Cryptococcus neoformans (San Felice) Vuillemin is an encapsulated yeast of the class Basidiomycetes which produces life-threatening fungal infections on especially immunosuppressed individuals. ...Although flora of Eucalyptus camaldulensis (Dehn.) (Which is considered for natural niche for C. neoformans) exists in various locations in Turkey, the isolation of the yeast is lower than expected.In this study, swabbing technique was used for environmental screening of C. neoformans in Gökova-Akçapınar region where C. neoformans has been isolated in the area in 2011. All of the E. camaldulensis wood debris in this region was involved. C. neoformans colonization was discovered in 11 of 32 trees in Staib and V8 broths. (36,6%). Pure C. neoformans (Aα) ATCC 208821 (10 μl) and C. neoformans (Aa) IUM 96-2828 (10 μl) strains were mixed and inoculated in E. camaldulensis wood debris broth. The mating (sexual reproduction) capability of C. neoformans was investigated and conjugation tube was observed in 59.3% of these broths. Mating capability of C. neoformans increases the risk of life-threatening meningoencephalitis in immunocompromised patients. Moreover, Laetiporus sulphureus (Bull.) Murrill fungous was discovered on all of E. camaldulensis where C. neoformans was isolated.
Hurricanes Irma and Maria struck Puerto Rico on the 6th and 20th of September 2017, respectively. These two powerful Cat 5 hurricanes severely defoliated forest canopy and deposited massive amounts ...of litterfall in the forests across the island. We established a 1-ha research plot in each of four forests (Guánica State Forest, Río Abajo State Forest, Guayama Research Area and Luquillo Experiment Forest) before September 2016, and had collected one full year data of litterfall production prior to the arrival of Hurricanes Irma and Maria. Hurricane-induced litterfall was collected within one week after Hurricane Irma, and within two weeks after Hurricane Maria. Each litterfall sample was sorted into leaves, wood (branches and barks), reproductive organs (flowers, fruits and seeds) and miscellaneous materials (mostly dead animal bodies or feces) after oven-drying to constant weight. Annual litterfall production prior to the arrival of Hurricanes Irma and Maria varied from 4.68 to 25.41 Mg/ha/year among the four forests, and annual litterfall consisted of 50–81% leaffall, 16–44% woodfall and 3–6% fallen reproductive organs. Hurricane Irma severely defoliated the Luquillo Experimental Forest, but had little effect on the other three forests, whereas Hurricane Maria defoliated all four forests. Total hurricane-induced litterfall from Hurricanes Irma and Maria amounted to 95–171% of the annual litterfall production, with leaffall and woodfall from hurricanes amounting to 63–88% and 122–763% of their corresponding annual leaffall and woodfall, respectively. Hurricane-induced litterfall consisted of 30–45% leaves and 55–70% wood. Our data showed that Hurricanes Irma and Maria deposited a pulse of litter deposition equivalent to or more than the total annual litterfall input with at least a doubled fraction of woody materials. This pulse of hurricane-induced debris and elevated proportion of woody component may trigger changes in biogeochemical processes and soil communities in these Puerto Rican forests.
The increased occurrence and intensity of flooding events have represented a real threat to bridge reliability and end-user safety. As flood vulnerability assessment is a valuable tool for enhancing ...the resilience of bridges to climate change, it is of interest to push the development of such methods. To this end, a computationally efficient methodology to assess the flood vulnerability of a bridge was developed and implemented in a case study. A particular focus was devoted to modelling wood debris loads on the bridge pier, for which two different approaches were implemented. The first is a standards-based approach, whereas the second is based on up-to-date research data. The results indicate that the second approach is less conservative as it leads up to a 40% higher exceedance probability for the considered limit states. The interaction between wood debris loads and local scour was also examined and proved to have a relevant impact on the vulnerability of the bridge. These results highlight the shortcomings of the existing standards in providing accurate results. It is perceived that not only will the new quantitative tool be valuable in ensuring optimal bridge design, but it will also be beneficial for assessing bridge risk mitigation measures.
The “Gadgil effect” hypothesizes that root associations may slow down decomposition through pre‐emptive competition. In the context of recalcitrant litter decomposition, specifically coarse wood ...debris, it is uncertain as to what is the relative importance of soil communities associated with living roots when compared to those without roots. Here, it is hypothesized that the presence of live roots and active photosynthates will enhance wood decomposition. To test this hypothesis, the presence or absence of temperate tree roots was used in this study. Sugar maple (Acer saccharum) and white oak (Quercus alba) roots were manipulated at three sites of either limestone or shale parent rock residuum. At each site, wood substrate was placed in soils beneath the canopy of either A. saccharum or Q. alba, while in the presence of roots (root+). At the same time, wood substrate was placed in the same soil community, but live root exposure was eliminated by trenching (root−). This eliminated active photosynthate supply to the soil microbial community. Results determined that live root exposure promoted faster decomposition and greater mycelial colonization of wood substrate. Also, sites of shale parent rock residuum had higher rates of decomposition in comparison with limestone parent rock residuum. Although additional work is needed to determine the extent in which roots and lithology can facilitate wood decomposition, these findings suggest that living roots impact decomposers and provide a pathway towards humus and soil organic matter formation.
Coarse wood debris (CWD) plays a critical role in forest productivity, nutrient cycling, decomposition, and carbon sequestration, and shapes the carbon pool in the forest ecosystem. However, the ...elemental composition of CWD varies among different forest types and decay classes for the same dominant tree species (Pinus koraiensis, PK). We compared CWD elemental composition across different forest types (Picea koraiensis-Abies nephrolepis-Pinus koraiensis forest (PAPF), Betula costata-Pinus koraiensis forest (BPF), Tilia amurensis-Pinus koraiensis forest (TPF)), considering four classes of wood decay. Results showed that N, P, Mg, Mn, Na, Zn, S, Al, and Fe concentrations almost totally increased with decay level for all three forest types, except for K in all three forest types and B in Picea koraiensis-Abies nephrolepis-Pinus koraiensis forest (PAPF). Similarly, maximum concentrations of N, P, B, Mg, K, C, Zn, and Mn of CWD were observed in Betula costata-Pinus koraiensis forest (BPF) under varying decay classes, but their maximum concentrations of Fe and S were found in Picea koraiensis-Abies nephrolepis-Pinus koraiensis forest (PAPF) and Tilia amurensis-Pinus koraiensis forest(TPF), respectively. Only C content did not significantly differ in decay classes across all three forest types. The C:N ratio decreased significantly with increasing decay levels across all forest types. The decay rates were significantly related to N concentration and C:N ratio in decay classes across all forest types. These results suggest that C and N concentration are the key factors affecting its decomposition. The variation in nutrient concentrations observed here underscores the complexity of nutrients stored in wood debris in forested ecosystems.
The present paper introduces the topical area of the Polish-Swiss research project FLORIST (Flood risk on the northern foothills of the Tatra Mountains), informs on its objectives, and reports on ...initial results. The Tatra Mountains are the area of the highest precipitation in Poland and largely contribute to flood generation. The project is focused around four competence clusters: observation-based climatology, model-based climate change projections and impact assessment, dendrogeomorphology, and impact of large wood debris on fluvial processes. The knowledge generated in the FLORIST project is likely to have impact on understanding and interpretation of flood risk on the northern foothills of the Tatra Mountains, in the past, present, and future. It can help solving important practical problems related to flood risk reduction strategies and flood preparedness.
Under temperate climatic conditions, temperature is a key abiotic factor that controls the decomposition of coarse woody debris including bark. Using aspen bark (AB), we have carried out a 12-month ...laboratory experiment at three contrasting temperatures (2, 12, and 22°C) and constant sufficient moisture to quantify the temperature effect on the decomposition rate (DecR) and decay constant (k) of aspen bark. The effect of temperature on the total loss of C–CO
2
and changes in the chemical composition of AB throughout the experiment are also estimated. An increase in the incubation temperature from 2 to 12°C and from 12 to 22°C induces a similar increase in the average (over 12 months) value of the DecR: the Q
10
values are 1.30 and 1.41 in these temperature intervals, respectively. The most significant effect of temperature on the DecR dynamics is revealed during the 1st and 2nd months of the experiment. The maximum losses of C–CO
2
(284 ± 16 mg C g bark
–1
, or 55.2 ± 3.2% of the initial C content) are observed at 22°C. The decay constants of AB, calculated by the one-component exponential model, significantly increase with the growth of the incubation temperature: from 0.46 ± 0.01 yr
–1
at 2°C to 1.02 ± 0.09 yr
–1
at 22°C. Changes in the chemical composition of aspen bark due to the processes of biogenic decomposition include a significant reduction in the amount of alcohol-soluble organic compounds and cellulose to 18–32 and 41–57% of their initial amount, respectively. Lignin losses are less significant, being only 9–18% of their content in AB before the incubation. The quantitative changes in the chemical composition of aspen bark are similar at 2 and 12°C and less pronounced than those at 22°C, which may be explained by an increase in the growing activity of organisms, are actively involved in bark decomposition at 22°C.
The combination of changing climate and anthropogenic activities is increasing the probability of wildfire around the world. When fires occur in riparian zones, associated tree mortality can add wood ...directly to streams or wood may fall to the forest floor and remain there for some time before being transported into stream channels. Wood provides critical structure for aquatic macroinvertebrates, so our objectives were to assess the effects of wood burn status, conditioning, and their interaction on macroinvertebrate community composition, taxon and functional diversity, and trait affinities. We conducted a field experiment with pieces of freshly cut wood (length = 10 cm, diameter ≈ 7.5 cm) for which we first manipulated burn status (burned, unburned) and then, conditioned by placing burned and unburned wood directly into streams (no conditioning) or by leaving pieces in streams (water conditioning) or on the forest floor (soil conditioning) for a year before submergence. We used distance-based redundancy analysis to assess community structure by wood treatments and linear mixed-effects modeling to assess effects of wood treatments on taxon and functional diversity and trait affinity. Changes in wood quality resulting from fire may not alter macroinvertebrate community structure. Taxonomic and functional patterns of stream invertebrate colonization did not differ between burned and unburned wood, even after a year of incubation in the stream or on the forest floor. Conditioning status affected taxonomic composition, taxon and functional diversity, and trait affinities of wood invertebrate communities. The terrestrial legacy of soil conditioning was clearly important in structuring macroinvertebrate assemblages. Our results suggest that macroinvertebrate communities may be more sensitive to fire effects on the dynamics of wood input than to effects of fires on the wood itself.
Wood debris is an important component of mountain streams. It causes serious damage and renders difficulty of water resource management in Taiwan. In this study, the quantity of wood debris and ...variation of migratory wood debris during flood events were examined. The downstream of Gaoshan Creek and Qijiawan Creek, located at Central Taiwan, was selected as the study area. The distribution and dynamic of wood debris in a high gradient headwater catchment were quantified using field surveys. A formula of critical depth for wood debris entrainment was used to evaluate the wood debris migration during three flooding events. In the study area, wood abundance and unit volume increased downstream, and wood density decreased downstream within a channel network. The channel morphology, riparian vegetation, and wood debris characteristics were found to influence the wood storage. As a result, the wood debris has an irregular accumulative distribution in the steep stream, and it migrates easily in the stream because of a high flow discharge. Strong relationships between the channel width and wood debris variables are discovered. Moreover, wood debris has a tendency to accumulate at sites with low stream power and wood debris dams, topographical notches, and unique geological structures. Our findings assist in the understanding of the effects of channel characteristics on distributions of wood debris in steep stream systems.
The long-term effect of spruce stand decay on the CO
2
balance was studied in the taiga of Valdai (Russia, Novgorod oblast). The CO
2
emission from soil, the respiration of coarse wood debris, the ...total respiration, and the net fluxes of CO
2
and water vapor were evaluated. In areas of dead spruce forest affected by xylophages and saprotrophs, as well as by windfall, a noticeable decrease in specific gross respiration is absent. This is related to the fact that reduced CO
2
respiration of living trees is compensated by emission from coarse wood debris and a sharp (3- to 3.5-fold) and long-term (no less than six years long) rise in soil respiration (hotspots) under dead-standing spruce trees. The contribution to carbon emission from soil hotspots per unit area in dead spruce stands under dry standing trees is greater than the role of decomposition of coarse wood debris (14.4 and 9%, respectively). The observation period is characterized by a significant decrease in the annual net CO
2
sink in the area studied: from –300 to –95 g C m
–2
year
–1
, which is followed by reduced evapotranspiration (0.0116 g H
2
O m
–2
s
–1
in May–October 2018 as compared to 0.0142 g H
2
O m
–2
s
–1
in the same period of 2010). We assume that the observed decrease in carbon uptake is related both to the reduction in the primary spruce productivity and to an increase in gross respiration from larger areas of decomposed spruce trees. The calculations show that if the area of the dead spruce stands is further increased to 27%, the resulting net balance of the territory will switch to a CO
2
source for the atmosphere. This should be taken into account for remote forecasting.
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