Dissolved Organic Matter Dynamics in Reference and Calcium Silicate‐Treated Watersheds at Hubbard Brook Experimental Forest, NH, USA

LoRusso, Nicholas Alexander; Bailey, Scott W.; Zeng, Teng; Montesdeoca, M.; Driscoll, Charles T.

doi:10.1029/2021jg006352

Cited by 5 publications

(1 citation statement)

References 87 publications

(136 reference statements)

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“…In the short term, dissolution of lime (CaCO 3 + H 2 O → Ca 2+ + HCO 3 − + OH − ) provides hydroxide ions that directly neutralize acidity and provides calcium for cation exchange sites, raising base saturation. In the long term, ecosystem feedbacks cause indirect effects driven by the recycling of calcium in plant litter, changes in plant carbon (C) allocation to roots and microbial symbionts (Fahey et al, 2016), and the effects of Ca on organic matter quality and solubility (LoRusso et al, 2021; Rowley et al, 2018), and the CEC of organic soil horizons (Johnson et al, 2014). Direct effects of liming on microbiome composition, driven by proton concentration, should be apparent in short‐term experiments, while indirect effects are likely to manifest only after long periods of time.…”

Section: Introductionmentioning

confidence: 99%

Watershed‐scale liming reveals the short‐ and long‐term effects ofpHon the forest soil microbiome and carbon cycling

Sridhar

Lawrence

Debenport

et al. 2022

Environmental Microbiology

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Soil microbial community composition routinely correlates with pH, reflecting both direct pH effects on microbial physiology and long-term biogeochemical feedbacks. We used two watershed-scale liming experiments to identify short-(2 years) and long-term (25 years) changes in the structure and function of bacterial and fungal communities in organic horizons (O e and O a ) of acid forest soils. Liming increased soil pH, extractable calcium, and soil carbon stocks, reduced biomass-specific respiration, and caused major changes in the soil microbiome in the short and long term. More taxa responded to liming in the short term (70%) than in the long term (30%), with most showing consistent directional responses at both sites. The ratio of change in relative abundance between limed and reference sites was twofold higher at the long than the short-term site, indicating that the effects of liming grew over time. Liming impacts were most pronounced in fungi, as steep declines of dominant ectomycorrhizal fungi (Cenococcum and Russula) occurred at both sites. Liming favoured neutrophilic bacteria over acidophilic populations according to estimated environmental pH optima. Collectively, these results demonstrate that a liming-induced change of one pH unit has an immediate and persistent effect on the structure and function of microbial communities in acid forest soils. The corresponding suppression of respiration indicates that anthropogenic alterations of soil pH, as driven by acid deposition or liming, can affect forest floor C stocks due to pH-driven shifts in community structure.

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Section: Introductionmentioning

confidence: 99%

Watershed‐scale liming reveals the short‐ and long‐term effects ofpHon the forest soil microbiome and carbon cycling

Sridhar

Lawrence

Debenport

et al. 2022

Environmental Microbiology

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Response of stream habitat and microbiomes to spruce budworm defoliation: New considerations for outbreak management

McCaig,

Kidd,

Smenderovac

et al. 2024

Ecological Applications

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Defoliation by eastern spruce budworm is one of the most important natural disturbances in Canadian boreal and hemi‐boreal forests with annual area affected surpassing that of fire and harvest combined, and its impacts are projected to increase in frequency, severity, and range under future climate scenarios. Deciding on an active management strategy to control outbreaks and minimize broader economic, ecological, and social impacts is becoming increasingly important. These strategies differ in the degree to which defoliation is suppressed, but little is known about the downstream consequences of defoliation and, thus, the implications of management. Given the disproportionate role of headwater streams and their microbiomes on net riverine productivity across forested landscapes, we investigated the effects of defoliation by spruce budworm on headwater stream habitat and microbiome structure and function to inform management decisions. We experimentally manipulated a gradient of defoliation among 12 watersheds during a spruce budworm outbreak in the Gaspésie Peninsula, Québec, Canada. From May through October of 2019–2021, stream habitat (flow rates, dissolved organic matter [DOM], water chemistry, and nutrients), algal biomass, and water temperatures were assessed. Bacterial and fungal biofilm communities were examined by incubating six leaf packs for five weeks (mid‐August to late September) in one stream reach per watershed. Microbiome community structure was determined using metabarcoding of 16S and ITS rRNA genes, and community functions were examined using extracellular enzyme assays, leaf litter decomposition rates, and taxonomic functional assignments. We found that cumulative defoliation was correlated with increased streamflow rates and temperatures, and more aromatic DOM (measured as specific ultraviolet absorbance at 254 nm), but was not correlated to nutrient concentrations. Cumulative defoliation was also associated with altered microbial community composition, an increase in carbohydrate biosynthesis, and a reduction in aromatic compound degradation, suggesting that microbes are shifting to the preferential use of simple carbohydrates rather than more complex aromatic compounds. These results demonstrate that high levels of defoliation can affect headwater stream microbiomes to the point of altering stream ecosystem productivity and carbon cycling potential, highlighting the importance of incorporating broader ecological processes into spruce budworm management decisions.

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Combination of factors rather than single disturbance drives perturbation of the nitrogen cycle in a temperate forest

Green,

Pardo,

Campbell

et al. 2023

Biogeochemistry

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Dissolved Organic Matter Dynamics in Reference and Calcium Silicate‐Treated Watersheds at Hubbard Brook Experimental Forest, NH, USA

Cited by 5 publications

References 87 publications

Watershed‐scale liming reveals the short‐ and long‐term effects ofpHon the forest soil microbiome and carbon cycling

Watershed‐scale liming reveals the short‐ and long‐term effects ofpHon the forest soil microbiome and carbon cycling

Response of stream habitat and microbiomes to spruce budworm defoliation: New considerations for outbreak management

Combination of factors rather than single disturbance drives perturbation of the nitrogen cycle in a temperate forest

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