TY - JOUR

T1 - Extracellular enzyme ratios reveal locality and horizon-specific carbon, nitrogen, and phosphorus limitations in Arctic permafrost soils

AU - Varsadiya, Milan

AU - Liebmann, Patrick

AU - Petters, Sebastian

AU - Hugelius, Gustaf

AU - Urich, Tim

AU - Guggenberger, Georg

AU - Bárta, Jiří

N1 - Funding Information: Present work was supported by Czech Science Foundation [project n. 20-2125 J].

PY - 2022/11

Y1 - 2022/11

N2 - Permafrost affected soils are highly vulnerable to climate change. These soils store huge amounts of organic carbon (C), and a significant proportion of this carbon is stored in subsoil horizons where it might become available to microbial decomposition under global warming. An important factor in understanding and quantifying the C release from soils include the limitation of resources for microbes. Microbes decompose soil organic matter (SOM) by secreting extracellular enzymes into the soil, thus enzyme activity and their ratios are considered important indicators of soil nutrient availability and microbial substrate limitation. To evaluate nutrient limitation and the limitation of microbial substrate utilization, we investigated the potential enzyme activity from whole soil profiles, including topsoil, cryoturbated organic matter, mineral subsoil, and permafrost of Herschel Island (Canada) and Disko Island (Greenland). We included seven enzymes (five hydrolytic and two oxidative) and related them to bacterial and fungal gene abundance. The results showed hydrolytic enzymatic activity was strongly influenced by soil type, whereas oxidative enzymes varied between different localities. The enzyme ratios indicated that the topsoil microbial communities were C and phosphorus (P) co-limited in both localities, whereas the subsoil communities were nitrogen (N) limited from HI and C, P limited from DI. A strong positive correlation between all measured enzymes and bacterial gene abundance compared to that of fungi suggested that bacteria might play a more important role in SOM decomposition in permafrost soil horizons. This study suggests that Arctic permafrost microbial communities were not only limited by N, but also by C, P, and their co-limitation under specific conditions (i.e., higher abundance of bacteria and lower abundance of fungi).

AB - Permafrost affected soils are highly vulnerable to climate change. These soils store huge amounts of organic carbon (C), and a significant proportion of this carbon is stored in subsoil horizons where it might become available to microbial decomposition under global warming. An important factor in understanding and quantifying the C release from soils include the limitation of resources for microbes. Microbes decompose soil organic matter (SOM) by secreting extracellular enzymes into the soil, thus enzyme activity and their ratios are considered important indicators of soil nutrient availability and microbial substrate limitation. To evaluate nutrient limitation and the limitation of microbial substrate utilization, we investigated the potential enzyme activity from whole soil profiles, including topsoil, cryoturbated organic matter, mineral subsoil, and permafrost of Herschel Island (Canada) and Disko Island (Greenland). We included seven enzymes (five hydrolytic and two oxidative) and related them to bacterial and fungal gene abundance. The results showed hydrolytic enzymatic activity was strongly influenced by soil type, whereas oxidative enzymes varied between different localities. The enzyme ratios indicated that the topsoil microbial communities were C and phosphorus (P) co-limited in both localities, whereas the subsoil communities were nitrogen (N) limited from HI and C, P limited from DI. A strong positive correlation between all measured enzymes and bacterial gene abundance compared to that of fungi suggested that bacteria might play a more important role in SOM decomposition in permafrost soil horizons. This study suggests that Arctic permafrost microbial communities were not only limited by N, but also by C, P, and their co-limitation under specific conditions (i.e., higher abundance of bacteria and lower abundance of fungi).

KW - Climate change

KW - Enzyme stoichiometry

KW - Microbial abundance

KW - Nutrient limitation

KW - Permafrost

UR - http://www.scopus.com/inward/record.url?scp=85138280017&partnerID=8YFLogxK

U2 - 10.1007/s10533-022-00967-z

DO - 10.1007/s10533-022-00967-z

M3 - Article

AN - SCOPUS:85138280017

VL - 161

SP - 101

EP - 117

JO - BIOGEOCHEMISTRY

JF - BIOGEOCHEMISTRY

SN - 0168-2563

IS - 2

ER -