SPRUCE Peatland Warming Microbial Community

Community ID CommunityMech:000319

Ecological State STABLE

Environment peatland
ENVO:00000044

Microbial community from the SPRUCE (Spruce and Peatland Responses Under Changing Environments) whole-ecosystem warming experiment at Marcell Experimental Forest, Minnesota. This long-term DOE-funded experiment (ORNL) provides a unique whole-ecosystem warming gradient (+0°C to +9°C) with elevated CO2 (eCO2) treatments in a northern boreal peatland. The natural microbial community has been extensively characterized through amplicon sequencing (16S rRNA for bacteria/archaea, ITS for fungi) and metatranscriptomics, revealing climate change-driven shifts in community composition and function. Key findings include: (1) warming promotes saprophytic fungi and chemoorganoheterotrophic bacteria in root-associated environments, (2) eCO2 enhances ectomycorrhizal fungal associations with vascular plants, particularly short-distance exploration strategies targeting labile soil nitrogen, (3) vascular plant fine root traits mediate climate effects on microbial communities, serving as a critical mechanism for peatland vegetation responses to global change. The community exhibits distinct niche partitioning between aquatic (waterlogged surface peat) and terrestrial (deeper peat) zones. Viral communities (4,326 vOTUs) show strong correlations with peat depth, water content, and carbon chemistry (CH4/CO2) but not temperature during initial warming phases. This represents one of the most comprehensively studied natural microbial communities under realistic climate change scenarios, with implications for carbon cycling, methane emissions, and ecosystem feedbacks in boreal peatlands. Northern peatlands store approximately one-third of global soil carbon despite covering only 3% of land area, making their responses to warming and eCO2 critical for global carbon cycle feedbacks. The comprehensive multi-omics datasets (amplicon, metagenome, metatranscriptome, virome) make this community exceptionally well-characterized for mechanistic modeling of climate-microbe-plant-carbon interactions.

Taxonomy

Taxon	Ontology ID	Functional Roles	Abundance
Bacteria	NCBITaxon:2	PRIMARY_DEGRADER SECONDARY_FERMENTER	DOMINANT
PMID:38515239 - SUPPORT (IN_VIVO) "Warming promoted self-reliance for resource uptake in trees and shrubs, while saprophytic fungi and putative chemoorganoheterotrophic bacteria utilizing plant-derived carbon substrates were favored in the root zone"
Archaea	NCBITaxon:2157	SECONDARY_FERMENTER	COMMON
PMID:34836550 - SUPPORT (IN_VIVO) "Here, 87 metagenomes and five viral size-fraction metagenomes (viromes) from a boreal peatland in northern Minnesota"
Fungi	NCBITaxon:4751	PRIMARY_DEGRADER SYNTROPHIC_PARTNER	DOMINANT
PMID:38515239 - SUPPORT (IN_VIVO) "Warming promoted self-reliance for resource uptake in trees and shrubs, while saprophytic fungi and putative chemoorganoheterotrophic bacteria utilizing plant-derived carbon substrates were favored in the root zone" PMID:38515239 - SUPPORT (IN_VIVO) "Trees mostly associated with short-distance exploration-type fungi that preferentially use labile soil N"
Viruses	NCBITaxon:10239	PRIMARY_DEGRADER	ABUNDANT
PMID:34836550 - SUPPORT (IN_VIVO) "Of the 4326 SPRUCE vOTUs" PMID:34836550 - SUPPORT (IN_VIVO) "viral community composition was significantly correlated with peat depth, water content, and carbon chemistry, including CH4 and CO2 concentrations, but not with temperature during the first 2 years of warming treatments" PMID:34836550 - SUPPORT (IN_VIVO) "Peat vOTUs with aquatic-like signatures (shared predicted protein content with marine and/or freshwater vOTUs) were significantly enriched in more waterlogged surface peat"

Ecological Interactions

Taxon

Mutualism

Niche partitioning

Other

Warming-Enhanced Saprophytic Decomposition

MUTUALISM

Source Taxon: Fungi

Target Taxon: Bacteria

Metabolites: carbon dioxide (CHEBI:16526), methane (CHEBI:16183)

Biological Processes:

cellulose catabolic process (GO:0030245)
lignin catabolic process (GO:0046274)

Evidence

PMID:38515239 - SUPPORT (IN_VIVO)

"Warming promoted self-reliance for resource uptake in trees and shrubs, while saprophytic fungi and putative chemoorganoheterotrophic bacteria utilizing plant-derived carbon substrates were favored in the root zone"

Elevated CO2-Enhanced Ectomycorrhizal Symbiosis

MUTUALISM

Source Taxon: Fungi

Metabolites: glucose (CHEBI:17234), L-glutamine (CHEBI:18050), ammonium (CHEBI:28938)

Biological Processes:

acquisition of nutrients from host (GO:0044002)
acquisition of nutrients from symbiont (GO:0051850)

Evidence

PMID:38515239 - SUPPORT (IN_VIVO)

"Conversely, eCO2 promoted associations between trees and ectomycorrhizal fungi"
PMID:38515239 - SUPPORT (IN_VIVO)

"Trees mostly associated with short-distance exploration-type fungi that preferentially use labile soil N"

Root Trait-Mediated Microbial Community Assembly

NICHE_PARTITIONING

Biological Processes:

response to other organism (GO:0051707)

Evidence

PMID:38515239 - SUPPORT (IN_VIVO)

"Our results indicate that plant fine-root trait variation is a crucial mechanism through which vascular plants in peatlands respond to climate change via their influence on microbial communities that regulate biogeochemical cycles"

Viral-Host Dynamics and Niche Partitioning

PREDATION

Source Taxon: Viruses

Biological Processes:

viral entry into host cell (GO:0046718)
host cell lysis by virus (GO:0019076)

Evidence

PMID:34836550 - SUPPORT (IN_VIVO)

"Predicted host ranges for SPRUCE vOTUs were relatively narrow, generally within a single bacterial genus"
PMID:34836550 - SUPPORT (IN_VIVO)

"viral community composition was significantly correlated with peat depth, water content, and carbon chemistry"

Associated Datasets

Dataset	Type	Accession
SPRUCE 16S rRNA amplicon sequencing 16S rRNA amplicon sequencing of bacterial and archaeal communities from plant fine roots, rhizospheres, and bulk peat across warming and eCO2 treatments	AMPLICON_16S	PMID:38515239
SPRUCE ITS amplicon sequencing ITS amplicon sequencing of fungal communities from plant fine roots, rhizospheres, and bulk peat across warming and eCO2 treatments, identifying saprophytic and ectomycorrhizal functional guilds	AMPLICON_ITS	PMID:38515239
SPRUCE peat metagenomes 87 shotgun metagenomes from peat samples across depth gradients, warming treatments, and eCO2 treatments, enabling viral-host linkage prediction and taxonomic profiling	METAGENOMICS	PMID:34836550
SPRUCE peat viromes 5 viral size-fraction metagenomes (viromes) from peat samples, recovering 4,326 vOTUs with 32x higher vOTU recovery per sample than total metagenomes	METAGENOMICS	PMID:34836550
SPRUCE metatranscriptomes Metatranscriptomic profiling of active gene expression in peat microbial communities under warming and eCO2, revealing functional responses to climate treatments	METATRANSCRIPTOMICS	PMID:38515239

Environmental Factors

Factor	Value	Unit
Temperature Gradient	+0 to +9	°C above ambient
PMID:38515239 - SUPPORT (IN_VIVO) "Whole-ecosystem warming gradient +0°C to 9°C"
Elevated CO2	+500	ppm above ambient
PMID:38515239 - SUPPORT (IN_VIVO) "to explore the effects of a whole-ecosystem warming gradient (+0°C to 9°C) and eCO2 on vascular plant fine roots and their associated microbes"
Peat Depth Gradient	0-200	cm depth
PMID:34836550 - SUPPORT (IN_VIVO) "viral community composition was significantly correlated with peat depth"
Water Content	Variable	% volumetric water content
PMID:34836550 - SUPPORT (IN_VIVO) "significantly correlated with peat depth, water content"
Carbon Chemistry	Variable CH4/CO2	ppm in pore water
PMID:34836550 - SUPPORT (IN_VIVO) "carbon chemistry, including CH4 and CO2 concentrations"
pH	3.5-4.5	pH units
Nutrient Status	Oligotrophic	N/A