Carbon Availability Research Articles

Shifts in fungal communities drive soil profile nutrient cycling during grassland restoration.

Soil microbial diversity and community life strategies are crucial for nutrient cycling during vegetation restoration. Although the changes in topsoil microbial communities during restoration have been extensively studied, the structure, life strategies, and function of microbial communities in the subsoil remain poorly understood, especially regarding their role in nutrient cycling during vegetation restoration. In this study, we conducted a comprehensive investigation of the changes in the soil microbial community, assembly process, life strategies, and nutrient cycling functional genes in soil profiles (0-100 cm) across a 36 year chronosequence (5, 15, 28, and 36 years) of fenced grassland and one grazing grassland on the Loess Plateau of China. Our results revealed that soil organic carbon increased by 76.0% in topsoil and 91.6% in subsoil after 36 years of restoration. The bacterial communities were influenced primarily by soil depth, while the fungal communities were highly sensitive to the years of restoration. Microbes in the subsoil recovered faster, and the microbial community structure and functional genes in the soil profiles gradually became more consistent following restoration. In addition, we observed a transition in microbial life history strategies from a persistent K-strategy to a rapid r-strategy during restoration. Notably, the fungal community assembly process played an important role in changes in nutrient cycling genes, which were accompanied by increased carbon fixation and nitrogen mineralization function. Overall, our findings provide several novel insights into the impact of changes in the fungal community on soil nutrient cycling in the soil profile during vegetation restoration.IMPORTANCEOur study revealed that microbes in the subsoil recovered faster than those in the topsoil, which contributed to the reduction in differences in microbial community structure and the distribution of functional genes throughout the soil profile during the restoration process. Importantly, the assembly of fungal communities plays a pivotal role in driving changes in nutrient cycling genes, such as increased carbon fixation and nitrogen mineralization, alongside a reduction in carbon degradation gene abundance. These alterations increase soil organic carbon and nutrient availability during restoration. Our results increase the understanding of the critical role of fungal communities in soil nutrient cycling genes, which facilitate nutrient accumulation in soil profiles during grassland restoration. This insight can guide the development of strategies for manipulating fungal communities to increase soil nutrients in grasslands.

Abiotic Stress-Induced Chloroplast and Cytosolic Ca2+ Dynamics in the Green Alga Chlamydomonas reinhardtii.

Calcium (Ca2+)-dependent signalling plays a well-characterised role in the perception and response mechanisms to environmental stimuli in plant cells. In the context of a constantly changing environment, it is fundamental to understand how crop yield and microalgal biomass productivity are affected by external factors. Ca2+ signalling is known to be important in different physiological processes in microalgae but many of these signal transduction pathways still need to be characterised. Here, compartment-specific Ca2+ dynamics were monitored in Chlamydomonas reinhardtii cells in response to environmental stressors, such as nutrient availability, osmotic stress, temperature fluctuations and carbon sensing. An in vivo single-cell imaging approach was adopted to directly visualise changes of Ca2+ concentrations at the level of specific subcellular compartments, using C. reinhardtii lines expressing a genetically encoded ratiometric Ca2+ indicator. Hyper-osmotic shock caused cytosolic and chloroplast Ca2+ elevations, whereas high temperature and inorganic carbon availability primarily induced Ca2+ transients in the chloroplast. In contrast, hypo-osmotic stress only induced Ca2+ elevations in the cytosol. The results herein reported show that in Chlamydomonas cells compartment-specific Ca2+ transients are closely related to specific external environmental stimuli, providing useful guidance for studying signal transduction mechanisms exploited by microalgae to respond to specific natural conditions.

Seasonal patterns in sediment nitrification rates and their linkages to ammonium cycling in three agricultural streams

Nitrification, or the microbial transformation of ammonium (NH4+–N) to nitrate, is influenced by NH4+–N and dissolved oxygen availability, water temperature, and carbon-to-nitrogen ratios. Open-canopy agricultural streams receive excess inorganic nitrogen (N) from the surrounding landscape and the mineralization of organic-rich sediments, and the form and timing of these N inputs varies throughout the year. Compared to forested streams, the seasonality of nitrification rates in agricultural streams are not well documented. We conducted nitrification assays on stream sediments to estimate seasonal rates in three agricultural streams from summer 2020 to spring 2021. We documented seasonal variation in nitrification rates and identified changes in environmental controls [e.g., stream temperature, NH4+–N and dissolved organic carbon (DOC) availability, chlorophyll-a]. Nitrification rates were highest in spring (54.4 ± 12.7 mg N m−2 d−1; p = 0.02), coinciding with elevated NH4+–N and higher stream temperatures relative to winter (p < 0.001). Rates were lowest in autumn (19.9 ± 3.5 mg N m−2 d−1) when organic carbon concentrations peaked (17.2 ± 10.3 mg C L−1; p = 0.01). Algal senescence in autumn may allow heterotrophs to outcompete nitrifiers for NH4+–N. However, partial least square regression analyses indicated that sediment organic matter (as %OM) is an important positive predictor of nitrification, suggesting carbon can be an indirect positive control on nitrification. In the context of previous studies, agricultural streams had elevated NH4+–N concentrations, but nitrification rates were comparable to those in less impacted systems. Although complex interactions exist among rates and drivers, rates from this study help expand documentation of nitrification in agricultural streams, and provide insight into temporal variation and dominant controls.

Patterns of siderophore production and utilization at Station ALOHA from the surface to mesopelagic waters

AbstractThe North Pacific subtropical gyre is a globally important contributor to carbon uptake despite being a persistently oligotrophic ecosystem. Supply of the micronutrient iron to the upper ocean varies seasonally to episodically, and when coupled with rapid biological consumption, results in low iron concentrations. In this study, we examined changes in iron uptake rates, along with siderophore concentrations and biosynthesis potential at Station ALOHA across time (2013–2016) and depth (surface to 500 m) to observe changes in iron acquisition and internal cycling by the microbial community. The genetic potential for siderophore biosynthesis was widespread throughout the upper water column, and biosynthetic gene clusters peaked in spring and summer along with siderophore concentrations, suggesting changes in nutrient delivery, primary production, and carbon export seasonally impact iron acquisition. Dissolved iron turnover times, calculated from iron‐amended experiments in surface (15 m) and mesopelagic (300 m) waters, ranged from 9 to 252 d. The shortest average turnover times at both depths were associated with inorganic iron additions (14 9 d) and the longest with iron bound to strong siderophores (148 225 d). Uptake rates of siderophore‐bound iron were faster in mesopelagic waters than in the surface, leading to high Fe : C uptake ratios of heterotrophic bacteria in the upper mesopelagic. The rapid cycling and high demand for iron at 300 m suggest differences in microbial metabolism and iron acquisition in the mesopelagic compared to surface waters. Together, changes in siderophore production and consumption over the seasonal cycle suggest organic carbon availability impacts iron cycling at Station ALOHA.

From thaw till fall: Interacting hydrology, carbon cycle, and greenhouse gas dynamics in a subarctic stream-lake continuum.

Carbon-water interaction studies between aquatic and terrestrial ecosystems are especially needed today in Arctic and Boreal regions, as they are facing drastic warming and precipitation shifts. Despite the importance of streams in the carbon cycle, northern stream-based studies are scarce, owing to a lack of measurements throughout the north, and possibly skewing global greenhouse gas estimates. We used a combination of multiscale measurements to quantify water sources (H2O isotope proxies), carbon availability (dissolved in/organic carbon concentrations) and quality (water absorbance, SUVA254 -index), microbial community structure (16S rRNA sequencing), and carbon dioxide (CO2) and methane (CH4) fluxes and concentrations. Our study site comprises a groundwater-influenced and peatland-dominated second-order stream, along with its adjacent lake inlet located in Northern Finland. Sampling was conducted three times during the summer of 2019 at 21 locations along the stream-lake continuum. Temporal and spatial shifts in water sources altered carbon characteristics, with CH4 concentrations being the key environmental factor shaping the microbial communities, overriding the influence of dissolved organic carbon amount and quality. The prevalence of methanotrophic bacteria highlighted the importance of CH4 as a carbon source and the methanotrophic groups as drivers of the CH4/CO2 source-sink attributes of subarctic stream systems. Our results highlight the value of integrated hydrological, biogeochemical, and microbiological measures to resolve the biocomplexity of carbon-water interactions in northern headwater catchments.

Unravelling depth layers of microbial communities, nitrogen transformation rate, and extracellular polymeric substances in anammox granules

Anammox granules harbor a variety of bacteria, with each granule layer providing a niche for bacteria with specific metabolic functions. To investigate microbial distribution, nitrogen transformation rates, and extracellular polymeric substance (EPS) content across the depth layers of anammox granules, granules sized 0.9–2.0 mm were sheared into seven layers. The outer layers exhibited higher anammox bacterial abundance (9.9 %) than the inner layers (8.1 %). In contrast, the abundance of denitrifying bacteria increased from 25.0 % in outer layers to 34.9 % in inner layers. Nitrifying bacteria, along with heterotrophic nitrifying and aerobic denitrifying bacteria, were predominantly found in outer layers. Despite the higher EPS content in inner layers, denitrification rates remained low across all layers, likely due to limited carbon availability from microbial lysis or EPS. These findings offer valuable insights into the niche distribution of microbial communities within anammox granules.

Co-application of glucose and phosphorus with recalcitrant high-carbon soil amendments improves N retention in a reclaimed soil: a long-term incubation study

ABSTRACT Incorporation of soil amendments with high organic carbon content (HCA) can reduce losses of mineral nitrogen (N) from agricultural soils. The magnitude of N immobilization and remobilization is strongly controlled by the availability of carbon (C) and phosphorus (P). However, the exact mechanisms and interactions between C, N, and P availability are poorly understood. An eight-month incubation experiment was conducted on recultivated mine soil with low organic C, mineral N and P background concentrations to investigate the effects of HCA in combination with 13C-labelled glucose and mineral P fertilization on greenhouse gas emissions, soil nutrient status (dissolved organic C (DOC), nitrate (NO3 –), extractable P), and microbial biomass growth. The experiment had a factorial design of one N level × two P levels × six C treatments (control, wheat straw, poplar sawdust, glucose, and combinations of wheat straw or sawdust with glucose). The HCA increased the cumulative CO2 and CH4 emissions but decreased N2O emission, except for wheat straw. Addition of 13C-labelled glucose decreased the cumulative CH4 emission by 59 and 85 % in the sawdust and sawdust + P treatment, respectively. Glucose application reduced the NO3 – content in the HCA-amended soil by 26–64 %, while P fertilizer further decreased the NO3 – content in the wheat straw and sawdust treatments by 20 and 24 %, respectively. Both HCA and glucose treatments promoted microbial biomass growth and reduced the soil mineral N content. The δ13C of microbial biomass (δ13CMB) showed an increasing trend during the whole experiment, although 13C-labelled glucose was added only once at the beginning of the experiment. Addition of HCA decreased δ13CMB, while P addition had the opposite effect. In conclusion, adding a readily available C source to HCA may increase the efficacy of retaining N in post-harvest soils, particularly of more recalcitrant types of HCA like sawdust.

A conceptual model explaining spatial variation in soil nitrous oxide emissions in agricultural fields

Soil emissions of nitrous oxide contribute substantially to global warming from agriculture. Spatiotemporal variation in nitrous oxide emissions within agricultural fields leads to uncertainty in the benefits of climate-smart agricultural practices. Here, we present a conceptual model explaining spatial variation in temporal patterns of soil nitrous oxide emissions developed from high spatial resolution measurements of soil nitrous oxide emissions, gross nitrous oxide fluxes, and soil physicochemical properties in two maize fields in Illinois, USA. In sub-field locations with consistently low nitrous oxide emissions, soil nitrate and dissolved organic carbon constrained nitrous oxide production irrespective of changes in soil moisture. In sub-field locations where high emissions occurred episodically, soil nitrate and dissolved organic carbon availability were higher, and increases in soil moisture stimulated nitrous oxide production. These findings form the ‘cannon model’ which conceptualizes how sub-field scale variation in soil nitrate and dissolved organic carbon determines where increases in soil moisture can trigger high soil nitrous oxide emissions within agricultural fields.

Fungal degradation of complex organic carbon supports denitrification in saturated woodchip bioreactors

Woodchip bioreactor (WBR) is a promising technology for the removal of nitrate from agricultural drainage, although the performance of WBRs is dependent on the decomposition of lignocellulosic biomass and the carbon availability for microbial denitrification. Fungal species are more efficient than bacterial counterparts in driving wood decomposition; however, little is known about the fungal community structure and functions in saturated WBRs. In this study, we investigated the dynamics of the mycobiome in field-scale, constantly saturated WBRs located in Willmar, Minnesota, USA. Fungal community analysis suggested that wood-rotting fungi were abundant in WBRs, especially near their inlet locations where microbial denitrification was most active. Complex network structures of fungal hyphae associated with a decayed cavity on the woodchip surface was further evidenced by confocal and scanning electron microscopy. These results suggest that fungi play a major role in wood degradation in WBRs, thereby promoting denitrification activity.

Symbiodiniaceae algal symbionts of Pocillopora damicornis larvae provide more carbon to their coral host under elevated levels of acidification and temperature

Climate change destabilizes the symbiosis between corals and Symbiodiniaceae. The effects of ocean acidification and warming on critical aspects of coral survical such as symbiotic interactions (i.e., carbon and nitrogen assimilation and exchange) during the planula larval stage remain understudied. By combining physiological and stable isotope techniques, here we show that photosynthesis and carbon and nitrogen assimilation (H13CO3− and 15NH4+) in Pocillopora damicornis coral larvae is enhanced under acidification (1000 µatm) and elevated temperature (32 °C). Larvae maintain high survival and settlement rates under these treatment conditions with no observed decline in symbiont densities or signs of bleaching. Acidification and elevated temperature both enhance the net and gross photosynthesis of Symbiodiniaceae. This enhances light respiration and elevates C:N ratios within the holobiont. The increased carbon availability is primarily reflected in the 13C enrichment of the host, indicating a greater contribution of the algal symbionts to the host metabolism. We propose that this enhanced mutualistic symbiotic nutrient cycling may bolster coral larvae’s resistance to future ocean conditions. This research broadens our understanding of the early life stages of corals by emphasizing the significance of symbiotic interactions beyond those of adult corals.

Integrated proteome and metabolome analysis of the penultimate internodes revealing remobilization efficiency in contrasting barley genotypes under water stress

The remobilization of stored assimilates from stems to seeds plays a pivotal role in augmenting barley yield, particularly under water stress conditions. This study examines the molecular mechanisms underlying stem reserve utilization by conducting a comparative analysis of the proteome and metabolome across three barley contrasting genotypes: Yousef, Morocco, and PBYT17. Evaluations were performed at 21 and 28 days after anthesis (DAA) under both water stress and control conditions. The results indicate that the Yousef genotype exhibits superior remobilization of stem reserves, thereby demonstrating its potential to thrive even in adverse environmental conditions. Utilizing advanced quantitative proteomics and targeted metabolomics, this investigation identified a significant number of metabolites and proteins exhibiting differential accumulation across the genotypes. Specifically, 17 metabolites and 1580 proteins were catalogued, highlighting the intricate biochemical responses to water stress. Noteworthy enzymes such as sucrose synthase, inositol monophosphatase 3, and galactokinase were found to be closely associated with remobilization efficiency. In the drought-tolerant genotype, these enzymes maintained stable levels, in stark contrast to the decline observed in the susceptible genotype. This stability is crucial for promoting seed development through ascorbic acid synthesis and for mitigating oxidative stress, which is exacerbated by drought conditions. The elevated levels of certain metabolites, including glucose 6-phosphate, and UDP-glucose, in the drought-tolerant genotype suggest a robust mechanism for maintaining signalling molecules for carbon availability, which is then instrumental in regulating plant growth and seed size development. The findings from this study strongly imply that the drought-tolerant genotype, through enhanced antioxidant capacity, can effectively produce energy-rich storage compounds, thereby optimizing carbon allocation under water stress. Such insights are invaluable for future breeding strategies aimed at improving barley resilience in the face of climate variability.

Classical Batch Distillation of Anaerobic Digestate to Isolate Ammonium Bicarbonate: Membrane Not Necessary!

The excessive mineralization of organic molecules during anaerobic fermentation increases the availability of nitrogen and carbon. For this reason, the development of downstream processing technologies is required to better manage ammonia and carbon dioxide emissions during the storage and land application of the resulting soil organic amendment. The present work investigated classical distillation as a technology for valorizing ammoniacal nitrogen (NH4+-N) in anaerobic digestate. The results implied that the direct isolation of ammonium bicarbonate (NH4HCO3) was possible when applying the reactive distillation to the food waste digestate (FWD) with a high content of NH4+-N, while the addition of antifoam to the agrowaste digestate (AWD) was necessary to be able to produce an aqueous solution of NH4HCO3 as the distillate. The reason was that the extraction of NH4HCO3 from the AWD required a higher temperature (>95 °C) and duration (i.e., steady state in batch operation) than the recovery of the inorganic fertilizer from the FWD. The titration method, when applied to the depleted digestate, offered the quickest way of monitoring the reactive distillation because the buffer capacity of the distillate was much higher. The isolation of NH4HCO3 from the FWD was attained in a transient mode at a temperature below 90 °C (i.e., while heating up to reach the desired distillation temperature or cooling down once the batch distillation was finished). For the operating conditions to be regarded as techno-economically feasible, they should be attained in the anaerobic digestion plant by integrating the heat harvested from the engines, which convert the biogas into electricity.

Greenwashing of Corporate Carbon Information and Availability of Bank Credit

In recent years, as China&amp;apos;s economy has gradually shifted to high-quality development, climate policies and sustainable finance have received widespread attention. In the current era of promoting the &amp;quot;dual-carbon&amp;quot; strategy, green finance plays an indispensable role in helping corporates achieve green transformation. However, it has been found that greenwashing behavior by corporates exists to different degrees in the environmental information disclosure of listed companies in China, and the phenomenon of selective disclosure and only talking about environmental performance is particularly prominent. Given that carbon information disclosure has become one of the credit standards for financial institutions to provide loans, this greenwashing behavior may hinder financial institutions from providing green loans and lead to an uneven distribution of credit resources. Based on the data of listed manufacturing companies in China from 2013 to 2022, this paper uses text analysis to measure the &amp;quot;greenwashing&amp;quot; behavior of corporates in terms of carbon information and discusses the impact of such speculation on the availability of bank credit. The study finds that the &amp;quot;greenwashing&amp;quot; behavior of corporates in terms of carbon information can improve the availability of bank credit. Moreover, this credit resource access effect is stronger in non-state-owned corporates, low-value corporates and corporates with high information opacity. However, this paper also confirms that media supervision and regional environmental regulations can mitigate the impact of cleaning on financing. The research results of this paper have policy significance for the sustainable development of corporates.

Internal physiological drivers of leaf development in trees: Understanding the relationship between non‐structural carbohydrates and leaf phenology

Abstract Plant phenology is crucial for understanding plant growth and climate feedback. It affects canopy structure, surface albedo, and carbon and water fluxes. While the influence of environmental factors on phenology is well‐documented, the role of plant intrinsic factors, particularly internal physiological processes and their interaction with external conditions, has received less attention. Non‐structural carbohydrates (NSC), which include sugars and starch essential for growth, metabolism and osmotic regulation, serve as indicators of carbon availability in plants. NSC levels reflect the carbon balance between photosynthesis (source activity) and the demands of growth and respiration (sink activity), making them key physiological traits that potentially influence phenology during critical periods such as spring leaf‐out and autumn leaf senescence. However, the connections between NSC concentrations in various organs and phenological events are poorly understood. This review synthesizes current research on the relationship between leaf phenology and NSC dynamics. We qualitatively delineate seasonal NSC variations in deciduous and evergreen trees and propose testable hypotheses about how NSC may interact with phenological stages such as bud break and leaf senescence. We also discuss how seasonal variations in NSC levels, align with existing conceptual models of carbon allocation. Accurate characterization and simulation of NSC dynamics are crucial and should be incorporated into carbon allocation models. By comparing and reviewing the development of carbon allocation models, we highlight the shortcomings in current methodologies and recommend directions to address these gaps in future research. Understanding the relationship between NSC, source–sink relationships, and leaf phenology poses challenges due to the difficulty of characterizing NSC dynamics with high temporal resolution. We advocate for a multi‐scale approach that combines various methods, which include deepening our mechanistic understanding through manipulative experiments, integrating carbon sink and source data from multiple observational networks with carbon allocation models to better characterize the NSC dynamics, and quantifying the spatial pattern and temporal trends of the NSC‐phenology relationship using remote sensing and modelling. This will enhance our comprehension of how NSC dynamics impact leaf phenology across different scales and environments. Read the free Plain Language Summary for this article on the Journal blog.

Microbial Ecology of Denitrification Process and Its Application in Wastewater: Treatment, Challenges and Opportunities

Denitrification is a crucial microbial process in the nitrogen cycle, transforming nitrate (NO₃⁻) into nitrogen gas (N₂), thereby mitigating nitrogen pollution in aquatic ecosystems. This microbial activity plays a vital role in wastewater treatment by removing excess nitrogen, which contributes to eutrophication and water contamination. The denitrification process involves various microbial communities, including bacteria such as Pseudomonas, Paracoccus, and Bacillus, which operate under anoxic conditions to achieve nitrogen reduction, an optimizing denitrification in wastewater treatment presents several challenges, such as maintaining ideal environmental conditions (e.g., carbon availability, oxygen levels, pH) and overcoming issues related to incomplete denitrification, which can lead to the production of harmful intermediates like nitrous oxide (N₂O). Despite these hurdles, recent advancements in microbial ecology, such as the use of biofilms, bioreactors, and genetic engineering, offer promising opportunities to enhance denitrification efficiency. This review explores the microbial ecology of the denitrification process, its application in wastewater treatment, and the challenges and opportunities associated with its practical implementation in reducing nitrogen pollution.

Interplay between CO2 and light governs carbon partitioning in Chlamydomonas reinhardtii.

Increasing CO2 availability is a common practice at the industrial level to trigger biomass productivity in microalgae cultures. Still, the consequences of high CO2 availability in microalgal cells exposed to relatively high light require further investigation. Here, the photosynthetic, physiologic, and metabolic responses of the green microalga model Chlamydomonas reinhardtii were investigated in high or low CO2 availability conditions: high CO2 enabled higher biomass yields only if sufficient light energy was provided. Moreover, cells grown in high light and high CO2 availability were characterized, compared to cells grown in high light and low CO2, by a relative increase of the energy-dense triacylglycerols and decreased starch accumulation per dry weight. The photosynthetic machinery adapted to the increased carbon availability, modulating Photosystem II light-harvesting efficiency and increasing Photosystem I photochemical activity, which shifted from being acceptor side to donor side limited: cells grown at high CO2 availability were characterized by increased photosynthetic linear electron flow and by the onset of a balance between NAD(P)H oxidation and NAD(P)+ reduction. Mitochondrial respiration was also influenced by the conditions herein applied, with reduced respiration through the cytochrome pathway compensated by increased respiration through alternative pathways, demonstrating a different use of the cellular reducing power based on carbon availability. The results suggest that at high CO2 availability and high irradiance, the reducing power generated by the oxidative metabolism of photosynthates is either dissipated through alternative oxidative pathways in the mitochondria or translocated back to the chloroplasts to support carbon assimilation and energy-rich lipids accumulation.

Nitrogen and sulfur metabolism in anaerobic hydrogen-producing microbiome as a challenge for 2,4-DCP dechlorination

This research aimed to assess the effectiveness of anaerobic hydrogen-producing microbiomes (HMb) in treating different concentrations of 2,4-dichlorophenol (2,4-DCP) under controlled conditions. The dechlorination experiments were conducted at 41°C in 120-mL vials using a rotary culture device to ensure thorough mixing. The study focused on dechlorination kinetics and efficiency, dynamic changes in the nitrogen-sulfur cycle, and the impact of organic carbon availability. Results indicated that at concentrations below 50 mg/L, HMb achieved a maximum dechlorination rate (Rm) of about 0.7 mg/L-day, which declined to 0.3 mg/L-day at 100 mg/L, suggesting inhibition at higher concentrations. Over 180 days, NH4+-N concentrations decreased, while NO3--N fluctuated, highlighting complex nitrogen transformations influenced by carbon supply and microbial activity. Sulfate concentrations significantly declined in the first 60 days due to sulfur-oxidizing bacteria, including nitrogen-reducing sulfur-oxidizing bacteria (NR-SOB), which promoted anaerobic hydrogen production. Firmicutes increased from 19.5 % to 69.2 %, while Actinobacteria decreased from 73.0 % to 26.8 %, showing response to environmental conditions. The study highlights HMb's potential in bioremediation, enhancing dechlorination processes for environmental and renewable energy benefits.

Increasing tree phylogenetic diversity stimulates microbial functional potential in a subtropical forest

Abstract Soil microbial functions are closely related to ecosystem productivity, carbon sequestration and their responses to global change. Tree phylogenetic diversity has been found to impact microbial community composition, diversity, and functions, but how it modulates the linkage between microbial community facets and functions remains unclear. Here, 45 plots covering a natural gradient of tree phylogenetic diversity (TPD) were selected in a subtropical forest of southwest China to explore how increasing TPD impacts soil microbial community facets and microbial functional potential. The microbial functional potential was evaluated based on the abundances of carbon, nitrogen, and phosphorus cycling-related functional genes. Soil fungal alpha diversity increased significantly, but bacterial alpha diversity did not change as TPD increased. Both soil microbial network complexity and stability improved significantly with increasing TPD. Ultimately, increasing TPD promoted soil microbial functional potential by stimulating soil carbon and nitrogen availability, microbial keystone diversity, and network stability collectively. These findings emphasize the critical roles of keystone taxa and network stability as microbial factors in stimulating soil microbial function in response to increasing TPD. Therefore, it is strongly recommended to increase TPD in order to stimulate soil microbial functions and other ecosystem functions when implementing afforestation or ecological restoration projects.

Conservation Tillage's Relevance in Potato Production: Improving Soil Quality and Growth Performance

In the conventional system, potato crop is grown under intensive tillage along with use of high inputs that led to deterioration of soil health and environment. Hence, practicing of intensive tillage create hindrance for accommodating a second crop immediately after harvesting of rice. That’s why in many parts of India, rice stubble burning is a common practice done by farmers to advance the time of planting. Thus, rice stubble burning which is accountable for the emission of CO2 considered as a serious issue in most of the rice growing areas. Considering the farmer’s benefit as well as soil health and environment, conservation tillage i.e., zero/minimum tillage could be one of the vital alternative options that could help to overcome the problem associated with conventional tillage. Therefore, an attempt has been made to interpret the findings of conservation tillage on performance of potato crop and its subsequent effect on soil health. Results showed variable response on crop performances due to conservation tillage, but improved the soil health and quality by increasing the soil organic carbon and nutrient availability.

Recovery of Soil Microbial Metabolism After Rewetting Depends on Interacting Environmental Conditions and Changes in Functional Groups and Life History Strategies.

Climate change is causing an intensification of soil drying and rewetting events, altering microbial functioning and potentially destabilizing soil organic carbon. After rewetting, changes in microbial community carbon use efficiency (CUE), investment in life history strategies, and fungal to bacterial dominance co-occur. Still, we have yet to generalize what drives these dynamic responses. Here, we collated 123 time series of microbial community growth (G, sum of fungal and bacterial growth, evaluated by leucine and acetate incorporation, respectively) and respiration (R) after rewetting and calculated CUE = G/(G + R). First, we characterized CUE recovery by two metrics: maximum CUE and time to maximum CUE. Second, we translated microbial growth and respiration data into microbial investments in life history strategies (high yield (Y), resource acquisition (A), and stress tolerance (S)). Third, we characterized the temporal change in fungal to bacterial dominance. Finally, the metrics describing the CUE recovery, investment in life history strategies, and fungal to bacterial dominance after rewetting were explained by environmental factors and microbial properties. CUE increased after rewetting as fungal dominance declined, but the maximum CUE was explained by the CUE under moist conditions, rather than specific environmental factors. In contrast, higher soil pH and carbon availability accelerated the decline of microbial investment in stress tolerance and fungal dominance. We conclude that microbial CUE recovery is mostly driven by the shifting microbial community composition and the metabolic capacity of the community, whereas changes in microbial investment in life history strategies and fungal versus bacterial dominance depend on soil pH and carbon availability.