Articles de revues : « Deadwood decomposition dynamics »

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Shannon, V. L., E. I. Vanguelova, J. I. L. Morison, L. J. Shaw et J. M. Clark. « The contribution of deadwood to soil carbon dynamics in contrasting temperate forest ecosystems ». European Journal of Forest Research 141, n^o 2 (16 décembre 2021) : 241–52. http://dx.doi.org/10.1007/s10342-021-01435-3.

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AbstractDeadwood forms a significant carbon pool in forest systems and is a potential source of dissolved organic carbon (DOC) input to soil, yet little is known about how deadwood effects forest soil carbon cycling. Deadwood DOC inputs to soil may be retained through sorption or may prime microbial decomposition of existing organic matter to produce additional DOC. To determine impacts of deadwood on soil C cycling, we analysed surface soil from beneath deadwood or leaf litter only, along chronosequences of stands of lowland oak and upland Sitka spruce. The concentration and quality (by optical indices) of water-extracted soil DOC (water-extractable organic carbon; WEOC), in situ decomposition ‘tea bag index’ (TBI) parameters and enzymatic potential assays (β-D-cellubiosidase, β-glucosidase, β-xylosidase, leucine aminopeptidase, phosphatase, phenol oxidase) were determined. Presence of deadwood significantly (p < 0.05) increased WEOC concentration (~ 1.5 to ~ 1.75 times) in the mineral oak soil but had no effect on WEOC in spruce soils, potentially because spruce deadwood DOC inputs were masked by a high background of WEOC (1168 mg kg−1 soil) and/or were not retained through mineral sorption in the highly organic (~ 90% SOM) soil. TBI and enzyme evidence suggested that deadwood-derived DOC did not impact existing forest carbon pools via microbial priming, possibly due to the more humified/aromatic quality of DOC produced (humification index of 0.75 and 0.65 for deadwood and leaf litter WEOC, respectively). Forest carbon budgets, particularly those for mineral soils, may underestimate the quantity of DOC if derived from soil monitoring that does not include a deadwood component.

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Chećko, Ewa, Bogdan Jaroszewicz, Katarzyna Olejniczak et Anna J. Kwiatkowska-Falińska. « The importance of coarse woody debris for vascular plants in temperate mixed deciduous forests ». Canadian Journal of Forest Research 45, n^o 9 (septembre 2015) : 1154–63. http://dx.doi.org/10.1139/cjfr-2014-0473.

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Deadwood in various stages of decomposition and diverse spatial arrangements provides habitat for numerous organisms. However, knowledge on the colonization of deadwood by vascular plants in mixed deciduous forests is insufficient. We carried out our study in an oak–lime–hornbeam forest in northeastern Poland. Downed logs were colonized by 49 vascular plant species, a number higher than reported from any other type of forest. Species richness and abundance of plants increased with log diameter and decomposition. The former was higher on broadleaf deadwood than on coniferous deadwood (46 vs. 38 species). The frequency and abundance on logs were higher for small-seeded plants (<1 mg) than for bigger, heavier seeded plants. Deadwood surface served as an ecological filter, keeping small seeds in cracks, but allowing bigger seeds to roll down. Tree seedling density increased with wood decomposition. However, for eight of nine species, it was higher on the ground than on deadwood. Only spruce seedlings were recorded almost exclusively on deadwood, constituting a crucial substrate for spruce regeneration in meso-eutrophic forests. Therefore, we stress the importance of constant deadwood supply, on the scale of decades, to ensure the diversity of this substrate and to allow the natural dynamics of deadwood-dependent species populations.

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Jacobs, Jenna M., et Timothy T. Work. « Linking deadwood-associated beetles and fungi with wood decomposition rates in managed black spruce forests1This article is one of a selection of papers from the International Symposium on Dynamics and Ecological Services of Deadwood in Forest Ecosystems. » Canadian Journal of Forest Research 42, n^o 8 (août 2012) : 1477–90. http://dx.doi.org/10.1139/x2012-075.

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Deadwood-associated insects and saprotrophic fungi are principal agents of wood decomposition in boreal forest. Silvicultural treatments that alter microclimate and availability of deadwood likely affect composition and growth rates of both insect and fungal communities, leading to changes in wood decomposition rates. Here, we relate both saproxylic beetle and dominant polypore assemblages with woody decomposition rates and environmental variables in experimental partial cuts, clearcuts, and uncut controls using a series of causal models to determine the relationship between stand structure, biodiversity, and ecosystem function in black spruce ( Picea mariana (Mill.) BSP) forests. Overall beetle and fungal composition differed between uncut stands and harvested stands. Main effects of harvesting included large increases in wood-feeding beetles and the fungus Gloeophyllum sepiarium (Wul.:Fr.) Karst. We suggest that these species were promoted by specific alterations in microhabitat conditions of deadwood. Within clearcuts specifically, changes in species composition and significantly more fungal degree-days resulted in significantly higher decomposition rates. We concluded that levels of partial cutting in the range of 15%–20% retention were not sufficient to maintain predisturbance communities but were sufficient to maintain wood decomposition rates similar to uncut stands.

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Yarotskiy, Volodymyr Yu, Volodymyr P. Pasternak et Vitalii V. Nazarenko. « Deadwood in the oak forests of the Left Bank Forest-steppe of Ukraine ». Folia Forestalia Polonica 61, n^o 4 (1 décembre 2019) : 247–54. http://dx.doi.org/10.2478/ffp-2019-0024.

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Abstract Deadwood is an important component of forest ecosystems, and difference in the deadwood carbon stock depends on many variables including forest management. The aim of our study was to determine the patterns of formation of deadwood stocks in oak (Quercus robur L.) forests in the Left Bank Forest-steppe of Ukraine. As an outcome of the research, the data on deadwood parameters were obtained. The growth characteristics and coarse woody debris (CWD) characteristics were measured on intensive monitoring and inventory plots. Assessment of morphometric parameters of the CWD in oak stands was carried out by measuring diameters at top and bottom cut and length; to determine the carbon content, deadwood density was used. The distribution of deadwood by tree species, sizes and stages of decomposition was defined. The stock of dead trees (snags) in oak forest is 15.2 m3/ha and that of logs is 21.5 m3/ha. The carbon accumulation in oak forest stands in the Left Bank Forest-steppe of Ukraine was 3.4 and 4.5 t C/ha in dead trees and logs, respectively. The dynamics of deadwood stocks according to the results of repeated observations was given.

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Collepardi, Ilaria, Emanuele Ziaco, César Pérez-Cruzado et Angela Lo Monaco. « Characterisation of Woody Necromass in Beech Forests with Different Anthropic Accessibility : The Case of La Rioja (Spain) ». Environmental Sciences Proceedings 3, n^o 1 (13 novembre 2020) : 26. http://dx.doi.org/10.3390/iecf2020-08111.

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In this study, a comprehensive analysis of deadwood was conducted in four macro-areas located in two beech forests of public utility in Enciso (La Rioja, Spain). Dendrometric data, as well as qualitative and quantitative characteristics of deadwood, were collected and analysed with respect to the degree of accessibility to the forest to determine the effect of different levels of forest accessibility on deadwood volume and carbon stocks. All decomposition classes were present except the first, highlighting the development of natural degradation dynamics. Deadwood stored 6.9 t/ha of C in the easy accessibility class, 5.7 t/ha of C in the medium accessibility class and 2.2 t/ha of C in the difficult accessibility class. The average volume of deadwood and carbon stored calculated in this study were higher than the values reported in the Spanish and Italian national forest inventories, including one developed for Riojan beech forests. Deadwood volume was on average 22.5 m3/ha, showing an unequal distribution, with the lowest values found far from the access roads, despite forest accessibility generally being considered a factor that facilitates the human collection of deadwood. The distribution patterns of deadwood in beech forests of La Rioja, apparently counterintuitive, were due to a combination of different factors, including slope, cattle grazing, and weather conditions which might have favoured downward movement of the deadwood.

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Přívětivý, Tomáš, et Pavel Šamonil. « Variation in Downed Deadwood Density, Biomass, and Moisture during Decomposition in a Natural Temperate Forest ». Forests 12, n^o 10 (3 octobre 2021) : 1352. http://dx.doi.org/10.3390/f12101352.

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Deadwood is a resource of water, nutrients, and carbon, as well as an important driving factor of spatial pedocomplexity and hillslope processes in forested landscapes. The applicability of existing relevant studies in mountain forests in Central Europe is limited by the low number of data, absence of precise dating, and short time periods studied. Here, we aimed to assess the decomposition pathway in terms of changes and variability in the physical characteristics of deadwood (wood density, biomass, and moisture) during the decomposition process, and to describe differences in decomposition rate. The research was carried out in the Žofínský Primeval Forest, one of the oldest forest reserves in Europe. Samples were taken from sapwood of downed logs of the three main tree species: Fagus sylvatica L., Abies alba Mill., and Picea abies (L.) Karst. The time since the death of each downed log was obtained using tree censuses repeated since 1975 and dendrochronology. The maximal time since the death of a log was species-specific, and ranged from 61–76 years. The rate of change (slope) of moisture content along the time since death in a linear regression model was the highest for F. sylvatica (b = 3.94) compared to A. alba (b = 2.21) and P. abies (b = 1.93). An exponential model showing the dependence of biomass loss on time since death revealed that F. sylvatica stems with a diameter of 50–90 cm had the shortest decomposition rate—51 years—followed by P. abies (71 years) and A. alba (72 years). Our findings can be used in geochemical models of element cycles in temperate old-growth forests, the prediction of deadwood dynamics and changes in related biodiversity, and in refining management recommendations.

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Boulanger, Yan, et Luc Sirois. « Postfire dynamics of black spruce coarse woody debris in northern boreal forest of Quebec ». Canadian Journal of Forest Research 36, n^o 7 (1 juillet 2006) : 1770–80. http://dx.doi.org/10.1139/x06-070.

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In this study, postfire coarse woody debris (CWD) dynamics in northern Quebec, Canada, were assessed using a 29-year chronosequence. Postfire woody-debris storage, decomposition rates, and variation of nitrogen and carbon contents of black spruce CWD (Picea mariana (Mill.) BSP) are estimated. The decomposition rate for postfire snags is exceptionally slow (k = 0.00), while the decomposition rate for logs (k = 0.019–0.021) is within previously recorded values for the boreal forest. The low decomposition rate for snags could be related to low moisture content associated with the position of debris and fast bark shedding. Given the low CWD decomposition rates and CWD storage (21.3–66.8 m3·ha–1), carbon losses from postfire CWD are relatively low, varying between 35.5 and 128.8 kg·ha–1·year–1 at the study sites. The nitrogen content in CWD drops quickly between living trees and snags and increases slightly with time since fire in logs. Nitrogen content is not related to wood density or to moisture content of deadwood. Rapid loss of nitrogen is associated with fast decomposition of subcortical tissues, leaching, and insect comminution. The increase in nitrogen content at the oldest site could result from asymbiotic nitrogen fixation, although a longer time span in the chronosequence would probably have revealed a greater nitrogen gain in increasingly decayed CWD.

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Griffiths, Hannah M., Paul Eggleton, Nicole Hemming‐Schroeder, Tom Swinfield, Joel S. Woon, Steven D. Allison, David A. Coomes, Louise A. Ashton et Catherine L. Parr. « Carbon flux and forest dynamics : Increased deadwood decomposition in tropical rainforest tree‐fall canopy gaps ». Global Change Biology 27, n^o 8 (27 janvier 2021) : 1601–13. http://dx.doi.org/10.1111/gcb.15488.

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Lasota, Jarosław, Ewa Błońska, Wojciech Piaszczyk et Małgorzata Wiecheć. « How the deadwood of different tree species in various stages of decomposition affected nutrient dynamics ? » Journal of Soils and Sediments 18, n^o 8 (31 octobre 2017) : 2759–69. http://dx.doi.org/10.1007/s11368-017-1858-2.

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Tobin, Brian, Giovanni Pastore et Maarten Nieuwenhuis. « Carbon Losses from Decomposing Windrowed Sitka Spruce Woody Debris Over a 16-Year Chronosequence ». Forests 12, n^o 2 (20 février 2021) : 244. http://dx.doi.org/10.3390/f12020244.

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Meeting the reporting requirements of the Kyoto Protocol has focused attention on the potential of forests in sustainably sequestering carbon (C) to mitigate the effects of rising levels of atmospheric CO2. Much uncertainty remains concerning the ultimate effect of management on such sequestration effects. The management of woody debris (WD) and other deadwood stocks is an example of a management intervention with the scope of affecting the source-sink dynamics of forest C. Windrowing is the most commonly employed approach to the management of post-harvest WD. This study investigated the quantities of windrowed deadwood C across a chronosequence of reforested commercial Sitka spruce stands in Ireland and how its decomposition rate affected its contribution to forest C sequestration. The C stocks in windrowed WD ranged from 25 to 8 t C ha−1 at the 4- and 16-year-old stands, respectively. Losses due to the decomposition of these stocks ranged from 5.15 t C ha−1 yr−1 at the youngest site (4 years old) to 0.68 t C ha−1 yr−1 at the oldest site (16 years old). Using a visual decay-class categorization of WD components and an assessment of wood density, decay rate constants were estimated for logs, branches, and stumps (the main WD constituents of windrows) as 0.037, 0.038, and 0.044, respectively. These results, derived from stand stock evaluations, were placed into context with data previously published from the same chronosequence that characterized the day-to-day fluxes to or from this pool. This comparison indicated that though only a very small quantity of C was lost in dissolved leachate form, the most significant pathway for loss was respiratory and ranged from 16 to 8 t C ha−1 yr−1 at the 9- and 16-year-old sites. These estimates were many times greater in extent than estimates made using a density-loss approach, the difference indicating that fragmentation and weathering play a large role in woody decomposition in intensively managed forests.

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Arnstadt, Tobias, Björn Hoppe, Tiemo Kahl, Harald Kellner, Dirk Krüger, Jürgen Bauhus et Martin Hofrichter. « Dynamics of fungal community composition, decomposition and resulting deadwood properties in logs of Fagus sylvatica, Picea abies and Pinus sylvestris ». Forest Ecology and Management 382 (décembre 2016) : 129–42. http://dx.doi.org/10.1016/j.foreco.2016.10.004.

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Tello, Francisco, Mauro E. González, Estefanía Micó, Nelson Valdivia, Fernanda Torres, Antonio Lara et Alejandra García-López. « Short-Interval, Severe Wildfires Alter Saproxylic Beetle Diversity in Andean Araucaria Forests in Northwest Chilean Patagonia ». Forests 13, n^o 3 (11 mars 2022) : 441. http://dx.doi.org/10.3390/f13030441.

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The occurrence of short-interval, severe wildfires are increasing drastically at a global scale, and appear as a novel phenomenon in areas where fire historically returns in large time lapses. In forest ecosystems, these events induce drastic changes in population dynamics, which could dramatically impact species diversity. Here, we studied the effect on diversity of recent short-interval, severe wildfires (SISF), which occurred in rapid succession in the summers of 2002 and 2015 in Chilean Northern Patagonian Araucaria–Nothofagus forests. We analyzed the diversity of deadwood-dependent (i.e., saproxylic) and fire-sensitive beetles as biological indicators across four conditions: 2002-burned areas, 2015-burned areas, SISF areas (i.e., burned in 2002 and again in 2015), and unburned areas. Saproxylic beetles were collected using window traps in 2017 to 2019 summer seasons. To investigate the mechanisms underpinning the fire-related disturbance of the assemblage, we evaluated the effects of post-fire habitat quality (e.g., dead wood decomposition) and quantity (e.g., burned dead wood volume and tree density) on the abundances and species richness of the entire assemblage and also multiple trophic groups. Compared with the unburned condition, SISF drastically reduced species richness, evenness, and Shannon’s diversity and altered the composition of the saproxylic beetle assemblages. The between-condition variation in composition was accounted for by a species replacement (turnover) between SISF and 2015-burned areas, but both species replacement and extinction (nestedness) between SISF and unburned areas. Dead wood decomposition and tree density were the variables with the strongest effects on the abundance and species richness of the entire saproxylic beetle assemblage and most trophic groups. These results suggest that SISF, through degraded habitat quality (dead wood decomposition) and quantity (arboreal density), have detrimental impacts on diversity and population dynamics of saproxylic beetle assemblages. Therefore, habitat loss is a central mechanism underpinning fire-related biodiversity loss in these forest ecosystems.

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Arseneault, Julie, Nicole J. Fenton et Yves Bergeron. « Effects of variable canopy retention harvest on epixylic bryophytes in boreal black spruce – feathermoss forests1This article is one of a selection of papers from the International Symposium on Dynamics and Ecological Services of Deadwood in Forest Ecosystems. » Canadian Journal of Forest Research 42, n^o 8 (août 2012) : 1467–76. http://dx.doi.org/10.1139/x2012-054.

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Modification of forest attributes and structural components like downed wood (DW) during forest harvest can lead to local species loss. Epixylic bryophytes have been proposed as good indicators of such changes. Unharvested control, variable canopy retention, and single pass harvest represent a gradient in forest harvest impact and can be used to test the response of epixylic bryophytes to different levels of environmental change. The objective of this study was to see if variable canopy retention attenuates environmental change associated with harvesting, consequently maintaining an epixylic community more similar to unharvested stands than single pass harvesting. Environmental conditions and DW characteristics were sampled on 225 DW pieces distributed in 45 permanent plots. Results showed that treatment affected epixylic richness through its impact on canopy openness and DW diameter and decomposition class. Fewer species were found in more open habitats and more species were found on bigger and more decomposed DW. Most epixylic species were more commonly found on the forest floor than on the DW. In conclusion, variable canopy retention harvest offered microclimatic conditions and DW availability and quality more suitable for epixylic species than single pass harvest, which was less suitable for epixylic species.

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Probst, Maraike, Judith Ascher-Jenull, Heribert Insam et María Gómez-Brandón. « The Molecular Information About Deadwood Bacteriomes Partly Depends on the Targeted Environmental DNA ». Frontiers in Microbiology 12 (27 avril 2021). http://dx.doi.org/10.3389/fmicb.2021.640386.

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Microbiome studies mostly rely on total DNA extracts obtained directly from environmental samples. The total DNA consists of both intra- and extracellular DNA, which differ in terms of their ecological interpretation. In the present study, we have investigated for the first time the differences among the three DNA types using microbiome sequencing of Picea abies deadwood logs (Hunter decay classes I, III, and V). While the bacterial compositions of all DNA types were comparable in terms of more abundant organisms and mainly depended on the decay class, we found substantial differences between DNA types with regard to less abundant amplicon sequence variants (ASVs). The analysis of the sequentially extracted intra- and extracellular DNA fraction, respectively, increased the ecological depth of analysis compared to the directly extracted total DNA pool. Both DNA fractions were comparable in proportions and the extracellular DNA appeared to persist in the P. abies deadwood logs, thereby causing its masking effect. Indeed, the extracellular DNA masked the compositional dynamics of intact cells in the total DNA pool. Our results provide evidence that the choice of DNA type for analysis might benefit a study’s answer to its respective ecological question. In the deadwood environment researched here, the differential analysis of the DNA types underlined the relevance of Burkholderiales, Rhizobiales and other taxa for P. abies deadwood decomposition and revealed that the role of Acidobacteriota under this scenario might be underestimated, especially compared to Actinobacteriota.

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Feschenko, R. O., R. K. Matyashuk et A. M. Bilous. « Tree stand mortality in nationally important park-monument of landscape art Feofaniya ». Naukovì dopovìdì Nacìonalʹnogo unìversitetu bìoresursiv ì prirodokoristuvannâ Ukraïni, n^o 3(91) (30 juin 2021). http://dx.doi.org/10.31548/dopovidi2021.03.011.

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Tree stand mortality in urban ecosystems indicates the influence level of biotic and abiotic factors primarily on their life state. The significance of these processes lies in the knowledge of the forest stands patterns development and their use for forecasting and assessing ecosystem services. The territories of the nature reserve fund have been taken as research sites, as significant indicators of anthropogenically altered territories. The structure of biomass and forest stands species composition was found to be associated with the growth and development of living trees and the formation of dead trees. Biotic and abiotic factors, intraspecific competition and peculiarities of local formation condition and stands growth are determined to affect the life state of the main forest-forming species directly and indirectly. It was revealed that in the medieval oak plantation, the loss of trees during the research period (2016-2020) prevailed over the increase in the stand ground phytomass. It was found that the carbon deposited amount in the forest stands aboveground phytomass reflects the unusual dynamics for the overwhelming number of territory indicators. The litter formation caused the changes in the deposited carbon structure of the research stands phytomass by tree species. It also led to an increase in the deadwood carbon pool and the onset of carbon emissions from the detritus decomposition.

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