Litter fingerprint on microbial biomass,activity, and community structure in the underlying soil

Aims

Little is known about how plant leaf litter decomposing on the soil surface is affecting microbial communities in the underlying soil. Here we examined the effects of decomposing leaf litter of different initial chemistry on biomass, stoichiometry, community structure and activity of microorganisms in the soil underneath the decaying litter layer.

Methods

Leaf litter from six different neotropical tree species with contrasted quality decomposed on top of a common tropical soil in a laboratory microcosm experiment over 98 days. At the end of the experiment we determined microbial biomass C, N, and P, microbial community structure (PLFA), and community level physiological profiles (CLPP) from the top soil.

Results

Despite growing in a common soil substrate, soil microorganisms were strongly affected by litter species, especially by the soluble litter fraction. While litters with low soluble C content did not affect the soil microbial community, litters with high soluble C content led to an increase of microbial biomass and to a structural shift to relatively more Gram-negative bacteria. Changing community structure resulted in changes of catabolic capacity of microorganisms to metabolize a range of different C substrates. The large differences in leachate N and P among litter species, in contrast, had no effect on soil microbial parameters.

Conclusions

Our data suggest that plant litter decomposing on the soil surface exhibit a strong and predictable leachate C-control over microbial community biomass, structure and function in the underlying soil.

     

Fine-root trait plasticity of beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>) and spruce (<Emphasis Type="Italic">Picea abies</Emphasis>) forests on two contrasting soils

Aim

The fine roots of trees may show plastic responses to their resource environment. Several, contrasting hypotheses exist on this plasticity, but empirical evidence for these hypotheses is scattered. This study aims to enhance our understanding of tree root plasticity by examining intra-specific variation in fine-root mass and morphology, fine-root growth and decomposition, and associated mycorrhizal interactions in beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karst.) forests on soils that differ in resource availability.

Methods

We measured the mass and morphological traits of fine roots (i.e. ≤ 2 mm diameter) sampled to 50 cm depth. Fine-root growth was measured with ingrowth cores, and fine-root decomposition with litter bags. Mycorrhizal fungal biomass was determined using ingrowth mesh bags.

Results

Both tree species showed more than three times higher fine-root mass, and a ten-fold higher fine-root growth rate on sand than on clay, but no or marginal differences in overall fine-root morphology. Within the fine-root category however, beech stands had relatively more root length of their finest roots on clay than on sand. In the spruce stands, ectomycorrhizal mycelium biomass was larger on sand than on clay.

Conclusions

In temperate beech and spruce forests, fine-root mass and mycorrhizal fungal biomass, rather than fine-root morphology, are changed to ensure uptake under different soil resource conditions. Yet enhancing our mechanistic understanding of fine-root trait plasticity and how it affects tree growth requires more attention to fine-root dynamics, the functional diversity within the fine-roots, and mycorrhizal symbiosis as an important belowground uptake strategy.

     

Responses of litter decomposition and nutrient release rate to water and nitrogen addition differed among three plant species dominated in a semi-arid grassland

Background and aims

Precipitation and nitrogen (N) deposition are predicted to increase in northern China. The present paper aimed to better understand how different dominant species in semi-arid grasslands in this region vary in their litter decomposition and nutrient release responses to increases in precipitation and N deposition.

Methods

Above-ground litter of three dominant species (two grasses, Agropyron cristatum and Stipa krylovii, and one forb, Artemisia frigida) was collected from areas without experimental treatments in a semi-arid grassland in Inner Mongolia. Litter decomposition was studied over three years to determine the effects of water and N addition on litter decomposition rate and nutrient dynamics.

Results

Litter mass loss and nutrient release were faster for the forb species than for the two grasses during decomposition. Both water and N addition increased litter mass loss of the grass A. cristatum, while the treatments showed no impacts on that of the forb A. frigida. Supplemental N had time-dependent, positive effects on litter mass loss of the grass S. krylovii. During the three-year decomposition study, the release of N from litter was inhibited by N addition for the three species, and it was promoted by water addition for the two grasses. Across all treatments, N and potassium (K) were released from the litter of all three species, whereas calcium (Ca) was accumulated. Phosphorus (P) and magnesium (Mg) were released from the forb litter but accumulated in the grass litter after three years of decomposition.

Conclusions

Our findings revealed that the litter decomposition response to water and N supplementation differed among dominant plant species in a semi-arid grassland, indicating that changes in dominant plant species induced by projected increases in precipitation and N deposition are likely to affect litter decomposition, nutrient cycling, and further biogeochemical cycles in this grassland. The asynchronous nutrient release of different species’ litter found in the present study highlights the complexity of nutrient replenishment from litter decomposition in the temperate steppe under scenarios of enhancing precipitation and N deposition.

     

Leaf litter thickness,but not plant species,can affect root detection by ground penetrating radar

Aim

Ground penetrating radar (GPR), a nondestructive tool that can detect coarse tree roots, has not yet become a mature technology for use in forests. In this study, we asked two questions concerning this technology: (i) Does the leaf litter layer influence root detection and major indices based on the time interval between zero crossings (T) and the amplitude area (A)? (ii) Can GPR images discriminate roots of different plant species?

Methods

Roots buried in a sandy bed, which was covered with different thicknesses of leaf litter, were scanned using a 900 MHz GPR antenna. Roots of four plant species in the bed were also scanned.

Results

Leaf litter decreased root reflections without distorting the shape of the hyperbolas in the radar profile. A values decreased with increasing litter thickness, whereas T was independent of litter thickness. For all species combined, GPR indices were significantly correlated with root diameter.

Conclusions

Leaf litter dramatically decreased root detection, but the influence of the litter could be ignored when the sum of T for all reflection waveforms (ΣT) is adopted to estimate root diameter. To use A values to detect roots, litter should be removed or equalized in thickness. Radar profiles could not reliably differentiate among roots belonging to plants of different species.

     

Higher accumulation capacity of cadmium than zinc by <Emphasis Type="Italic">Arabidopsis halleri ssp. germmifera</Emphasis> in the field using different sowing strategies

Background and Aims

Litter decomposition serves an important role in maintaining nitrogen (N) availability within forest ecosystems. However, the interactive effects of exogenous N, drought, and litter quality and mixing on N immobilization during decomposition remain unclear. The aim of this study was to assess the effects of litter quality, reduced precipitation, N addition, and their interactions on litter mass loss and N immobilization.

Methods

This field study analyzed the effects of N addition and decreased precipitation on the decomposition rates and associated N immobilization of four types of litter: Quercus mongolica (QM), Tilia amurensis (TA), Pinus koraiensis (PK), and a mixture (MIX) of all three. The chemical quality of the MIX was prepared in a 4:3:3 (mass) ratio of PK, TA, and QM litters. Litterbags were placed in an N addition and precipitation manipulation forest field and collected after 92, 154, 365, 457, and 874 days. Decomposing litter residues were characterized for mass loss and N content to assess N immobilization.

Results

The addition of N had no significant effect on litter decomposition under both precipitation conditions, but a reduction in precipitation significantly depressed litter decomposition. The increases in N immobilization with N addition depended on the litter type and decomposition period. Precipitation reduction had significant effects on N immobilization and enhanced the magnitude and duration of N immobilization in decomposing litter, and both of which can be increased by N addition. The results indicate that the litter species is the major regulator that controls mass loss and N immobilization. Furthermore, the MIX treatment did not show non-additive effects on mass loss but did exhibit some weak synergistic effects on N immobilization.

Conclusions

Our results suggest that decomposing litters could help to sequester N depending on the litter identity and water regime in temperate forest ecosystems.

     

Long-term impact of elevated CO<Subscript>2</Subscript> on phosphorus fractions varies in three contrasting cropping soils

Background and aims

Leaf litters commonly interact during decomposition in ways that can synergistically increases rates of decay. These interactions have been linked to moisture availability, suggesting that drought could slow decomposition rates by disrupting litter interactions. Slowed decomposition may reduce competitive ability of exotic species that exploit rapid decomposition rates as part of niche construction mechanisms. Here, we evaluated the impacts of drought on interactions between native and exotic species’ litter decomposition.

Methods

We considered litter mixtures of Lupinus polyphyllus (exotic N-fixing forb), Trifolium pratense (native N-fixing forb), Senecio inaequidens (exotic non-N-fixing forb), and Senecio jacobaea (native non-N-fixing forb) with the native grass Alopecurus pratensis and evaluated the difference between the observed rate of decay and the one expected based on species decomposing in monocultures. Litters were deployed in Belgium and Germany and exposed to a 56 day drought, which resembled local millennium drought (statistical recurrence of duration in local precipitation series >1000 years).

Results

Litter interactions reduced mass remaining by 81% in Belgium and 15% in Germany, averaged across mixtures. Similarly, litter interactions reduced N remaining by 93% in Belgium and 14% in Germany. Drought consistently removed these interactions and resulted in additive litter decay. Litters of native and exotic species did not differ in their response to drought.

Conclusions

These findings support moisture availability as a key regulator of interactions between litters during decomposition. Thus, increasing frequency of drought may slow nutrient cycling to a greater extent than previously thought.

     

Boreal peat properties link to plant functional traits of ecosystem engineers

Aims

Warming has the potential to alter plant litter mass loss and nutrient release during decomposition. However, a great deal of uncertainty remains concerning how other factors such as litter species or substrate quality might modify the effects of increased temperature on decomposition. Meanwhile, the temperature sensitivity of plant litter decay in tropical and subtropical forest ecosystems remains poorly resolved.

Methods

This study was designed to assess the effects of experimental warming on litter decomposition and nutrient release of two contrasting tree species (Schima superba and Machilus breviflora) by translocating model forest ecosystems from the high-elevation sites to the lower-elevation sites in subtropical China. Translocating model mountain evergreen broad-leaved forest (MEBF) to the altitude of 300 m and 30 m increased the average monthly soil temperature at 5 cm depth by 0.88 and 1.84 °C, respectively during the experimental period. Translocating model coniferous and broad-leaved mixed forest (CBMF) to the altitude of 30 m increased the average monthly soil temperature at 5 cm depth by 0.85 °C.

Results

We found that experimental warming accelerated litter decomposition in both model forest types, and the promoting efficiency was greater when the temperature increased. The litter with high quality (Schima superba) had stronger response to warming than low quality litter (Machilus breviflora). Warming accelerated Na, K, Mg, P, N and Ca release from Schima superba litter, but only simulated Ca release from Machilus breviflora litter. Overall, litter decomposition was controlled by the order: soil temperature > litter quality > soil moisture > litter incubation forest type under experimental warming in the subtropical China.

Conclusion

We conclude that leaf litter decomposition was facilitated by experimental warming in subtropical China. Litter species might modify the effects of increased temperature on litter decomposition; however, forest type has no effect on litter decomposition.

     

Biochemical determinants of litter quality in 15 species of <Emphasis Type="Italic">Sphagnum</Emphasis>

Background and aims

Sphagnum mosses are ecosystem engineers that create and maintain boreal peatlands. With unique biochemistry, waterlogging and acidifying capacities, they build up meters-thick layers of peat, reducing competition and impeding decomposition. We quantify within-genus differences in biochemical composition to make inferences about decay rates, related to hummock–hollow and fen–bog gradients and to phylogeny.

Methods

We sampled litter from 15 Sphagnum species, abundant over the whole northern hemisphere. We used regression and Principal Components Analysis (PCA) to evaluate general relationships between litter quality parameters and decay rates measured under laboratory and field conditions.

Results

Both concentrations of the polysaccharide sphagnan and the soluble phenolics were positively correlated with intrinsic decay resistance, however, so were the previously understudied lignin-like phenolics. More resistant litter had more of all the important metabolites; consequently, PC1 scores were related to lab mass loss (R²?=?0.57). There was no such relationship with field mass loss, which is also affected by the environment. PCA also revealed that metabolites clearly group Sphagnum sections (subgenera).

Conclusions

We suggest that the commonly stated growth-decomposition trade-off is largely due to litter quality. We show a strong phylogenetic control on Sphagnum metabolites, but their effects on decay are affected by nutrient availability in the habitat.

     

The legacy of climate change effects: previous drought increases short-term litter decomposition rates in a temperate mixed grass- and shrubland

Aims

Fungi play a central role in litter decomposition, a key process controlling the terrestrial carbon cycle and nutrient availability for plants and microorganisms. Climate change and elevated CO₂ affect soil fungi, but the relative importance of the global change variables for litter decomposition is still uncertain. The main objective was therefore to assess the short-term litter decomposition and associated fungal community in a global change manipulated temperate heath ecosystem.

Methods

The heath had been exposed to 6 years of warming, elevated atmospheric CO₂ and an extended pre-summer drought. Litterbags with litter from heather (Calluna vulgaris) and wavy-hair grass (Deschampsia flexuosa) were incubated in the litter layer for 6 months, where after we analyzed the litter-associated fungal community, litter loss, CO₂ respiration, and total content of carbon, nitrogen and phosphorus.

Results

Elevated temperature tended to increase litter decomposition rates, whereas elevated CO₂ had no effect on the process. The pre-summer drought treatment had a positive impact on litter decomposition, CO₂ respiration and fungal abundance in the litterbags, although we observed no major changes in fungal community composition.

Conclusions

The drought treatment during pre-summer had a legacy effect on litter decomposition as decomposition rates were positively affected later in the year. The community structure of litter-decomposing fungi was not affected by the drought treatment. Hence, the legacy effect was not mediated by a change in the fungal community structure.

     

Nitrogen nutrition of beech forests in a changing climate: importance of plant-soil-microbe water,carbon, and nitrogen interactions

Background

For 15+ years, a beech (Fagus sylvatica L.) dominated forest on calcareous soil was studied on two opposing slopes with contrasting microclimate in Tuttlingen, Swabian Alb, Germany. The cool-humid NE aspect of these slopes represents the majority of beech forests under current climate, the warmer and drier SW aspect represents beech forests under future climate conditions. The field studies were supplemented by investigations under controlled conditions.

Scope

The research program aimed to provide a comprehensive understanding of plant-soil-microbe water, carbon and nitrogen feedbacks in a changing climate and a holistic view of the sensitivity of beech to climate change.

Conclusions

The results of comparative and experimental studies underpin the high vulnerability of adult beech and its natural regeneration on calcareous soil to both direct climate change effects on plant physiology and indirect effects mediated by soil biogeochemical cycles. Mechanisms contributing to this vulnerability at the ecosystem and organismic level indicate a high significance of competitive interactions of beech with other vegetation components and soil microbial communities. Obvious forest management practices such as selective felling did not necessarily counteract negative effects of climate change.

     

Temporal dynamics of ultraviolet radiation impacts on litter decomposition in a semi-arid ecosystem

Background and aims

The emerging consensus posits that ultraviolet (UV) radiation accelerates litter decomposition in xeric environments mainly by preconditioning litter for subsequent microbial decomposition. However, how UV radiation affects the interactions among litter chemistry, microbes, and eventually litter mass during different decomposition stages is still poorly understood.

Methods

Here, we conducted a 29-month in situ decomposition experiment with litter exposed to ambient and reduced UV in a semi-arid grassland.

Results

The decomposition rate for Cleistogenes squarrosa and Stipa krylovii under ambient UV was 82 and 111% greater than that under reduced UV, respectively. UV’s positive effect showed three-stage temporal dynamics. During the early stage, UV had no impact on either litter chemistry or mass loss. During the intermediate stage, UV decreased litter carbon concentration and increased dissolved organic carbon concentration, but still had no effect on litter mass. During the late stage, UV exposure increased microbial population size in the surface soil and significantly increased litter mass loss.

Conclusions

Overall, our study suggested that UV exposure accelerated litter decomposition first by improving litter biodegradability during the intermediate stage and then by enhancing microbial decomposition during the late stage. More long-term photodegradation experiments are needed to explore the biotic and abiotic interactions during different decomposition stages.

     

Plant growth-promoting effect and genomic analysis of the beneficial endophyte <Emphasis Type="Italic">Streptomyces</Emphasis> sp. KLBMP 5084 isolated from halophyte <Emphasis Type="Italic">Limonium sinense</Emphasis>

Background and aims

Xylem-tapping mistletoes may experience relaxed selective pressure to use water efficiently during photosynthesis because of lower per-unit costs for water acquisition than experienced by host plants. As a result, we hypothesised that mistletoes would exhibit parallel but dampened leaf-level adaptations and responses to aridity, compared to those seen in hosts.

Methods

Photosynthetic traits, leaf dark respiration, nutrient concentrations and specific leaf area (SLA) were measured on 42 mistletoe-host species-pairs sampled from five sites in Australia and Brazil that vary widely in aridity.

Results

Mistletoes exhibited similar trait-shifts to hosts in relation to site aridity. In both groups, arid-site species showed stronger control over stomatal water loss, larger drawdown of CO₂ during photosynthesis (lower c_i: c_a), higher leaf N and P concentrations per unit leaf area, and lower SLA. Nevertheless, mistletoes were profligate water users compared to their hosts and showed substantially less efficient use of water during photosynthesis. On average, mistletoes showed twice higher leaf dark respiration rates at a given photosynthetic capacity, suggesting relatively higher leaf maintenance costs for these parasitic plants.

Conclusions

Despite fundamental differences in lifestyle and in photosynthetic traits, mistletoes exhibit trait responses and adaptations to site aridity in parallel and to approximately the same extent as their hosts.

     

Tree development in structural soil – an empirical below-ground in-situ study of urban trees in Copenhagen,Denmark

Aims

The purpose of this study is to evaluate root and stem growth, nutrient status and soil properties of a tree planting in structural soil.

Methods

Root and stem growth were measured at an 10-year-old urban planting of Tilia x europaea L. ‘Pallida’ established in structural soil on a paved square in Copenhagen, Denmark.Root abundance was quantified and soil profiles were established at three different distances from 10 trees (1.0, 1.9, and 2.9 m). Soil and leaf samples were analysed for nutrient concentrations.

Results

Abundant root presence was measured across the entire profile of structural soil (160?×?60 cm) at all distances, provided that structural soil layers were constructed correctly. Erroneously constructed structural soil layers however, resulted in impaired tree and root growth. Coarse root morphology was affected by the confined growing space in the voids of the stone matrix. The soil was relatively alkaline with an average pH (CaCl₂) of 7.3. Foliar analysis revealed deficiencies of K and Mn. These deficiencies might be due to a combined effect of high pH and low soil concentrations of these nutrients.

Conclusions

The study documents that correctly constructed structural soils allow and encourage root growth in load bearing layers.

     

Soil microalgae modulate grain arsenic accumulation by reducing dimethylarsinic acid and enhancing nutrient uptake in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Background and aims

Microalgae are ubiquitous in paddy soils. However, their roles in arsenic (As) accumulation and transport in rice plants remains unknown.

Methods

Two green algae and five cyanobacteria were used in pot experiments under continuously flooded conditions to ascertain whether a microalgal inoculation could influence rice growth and rice grain As accumulation in plants grown in As-contaminated soils.

Results

The microalgal inoculation greatly enhanced nutrient uptake and rice growth. The presence of representative microalga Anabaena azotica did not significantly differ the grain inorganic As concentrations but remarkably decreased the rice root and grain DMA concentrations. The translocation of As from roots to grains was also markedly decreased by rice inoculated with A. azotica. This subsequently led to a decrease in the total As concentration in rice grains.

Conclusions

The results of the study indicate that the microalgal inoculation had a strong influence on soil pH, soil As speciation, and soil nutrient bioavailability, which significantly affected the rice growth, nutrient uptake, and As accumulation and translocation in rice plants. The results suggest that algae inoculation can be an effective strategy for improving nutrient uptake and reducing As translocation from roots to grains by rice grown in As-contaminated paddy soils.

     

Do litter-mediated plant-soil feedbacks influence Mediterranean oak regeneration? A two-year pot experiment

Background & Aims

Oak seedling establishment is difficult and may be partly explained by litter-mediated interactions with neighbors. Litter effects can be physical or chemical and result in positive or negative feedback effects for seedlings. Mediterranean species leaves contain high levels of secondary metabolites which suggest that negative litter effects could be important.

Methods

Seedlings of Quercus ilex and Quercus pubescens were grown for two years in pots with natural soil and litter inputs from 6 Mediterranean woody species, artificial litter (only physical effect) or bare soil.

Results

Litter types had highly different mass loss (41–80%), which correlated with soil organic C, total N and microbial activity. Litter of Q. pubescens increased soil humidity and oak seedlings aerial biomass. Litters of Cotinus coggygria and Rosmarinus officinalis, containing high quantities of phenolics and terpenes respectively, decomposed fast and led to specific soil microbial catabolic profiles but did not influence oak seedling growth, chemistry or mycorrhization rates.

Conclusions

Physical litter effects through improved soil humidity seem to be predominant for oak seedling development. Despite high litter phenolics content, we detected no chemical effects on oak seedlings. Litter traits conferring a higher ability to retain soil moisture in dry periods deserve further attention as they may be critical to explain plant-soil feedbacks in Mediterranean ecosystems.

     

The contrasting effects of nutrient enrichment on growth,biomass allocation and decomposition of plant tissue in coastal wetlands

Background

Most studies focus on macronutrient of C, N and P and ignore other elements, which restrict our understanding on the strategy of plant nutrient adaption and nutrient cycling.

Methods

We investigated 14 element (C, N, P, S, K, Ca, Mg, Fe, Mn, Zn, Cu, Na, Al, and Ba) concentrations of green and senesced leaves in Quercus variabilis along the altitude in the Baotianman Mountains, China, and assessed their relationships with climate, soil, and plant functional traits.

Results

Leaf N,S and K increased with, C, Ca, Na, Fe, Mn, Cu and Ba decreased with, and P, Mg, Al, Zn and N:P did not change significantly with altitude. NRE and SRE increased with, and CRE decreased with altitude (p < 0.05). Among the 14 elements, nucleic acid-protein elements (N, K, S and P) were resorbed preferentially, compare to structural (Ca, Mn, and B) and enzymatic (C, Cu, Mg and Zn) that were discriminated against, and toxic (Al and Fe) elements that were totally excluded.

Conclusions

Q. variabilis can synergetically regulate green leaf multielement stoichiometry and nutrient resorption in responses to environment change. Deciduous plants may have a trade-off mechanism at the end of growing season to rebalance somatic nutrients.

     

Volatile organic compounds (VOCs) drive nutrient foraging in the clonal woodland strawberry, <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Background and Aims

It was previously demonstrated that stolons of Fragaria vesca respond to patches of varying nutrient quality; however, the mechanism of patch-detection remained unknown. Here we provide support for a process by which F. vesca perceives nutrient-rich patches, consistent with nutrient foraging prior to rooting.

Methods

Volatile organic compounds (VOCs) emitted from unsterilized and sterilized field substrates were collected and analyzed by stir-bar headspace extraction gas chromatography-mass spectrometry using a method modified for soil and litter systems. Selected compounds were chosen to represent unsterilized and sterilized field substrates. These synthetic volatile compound mixtures were then applied to neutral substrate to test the ability of F. vesca to choose between unsterilized versus sterilized substrates.

Results

Primary stolons exhibited chemotropism towards unsterilized (natural) substrates and grew away from the sterilized volatile substrates when the alternate choice was a negative control. We conclude that the presence of carboxylic acids tends to stimulate stolon elongation and chemotropism while aldehydes, ketones and monoterpenes tend to suppress it.

Conclusions

We provide evidence that developing stolons of F. vesca forage for nutrient-rich patches via volatile cues similar to those emitted from the soil through microflora activity.

     

A lost opportunity for science: journals promote data sharing in metabolomics but do not enforce it

Introduction

Data sharing is being increasingly required by journals and has been heralded as a solution to the ‘replication crisis’.

Objectives

(i) Review data sharing policies of journals publishing the most metabolomics papers associated with open data and (ii) compare these journals’ policies to those that publish the most metabolomics papers.

Methods

A PubMed search was used to identify metabolomics papers. Metabolomics data repositories were manually searched for linked publications.

Results

Journals that support data sharing are not necessarily those with the most papers associated to open metabolomics data.

Conclusion

Further efforts are required to improve data sharing in metabolomics.

     

Optimization of fecal sample preparation for untargeted LC-HRMS based metabolomics

Introduction

Collecting feces is easy. It offers direct outcome to endogenous and microbial metabolites.

Objectives

In a context of lack of consensus about fecal sample preparation, especially in animal species, we developed a robust protocol allowing untargeted LC-HRMS fingerprinting.

Methods

The conditions of extraction (quantity, preparation, solvents, dilutions) were investigated in bovine feces.

Results

A rapid and simple protocol involving feces extraction with methanol (1/3, M/V) followed by centrifugation and a step filtration (10 kDa) was developed.

Conclusion

The workflow generated repeatable and informative fingerprints for robust metabolome characterization.

     

Variation of soil respiration and its components in hemiboreal Norway spruce stands of different ages

Aims

Understanding the linkage of soil respiration (Rs) with forest development is essential for long-term C cycle models. We estimated the variation and temperature sensitivity (Q₁₀ value) of Rs and its hetero-, (Rh) and autotrophic (Ra) components in relation to abiotic and biotic factors in Norway spruce stands of different ages, and the effect of trenching on microbial and soil characteristics.

Methods

Trenching method was used to partition Rs into Rh and Ra. Ingrowth core method was used to estimate fine root production. Soil microbial biomass was measured using manometric respirometers.

Results

Rs varied in differently aged stands demonstrating non-linear response to development stage. The variation of Rs was explained by changes in biotic factors rather than by changes in soil microclimate. Rh was more sensitive to Ts than Rs or Ra. After 4 years of trenching soil pH, N, SOM and dehydrogenase activity were significantly changed in trenched plots compared to control plots.

Conclusions

Different Q₁₀ values of Rh and Ra in stands of different ages indicate the importance of Rs partitioning. Trenching should be used during a limited number of years because of the possible changes in chemical characteristics of soil and in the activity of soil microbial community.