structural changes and microbial responses, improving our understanding of Arctic soil C dynamics. 2023-01-01T00:00:00Z