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"Soil fungi"
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Effects of rewatering on soil fungi and soil enzymes in a spruce-beech forest after a 5-year experimental drought
Backgrounds and aims
The functioning of temperate forests may change dramatically in the future due to more extreme precipitation events. In contrast to drought effects, little is known about the reaction of soil fungi to rewatering. We studied soil fungal communities and soil enzymatic activities over a period of 3 months following rewatering after 5 years of experimental drought.
Results
The most pronounced changes compared to the drought phase occurred early after rewatering in the beech root zone and were mainly attributed to litter decomposers. In the spruce zone, the relative abundance of ectomycorrhizal fungi (ECMf) was lower during the initial phase of response to rewatering but approached control levels after 3 months. The previous drought treatment was influencing the structure of the saprotrophic fungal community (SAPf) more than that of the ECMf community during rewatering. The composition of the SAPf community was associated with changes in nitrogen (mineral nitrogen: control 2.86, rewatering = 1.53), while that of the ECMf community was associated with the soil water content (control = 26%, and rewatering = 22%). Soil enzyme activities were positively correlated with the diversity and composition of SAPf communities, especially in previously drought-treated plots. In beech and mixed root zones, plant cell wall-degrading enzyme activities were elevated in rewatered plots compared with control plots, while in spruce, only cellobiohydrolase and β-glucosidase were elevated.
Conclusion
Structural changes within SAPf communities associated with nitrogen dynamics correlated with enzymatic activity in response to rewatering. A low responsiveness of fungal community composition in the mixed root zone suggests its buffering capacity against fluctuating soil moisture conditions.
Journal Article
Long-lasting effects of land use history on soil fungal communities in second-growth tropical rain forests
Our understanding of the long-lasting effects of human land use on soil fungal communities in tropical forests is limited. Yet, over 70% of all remaining tropical forests are growing in former agricultural or logged areas. We investigated the relationship among land use history, biotic and abiotic factors, and soil fungal community composition and diversity in a second-growth tropical forest in Puerto Rico. We coupled high-throughput DNA sequencing with tree community and environmental data to determine whether land use history had an effect on soil fungal community descriptors. We also investigated the biotic and abiotic factors that underlie such differences and asked whether the relative importance of biotic (tree diversity, basal tree area, and litterfall biomass) and abiotic (soil type, pH, iron, and total carbon, water flow, and canopy openness) factors in structuring soil fungal communities differed according to land use history. We demonstrated longlasting effects of land use history on soil fungal communities. At our research site, most of the explained variation in soil fungal composition (R2 = 18.6%), richness (R2 = 11.4%), and evenness (R2 = 10%) was associated with edaphic factors. Areas previously subject to both logging and farming had a soil fungal community with lower beta diversity and greater evenness of fungal operational taxonomic units (OTUs) than areas subject to light logging. Yet, fungal richness was similar between the two areas of historical land use. Together, these results suggest that fungal communities in disturbed areas are more homogeneous and diverse than in areas subject to light logging. Edaphic factors were the most strongly correlated with soil fungal composition, especially in areas subject to light logging, where soils are more heterogenous. High functional tree diversity in areas subject to both logging and farming led to stronger correlations between biotic factors and fungal composition than in areas subject to light logging. In contrast, fungal richness and evenness were more strongly correlated with biotic factors in areas of light logging, suggesting that these metrics might reflect long-term associations in old-growth forests. The large amount of unexplained variance in fungal composition suggests that these communities are structured by both stochastic and niche assemblage processes.
Journal Article
Comparison of Soil Properties, Understory Vegetation Species Diversities and Soil Microbial Diversities between Chinese Fir Plantation and Close-to-Natural Forest
With the continuous increase in plantation areas, the reduction of natural forest areas, and the unreasonable management of plantations by human beings, the service function of forest ecosystems has gradually reduced. Therefore, close-to-natural forestry has become important for the sustainable development of modern forestry. However, the differences in soil properties, enzyme activities, microbial diversities, and undergrowth vegetation species diversities have not been systematically explained for Chinese fir (Cunninghamia lanceolata). How do these indicators interact? The purpose of this paper was to study the difference in soil properties and biodiversity in different aged Chinese fir plantations and close-to-natural forests to explore their interactions and to provide direction for close-to-nature management. The results showed that the above indicators were significantly different in different aged Chinese fir plantations, soil pH, organic matter, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzed nitrogen, available phosphorus concentrations, and urease activities in close-to-natural forests were significantly higher than plantations. It is worth mentioning that the richness of undergrowth vegetation species diversity (especially shrubs) and soil microbial diversities (especially fungi) in the close-to-natural forests were obviously higher than those in plantations. The correlation analysis results showed that the diversity of shrub species with respect to soil properties presented a higher correlation than herb species, the diversity of fungi with respect to soil properties presented a higher correlation than that observed for bacteria, and the diversity of fungi were significantly correlated with the diversity of undergrowth vegetation species diversities, but the correlation between bacteria and undergrowth vegetation species diversities was not significant. Our results suggest that the above factors are fundamental factors for the transformation of Chinese fir plantations to close-to-natural forests. To realize close-to-natural forestry, we must change the tree structure, combine the difference of those factors in different aged plantations, restore undergrowth vegetation species diversity, and thus improve microbial diversity and increase decomposition, transformation, and improvement of soil properties.
Journal Article
Interactive effects of nitrogen fertilizer and altered precipitation on fungal communities in arid grasslands of northern China
PurposeFungi play an essential role in regulating the functioning of terrestrial ecosystems and are sensitive to climate change factors. Climate change incidents, such as N deposition and altered precipitation, create abiotic stress regarding the water use efficiency of soil and nutrient limitation impacting the activity of soil fungi. This study aimed to examine the combined effects of N fertilization and altered precipitation on soil fungal diversity and composition in the desert steppe.Materials and methodsIn the present study, we carried out a field experiment to assess the soil fungal diversity and composition of the desert steppe in response to N fertilizer (0 or 35 kg N ha−1 year−1) and precipitation changes (control, − 50% precipitation, or + 50% precipitation) in the desert steppe. The study was initiated in 2012, and plant and soil samples were collected after 5 years (August, 2017) of field treatments. High-throughput sequencing was applied to estimate the fungal diversity and composition.Results and discussionThe soil fungal communities were dominated by Ascomycota (87.85% ± 1.26%), which primarily drove the fungal community composition. Decreased precipitation promoted strong shifts in fungal community composition under both N fertilizer levels. Increased precipitation significantly reduced Shannon-Wiener indices by 9.96%. The increasing relative abundances of fungal functional groups (lichenized saprotroph, animaland plant pathogens) resulted in a marked shift in fungal community composition from decreased precipitation to increased precipitation, which is attributed to the important role of the Ascomycota phylum in fungal communities. Structural equation modeling (SEM) indicated that C4 biomass was the predominant factor determining the Shannon-Wiener index for these fungi. Direct altered precipitation, indirect soil pH, and C4 biomass together controlled soil fungal community composition, with altered precipitation as the main driver.ConclusionsThe interactive effects of N fertilizer and altered precipitation on grassland plant density, biomass, and soil properties may play an essential role in determining fungal diversity and community composition. Precipitation is a primary limiting factor that influences fungal community composition. Effects of N fertilizer on soil fungal community composition are highly dependent on changes in precipitation.
Journal Article
Effects of secondary succession on soil fungal and bacterial compositions and diversities in a karst area
AimsWe explored the trends in soil fungal and bacterial patterns and their responses to plant and soil characteristics with increasing site age in abandoned farmland in karst areas.MethodsIllumina sequencing of 16S rRNA and ITS genes was used to characterize the soil bacterial and fungal diversities in farmland, farmland abandoned for 3, 6, 20, and 40 years, and old-growth forests in Southwest China. Plant diversity, community-weighted mean (CWM) leaf and branch traits, soil physical and chemical properties and metal element concentrations were also investigated.ResultsBacterial diversity decreased slightly with increasing site age, while fungal diversity first increased and then decreased. Ascomycota was the dominant fungal phylum, and its abundance decreased significantly, from 83.21% in farmland to 49.66% in old-growth forests, while that of Basidiomycota increased significantly from 4.52 to 35.43%. The soil bacterial community was dominated by Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi. The fungal and bacterial diversities were mainly affected by soil properties. At the older sites, high levels of soil nitrate nitrogen (N), ammonium-N, total N, soil organic carbon, calcium, and magnesium and relatively low levels of soil potassium and available phosphorus (P) resulted in decreased bacterial diversity. Fungal diversity was positively affected by soil total P and pH and negatively affected by soil iron and copper. The bacterial and fungal compositions were jointly affected by soil properties and CWM leaf and branch traits.ConclusionsOur findings indicate that soil bacterial and fungal diversities and compositions changed significantly during secondary succession in karst areas. Microbial diversity was determined by soil properties, and compositions were jointly driven by plant and soil properties.
Journal Article
Saprotrophic soil fungi to improve phosphorus solubilisation and release
Modern agriculture is dependent on phosphate rock (PR), which is a nonrenewable resource. Improvement of phosphorus (P) availability for crops in agricultural soils represents a key strategy to slow down the depletion of PR. The aim of this study was to identify potential P biofertilisers among saprotrophic fungal species. We tested 30 fungal strains belonging to 28 taxa (4 Zygomycota and 24 Ascomycota) and with different life strategies. The study showed that many saprotrophic fungi have the ability to mobilise P from insoluble forms according to a variety of mechanisms. Our results expand the pool of P solubilising fungal species, also suggesting a new solubilisation index and shedding light on parameters that could be basic in the selection of efficient soil P-biofertilisers fungi. Rhizopus stolonifer var. stolonifer, Aspergillus niger and Alternaria alternata were found to be the best performing strains in terms of amounts of TCP solubilisation.
Journal Article
Plant root growth, architecture and function
Without roots there would be no rhizosphere and no rhizodeposition to fuel microbial activity. Although micro-organisms may view roots merely as a source of carbon supply this belies the fascinating complexity and diversity of root systems that occurs despite their common function. Here, we examine the physiological and genetic determinants of root growth and the complex, yet varied and flexible, root architecture that results. The main functions of root systems are also explored including how roots cope with nutrient acquisition from the heterogeneous soil environment and their ability to form mutualistic associations with key soil micro-organisms (such as nitrogen fixing bacteria and mycorrhizal fungi) to aid them in their quest for nutrients. Finally, some key biotic and abiotic constraints on root development and function in the soil environment are examined and some of the adaptations roots have evolved to counter such stresses discussed.
Journal Article
Increasing Ages of Inga punctata Tree Soils Facilitate Greater Fungal Community Abundance and Successional Development, and Efficiency of Microbial Organic Carbon Utilization
Leguminous Inga trees are thought to enhance soil carbon (C) accumulation following reforestation, through mostly unknown mechanisms. This study amplified soil DNA using the ITS1F and ITS4 primers for PCR and Illumina MiSeq methods to identify fungal taxa, and traditional C analysis methods to evaluate how planted 4-, 8-, and 11-year-old Inga punctata trees affected soil fungal community compositions and C utilization patterns compared to old-growth I. punctata trees and an adjacent unplanted pasture within the same reforestation zone in Monteverde, Costa Rica. Along the tree age gradient, the planted I. punctata trees enhanced the tree soil C capture capacity, as indicated by increased levels of soil biomass C, Respiration, and efficiency of organic C use (with lower qCO2 values), and development of increasingly more abundant, stable, and successionally developed fungal communities, including those associated with the decomposition of complex organic C compounds. The level and strength of differences coincided with differences in the time of separation between the pasture and tree age or between the different tree ages. Fungal taxa were also identified as potential indicators of the early and late stages of soil recovery. Thus, planting I. punctata should be part of future reforestation strategies used in this region of the Monteverde Cloud Forest in Costa Rica.
Journal Article
Efficiency of different strains of Trichoderma on the control of Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotium cepivorum
The aim of this work was to verify the efficiency of different isolates of Trichoderma spp. on the control of Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotium cepivorum, and the influence they pose on the conidia production of Trichoderma spp. For mycelial growth, discs with inoculum of phytopathogens were placed on the center of the Petri dishes followed by the addition of two Trichoderma sp. discs on the opposite sides of the plate after 24 hours. Every 12 hours data were collected from colonies diameters and used for the analyses of Mycelial Growth Index (MGI) and Area Under the Curve of Mycelial Growth (AUCMG). The analyses were performed by a completely randomized design with two controls, a negative one without Trichoderma sp. and one with a commercial strain of Trichoderma harzianum. Spore solution for evaluation of conidia production were made by adding 10 mL of distilled water and scratching the surface of the colonies. For S. cepivorum, all Trichoderma spp. strains reduced both indexes tested. However, while for MGI S. sclerotiorum also presented some reduction on the growth rate, the total area of this fungus was not affected. Sclerotium rolfsii strains of Trichoderma sp. from Lages and Curitibanos showed an effect on the reduction of AUCMG of this fungus, although none of the Trichoderma affected the growth rate of this phytopathogen. On the presence of S. sclerotiorum and S. cepivorum, none of the Trichoderma spp. showed any difference on conidia production when compared among themselves, nonetheless we did notice that on the presence of S. cepivorum, the strain from Rio do Sul retained its reproductive ability compared to control. Results obtained from this research can demonstrate the importance of biocontrol agents against different plant pathogens since it might have a specific antagonist-pathogen relation.
Journal Article