Cellulose Decomposition Rates Research Articles

Decomposição de palha de cana-de-açúcar recolhida em diferentes níveis após a colheita mecânica

Resumo O objetivo deste trabalho foi determinar o efeito do recolhimento de quantidades variáveis da palha de cana-de-açúcar sobre sua decomposição na superfície do solo, após subsequentes socas. O experimento foi realizado por duas socas subsequentes, com a variedade de cana-de-açúcar RB-845210, tendo-se testado quatro quantidades remanescentes de palha após a colheita: 11,3, 8,5, 5,7 e 2,8 Mg ha-1. Foram avaliadas as taxas de decomposição de biomassa, carbono, nitrogênio, celulose, hemicelulose e lignina, bem como a relação C/N e a quantidade de C e N mineralizada a partir da palha. O recolhimento variável da palha da cana-de-açúcar não alterou as taxas de decomposição da biomassa nem a mineralização de carbono, hemicelulose, celulose e lignina, em uma mesma soca. O processo de decomposição da palha não se esgota, mesmo após duas socas, independentemente da quantidade inicial de resíduo sobre o solo. A relação C/N e a decomposição da lignina servem como indicadores para verificar diferenças nas taxas de decomposição entre os níveis de palha avaliados, enquanto a decomposição da hemicelulose e da celulose somente detecta alterações nessas taxas ao longo do tempo. Em termos absolutos, quanto menor a retirada da palha do campo, maior a quantidade de carbono e nitrogênio mineralizada, mesmo que não haja diferenças na taxa de decomposição.

Nitrogen and Phosphorus Availability Effect on Activity of Cellulolytic Microorganisms in Meadows

Meadows occupy more than 23 % of agricultural land in the Czech Republic and also represent the largest pool of carbon in soil organic matter. The organic material is an essential component of healthy soil. Decomposition of organic matter is a biological process, affected by high amount of N and P fertilizer applied in the second half of the twentieth century. This work presents the analysis of the effect of available nutrients nitrogen and phosphorus on the activity of cellulolytic microorganisms in permanent grassland of Sanguisorba-Festucetum comutatae association in the soil surface in the Protected Landscape Area of Žďárské Hills. Contents of available nutrients established by the Mehlich III method were measured ex situ. Data referring cellulose decomposition rates were obtained in situ using the standard mesh-bag method. In the field experiment, the highest loss of cellulose was recorded in variants with the addition of nutrients (PK, 90N + PK and 180N + PK) with result 90.38 % on average. The difference was statistically significant, compared with the control variant without added nutrients 27.87 % (P < 0.05). The added amount of nitrogen in the variant 90 kg of N + PK per ha had no significant effect on loss of cellulose compared to PK variant, as well as variant 180 kg of N + PK per ha. From the results obtained, it is evident that the highest decomposition of cellulose was observed at variant with added phosphorus, compared to variant with nitrogen. Moreover, the effect of different intensity of grassland utilization was found: the amount of decomposed cellulose was higher in two variants (control and 90N + PK) of two cut system in comparison with the same variant in three cut system.

Monitoring of the ground‐dwelling beetle community and forest floor environment in 22 temperate forests across Japan

AbstractThis data paper reports census data of ground‐dwelling beetle and other fauna of the forest floor environment; collections were made from a network of 22 forest sites in Japan. To our knowledge, this represents the largest dataset for long‐term monitoring of a ground‐dwelling beetle community and other taxa in a ground environment in forests, which covers a broad climatic range in the temperate zone and is freely available. The network forms part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subalpine, cool‐ and warm‐temperate and subtropical climatic zones and the four major forest types of Japan. Thirty‐three permanent plots usually 1 ha in size were established in old‐growth, secondary natural and a few plantation forests. Censuses of the ground‐dwelling beetle community were conducted using pitfall trapping and forest floor environment monitoring every year from 2004 to the present. During the initial 9 years of the census (2004–2012), 59,762 beetle individuals (including 3182 larvae) of more than 314 species were recorded. This dataset includes taxonomy and biomass of each beetle individual and each taxonomic group of other invertebrates coincidently captured in pitfall trapping. The dataset also includes data related to ground coverage by forest floor vegetation, dry mass of the accumulated organic litter layer, and carbon and nitrogen contents and cellulose decomposition rate in organic layer and surface mineral soil. The data could be used to investigate geographical patterns and intra‐ and inter‐annual dynamics of individual body mass, populations and community structures of ground‐dwelling beetles, and their relationships with the forest floor environment. Furthermore, the data could be analyzed with other open datasets related to tree community dynamics and litter fall continuously measured in the same study plots. This dataset also provides information related to the distribution and average body mass of each beetle species.

Kinetic Study of the Decomposition of Cellulose to 5-Hydroxymethylfurfural in Ionic Liquid

The kinetics of cellulose decomposition in ionic liquid was investigated using microcrystalline cellulose as a raw material. Curve fitting of cellulose degradation kinetic data was carried out by MATLAB. Experimental results demonstrated that the cellulose decomposition rate constant, k1, was less than the constant for glucose decomposition to 5-hydroxymethylfurfural (5-HMF), k2, in the ionic liquid system, gaining a larger gap with increasing temperature. Results indicated that cellulose degradation is a slow reaction compared with glucose decomposition, which controls the speed of the overall reaction steps. CrCl3 increased the rate constant of cellulose and glucose degradation to almost the same degree, thus achieving simultaneous conversion of cellulose, glucose, and 5-HMF. Compared with other reaction systems, the ionic liquid system considerably reduced activation energy. Regression analysis of kinetic data indicated that the catalytic decomposition reactions of cellulose, glucose, and 5-HMF are all first-order reactions.

Secretome analysis of Pleurotus eryngii reveals enzymatic composition for ramie stalk degradation.

Pleurotus eryngii (P. eryngii) can secrete large amount of hydrolytic and oxidative enzymes to degrade lignocellulosic biomass. In spite of several researches on the individual lignolytic enzymes, a direct deconstruction of lignocellulose by enzyme mixture is not yet possible. Identifying more high-performance enzymes or enzyme complexes will lead to efficient in vitro lignocelluloses degradation. In this report, secretomic analysis was used to search for the new or interesting enzymes for lignocellulose degradation. Besides, the utilization ability of P. eryngii to ramie stalk substrate was evaluated from the degradation of cellulose, hemicellulose, and lignin in medium and six extracellular enzymes activities during different growth stages were discussed. The results showed that a high biological efficiency of 71% was obtained; cellulose, hemicelluloses, and lignin decomposition rates of P. eryngii were 29.2, 26.0, and 51.2%, respectively. Enzyme activity showed that carboxymethyl cellulase, xylanase, laccase, and peroxidase activity peaks appeared at the primordial initiation stage. In addition, we profiled a global view of the secretome of P. eryngii cultivated in ramie stalk media to understand the mechanism behind lignocellulosic biomass hydrolysis. Eighty-seven nonredundant proteins were identified and a diverse group of enzymes, including cellulases, hemicellulases, pectinase, ligninase, protease, peptidases, and phosphatase implicated in lignocellulose degradation were found. In conclusion, the information in this report will be helpful to better understand the lignocelluloses degradation mechanisms of P. eryngii.

Consolidated bioprocessing of cellulose to isobutanol using Clostridium thermocellum

Consolidated bioprocessing (CBP) has the potential to reduce biofuel or biochemical production costs by processing cellulose hydrolysis and fermentation simultaneously without the addition of pre-manufactured cellulases. In particular, Clostridium thermocellum is a promising thermophilic CBP host because of its high cellulose decomposition rate. Here we report the engineering of C. thermocellum to produce isobutanol. Metabolic engineering for isobutanol production in C. thermocellum is hampered by enzyme toxicity during cloning, time-consuming pathway engineering procedures, and slow turnaround in production tests. In this work, we first cloned essential isobutanol pathway genes under different promoters to create various plasmid constructs in Escherichia coli. Then, these constructs were transformed and tested in C. thermocellum. Among these engineered strains, the best isobutanol producer was selected and the production conditions were optimized. We confirmed the expression of the overexpressed genes by their mRNA quantities. We also determined that both the native ketoisovalerate oxidoreductase (KOR) and the heterologous ketoisovalerate decarboxylase (KIVD) expressed were responsible for isobutanol production. We further found that the plasmid was integrated into the chromosome by single crossover. The resulting strain was stable without antibiotic selection pressure. This strain produced 5.4g/L of isobutanol from cellulose in minimal medium at 50oC within 75h, corresponding to 41% of theoretical yield.

Changes in canopy structure and ant assemblages affect soil ecosystem variables as a foundation species declines

The decline of Tsuga canadensis (eastern hemlock)—a foundation tree species—due to infestation by Adelges tsugae (hemlock woolly adelgid) or its complete removal from a stand by salvage logging dramatically affects associated faunal assemblages. Among these assemblages, species composition (richness and abundance) of ants increases rapidly as T. canadensis is lost from the stands. Because ants live and forage at the litter‐soil interface, we hypothesized that environmental changes caused by hemlock loss (e.g., increased light and warmth at the forest floor, increased soil pH) and shifts in ant species composition would interact to alter soil ecosystem variables. In the Harvard Forest Hemlock Removal Experiment (HF‐HeRE), established in 2003, T. canadensis in large plots were killed in place or logged and removed to mimic adelgid infestation or salvage harvesting, respectively. In 2006, we built ant exclosure subplots within all of the canopy manipulation plots to examine direct and interactive effects of canopy change and ant assemblage composition on soil and litter variables. Throughout HF‐HeRE, T. canadensis was colonized by the adelgid in 2009, and the infested trees are now declining. The experimental removal of T. canadensis from the canopy was associated with an increase in the rate of cellulose decomposition by >50%, and exclosure of ants from subplots directly reduced their soil nitrate availability by 56%. Partial least squares path models revealed sequential interactive effects prior to adelgid infestation: canopy change (as a proxy for associated environmental changes) altered both decomposition and ant assemblage structure; changes in ant assemblage structure and decomposition rates altered nitrogen availability. The results illustrate that biotic changes directly associated with decline of T. canadensis can have cascading effects on ecosystem nutrient availability and cycling.

Variation in stream organic matter processing among years and benthic habitats in response to forest clearfelling

We assessed rates of organic matter (OM) processing in coarse gravel and fine benthic sediment, along with water temperature, in four clearfell harvested and two undisturbed headwater streams flowing through wet eucalypt forest in southern Tasmania, Australia. Clearfell forestry in Tasmanian wet eucalypt forest involves felling of all timber followed by a high intensity regeneration burn to provide a receptive mineral seedbed for seedling growth. Bacterial carbon production and cellulose decomposition potential (together referred to as OM processing) were measured seasonally 3–5years before and 2–4years after harvesting in each stream. We employed a staircase design (staggered harvesting treatments) within a multiple before–after control–impact design to distinguish harvesting effects from natural variation. Clearfell harvesting raised the yearly mean water temperature by between 0.25°C and 0.94°C, and raised the maximum water temperature by between 0.84 and 1.6°C. Rates of cellulose decomposition were not significantly correlated with sediment temperature but bacterial carbon production showed weak, significant correlations with temperature in fine (r=0.20, P=0.01, n=137) and coarse gravel sediment (r=0.39, P<0.001, n=137). The response in OM processing to clearfell harvesting differed between years and among benthic habitats. In coarse gravel habitat, there was a significant decrease in rates of cellulose decomposition potential in the 2nd and 4th year after harvesting, and a significant decrease in bacterial carbon production in the 3rd year after harvesting. However, we found a significant increase in rates of bacterial carbon production of fine sediment habitat in the 2nd and 4th year after harvesting. The contrasting response of OM processing between habitats indicates that habitat-specific changes occur after clearfell harvesting, which inhibit attempts to quantitatively predict downstream cumulative effects. Scaling up the habitat-specific responses will not only require estimates of the relative abundances of the distinct habitats, but may also require research into how different spatial configurations of habitats may affect reach- and catchment-scale estimates of OM processing.

Volatile species release during torrefaction of biomass and its macromolecular constituents: Part 2 – Modeling study

Based on the torrefaction experiments carried out on beechwood and on its macromolecular constituents – cellulose, lignin and xylan – in part 1 of this paper, a simple torrefaction model was developed to predict both solid and the eight main volatile species yields versus temperature, residence time and biomass macromolecular composition. This model consisted in the superposition of kinetic “sub-models” describing the torrefaction of each constituent. The interactions observed in part 1 between constituents were then taken into account by means of an empirical factor related to cellulose decomposition rate. The model reproduced quite well the experiments and enabled to show the influence of each constituent on torrefaction yields.

Microbial communities respond to experimental warming, but site matters.

Because microorganisms are sensitive to temperature, ongoing global warming is predicted to influence microbial community structure and function. We used large-scale warming experiments established at two sites near the northern and southern boundaries of US eastern deciduous forests to explore how microbial communities and their function respond to warming at sites with differing climatic regimes. Soil microbial community structure and function responded to warming at the southern but not the northern site. However, changes in microbial community structure and function at the southern site did not result in changes in cellulose decomposition rates. While most global change models rest on the assumption that taxa will respond similarly to warming across sites and their ranges, these results suggest that the responses of microorganisms to warming may be mediated by differences across the geographic boundaries of ecosystems.

Cellulose decomposition rate and features of organic matter in forest soils in the Tatra mountains

The cellulose decomposition rate measurement and soil micromorphology have been used to determine the influence of parent material and tree species on mechanisms responsible for organic matter form differentiation in woodland soils in the Tatra Mountains in Poland. The study area is located in the lower montane belt of the Tatra Mountains. Investigated soils are developed on dolomites and shale. In the past, beech and beech-fir forests had been the dominant form of vegetation in the study area. Since the 16th century, these areas were deforested until the 19th century, when reforestation efforts were undertaken. Reforestation efforts provided mainly spruce; hence, it is the dominant species in the lower montane belt at the moment, although in some areas, natural or semi-natural beech and beech-fir forests have survived. Four plots were compared – two with soils developed on calcareous material (Rendzic Leptosols), one under beech forest and one under spruce forest, and two developed on shale (Haplic Cambisols), one under beech forest and one under spruce forest. Cellulose filters were placed in organic O-horizons and humus A-horizons in every plot to measure the cellulose decomposition rate. Before being placed in the soil, cellulose filters were boiled in KOH, rinsed in distilled water, dried, weighed, and set on glass plates in a nylon bag (1.5 mm mesh). The bags were placed in the soil vertically at approx. 15 cm intervals. After taken up, the filters were boiled in KOH, rinsed, dried, and weighed. The amount of ash was determined via combustion. The research was carried out during a period of 10 weeks between June and August as well as during a period of 1 year. Measurements were repeated ten times. A weighted average and standard deviation were calculated for every plot. The cellulose filter method is useful because of the homogeneity of the substrate, which helps to exclude differences connected with the chemical composition of the plant material, a factor that affects the decomposition rate. Undisturbed soil samples were taken from humus A-horizons in every soil profile. The thin sections were prepared and features of organic matter were described. It was concluded that the presence of calcarous material negatively affects organic matter decomposition rates which is pronounced in both: higher amount of organic matter residues in humus-A horizons and slower cellulose decomposition rates in Rendzic Leptosols than in Haplic Cabisols. The influence of tree species on organic matter features is observed only in Haplic Cambisols, where the cellulose decomposition rate under spruce is lower than under beech. This suggests that tree species indirectly affect the cellulitic microflora only in acidic soils.

Quantifying lignin and holocellulose content in coniferous decayed wood using near-infrared reflectance spectroscopy

To determine the independent decomposition rates of lignin and cellulose of decayed woody debris, a technique for the rapid analysis of lignin and cellulose is required. We applied a near-infrared spectroscopy (NIRS) technique to measure the lignin and holocellulose content in decayed wood. We succeeded in creating partial least-squares (PLS) models to estimate the lignin and holocellulose content in the decayed wood of five species using NIR spectra. Although the accuracy was acceptable for the estimation of a five-species mixed model (R2 = 0.970 for lignin and R2 = 0.962 for holocellulose), it was further improved when the model was applied to each species independently. This combination of NIRS and a PLS model is a valuable tool for the determination of the lignin and holocellulose content in decayed wood. The technique is time efficient (3 min per sample) and non-hazardous (no acid treatment is required).

Pyrolytic Behavior and Kinetic Analysis of Wheat Straw and Lignocellulosic Biomass Model Compound

From a carbon cycle perspective, the thermochemical conversion of lignocellulosic biomass is inherently carbon neutral. Pyrolysis of biomass for energy supplying, such as bio-oil and bio-char, has been attracted much attention worldwide. Successful understanding the fundamental issues about the pyrolysis, including pyrolytic behavior and kinetic analysis of lignocellulosic biomass model compounds and real biomass, is essential for the further understanding and optimizing the pyrolysis process. In this paper, pyrolytic behavior of a typical lignocellulosic agricultural residue (wheat straw) and model compounds (cellulose) were measured through thermogravimetric analysis with various heating rates (10, 20, 40 °C·min-1) under nitrogen atmosphere. The results indicated that the interval of the weight loss for both wheat straw and cellulose moved upwards with the increment of heating rates. The maximum decomposition rates of cellulose were higher than those of wheat straw, and the temperature of maximum decomposition rates increased with the heating rates. Values of activation energy were solved through iso-conversional method. And the average values of activation energy for wheat straw and cellulose were 146.89 kJ·mol-1 and 134.56 kJ·mol-1 calculated from Flynn-Wall-Ozawa method, 144.05 kJ·mol-1 and 130.91 kJ·mol-1 calculated from Kissinger-Akahira-Sunose method, respectively.

Effects of climatic and soil properties on cellulose decomposition rates in temperate and tropical forests

Cellulose decomposition experiments were conducted under field conditions to analyze the effects of climatic and soil properties on rates of organic matter decomposition in temperate and tropical forests. The mass loss rates of cellulose filter papers buried in the soil surface were measured to estimate the respiratory C fluxes caused by cellulose decomposition and mean residence time (MRT) of cellulose. The rates of cellulose decomposition increased with soil temperature, except for during the dry season, while rate constants of decomposition (normalized for temperature) decreased with decreasing pH because of lower cellulase activity. The estimated MRTs of soil cellulosic carbohydrates varied from 81 to 495 days for the temperate forests and from 31 to 61 days for the tropical forests. As a major organic substrate, the C fluxes from cellulose decomposition can account for a substantial fraction of heterotrophic (basal) soil respiration. However, the respiratory C fluxes can be limited by the low substrate availability and low pH in tropical soils, despite high microbial activity. The rate-regulating factors of cellulose decomposition, i.e., temperature, soil pH, and substrate availability, can accordingly influence the rates of heterotrophic soil respiration.

Systems-level Modeling with Molecular Resolution Elucidates the Rate-limiting Mechanisms of Cellulose Decomposition by Cellobiohydrolases

Interprotein and enzyme-substrate couplings in interfacial biocatalysis induce spatial correlations beyond the capabilities of classical mass-action principles in modeling reaction kinetics. To understand the impact of spatial constraints on enzyme kinetics, we developed a computational scheme to simulate the reaction network of enzymes with the structures of individual proteins and substrate molecules explicitly resolved in the three-dimensional space. This methodology was applied to elucidate the rate-limiting mechanisms of crystalline cellulose decomposition by cellobiohydrolases. We illustrate that the primary bottlenecks are slow complexation of glucan chains into the enzyme active site and excessive enzyme jamming along the crowded substrate. Jamming could be alleviated by increasing the decomplexation rate constant but at the expense of reduced processivity. We demonstrate that enhancing the apparent reaction rate required a subtle balance between accelerating the complexation driving force and simultaneously avoiding enzyme jamming. Via a spatiotemporal systems analysis, we developed a unified mechanistic framework that delineates the experimental conditions under which different sets of rate-limiting behaviors emerge. We found that optimization of the complexation-exchange kinetics is critical for overcoming the barriers imposed by interfacial confinement and accelerating the apparent rate of enzymatic cellulose decomposition.

Linkages between grazing history and herbivore exclusion on decomposition rates in mineral soils of subalpine grasslands

Background & aims Herbivore-driven changes to soil properties can influence the decomposition rate of organic material and therefore soil carbon cycling within grassland ecosystems. We investigated how aboveground foraging mammalian and invertebrate herbivores affect mineral soil decomposition rates and associated soil properties in two subalpine vegetation types (shortgrass and tall-grass) with different grazing histories. Methods Using exclosures with differing mesh sizes, we progressively excluded large, medium and small mammals and invertebrates from the two vegetation types in the Swiss National Park (SNP). Mineral soil decomposition rates were assessed using the cotton cloth (standard substrate) method between May and September 2010. Results Decomposition displayed strong spatiotemporal variability, best explained by soil temperature. Exclusion of large mammals increased decomposition rates, but further exclusion reduced decomposition rates again in the lightly grazed (tall-grass) vegetation. No difference among treatments was found in the heavily grazed (short-grass) vegetation. Heavily grazed areas had higher decomposition rates than the lightly grazed areas because of higher soil temperatures. Microbial biomass carbon and soil C:N ratio were also linked to spatio-temporal decomposition patterns, but not to grazing history. Conclusions Despite altering some of the environmental controls of decomposition, cellulose decomposition rates in the SNP’s subalpine grasslands appear to be mostly resistant to short-term herbivore exclusion.

Snow removal reduces annual cellulose decomposition in a riparian boreal forest

Kreyling, J., Haei, M. and Laudon, H. 2013. Snow removal reduces annual cellulose decomposition in a riparian boreal forest. Can. J. Soil Sci. 93: 427–433. Decomposition is a key process in carbon and nutrient cycling. However, little is known about its response to altered winter soil temperature regimes in boreal forests. Here, the impact of soil frost on cellulose decomposition over 1 yr and soil biotic activity (bait-lamina sticks) over winter, in spring, and in summer was investigated using a long-term (9-yr) snow-cover manipulation experiment in a boreal Picea abies forest. The experiment consisted of the treatments: snow removal, increased insulation, and ambient control. The snow removal treatment caused longer and deeper soil frost (minimum temperature −8.6°C versus −1.4°C) at 10 cm soil depth in comparison with control, while the increased insulation treatment resulted in nearly no soil frost during winter. Annual cellulose decomposition rates were reduced by 46% in the snow removal manipulation in comparison with control conditions. Increased insulation had no significant effect on decomposition. The decomposition was mainly driven by microorganisms, as no significant difference was observed for containers enclosed with a 44-µm and a 1-mm mesh. Soil biotic activity was slightly increased by both the snow removal and the increased insulation treatment in comparison with control conditions over winter. However, this effect disappeared over spring and summer. We conclude that soil frost can have strong effects on decomposition in boreal ecosystems. Further studies should investigate to which degree the observed reduction in decomposition due to reduced snow cover in winter slows or even offsets the expected increase in decomposition rates with global warming.

Snow removal reduces annual cellulose decomposition in a riparian boreal forest

Kreyling, J., Haei, M. and Laudon, H. 2013. Snow removal reduces annual cellulose decomposition in a riparian boreal forest. Can. J. Soil Sci. 93: 427-433. Decomposition is a key process in carbon and nutrient cycling. However, little is known about its response to altered winter soil temperature regimes in boreal forests. Here, the impact of soil frost on cellulose decomposition over 1 yr and soil biotic activity (bait-lamina sticks) over winter, in spring, and in summer was investigated using a long-term (9-yr) snow-cover manipulation experiment in a boreal Picea abies forest. The experiment consisted of the treatments: snow removal, increased insulation, and ambient control. The snow removal treatment caused longer and deeper soil frost (minimum temperature -8.6°C versus -1.4°C) at 10 cm soil depth in comparison with control, while the increased insulation treatment resulted in nearly no soil frost during winter. Annual cellulose decomposition rates were reduced by 46% in the snow removal manipulation in comparison with control conditions. Increased insulation had no significant effect on decomposition. The decomposition was mainly driven by microorganisms, as no significant difference was observed for containers enclosed with a 44-µm and a 1-mm mesh. Soil biotic activity was slightly increased by both the snow removal and the increased insulation treatment in comparison with control conditions over winter. However, this effect disappeared over spring and summer. We conclude that soil frost can have strong effects on decomposition in boreal ecosystems. Further studies should investigate to which degree the observed reduction in decomposition due to reduced snow cover in winter slows or even offsets the expected increase in decomposition rates with global warming.

The differences in cellulolytic activity of the Arctic soils of Calypsostranda, Spitsbergen

ABSTRACTThe aim of this study was to determine the differences in cellulolytic activity of soils around the coastal lowlands of the southwestern part of Wedel Jarlsberg Land (west Spitsbergen). Two positions (Calypso and Skilvika) representing typical soil types in this area were chosen for investigation. Within the area of Calypso, arctic brown soils formed from loamy sands with a significant addition of coarser gravel and pebble fractions occur. The Skilvika position represents the arctic gley soils of a loamy texture, with significant content of silt, associated with the occurrence of cell grounds created under the strong influence of cryogenic processes. Cellulolytic activity of the soils was determined by a gravimetric method involving estimation of a weight loss of cellulosic material buried in the surface soil horizons. The investigation showed significant differences in the cellulose decomposition rate between the two research locations. The cellulolytic activity of arctic brown soils –0,412–0,656 g*g−1*year−1 during the vegetation season (Olson's k = 0,231–0,563), was twice higher than the activity in the case of Skilvika gley soils –0,185–0,310g*g−1*year−1 during vegetation season (k = 0,089–0,131). This should be attributed, among other factors, to the grain size distribution, thereby determining more favourable water-air conditions of soils within the area of Calypso.

Application of wood ash accelerates soil respiration and tree growth on drained peatland

Forested peatlands contain large pools of terrestrial carbon. As well as drainage, forest management such as fertilizer application can affect these pools. We studied the effect of wood ash (application rates 0, 5 and 15 t ha−1) on the heterotrophic soil respiration (CO2 efflux), cellulose decomposition, soil nutrients, biomass production and amount of C accumulated in a tree stand on a pine‐dominated drained mire in central Finland. The ash was spread 13 years before the respiration measurements. The annual CO2 efflux was statistically modelled using soil temperature as the driving variable. Wood ash application increased the amounts of mineral nutrients of peat substantially and increased soil pH in the uppermost 10 cm layer by 1.5–2 pH units. In the surface peat, the decomposition rate of cellulose in the ash plots was roughly double that in control plots. Annual CO2 efflux was least on the unfertilized site, 238 g CO2‐C m−2 year−1. The use of wood ash nearly doubled CO2 efflux to 420–475 g CO2‐Cm−2 year−1 on plots fertilized with 5–15 t ha−1 of ash, respectively. Furthermore, ash treatments resulted also in increased stand growth, and during the measurement year, the growing stand on ash plots accumulated carbon 11–12 times faster than the control plot. The difference between peat C emission and amount of C sequestered by trees on the ash plots was 43–58 g C m−2, while on the control plot it was 204 g C m−2. Our conclusion is that adding wood ash as a fertilizer increases more C sequestration in the tree stand than C efflux from the peat.