Regenerated woody plants influence soil microbial communities in a subtropical forest

10 páginas.- 4 figuras.- 3 tablas.- referencias.- upplementary data to this article can be found online at https://doi. org/10.1016/j.apsoil.2023.104890Forests are critical for supporting multiple ecosystem services such as climate change mitigation. Microbial diversity in soil provides important functions to maintain and regenerate forest ecosystems, and yet a critical knowledge gap remains in identifying the linkage between attributes of regenerated woody plant (RWP) communities and the diversity patterns of soil microbial communities in subtropical plantations. Here, we investigated the changes in soil microbial communities and plant traits in a nine hectare Chinese fir (Cunninghamia lanceolata; CF) plantation to assess how non-planted RWP communities regulate soil bacterial and fungal diversity, and further explore the potential mechanisms that structure their interaction. Our study revealed that soil bacterial richness was positively associated with RWP richness, whereas soil fungal richness was negatively associated with RWP basal area. Meanwhile, RWP richness was positively correlated with ectomycorrhizal (ECM) fungal richness but negatively correlated with the richness of both pathogenic and saprotrophic fungi, suggesting that the RWP-fungal richness relationship was trophic guild-specific. Soil microbial community beta diversity (i.e., dissimilarity in community composition) was strongly coupled with both RWP beta diversity and the heterogeneity of RWP basal area. Our study highlights the importance of community-level RWP plant attributes for the regulation of microbial biodiversity in plantation systems, which should be considered in forest management programs in the future.This work was funded by the National Key Research and Development Program of China (2021YFD2201301 and 2022YFF1303003), the National Natural Science Foundation of China (U22A20612), and the Key Project of Jiangxi Province Natural Science Foundation of China (20224ACB205003).Peer reviewe

Responses of arbuscular mycorrhizal fungi to long-term inorganic and organic nutrient addition in a lowland tropical forest

Improved understanding of the nutritional ecology of arbuscular mycorrhizal (AM) fungi is important in understanding how tropical forests maintain high productivity on low-fertility soils. Relatively little is known about how AM fungi will respond to changes in nutrient inputs in tropical forests, which hampers our ability to assess how forest productivity will be influenced by anthropogenic change. Here we assessed the influence of long-term inorganic and organic nutrient additions and nutrient depletion on AM fungi, using two adjacent experiments in a lowland tropical forest in Panama. We characterised AM fungal communities in soil and roots using 454-pyrosequencing, and quantified AM fungal abundance using microscopy and a lipid biomarker. Phosphorus and nitrogen addition reduced the abundance of AM fungi to a similar extent, but affected community composition in different ways. Nutrient depletion (removal of leaf litter) had a pronounced effect on AM fungal community composition, affecting nearly as many OTUs as phosphorus addition. The addition of nutrients in organic form (leaf litter) had little effect on any AM fungal parameter. Soil AM fungal communities responded more strongly to changes in nutrient availability than communities in roots. This suggests that the 'dual niches' of AM fungi in soil versus roots are structured to different degrees by abiotic environmental filters, and biotic filters imposed by the plant host. Our findings indicate that AM fungal communities are fine-tuned to nutrient regimes, and support future studies aiming to link AM fungal community dynamics with ecosystem function

Biocrust adaptations to microhabitat alter bacterial communities in a semiarid ecosystem

15 páginas.- 6 figuras.- 4 tablas.- 52 referencias.- Supplementary Information The online version contains supplementary material available at https:// doi.org/ 10. 1007/ s11104- 023- 06184-3Aims Biocrusts, the living skin of dryland ecosystems, contain diverse soil microorganisms that are essential to biocrust formation and the maintenance of multiple ecological functions including nitrogen fixation, carbon sequestration, soil stability, and rainfall redistribution. We know that biocrusts are important modulators of the soil microbiomes, however, much less is known about how local conditions influence biocrust adaptation and subsequently alter the soil microbiomes. Methods To understand the effects of microhabitat on bacterial communities via changes in biocrust traits, we collected biocrusts and analyzed soil microbiomes from eight representative microhabitats present in a semiarid ecosystem from the Chinese Northern Loess Plateau. These microhabitats were located a) outside plant canopy on level land, on shady gentle slope, and sunny gentle slope; b) under plant canopy on level land, on shady gentle, and sunny gentle slope; and c) outside plant canopy on shady and sunny steep slope, respectively. We then used structural equation modeling to investigate the relative contribution of microhabitat factors on important bacterial community metrics through quantifying the changes in biocrust traits. Results Observed microhabitat conditions significantly (P ≤ 0.033) altered the traits of biocrusts (e.g., thickness, biomass, and chlorophyll content), which were associated with significant changes in the soil bacterial community. For example, the bacterial richness in biocrusts developing under plant canopy, on shady slopes, and on gentle slopes was 20.1%, 19.9%, and 15.4% higher than that of the biocrusts developing outside plant canopy, on sunny slopes, and on steep slopes, respectively. We further showed that microhabitat conditions significantly impacted the network structure of bacterial communities under biocrusts, and structural equation modeling revealed that microhabitat metrics had strong indirect effects on network connectivity through changing biocrust traits. Conclusions Our findings suggest that microhabitat factors can strongly influence soil bacterial communities via the changes in locally-adapted biocrust traits and soil properties. This knowledge is critical to understand the impacts of changing environments on biocrusts and associated soil bacterial communities, particularly as climate change progresses.This study was funded by the National Natural Science Foundation of China (No. 42077010), the "Light of West China" Program of the Chinese Academy of Sciences (No. 2019), and the Open Fund for Key Laboratory of Land Degradation and Ecological Restoration in Northwestern China of Ningxia University (No. LDER2022Z02)Peer reviewe

Dryland nitrogen deposition induces microbiome-driven increases in biocrust respiration and losses of soil carbon

12 páginas.- 4 figuras.- 2 tablas.- referencias.- Additional supporting information can be found online in the Support-ing Information section at the end of this articleBiocrusts are a dominant component in drylands worldwide and play critical roles in supporting soil microbial diversity and carbon (C) stocks. Nitrogen (N) fertilization associated with human activities threatens drylands, which are often considered N-limited ecosystems. Here, we conducted a field experiment in two contrasting soil types (loess vs. sand) to investigate the impacts of low (30 kg N ha−1 year−1) and high (90 kg N ha−1 year−1) fertilization on moss-biocrust dominated traits, soil nutrients, microbial taxonomic richness, soil C stocks and respiration rates (Rs). We showed that 5 months of N addition resulted in reductions in soil organic C content by 91% and increased both soil microbial richness and diversity. Our results further showed that relative to controls, low levels of N addition increased biocrust Rs by 52% through increased moss biomass and density (38% and 73%) and microbial taxonomic richness and diversity (18% and 23%), while no significant changes in biocrust Rs were observed after high levels of N addition. Considering multiple environmental factors simultaneously, we show that N fertilization indirectly promoted soil respiration and C losses via increases in microbial richness and diversity, which are critical drivers of soil function. Our work provides solid evidence that N deposition, even at low levels of N addition, can result in rapid losses of C in dryland soils. Our findings suggest that to maintain healthy dryland ecosystems and promote C, we must mitigate future land degradation and minimize anthropogenic N deposition.National Natural Science Foundation of China (No. 42077010), “Light of West China” Program of the Chinese Academy of Sciences (No. 2019), Open Fund for Key Laboratory of Land Degradation and Ecological Restoration in Northwestern China of Ningxia University (No. LDER2022Z02), TED2021-130908B-C41/AEI/10.13039/501100011033/Unión Europea Next Generation EU/PRTR, and Spanish Ministry of Science and Innovation for the I+D+i project PID2020-115813RA-I00 funded by MCIN/AEI/10.13039/501100011033.Peer reviewe

Tripartite mutualisms as models for understanding plant-microbial interactions

All plants host diverse microbial assemblages that shape plant health, productivity, and function. While some microbial effects are attributable to particular symbionts, interactions among plant-associated microbes can nonadditively affect plant fitness and traits in ways that cannot be predicted from pairwise interactions. Recent research into tripartite plant-microbe mutualisms has provided crucial insight into this nonadditivity and the mechanisms underlying plant interactions with multiple microbes. Here, we discuss how interactions among microbial mutualists affect plant performance, highlight consequences of biotic and abiotic context-dependency for nonadditive outcomes, and summarize burgeoning efforts to determine the molecular bases of how plants regulate establishment, resource exchange, and maintenance of tripartite interactions. We conclude with four goals for future tripartite studies that will advance our overall understanding of complex plant-microbial interactions

Allelopathy‐selected microbiomes mitigate chemical inhibition of plant performance

Summary Allelopathy is a common and important stressor that shapes plant communities and can alter soil microbiomes, yet little is known about the direct effects of allelochemical addition on bacterial and fungal communities or the potential for allelochemical‐selected microbiomes to mediate plant performance responses, especially in habitats naturally structured by allelopathy. Here, we present the first community‐wide investigation of microbial mediation of allelochemical effects on plant performance by testing how allelopathy affects soil microbiome structure and how these microbial changes impact germination and productivity across 13 plant species. The soil microbiome exhibited significant changes to ‘core’ bacterial and fungal taxa, bacterial composition, abundance of functionally important bacterial and fungal taxa, and predicted bacterial functional genes after the addition of the dominant allelochemical native to this habitat. Furthermore, plant performance was mediated by the allelochemical‐selected microbiome, with allelopathic inhibition of plant productivity moderately mitigated by the microbiome. Through our findings, we present a potential framework to understand the strength of plant–microbial interactions in the presence of environmental stressors, in which frequency of the ecological stress may be a key predictor of microbiome‐mediation strength

Acidification suppresses the natural capacity of soil microbiome to fight pathogenic Fusarium infections

Abstract Soil-borne pathogens pose a major threat to food production worldwide, particularly under global change and with growing populations. Yet, we still know very little about how the soil microbiome regulates the abundance of soil pathogens and their impact on plant health. Here we combined field surveys with experiments to investigate the relationships of soil properties and the structure and function of the soil microbiome with contrasting plant health outcomes. We find that soil acidification largely impacts bacterial communities and reduces the capacity of soils to combat fungal pathogens. In vitro assays with microbiomes from acidified soils further highlight a declined ability to suppress Fusarium, a globally important plant pathogen. Similarly, when we inoculate healthy plants with an acidified soil microbiome, we show a greatly reduced capacity to prevent pathogen invasion. Finally, metagenome sequencing of the soil microbiome and untargeted metabolomics reveals a down regulation of genes associated with the synthesis of sulfur compounds and reduction of key traits related to sulfur metabolism in acidic soils. Our findings suggest that changes in the soil microbiome and disruption of specific microbial processes induced by soil acidification can play a critical role for plant health

Supplementary Tables from A phosphorus threshold for mycoheterotrophic plants in tropical forests

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Supplementary Figures from A phosphorus threshold for mycoheterotrophic plants in tropical forests

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