Cellulose Decay Research Articles

Root collar rot, a new lethal disease on Tectona grandis caused by Kretzschmaria zonata in Brazil.

Tectona grandis L.f., known as teak, is one of the most valuable tropical hardwood species that has been extensively planted in tropical zones, covering about 6,8 million hectares (Kollert and Kleine 2017). Recent advances in silvicultural management and use of improved clones have enhanced productivity and wood quality of teak plantations in Brazil. However, the incidence of diseases has increased over time being a threat to sustainability of commercial teak plantations. Therefore, forest pathology studies have been conducted in Brazil to minimize the risks of losses caused by the diseases on teak, ensuring the expected economic profitability. In a recent disease survey conducted in Midwest of Brazil, almost one thousand teak trees showing typical die-back symptoms with root collar rot were found. The diseased trees showed undersize leaves displaying yellowish to pale brown color, followed by wilt, defoliation and death. At the base of the trunk, root collar rot was observed, with sloughing and deterioration of the bark exhibiting flattened and encrusted fungi fruiting bodies of gray to bright white color. Over the time, the wood of infected trees develops black zone lines and soft tissue due to both lignin and cellulose decay. The disease begins in the root and spreads to the collar of the tree, causing a collapse in sap flow leading to mortality. To discover the disease cause, samples of infected trees were collected to perform an accurate pathogen identification by polyphasic approach, as well as pathogenicity test. From isolation in Malt Extract Agar (MEA), one fungus showing white progressing to gray mycelial growth was consistently isolated. Two isolates named as GFP131 and GFP132 were characterized. Microscopic examination showed conidia aseptate, hyaline, ovoid to fusiform-ellipsoid shaped, measuring 6-8 x 2-4 μm; stromata with surface brown to dark brown; perithecia with variable shapes and ostioles papillate; and ascospores aseptate, dark brown, fusiform to ellipsoid, measuring 20-37 × 8-15 μm, displaying a straight germinal line slightly less than ascospore length. These morphological characteristics were similar to descriptions for genus Kretzschmaria (Rogers and Ju 1998; Stadler et al. 2013). Genomic DNA was extracted from mycelium, and the internal transcribed spacer (ITS) region of rDNA with primer pair ITS1/ITS4 was sequenced and then deposited under Genbank codes MH481853 and MH481854. A BLASTn search showed >99% identity with K. zonata sequence (KY660541). Phylogenetic inference by Maximum Likelihood method using Kimura 2-parameter model confirms that the isolates belong to Kretzschmaria zonata (Lév.) P.M.D. Martin. A pathogenicity test was established in a greenhouse with controlled conditions of temperature (28-30 °C) and humidity (80-90 %). Five plants were inoculated with GFP132 at the collar region with one mycelium disk of approximately 5 mm in diameter each, and the inoculated area was wrapped in plastic film. Disks of MEA culture media were placed on five additional plants as controls. Forty days after inoculation, all of the previously mentioned symptoms were observed for all inoculated plants, while control plants showed only scars at the inoculation point. The pathogen was reisolated from all five of the inoculated plants. Kretschmaria zonata has been reported on teak in Nigeria (West 1938) and in Mexico (Cibrian Tovar et al. 2014). However, this is the first report of K. zonata on T. grandis for Brazil and the first report anywhere to include Koch's postulates, proving the etiology of the disease.

Effects of water table on cellulose and lignin degradation of Carex cinerascens in a large seasonal floodplain

ABSTRACTWater table affects litter decomposition in wetlands, but its effects on the degradation of cellulose and lignin are poorly understood. We performed a decomposition experiment in Poyang Lake Wetland, to determine how water table affected the degradation of cellulose and lignin. After 60 days of decomposition at a site with a relatively highly water table, 46.19% of initial cellulose and 41.95% of initial lignin remained. Decay rates of both cellulose and lignin increased as the depth of the water table increased. Principle component analysis showed that the decay rates of cellulose and lignin increased with increasing soil pH, but decreased with increasing contents of clay and fungi: bacteria ratio. The path model accounted for 66% and 79% of the variation in cellulose and lignin decay rates, respectively, and considered the effects of interactions between the water table and related factors. The cellulose decay rate was affected by the water table with a direct coefficient of 0.47, and an indirect coefficient of 0.65, but the lignin decay rate was indirectly affected by water table (coefficient, 1.25) and directly affected by soil property (coefficient, 0.67). Thus, the water table affected the decomposition of cellulose and lignin via different mechanisms.

Aboveground macrodetritivores and belowground soil processes: Insights on species redundancy

Quantifying the level of overlap between species-specific effects in a given process – i.e. their functional redundancy–remains a central issue in predicting the shape of diversity-productivity or diversity-stability relationships. We compared the indirect effects of six aboveground macro-detritivores on two belowground processes, cellulose decay and nutrient mineralization, in single-species microcosms (n=5) containing standardized substratum, mixed litter, and four individuals of detritivores. In all microcosms, there was an overall increase in phosphate and decrease in nitrate and ammonium over four weeks. Cellulose decay was ≈30%. Compared to fauna-free controls, there were a few noticeable fauna effects: decay was higher in microcosms with Armadillidium vulgare and Porcellio scaber, nitrate immobilization was lower in Cylindroiulus caeruleocinctus microcosms, and ammonium immobilization was lower in A. vulgare and P. scaber microcosms. The multivariate effects were idiosyncratic and related to a high intraspecific variation. Contrary to our expectations, the most noticeable difference was between P. scaber and Trachelipus rathkii. Our results point to redundancy due to high intraspecific variation. It is postulated that, if redundancy arises from high intraspecific variation, upon the loss of species, large population sizes of remaining species from the same functional group might explain positive effects of redundancy on ecosystem resilience.

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.

Structural Degradation of Third Millennium B.C.E. Archaeological Wood from Shahr-i Sukhta, Iran

AbstractDetection of structural changes has a great importance in conservation and treatment of wooden artifacts found in burial environments. In this study, two wooden samples excavated in Shahr-i Sukhta, an important prehistoric site in eastern Persia, were tested by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). FTIR results showed that decay of lignin occurred. This was accompanied by cellulose degradation. SEM images showed detachment of wood fibers in cross sections and cell wall breakage in tangential sections of the wood samples. These results indicated that the structural change in cellulose and lignin has caused detachment of wood fibers and cell wall breaking. This is the sign of low physical characteristics of wood which has direct relevance to cellulose decay and lignin degradation in middle lamella of wood cells. Cellulose chain breaking over time, has produced stresses in the compound middle lamella layer of the cell wall, that became accelerated in the middle of the lamella layer. Consequently, wood fibers were detached, and disintegration and powdering of wood surfaces occurred.

Fertilizer Effect on Carbon Dynamics of Different Texture Soils under Tomato Cultures

The risk of nitrate (NO3) leaching is enhanced under tomato culture because of the high water demand, especially in fertilized coarse‐texture soils. To avoid this, slow‐release fertilizers or manure use is recommended. We studied the effect of a slow release and a common fertilizer on the carbon (C) and nitrogen (N) dynamics of drip‐irrigated tomato culture at a macro‐pot (lysimeter) field trial in three different texture soils. The treatments included an initial blanket application of slow‐release fertilizer to all the pots 1 week after planting, followed by supplemental application of N 3 or 6 weeks later. The C and N contents of the microbial biomass differed among the soils. They were significantly less in sandy soil than in the other loam texture soils. A close relation (r2 = 0.85) was found between microbial C and N. Their mean ratio was 6.7, being lowest in the sandy (6.0), and the highest in the clay loam (7.0) soil, but without significant difference. The rate of cellulose decomposition tended to decrease in the sandy soil in each of the three observed periods. The two highest N addition treatments (120 and 180 kg.ha−1 N) accelerated cellulose decay compared with the control and low N addition (60 kg.ha−1 N), especially in the clay loam soil. Nitrate adsorbed by ion‐exchange resin bags in the 0‐ to 30‐cm soil depth did not differ significantly between treatments, and there was no enhancement in nitrate leaching due to repeated fertilizer application.

The relationship between rates of lignin and cellulose decay in aboveground forest litter

We examined the rates of lignin decay (d C 3/d t) and holocellulose decay (d C 2/d t) in aboveground leaf litter of predominately northern conifer forests to test our hypothesis that the rate of lignin decay is a linear function of the lignocellulose index (LCI = lignin/[lignin + holocellulose]). We proposed that lignin decays only when LCI > 0.4 and that LCI cannot exceed 0.7, approximating humus. These constraints suggest that holocellulose content of litter is a control on lignin decay. We evaluated this hypothesis with a set of 112 field studies in two ways, by: (1) comparing simulations from a decomposition model to observations across the full range of litter decay and (2) analyzing the relative rate of lignin decay ([d C 3/d t]/[d C 2/d t + d C 3/d t]) as a function of litter LCI. Simulated dynamics of LCI in decaying litter were highly correlated to observed patterns, particularly when litter fractions of water and ethanol solubles from model output were pooled with holocellulose fractions (mean R 2 = 0.87 ± 0.02, P < 0.01). More detailed analyses of 64 of these studies yielded variable relationships between lignin decay rate and litter LCI; a regression based on pooled data ( N = 385; total number of observations) from these studies produced a slope and an intercept that were not significantly different from predicted (slope = 2.33, intercept = −0.93). Both site and litter characteristics had significant effects on the proposed LCI threshold for lignin decay (LCI ∼ 0.4), but no effects on slope or intercept, suggesting that the proposed lignocellulose control hypothesis is relatively robust across a range of litter and forest types used in this study.

Do Melaleuca ericifolia SM. leaves suppress organic matter decay in freshwater wetlands?

Essential oils of paperbarks, Melaleuca spp., have been shown in laboratory studies to inhibit bacterial activity and slow the rate of cellulose decay. Field (Gippsland Lakes, south-eastern Victoria, Australia) and glasshouse experiments were conducted to test the hypothesis that leaves of Melaleuca ericifolia SM. (the swamp paperbark) suppressed the decay of leaf litter under conditions existing or mimicking those in natural wetlands. Under field conditions, neither brown nor green M. ericifolia leaves, at loadings that would normally occur in a typical paperbark wetland and over a range of leaf-mass ratios, significantly affected the decay rate of two common freshwater macrophytes, Triglochin procerum (water ribbon) and Phragmites australis (common reed). In contrast, glasshouse experiments showed that Melaleuca ericifolia leaves (both intact and ground, and both brown and green) suppressed decay of T. procerum when placed in moist conditions on the sediment surface. However, no inhibitory effect was observed when leaves were flooded. Purified, commercially available Melaleuca essential oil (extracted from Melaleuca alternifolia leaves) decreased the rate at which T. procerum leaves decayed under glasshouse conditions by as much as 43 %. As with entire leaves, the inhibitory effect of purified Melaleuca essential oil was greatest when the leaves were placed in moist, but not submerged, conditions. Experiments designed to test the possibility that the inhibition was due to a simple, physical (coating) effect rather than metabolic inhibition of microbes showed clearly that the effect was not due simply to the hydrophobic nature of essential oils. This study indicates that M. ericifolia leaf litter in freshwater wetlands probably exerts only a small effect on the rate at which leaves from other wetland plant species decay. Any inhibitory effect is likely to be greater after water levels drop (e.g., seasonally in a Mediterranean climate) and remaining leaf material is left moist on the surface of water logged sediments than when material is totally submerged, as during the wetland's high water phase.

Decomposition ofCarex andNuphar plants in a subalpine marsh

To assess the effect of water depth on the decomposition process, I measured the losses in dry mass of the above- and belowground materials ofCarex utriculata andNuphar luteum ssp.potysepalum as well as cellulose (Whatman filter paper) in the top 10 cm of sediment/soil in a subalpine marsh. Samples were examined by the litter bag technique at three flooding levels (0 to 5, 60, and 100 cm water depth). Over a 374-d period, the % mass losses of cellulose,Carex leaves and roots, andNuphar leaves and rhizomes ranged from 98.5 to 99.0, 74.8 to 81.8, 36.3 to 44.9, 95.8 to 97.7, and 78.4 to 91.5%, respectively. Rates for cellulose decay in this study were much higher than for samples from other wetlands; this difference resulted from the location of the litter bag (in the top 10 cm of soilvs in the water column). Water depth significantly affected the decomposition ofCarex roots andNuphar rhizomes. The rate of loss for K was highest in all tissues ofCarex andNuphar, followed by Na inCarex and P inNuphar. N and Ca loss rates generally were low. The C/N ratio tended to converge to a common value over the long term. This convergence has an important implication in the paleoecological interpretation of the C/N ratio change in sediment; i.e., this ratio shift in the sediment core results from a change in the environment, rather than the source material.

Long-Term Modeling of Plutonium Solubility at a Desert Disposal Site, Including CO2 Diffusion, Cellulose Decay, and Chelation

The solubility of plutonium was estimated for waste buried at the Greater Confinement Disposal site in Nevada. The EQ3/6 thermochemical database was modified to include recent data on Pu complex formation, and the solubilities of two critical phases (probertite (CaNaB5O9·5H2O), added as a backfill material; and Ca sac-charate) were determined by experiment. Reaction path runs were used to model effects of cellulose degradation, including complexation of actinides by organic acids and carbonate, decay of the complexing agents, and the buildup and diffusive loss of CO2 through the permeable alluvium. For most waste interaction scenarios, long-term (≈103 years) concentrations of Pu in pore waters are ≤10−7 molal and are dominated by carbonate complexes, although organic complexes could dominate in the first ≈103 years. In unusual circumstances, carbonation of buried lithium could produce very high Pu solubilities; however, even in such a system, a slight lowering of the effective redox potential dramatically lowers Pu solubility. A sensitivity analysis suggests that the “base case” calculations are conservative, tending to overestimate long-term solubility, with the system redox and the identity of the organic acids the major sources of uncertainty.

Effects of DiPel® 176, a Bacillusthuringiensis subsp. kurstaki (B.t.k.) formulation, on the soil microflora and the fate of B.t.k. in an acid forest soil: a laboratory study

The effects of DiPel® 176, a commercially available Bacillusthuringiensis Berliner subsp. kurstaki (B.t.k.) formulation, on microbially mediated carbon and nitrogen mineralization processes, and the persistence of B.t.k. following application of DiPel® 176 to an acidic, coniferous forest soil were evaluated in the laboratory using simple microcosms. Litter (L) and fermentation–humus (FH) material were exposed to DiPel® at the recommended field application rate (FA), DiPel® at 1000× the field application rate (1000× FA), or left untreated. Respiration, substrate induced respiration (SIR), microbial biomass C, metabolic quotients (qCO2), NH4-N, NO3-N, cellulose decay, and B.t.k. viability were monitored regularly over 8 weeks. The FA treatment had no significant impact on soil processes in either the L or FH. The 1000× FA treatment increased SIR and biomass C and decreased qCO2 consistently in both the L and FH. No other effects of the 1000× FA treatment were evident in the L, while in the FH this treatment stimulated respiration initially, then reduced it below control levels; it enhanced cellulose decay; and it inhibited ammonification and nitrification after 8 weeks incubation. In both the L and FH there was no significant loss in viability of B.t.k. in either of the DiPel® treatments over 8 weeks. The microcosms used in this study were simple, inexpensive, and effective, with respiration, SIR, biomass C, and qCO2 being the least variable measurements and the most sensitive to perturbation. This approach is recommended for ecotoxicological and fate testing as outlined in the GuidelinesforRegistrationofNaturallyOccurringMicrobialPestControlAgents.

Carex litter decomposition and nutrient release in mires with different water chemistry

Losses of dry weight, nitrogen, phosphorus and potassium from shoot litter of Carex diandra Schrank and Carex acutiformis Ehrh. were studied in a 2-year litter bag experiment in two fens, each dominated by one of these species. Weight losses over time showed negative exponential curves during Year 1, with k values of 0.0018 and 0.0009 day −1 for Carex diandra and Carex acutiformis, respectively. Total weight loss during Year 1 equalled that during Year 2, and amounted to 45% and 27% of the initial weight for Carex diandra and Carex acutiformis, respectively. Total nitrogen in the litter bags remained approximately constant throughout the 2-year-period for Carex acutiformis, whereas it remained constant during Year 1 and then dropped to 23% of the initial value during Year 2 for Carex diandra. Total phosphorus showed a similar pattern: no changes for Carex acutiformis, and a substantial decrease to 15% of the initial value during Year 2 for Carex diandra. A study of cotton strip tensile strength loss showed that conditions for cellulose decay are much more suitable in the groundwater fed (base-rich) fen dominated by Carex diandra than in the rainwater fed (base-poor) fen with Carex acutiformis, which is in accordance with the results of the litter bag study. The slower nutrient release from Carex acutiformis litter does not lead to a lower mineralization rate of soil organic matter in the fen dominated by this species. The high release rates of inorganic nitrogen and phosphorus in this fen are probably because of the presence of Sphagnum-derived organic matter.

Cellulose Decay in Natural and Disturbed Peatlands in North Carolina

AbstractCarbon cycling is central to nutrient dynamics and accretion rates in wetlands. Drainage and conversion of wetlands has been occurring at an accelerating rate. This paper compares decay rates in natural and disturbed peatlands in the southeastern USA and examines relationships between edaphic factors and decay rates. Cellulose decay rates (as tensile strength loss of cotton fibers) were used to compare decomposition potentials in these peatlands. A 1984 pilot experiment included undisturbed short pocosin and several sites under various stages of agricultural conversion. A spring 1987 experiment included an increasing nutrient availability gradient in undisturbed communities from short pocosin to tall pocosin to gum swamp, drained pocosin with natural vegetation remaining, and pocosin converted to pine forestry and agriculture. In the 1984 experiment, disturbed sites had decay rates approximately nine times greater than undisturbed pocosin. In the 1987 experiment, disturbed sites had decay rates from 1.8 to 10.3 times natural sites. The greatest decay rates occurred in the agricultural site with its high nutrients, less acidic conditions, and relatively low soil moisture. Drained pocosin had the next highest decay rates, although pH and nutrients were low. Pine (Pinus taeda L.) forestry had intermediate rates of decay, while undisturbed sites had low rates. The more nutrient‐rich, but wet and low pH, gum swamp site had similar or slightly higher rates than the pocosin sites. Drainage, relieving excessive soil moisture and the resultant anaerobiosis, was the dominant factor explaining the greater decay rates in the disturbed sites. Other factors, such as nutrient availability and low pH, may have had secondary effects on cellulose decay. Rates were also compared to a global data set based on potential evapotranspiration. Natural sites have rates very close to those predicted, while disturbed sites have much higher rates (1.9–4.4 × predicted).

Cellulose decay rates measured by a modified cotton strip method

Cellulose decay rates measured by a modified cotton strip method