Forest Soils Research Articles

The Origin and Geography of Brown Forest Soils

Brown soils, Brown forest soils, Burozems or Cambisols have been studied for more than 100 years, and to this day, their nature, origin and process organization remain controversial. In addition, issues of their geography are quite controversial, especially in such a large country as Russia. A brief review of the literature on the morphological diversity features of the genesis and origin of brown soils in the various geographical locations of Eurasia is given. It was shown that the genesis of brown soils is not as closely related to the type of forest vegetation as previously thought, although, at the same time, the vast majority of brown soils are forest soils. Depending on the geographic situation and local climatic and geogenic conditions, Brown forest soils have related subtypes among adjacent soil types in different natural zones. Thus, in the polar zone, they are close to Entic Podzols, in the subtropics to Cinamonic soil, and in the forest-steppe, they replace zonal Retisols in positions with a relatively less contrasting and even climate. Being to a certain extent intrazonal soils, brown soils are combined with other more intrazonal soils—Rendzinas—and form the so-called Burozem-Rendzinas on uplands, composed of carbonate rocks in various natural zones. The article is illustrated with original photographs of Brown forest soils from various natural zones, taken by the author during numerous expeditions. It has been established that Burozems combine the characteristics of intrazonal soil, which is inherent in all natural zones, and have elements of zonal soils, as well as adjacent intrazonal soils in invariant combinations of soil-forming factors. From this, two conclusions can follow about their further classification fate: a more thorough justification for an independent soil type or a classification of structural metamorphism and in situ transformation of minerals among various existing zonal soil types.

Increased stability of a subtropic bamboo forest soil bacterial communities through integration of water and fertilizer management compared to conventional management.

Conventional management (CM), substantial fertilization and flooding irrigation, hasled to soil acidification, the decrease in soil bacterial diversity in bamboo forests. Integration of water and fertilizer management (IWF) can effectively improve the efficiency of water and fertilizer use, but its effect on soil environment, especially on microbial community, is still unclear. Here, we used next-generation high-throughput sequencing to compare soil properties and bacterial communities through different fertilization and irrigation methods under IWF and CM. Compared to the control group, CM significantly reduced soil pH and bacterial diversity, while IWF improved soil nutrition status, increased soil bacterial diversity and soil pH to a level similar to the control group. Compared with CM, IWF also improved the relative abundance of beneficial bacteria and copiotrophic bacteria community in the soil, and the bacterial community in IWF was similar to CK. The structure of the bacterial community was also significantly correlated with soil organic matter, total nitrogen, hydrolyzable nitrogen, and available potassium, while soil bacterial diversity was mainly associated with soil hydrolyzable nitrogen. IWF can play an important role in preventing soil acidification, the loss of soil bacterial diversity, and improving the structure of the bacterial community under specific conditions.

The effect of mini-till and no-till technologies on productivity and quality of malting barley grain

The purpose of the current work was to study the effect of mini-till, no-till and traditional agricultural technologies on productivity and quality of malting barley grain. Field trials were carried out in three crop rotation sequences ‘winter rye – spring wheat – barley’ on medium loamy gray forest soil of Chuvashia with 2.42 % of humus; 188 mg/kg of mobile phosphorus; 160 mg/kg of exchangeable potassium and 6.2 of exchangeable acidity. During the vegetation period of 2020, the hydrothermal coefficient was 1.04; in 2021 it was 0.60; and in 2022 it was 1.05. The object of the study was an early-maturing variety ‘Elf’. Traditional agricultural technology was based on autumn disk plowing and autumn plowing, early spring harrowing, seedbed cultivation and sowing with subsequent rolling. Mini-till cultivation included autumn disk plowing, spring cultivation and sowing with the multifunctional complex “Cultibar 9000”. No-till cultivation consisted of autumn treatment with the non-selective herbicide “Sprut Extra" and “direct” spring sowing “Cultibar 9000”. The seeding rate was 200 kg/ha. The dose of mineral fertilizers was N30P20К20. The crops were protected from weeds, diseases, and pests. On average, the largest (2.49 t/ha) productivity of malting barley grain was obtained using mini-till technology, and the smallest (2.34 t/ha) when using no-till. The mean productivity with traditional agricultural technology was lower than the maximum by 0.03 t/ha, but larger than the minimum by 0.12 t/ha. The analysis of the qualitative characteristics has shown a reliable effect of agricultural technologies on the brewing properties of barley grain. Thus, traditional technology contributed to obtaining grain of the 1st class, mini-till technology contributed to obtaining grain of the 2nd class, and no-till technology contributed to obtaining grain of the 3rd class of the interstate standard.

Oomycete communities in lowland tropical forest soils vary in species abundance and comprise saprophytes and pathogens of seeds and seedlings of multiple plant species.

The soils in lowland tropics are teeming with microbial life, which can impact plant community structure and diversity through plant-soil feedbacks. While bacteria and fungi have been the focus of most studies in the tropics, oomycetes may have an outsized effect on seed and seedling health and survival, given their affinity for moister, warmer environments. We assessed the diversity and pathogenicity of oomycete species present in a lowland tropical forest in Panama. We used a culture-dependent leaf-baiting assay and culture-independent soil DNA metabarcoding methods to quantify zoospore abundance and species diversity. A subset of the isolates from the baiting assay were used to evaluate pathogenicity and symptom severity on seedlings of three tree species. Oomycetes were ubiquitous and common members of the soil microbial community in lowland tropical forests, and zoospore abundance was far greater compared to similar studies from temperate and mediterranean forests. The various oomycete species also varied in the ability to infect host plants. Species of Pythium were more virulent, while species of Phytopythium caused less severe symptoms but were more diverse and commonly isolated from the soil. Finally, we found that individual hosts accumulated a distinct oomycete community and was the only factor that had an effect on community structure. Collectively, these findings demonstrate that oomycetes are ubiquitous, host-generalist pathogens and saprophytes, that can impact seed and seedling survival in lowland tropical forests.

Field Reduction of Ectomycorrhizal Fungi Has Cascading Effects on Soil Microbial Communities and Reduces the Abundance of Ectomycorrhizal Symbiotic Bacteria.

Specific interactions between bacteria and ectomycorrhizal fungi (EcMF) can benefit plant health, and saprotrophic soil fungi represent a potentially antagonistic guild to these mutualisms. Yet there is little field-derived experimental evidence showing how the relationship among these three organismal groups manifests across time. To bridge this knowledge gap, we experimentally reduced EcMF in forest soils and monitored both bacterial and fungal soil communities over the course of a year. Our analyses demonstrate that soil trenching shifts the community composition of fungal communities towards a greater abundance of taxa with saprotrophic traits, and this shift is linked to a decrease in both EcMF and a common ectomycorrhizal helper bacterial genus, Burkholderia, in a time-dependent manner. These results not only reveal the temporal nature of a widespread tripartite symbiosis between bacteria, EcMF and a shared host tree, but they also refine our understanding of the commonly referenced 'Gadgil effect' by illustrating the cascading effects of EcMF suppression and implicating soil saprotrophic fungi as potential antagonists on bacterial-EcMF interactions.

Vertical variations in enzymatic activity and C:N:P stoichiometry in forest soils under the influence of different tree species

Abstract Tree species play a crucial role in shaping soil properties, significantly influencing nutrient cycling and ecological dynamics within forest ecosystems. In this comprehensive study, we examined the influence of tree species on soil chemistry especially on C/N/P stoichiometry and enzymatic activities across soil profiles. We analyzed soil samples beneath eight distinct tree species at three vertical horizons of soil: organic (O), humus mineral (A), and mineral enrichment (B) horizons. Our study involved detailed assessment of soil carbon, nitrogen, and phosphorus contents, along with the activities of key enzymes: β-glucosidase, N-acetyl-β-glucosaminidase, and phosphatase. The study revealed pronounced vertical stratification in soil properties, significantly influenced by the tree species. General linear models (GLMs) highlighted differences in C: N:P stoichiometry and enzymatic activity across different soil horizons and among tree species. Enzymatic activity was strongly correlated with C, N and P content. The conducted research confirms the distinctiveness of coniferous and deciduous species in terms of C, N and P stoichiometry and the activity of the tested enzymes involved in the C, N and P circulation. These variations are indicative of the intricate interactions between tree species and soil processes. Our findings underscore the role of diversity of trees in modulating soil nutrient dynamics and enzyme-driven processes, which are crucial for understanding soil ecosystem functions and nutrient cycling. This study provides new insights into the role of tree species in shaping the soil environment, offering implications for forest management and conservation strategies. Taking into account the impact of individual tree species covered by the research on the soil, it is worth considering the cultivation of mixed stands.

Effects of vertical forest stratification on precipitation material redistribution and ecosystem health of Pinus massoniana in the Three Gorges Reservoir area of China.

Vertical stratification of forest plays important roles in the local material balance and in maintaining forest health by distributing and redistributing precipitation materials through adsorption, fixation, and release. Differences in runoff nutrient concentrations among vertical layers are closely related to vertical stratification (factors such as the trunk, canopy, forest litter, and soil physical and chemical properties). Long-term forest observations revealed significant spatial differences in Pinus massoniana (Pinus massoniana Lamb.) forests in the Three Gorges Reservoir area. Pinus massoniana forests on downslopes were characterized by a dense canopy, green needles, and rich forest vegetation, while those on upslopes were characterized by low vegetation cover, dead trees, and decreases in the tree height, diameter at breast height, and volume per plant with increasing slope. By analyzing the soil at different sites, we found that the pH of the forest land soil differed significantly among different slope positions. Soil on upper slopes was significantly more acidic than soil on lower slopes, indicating that acidic substances were intercepted by filtration through the broad litter layer and the soil surface layer. This filtration process resulted in a normal rhizosphere environment suitable for the absorption of nutrients by vegetation on the lower slopes. In this way, downhill sites provided a good microenvironment for the growth of Pinus massoniana and other vegetation. Our results show that direct contact between needles and acid rain was not the main cause of root death. Instead, the redistribution of rainfall substances by forest spatial stratification caused changes in the soil microenvironment, which inhibited the absorption of nutrients by the roots of Pinus massoniana and the growth of understory plants in Pinus massoniana forests on upper slopes. These findings emphasize that increasing land cover with forests with vertical structural stratification plays an important role in woodland material redistribution and forest conservation.

Global Spatial Projections of Forest Soil Respiration and Associated Uncertainties

The accurate prediction of global forest soil respiration (Rs) is critical for climate change research. Rs consists of autotrophic (Ra) and heterotrophic (Rh) respiration, which respond differently to environmental factors. Predicting Rs as a single flux can be biased; therefore, Ra and Rh should be predicted separately to improve prediction accuracy. In this study, we used the SRDB_V5 database and the random forest model to analyze the uncertainty in predicting Rs using a single global model (SGM) and Ra/Rh using a specific categorical model (SCM) and predicted the spatial dynamics of the distribution pattern of forest Ra, Rh, and Rs in the future under the two different climate patterns. The results show that Rs is higher under tropical and inland climatic conditions, while Rh fluctuates less than Ra and Rs. In addition, the SCM predictions better capture key environmental factors and are more consistent with actual data. In the SSP585 (high emissions) scenario, Rs is projected to increase by 19.59 percent, while in the SSP126 (low emissions) scenario, Rs increases by only 3.76 percent over 80 years, which underlines the need for SCM in future projections.

Draft genome sequence of Streptomyces noursei strain DS30.6, isolated from forest soil in Vietnam.

Streptomyces noursei strain DS30.6 was chosen to be resistant to Ralstonia pseudosolanacearum T2C-Rasto after being isolated from Vietnamese forest soil. The draft genome of this strain was reported to be 8,863,720 bp, with an average guanine-cytosine content of 72.67%.

Soil properties, climate, and topography jointly determine plant community characteristics in marsh wetlands.

Various environmental conditions influence the characteristics of plant communities within wetlands. Although the influence of key environmental factors on plant community traits within specific types of wetland ecosystems has been studied extensively, how they regulate plant communities across marsh wetland types remains poorly understood. We examined how environmental conditions influence plant communities in marsh wetlands along the lower Tumen River in northeastern China. We collected and analyzed data on the plant community characteristics (species, height, and coverage), soil physicochemical properties (organic carbon, inorganic nitrogen, and sulfur), and climatic and topographic factors (temperature, precipitation, and elevation) of 56 distinct marsh plots (29 herbaceous, 14 shrub, and 13 forested marshes) to understand how these variables correlate with plant community characteristics across marsh types. The wetland plant diversity varied, with the lowest, intermediate, and highest diversity occurring in herbaceous, shrub, and forested marshes, respectively. Climate, topography, and soil properties had crucial influences on plant diversity and biomass. Structural equation modeling showed that, in herbaceous marshes, plant biomass was primarily determined by soil and plant diversity, with climate exerting an indirect effect. In shrub marshes, soil, climate, and plant diversity directly influenced biomass. In forest marshes, soil and plant diversity directly affected biomass, whereas climate and topography had indirect effects. These findings highlight the complex interactions among environmental factors across marsh ecosystems and their influence mechanisms on biomass, aiding in formulating effective conservation and restoration strategies for marsh wetland ecosystems.

Land Use Legacy Landforms at the UNESCO Heritage Site Tarnowskie Góry, Upper Silesia, Poland—Stratigraphy, Soils and Age

ABSTRACTMetallurgy in Upper Silesia (Poland) has a long tradition of international significance, which was emphasized in 2017 when the historic silver mine in Tarnowskie Góry was inscribed as a UNESCO World Heritage site. The area consists of various anthropogenic landforms, the stratigraphy of which has hardly been studied so far. In this study, we describe five main morphological units: Unit I (RCH) and Unit II (RCH pit), resulting from charcoal production; Unit III (shaft) and Unit IV (shaft heap), resulting from mining; and Unit V (reference forest soil). The first four units are a variation of a Technosol with inherently different properties from the reference forest soil. Unit I exhibits typical properties of a relict charcoal hearth (RCH), whereas Unit II resembles a pit. Unit III consists of a mostly infilled mining shaft remain (MSR), characterized by relocated subsoil. Unit IV consists of material from the adjacent Unit III that has been dumped directly aside. The studied RCH was used no earlier than during the second half of the 17th century, probably between 1725 and 1813. The studied MSR was used most likely between the 3rd and 5th centuries, which is much older than described so far. Together, the units reflect the characteristic heterogeneity of soils in shaft mining and RCH areas.

Characterization and prediction of hydraulic properties of traffic-compacted forest soils based on soil information and traffic treatments

Key messageThe hydraulic properties of compacted and rutted soils were evaluated through in-situ infiltration experiments and predicted based on soil texture class and traffic treatments. A significant decrease in saturated soil water content and soil hydraulic conductivity at saturation was observed. The resulting soil hydraulic parameters, when integrated into a soil water transfer model, effectively simulated water dynamics in these impacted forest soils, providing a crucial first step toward developing decision support tools for real-time trafficability. This approach can assist forest managers in minimizing the extent of soil compaction.ContextTo overcome trafficability issues of forest soils induced by heavy logging machinery, planning support tools are needed to determine suitable soil moisture conditions for traffic.AimsThis study aimed to identify the soil properties that differ significantly between undisturbed and compacted soils and to provide several estimation tools to predict the hydraulic properties of compacted soils beneath the skid trails.MethodsFour hundred seventeen water infiltration tests were conducted on 19 forest sites, mostly in North-eastern France, and analysed with the BEST method to estimate the hydraulic properties of the skid trails and undisturbed soils. The hydraulic properties of the skid trails were predicted thanks to linear mixed effect models using a bulk treatment effect, a site effect, or a skid trail degradation score. The predicted hydraulic properties were tested using a water flow model to assess their relevance regarding the prediction of water dynamics in skid trails.ResultsThe compaction effect was only significant for the logarithm of the hydraulic conductivity at saturation (log10(Ksat)) and the soil water content at saturation (θsat). For the skid trails, θsat was reduced by - 0.02 and − 0.11 m3m−3 in the 0 − 10 cm and 15 − 25 cm layers respectively, compared to undisturbed topsoil (0 − 10 cm). log10(Ksat) was reduced by − 0.38 and − 0.85 for skid trails in the 0 − 10 and 15 − 25 cm soil layers respectively, compared to undisturbed topsoil. The use of a pedotransfer function, in replacement of water infiltration tests, and their combination with the same correction coefficients proved to efficiently simulate the difference in water dynamics between skid trails and undisturbed forest soils.ConclusionEstimation of soil hydraulic properties based on in situ water infiltration experiments proved efficient to simulate water dynamics in compacted and rutted forest soils. Yet, further studies are needed to identify the most adapted pedotransfer function to forest soils and to test the generalisation of our findings in different conditions, especially deeply rutted soils (rut depths > 12 cm).

Suspended soils enrich local forest floor soils during the rainy season in a tropical monsoon rainforest of Hainan Island, South China

Suspended soils enrich local forest floor soils during the rainy season in a tropical monsoon rainforest of Hainan Island, South China

The influence of tree species on small scale spatial soil properties and microbial activities in a mixed bamboo and broad-leaved forest

Soil enzyme activity and microbial biomass play a critical role in myriad ecological processes. Bamboo and broad-leaved mixed forests have received widespread attention as important forestry models for ecological restoration and sustainable development; however, our understanding the influences of broad-leaved tree species in mixed bamboo forests on soil properties and microbial activity remains unclear. Here we sampled twenty-seven spatially interspersed stands of bamboo-Castanopsis chinensis Hance mixed forest (CCB), bamboo-Alniphyllum fortune (Hemsl.) Makino mixed forest (AFB), and bamboo-Choerospondias axillaris mixed forest (CAB), with different mixing ratios (0–10 %, 10–20 %, 20–40 % canopy proportions) in subtropical China, to examine the effects of tree species and mixed ratio on soil nutrients, microbial biomass, and enzyme activity. We found that the different forests exhibited variations in soil nutrient levels. CAB forests exhibit notably higher mean C, N, and P contents than AFB and CCB, particularly at a 10–20 % mixing ratio where SOC concentration reached 46.50 g/kg. CAB forests demonstrated significantly higher activities of invertase (mean 701.83U/g), urease (8393.44U/g), and catalase (501.73U/g) compared to AFB and CCB forests, with peak enzyme activities observed at a 10–20 % mixing ratio. Soil microbial biomass C and N were notably greater in CAB and CCB forests than in AFB forests. CAB forests also exhibited the highest soil microbial biomass P (mean 48.68 mg/kg), which rose consistently with an increased mixing ratio. Multiple factor analysis revealed that the enzyme activities were significantly correlated with the annual growth of fine roots in the forest and were positively correlated with resident C, total N, total P, C: N, and C: P. Overall, the results provide insights into the importance of tree species and crown size in bamboo and broadleaved tree mixed forest in soil features and the microbial activity while providing management guidance for the selection of mixed tree species for sustainable management of bamboo forest soil microenvironment.

Hydraulic properties for a wide range of undisturbed and compacted French forest soils: in situ measurements and estimation with the BEST method

Key messageThe dataset provides hydraulic properties estimated using the Beerkan Estimation of Soil Transfer (BEST) method, on undisturbed and on compacted and rutted French forest soils. It allows a reliable assessment of the effect of traffic on soil permeability. However, hydraulic properties could not be estimated on extremely rutted soils, underscoring the necessity for tailored protocols for these conditions.

The Multifaceted Soils of Himachal Pradesh, India: Types and Characteristics

The soils of Himachal Pradesh face a multitude of pressing issues that threaten their health and agricultural productivity. The diverse geographical features, temperature regimes and biological zones of Himachal Pradesh have resulted into a vast range of soil types in the state. Alpine, forest, alluvial and sub-mountain soils are the four major soil categories into which the state's soils can be generally divided. Only a particular species and adapted plants can thrive in the extreme weather circumstances of alpine soils, which are located at higher elevations and possess soils having thin, stony and acidic in reaction. The mid-hill areas are dominated by forest soils which are distinguished by their high levels of organic matter and nutrients. These soils support luxuriant vegetation and make effective agricultural methods possible. Alluvial soils, which are mostly found in river valleys and are deposited by ravine systems are extremely rich and perfect in fertility and suitable for growing a range of crops including vegetables, rice and maize. Located in the foothills, sub-mountain soil exhibits a blend of traits from alluvial and forest soils, thus providing a range of uses for horticulture and agriculture. In addition to supporting a diverse array of plant and animal life, Himachal Pradesh's varied soil types are vital to the region's agricultural economy. One of the biggest problems is soil erosion, which is made worse by the steep terrain and abundant rainfall in the area. This results in the loss of topsoil and decreased fertility. Deforestation, overgrazing, and unsustainable farming methods all contribute to land degradation, which further reduces biodiversity and soil quality. Furthermore, crop development is impacted by soil acidity in high-altitude regions, which restricts nutrient availability. However, these issues need efficient conservation measures and soil management techniques. In order to maintain Himachal Pradesh's rich biodiversity and agricultural potential for future generations, sustainable agricultural development and environmental protection in this ecologically sensitive area depend on an understanding of the complex soil dynamics. Addressing these interconnected issues requires a comprehensive approach, emphasizing sustainable land management practices, community engagement, and restoration efforts to preserve the vital soil resources of this ecologically sensitive region.

Insight into the dynamics of protected and non-protected carbon pools in four soils with different land uses

Abstract Background and aims To provide insight into the patterns of soil organic matter decomposition, changes in the quantity of biopolymers and the correlation between them were followed using 2D correlation spectroscopy (2DCOS) FTIR. Methods Soil organic matter fractions with different vegetation/land use (grass, spruce, oak and arable) were examined in a 1-year laboratory incubation. The non-protected organic matter fraction was calculated in terms of particulate organic matter (POM), the carbon stabilized in aggregates as S + A (sand + aggregates), and the mineral-associated organic matter (MAOM) as the s + c (silt and clay) fraction. Results Forest soils (spruce, oak) exhibited high C and N accumulation in the POM fraction (48, 43% and 29, 22% for spruce and oak, respectively) due to the limited decomposition, caused by low pH and high soil C/N ratio. The 2DCOS analysis revealed that carbohydrate-protein and carbohydrate-lignin correlations could be observed most frequently during incubation. The carbohydrate-protein correlation was negative in all cases, for all fractions and for all vegetation types, which suggests biogeochemical linkage between these biopolymers. The temporal order of the spectral changes was widely varied for the vegetation types and especially for the SOM fractions. Lipid/Lignin → Carbohydrate or Lipid → Lignin/Carboxyl/Protein sequences were found for the protected carbon pools (S + A and s + c), possibly because of the readily available abundant N compounds present in MAOM. Conclusion Although lipids and lignin are considered as chemically stable materials that commonly remain constant during decomposition, these compounds were found to be very susceptible in all the fractions.

Reduced predation and energy flux in soil food webs by introduced tree species: Bottom‐up control of multitrophic biodiversity across size compartments

Abstract The introduction of non‐native tree species has become a global concern and may disrupt native communities and related ecosystem functions. Soil food webs regulate organic matter decomposition and nutrient cycling in forests with their feeding activities, but evaluating consequences of the introduction of tree species on soil invertebrates is challenging due to the complex trophic structure and wide range in body size of soil invertebrates. Here, we employed an energetic food web approach and estimated the energy flux in soil food webs using a four‐node model including soil meso‐ and macrofauna decomposers and predators. We examined pure and mixed stands of native European beech (Fagus sylvatica), introduced Douglas fir (Pseudotsuga menziesii) and native range‐expanding Norway spruce (Picea abies) across site conditions. Compared to native forests, introduced tree species reduced total fresh mass of macrofauna predators by 92% at sandy sites but not that of decomposers, suggesting trophic downgrading in soil food webs by Douglas fir. The energy flux in mixed forests was intermediate between respective monocultures, suggesting that tree mixtures mitigate potential negative impacts of introduced tree species on food web functioning. Across size classes, soil macrofauna responded more sensitively to changes in environmental conditions than soil mesofauna. Additionally, total energy flux positively correlated with species richness, pointing to the significance of soil biodiversity for trophic functionality. The energy flux through mesofauna outweighed that through macrofauna when considering energy loss to predators, highlighting the importance of mesofauna for decomposition processes in forest soil food webs. Overall, the study emphasizes the critical role of tree species composition, site conditions and soil biodiversity in driving energy flux through soil food webs and maintaining forest ecosystem functions. Read the free Plain Language Summary for this article on the Journal blog.

Fire-associated microbial shifts in soils of western conifer forests with Armillaria root disease.

With its influence on ecosystem processes and functions, the soil microbiome can interact with soilborne pathogens to facilitate or suppress plant disease development. These forest ecosystems are experiencing increased wildfire frequency and burn severity that could influence the fungal root pathogen, Armillaria solidipes, and interactions with the soil microbiome. We examined changes to the soil microbiome following three levels of burn severity, and examined how these changes correspond with A. solidipes, and a putatively beneficial species, A. altimontana. Following severe burn, there was a decreased relative abundance of ectomycorrhizal fungi associated A. altimontana. A. solidipes and associated microbial taxa dominated following high-severity burns, suggesting that severe fires provide suitable environmental conditions for these species. Our results suggest that shifts in the soil microbiome and an associated increase in the activity of A. solidipes following high-severity burns in conifer forests may result in priority areas for monitoring and proactive management of Armillaria root disease.

Microbial community structure in recovering forests of Mount St. Helens

IntroductionThe 1980 eruption of Mount St. Helens had devastating effects above and belowground in forested montane ecosystems, including the burial and destruction of soil microbes. Soil microbial propagules and legacies in recovering ecosystems are important for determining post-disturbance successional trajectories. Soil microorganisms regulate nutrient cycling, interact with many other organisms, and therefore may support successional pathways and complementary ecosystem functions, even in harsh conditions. Historic forest management methods, such as old-growth and clearcut regimes, and locations of small mammal enclo and clearcut forests, as well as in locations of historic short-term gopher enclosures (Thomomys talpoides), to evaluate community response to forest management practices and to examine vectors for dispersing microbial consortia to the surface of the volcanic landscape. These biotic interactions may have primed ecological succession in the volcanic landscape, specifically Bear Meadow and the Pumice Plain, by creating microsite conditions conducive to primary succession and plant establishment.Methods and resultsUsing molecular techniques, we examined bacterial, fungal, and AMF communities to determine how these variables affected microbial communities and soil properties. We found that bacterial/archaeal 16S, fungal ITS2, and AMF SSU community composition varied among forestry practices and across sites with long-term lupine plots and gopher enclosures. The findings also related to detected differences in C and N concentrations and ratios in soil from our study sites. Fungal communities from previously clearcut locations were less diverse than in gopher plots within the Pumice Plain. Yet, clearcut meadows harbored fewer ancestral AM fungal taxa than were found within the old-growth forest.DiscussionBy investigating both forestry practices and mammals in microbial dispersal, we evaluated how these interactions may have promoted revegetation and ecological succession within the Pumice Plains of Mount St. Helens. In addition to providing evidence about how dispersal vectors and forest structure influence post-eruption soil microbiomes, this project also informs research and management communities about belowground processes and microbial functional traits in facilitating succession and ecosystem function.