Divergent responses of soil microorganisms to throughfall exclusion across tropical forest soils driven by soil fertility and climate history

Chacon, Stephany S.; Cusack, Daniela; Khurram, Aizah; Bill, Markus; Dietterich, Lee H.; Bouskill, N.

doi:10.1016/j.soilbio.2022.108924

Cited by 3 publications

(3 citation statements)

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“…Changes in microbial community composition and activity with throughfall exclusion could also have contributed to reduced soil CO 2 fluxes, and may also have been a response to reduced nutrient transport into soils. Other work in the PARCHED drying experiment found significant changes in soil microbial community structure and the emergence of a “drought microbiome” with throughfall exclusion on infertile soils only, but no change in the fertile site (Chacon et al., 2023), which could help explain the different responses of soil CO 2 fluxes to drying among the sites by year four. This previous work also showed declines in wet season microbial biomass with drying, particularly for fungi, which could be related to instances of reduced soil CO 2 flux.…”

Section: Discussionmentioning

confidence: 91%

Soil Respiration Responses to Throughfall Exclusion Are Decoupled From Changes in Soil Moisture for Four Tropical Forests, Suggesting Processes for Ecosystem Models

Cusack

Dietterich

Sulman

2023

Global Biogeochemical Cycles

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Climatic drying is predicted for many tropical forests yet models remain poorly parameterized for these ecosystems, hampering predictions of forest‐climate interactions. We applied an integrated model–experiment approach, parameterizing an ecosystem model with tropical forest observational data and comparing model predictions to a field drying manipulation. We hypothesized that drying suppresses soil CO2 fluxes (i.e., respiration) in relatively dry tropical forests but increases CO2 fluxes in wetter tropical forests by alleviating anaerobiosis. We measured soil CO2 fluxes during wet‐dry cycles from 2015 to 2022 in four Panamanian forests that vary in rainfall and soil fertility. Measured soil CO2 fluxes declined in the dry season and peaked in the early wet season ahead of peak soil moisture, resulting in lower soil moisture optima for respiration than previously modeled. We then parameterized the model using field data and the new moisture‐respiration response functions. The updated model predicted increased soil CO2 fluxes with drying in wetter and fertile forests and suppressed fluxes in drier, infertile forests. In contrast to model predictions, a chronic throughfall exclusion experiment initially suppressed soil respiration across forests, with sustained suppression for four years in the wettest forest only (−28% ± 4% during the dry season). In the fertile forest, drying eventually elevated CO2 fluxes over this period (+75% ± 28% during the late wet season). The unexpected negative drying effect in the wettest, infertile forest could have resulted from reduced vertical flushing of nutrients into soils. Including hydro‐nutrient interactions in ecosystem models could improve predictions of tropical forest‐climate feedbacks.

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Section: Discussionmentioning

confidence: 91%

Soil Respiration Responses to Throughfall Exclusion Are Decoupled From Changes in Soil Moisture for Four Tropical Forests, Suggesting Processes for Ecosystem Models

Cusack

Dietterich

Sulman

2023

Global Biogeochemical Cycles

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“…Soil texture, pH, moisture availability, and nutrient supply emerge as additional parameters significantly impacting both enzyme and microbial activity ( Schneider et al, 2008 ; Cusack et al, 2011 ; Peña-Claros et al, 2012 ; Koranda et al, 2013 ; Chacon et al, 2023 ; Hartmann and Six, 2023 ; Wang L. et al, 2023 ). Soil texture influences water-holding capacity, with acidic soils potentially limiting nutrient availability and impacting microbial activity, while alkaline soils may affect enzymatic reactions.…”

Section: Discussionmentioning

confidence: 99%

“…In the ecosystems of forests, various microbial species play crucial functions in the soil process and dynamics ( Baldrian, 2017b ; Deng et al, 2022 ). Within forest soils, microorganisms play a pivotal role in breaking down complex organic matter and recycling essential nutrients, ultimately supporting soil fertility and facilitating plant growth ( Krishna and Mohan, 2017 ; Chacon et al, 2023 ; Li et al, 2023 ; Lv et al, 2023 ; Zhou et al, 2023 ). For instance, Cellulomonas sp.…”

Section: Introductionmentioning

confidence: 99%

Decoding seasonal changes: soil parameters and microbial communities in tropical dry deciduous forests

Solanki,

Gurjar,

Sharma

et al. 2024

Front. Microbiol.

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In dry deciduous tropical forests, both seasons (winter and summer) offer habitats that are essential ecologically. How these seasonal changes affect soil properties and microbial communities is not yet fully understood. This study aimed to investigate the influence of seasonal fluctuations on soil characteristics and microbial populations. The soil moisture content dramatically increases in the summer. However, the soil pH only gradually shifts from acidic to slightly neutral. During the summer, electrical conductivity (EC) values range from 0.62 to 1.03 ds m-1, in contrast to their decline in the winter. The levels of soil macronutrients and micronutrients increase during the summer, as does the quantity of soil organic carbon (SOC). A two-way ANOVA analysis reveals limited impacts of seasonal fluctuations and specific geographic locations on the amounts of accessible nitrogen (N) and phosphorus (P). Moreover, dehydrogenase, nitrate reductase, and urease activities rise in the summer, while chitinase, protease, and acid phosphatase activities are more pronounced in the winter. The soil microbes were identified in both seasons through 16S rRNA and ITS (Internal Transcribed Spacer) gene sequencing. Results revealed Proteobacteria and Ascomycota as predominant bacterial and fungal phyla. However, Bacillus, Pseudomonas, and Burkholderia are dominant bacterial genera, and Aspergillus, Alternaria, and Trichoderma are dominant fungal genera in the forest soil samples. Dominant bacterial and fungal genera may play a role in essential ecosystem services such as soil health management and nutrient cycling. In both seasons, clear relationships exist between soil properties, including pH, moisture, iron (Fe), zinc (Zn), and microbial diversity. Enzymatic activities and microbial shift relate positively with soil parameters. This study highlights robust soil-microbial interactions that persist mainly in the top layers of tropical dry deciduous forests in the summer and winter seasons. It provides insights into the responses of soil-microbial communities to seasonal changes, advancing our understanding of ecosystem dynamics and biodiversity preservation.

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Experimental warming and drying increase older carbon contributions to soil respiration in lowland tropical forests

McFarlane,

Cusack,

Dietterich

et al. 2024

Nat Commun

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Tropical forests account for over 50% of the global terrestrial carbon sink, but climate change threatens to alter the carbon balance of these ecosystems. We show that warming and drying of tropical forest soils may increase soil carbon vulnerability, by increasing degradation of older carbon. In situ whole-profile heating by 4 °C and 50% throughfall exclusion each increased the average radiocarbon age of soil CO2 efflux by ~2–3 years, but the mechanisms underlying this shift differed. Warming accelerated decomposition of older carbon as increased CO2 emissions depleted newer carbon. Drying suppressed decomposition of newer carbon inputs and decreased soil CO2 emissions, thereby increasing contributions of older carbon to CO2 efflux. These findings imply that both warming and drying, by accelerating the loss of older soil carbon or reducing the incorporation of fresh carbon inputs, will exacerbate soil carbon losses and negatively impact carbon storage in tropical forests under climate change.

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Divergent responses of soil microorganisms to throughfall exclusion across tropical forest soils driven by soil fertility and climate history

Cited by 3 publications

References 99 publications

Soil Respiration Responses to Throughfall Exclusion Are Decoupled From Changes in Soil Moisture for Four Tropical Forests, Suggesting Processes for Ecosystem Models

Soil Respiration Responses to Throughfall Exclusion Are Decoupled From Changes in Soil Moisture for Four Tropical Forests, Suggesting Processes for Ecosystem Models

Decoding seasonal changes: soil parameters and microbial communities in tropical dry deciduous forests

Experimental warming and drying increase older carbon contributions to soil respiration in lowland tropical forests

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