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•Mass loss of logs of 13 tree species over 9.8 years is best described by a linear or a sigmoidal model.•Logs of diffuse-porous angiosperms decay faster than ring-porous angiosperms ...and gymnosperms.•Logs of the same tree species exhibit large variability in mass loss across 29 forest sites.•Mass loss is highest in the region with higher temperature, dry and nutrient-poor soils.•Forest structure including deadwood stock in the neighborhood had little influence on mass loss.
Deadwood provides important ecological and biogeochemical functions in forest ecosystems. These functions rely on tree species-specific decay dynamics, but only few studies investigated how exogenous parameters affected the decay of deadwood at the regional scale. Here, we explore the influence of climate, soil traits and forest structure on decay dynamics and mass loss of logs of 13 tree species in 29 plots across three regions in Germany. This long-term experiment (BELongDead) comprises 1,066 logs of 9 angiosperms and 4 gymnosperms and covers a decay time of almost 10 years. Mass loss of logs was relatively high for the temperate climate with partly different half-lives ranging from 6 to 13 years (mean 8.9 ± 2.2 years). Diffuse-porous angiosperms lost 70 ± 13 % of their initial mass, followed by gymnosperms (49 ± 16 %) and ring-porous angiosperms (46 ± 12 %) within the study period. We applied three different mathematical models to fit mass loss in time and found that a linear model is most appropriate for 10 tree species. A sigmoidal model best described the mass loss of Fraxinus, Quercus and Pinus logs. A multivariate analysis revealed a significant effect of soil, temperature and precipitation on mass loss at the plot level. Mass loss increased with decreasing soil nutrient content, possibly as a result of enhanced bidirectional element translocations between nutrient-poor soils and logs by fungal hyphae. Temperature had a positive effect on mass loss, whereas increasing precipitation and soil moisture were negatively related to mass loss. The region with warmer, moderately humid climate and unfavourable soil properties led to overall higher mass loss (66 ± 4 %) whereas the other two regions were indifferent (both 57 ± 3 %). Forest structure, including canopy cover, share of coniferous trees and the stock of deadwood in the vicinity of the logs explained only a small part of the variability in mass loss. High variability within individual tree species suggests that other factors such as organismic diversity and microbial activity have stronger impact on the decay process at the regional scale than exogenous factors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Dead wood is initially a nitrogen (N) poor substrate, where the N content increases with decay, partly due to biological N2 fixation, but the drivers of the N accumulation are poorly known. We ...quantified the rate of N2 fixation in decaying Norway spruce logs of different decay stages and studied the potential regulators of the N2-fixation activity. The average rate for acetylene reduction in the decaying wood was 7.5 nmol ethylene g−1d−1, which corresponds to 52.9 μg N kg−1d−1. The number of nifH copies (g−1 dry matter) was higher at the later decay stages, but no correlation between the copy number and the in vitro N2 fixation rate was found. All recovered nifH sequences were assigned to the order Rhizobiales, and therein mostly (60%) to methane oxidizing genera. We confirm that nitrogen fixing methanotrophs are present in all the wood decay phases and suggest that their interaction between methane producing organisms in decaying wood should be further studied.
•N2 fixing bacteria are active in decaying wood.•The number of nifH copies was higher at later decay stages.•No correlation between nifH copy number and in vitro N2 fixation rate was found.•60% of the nifH sequences were assigned to methane oxidizing bacteria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In recent years there has been an increasing concern about the wood in debris flows and floodwaters, which results in extensive destruction of properties and infrastructures along river courses. In ...order to prevent the damage, appropriate installment of measures to control the outflow of the wood is necessary, with a reliable budget of coarse woody debris underpinned by solid understanding of its behavior. This study presents the budget for the Tottabetsu River catchment (153.4 km2) in Eastern Hokkaido for a record high rainfall brought by Typhoon No. 10 in August 2016. There were no control measures for woody debris in the river before the event. The budget was estimated by the combination of field investigation, an analysis of airborne LiDAR data obtained before and after the event, and an interpretation of a series of aerial photograph images. The storm intensively eroded riverbeds and banks, producing a large amount of woody debris. The wood, some of which remained jammed or captured in sediment deposits along the course after the event, was originated from both hillslopes and riparian forests. The outflow was estimated at 58,000 m3 from the Tottabetsu River in total, which was 70% of the inflow into the course. Dividing the catchment into units based on stream order, the proportion of the outflow of the wood ranged from 0.90 to 1.00 for the mountainous and from 0.17 to 0.86 for the alluvial parts. The outflow was positively correlated with catchment sediment yield for each unit. The outcomes in this study will help plan the control measures of coarse woody debris through the channel network, not only for the Tottabetsu River but also elsewhere with a range of catchment sizes.
•Enrichment of deadwood and canopy gaps during logging operations promote beetle diversity in production forests.•Higher abundance, species number and species richness of both saproxylic and ...non-saproxylic beetles were found in gaps.•Beetle species number and richness, but not abundance, was higher in stands with snags, logs and/or stumps.•Although stumps are immediately highly attractive, snags and logs provide longer-lasting deadwood resources.
Conservation tools to enrich habitat diversity in the widely distributed homogeneous production forests include stumps as logging residues but also the intentional creation of logs or snags, as well as varying canopy conditions. While an open canopy has been shown to foster forest biodiversity, the impact of different deadwood types at stand scale is less clear, which is crucial since this is the most relevant scale for silvicultural decisions. In this study, we experimentally manipulated canopy conditions (open vs. closed) and created deadwood (stumps, logs, snags) in different combinations in five mature European beech (Fagus sylvatica L.) forests to test the potential of active manipulations to increase the diversity of beetles, one of the most diverse insect orders in temperate forests. We estimated abundance, species number and species richness (controlled for abundance) of saproxylic (i.e., deadwood-dependent) and non-saproxylic beetles using flight-interception traps and analyzed species assemblages within the first 3 years of the experiment. Using generalized linear mixed effect models we found a 33.7 % and 43.4 % higher abundance as well as a 26.1 % and 23.5 % higher species number under open canopies for saproxylic and non-saproxylic beetles respectively, accompanied by a higher species richness of both groups. Stands with deadwood had a 38.6 % and 32.7 % higher species number followed by higher species richness of saproxylic and non-saproxylic beetles compared to stands without manipulation but manipulations did not affect beetle abundances. We identified sampling year, followed by canopy condition and deadwood type (in addition to an overall higher impact of spatial distance between stands and sites) by applying multiple regression analyses as most important to explain species assemblages of both beetle groups. Saproxylic abundance and species number in stump treatments were initially high but decreased over 3 years, while treatments containing snags and logs resulted in an increase in both abundance and species number over time. These temporal trends were mediated by canopy cover. Our findings provide three major insights for biodiversity-orientated management in mature beech forests: First, opening the canopy increases the stand-scale abundance, species number, and species richness of saproxylic and non-saproxylic beetles. Second, while stumps are attractive for saproxylics shortly after the logging operation, snags and logs provide longer-lasting deadwood resources, thus underlining longer sustainability of snag and log enrichment for forest biodiversity. Third, deadwood enrichment at the stand scale promotes not only deadwood-dependent but also other beetle species.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Whether CWD has a positive effect on C sequestration in forest soils remains to be debated.•We need a comparison of the role of C from CWD and from leafy litter in soil C stabilization.•To elucidate ...the contribution of CWD to stable soil C we need to trace individual compounds.•Management of CWD should also focus on increasing sequestration in stable C pools.
Worldwide, forests have absorbed around 30% of global anthropogenic emissions of carbon dioxide (CO2) annually, thereby acting as important carbon (C) sinks. It is proposed that leaving large fragments of dead wood, coarse woody debris (CWD), in forest ecosystems may contribute to the forest C sink strength. CWD may take years to centuries to degrade completely, and non-respired C from CWD may enter the forest soil directly or in the form of dissolved organic C. Although aboveground decomposition of CWD has been studied frequently, little is known about the relative size, composition and fate of different C fluxes from CWD to soils under various substrate-specific and environmental conditions. Thus, the exact contribution of C from CWD to C sequestration within forest soils is poorly understood and quantified, although understanding CWD degradation and stabilization processes is essential for effective forest C sink management. This review aims at providing insight into these processes on the interface of forest ecology and soil science, and identifies knowledge gaps that are critical to our understanding of the effects of CWD on the forest soil C sink. It may be seen as a “call-to-action” crossing disciplinary boundaries, which proposes the use of compound-specific analytical studies and manipulation studies to elucidate C fluxes from CWD. Carbon fluxes from decaying CWD can vary considerably due to interspecific and intraspecific differences in composition and different environmental conditions. These variations in C fluxes need to be studied in detail and related to recent advances in soil C sequestration research. Outcomes of this review show that the presence of CWD may enhance the abundance and diversity of the microbial community and constitute additional fluxes of C into the mineral soil by augmented leaching of dissolved organic carbon (DOC). Leached DOC and residues from organic matter (OM) from later decay stages have been shown to be relatively enriched in complex and microbial-derived compounds, which may also be true for CWD-derived OM. Emerging knowledge on soil C stabilization indicates that such complex compounds may be sorbed preferentially to the mineral soil. Moreover, increased abundance and diversity of decomposer organisms may increase the amount of substrate C being diverted into microbial biomass, which may contribute to stable C pools in the forest soil.
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•Deadwood harmonization efforts by forest type.•We used National Forest Inventory deadwood data encompassing more than 55,000 plots.•We create bridge functions to convert deadwood measurements to 7.5 ...and 10.0 cm.•Bridge equations validation statistics indicate that the models performed adequately.•The standing deadwood trees proportion is not a good indicator of the total deadwood.
National as well as international requirements have led to an increased need to quantify deadwood stocks in forest ecosystems given their important role not only in terms of carbon storage and regulation of the carbon cycle but also as biodiversity refugia. However, differences in definitions and field monitoring as well as gaps in existing data on deadwood mean that comparisons among countries and retrospective analyses are difficult. In this research, we propose two potential approaches to solve the most common gaps in forest deadwood monitoring. First, we develop bridging functions capable of converting deadwood measurements with a specific reference diameter to 7.5 cm (minimum diameter value in Spain) and 10.0 cm (the most common minimum value for international statistics) diameters for the main forest types while also addressing the effect of raising the minimum measurable size on the quantification of deadwood. Furthermore, we aim to calculate the ratios between the amount of standing deadwood, the most common indicator monitored in National Forest Inventories, and the entire deadwood pool as a proxy for estimating complete deadwood stocks when data are not available. For this objective, we use information obtained from the Spanish National Forest Inventory, linear models and 10-fold cross-validation. We estimate the percentage of deadwood omitted when the minimum deadwood size is increased for the main eight forest types in Spain as well as for the entire country, using two different approaches. The ratio between the amount of standing deadwood and the entire deadwood pool ranged between 0.14 and 0.45 depending on the forest type. The lowest values of this ratio were found in Open woodlands and the largest in Mediterranean conifers. The validation statistics (R2 ranging from 0.82 in Evergreen broadleaves to 0.97 in Macaronesian broadleaves) indicate that the bridging functions we propose are robust and accurate. However, the ratios between the amount of standing deadwood and the entire deadwood pool performed poorer (R2 ranging from 0.26 in Macaronesian conifers to 0.65 in Macaronesian broadleaves) and led to an overestimation of the total stocks. Our results are of value not only for the purposes of comparison and harmonization but also for the implementation of new forest monitoring systems.
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In Fennoscandian forests, evidence on the effects of variable tree retention, prescribed burning and deadwood creation on deadwood quantity and quality is still scarce. We studied the effects of ...prescribed burning, tree retention and downed wood creation on the deadwood profile in managed boreal Norway spruce forest stands over a 16-year period. The stand scale treatments of the experiment included cuttings with a constant volume of dispersed retention trees (50 m3 ha-1, ca. 200 trees per ha), and three levels of downed deadwood creation (5, 30 and 60 m3 ha-1), in both upland and paludified biotopes of Myrtillus site type, with or without prescribed burning, with three replicates each.
After 16 years since the treatments, the diverse deadwood profiles with varying distribution by decay class were formed. The volume of deadwood varied from 9 to 107 m3 ha-1 with a mean of 65 m3 ha-1. The index of deadwood diversity was positively influenced by prescribed burning and negatively influenced by deadwood creation. The volume of all deadwood and coarse woody debris (CWD), volume and number of logs, as well as dead to live volume ratio increased after prescribed burning and with the level of deadwood creation. The positive effect of deadwood creation on the total CWD volume was higher in the upland biotopes than in the paludified ones. The highest amounts of all deadwood, CWD and logs were recorded in the upland biotopes after prescribed burning without deadwood creation. Our findings highlight the impact of tree retention with prescribed burning and deadwood creation in diversifying deadwood profile and maintaining deadwood continuum for decades.
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•Prescribed burning ensures continuity and diversity of deadwood in the long term.•The highest amounts of deadwood were found in burned stands without cuttings.•More highly decomposed wood was found after higher deadwood creation level.•The results can be applied in developing deadwood enrichment strategies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Coarse woody debris of Scots pine hosts abundant and diverse mycobiota.•The Illumina technology proved to be very effective in detection of fungi.•Fungal communities in coarse dead wood are huge ...complexes with many previously undifferentiated taxa.•Sanitary cutting, commercial thinning and timber harvesting cause an increase in abundance of fungi and richness of fungal communities in decayed dead wood.•Faster decomposition of wood decreases the abundance and diversity of fungi.
Abundance of fungi and richness of fungal communities were studied in coarse wood debris of Scots pine in stands that were unmanaged or managed (by sanitary cutting, commercial thinning and timber harvesting) in an 85-year-old Scots pine forest in western Poland, in June 2014. Samples consisted of 20 × 20 × 20 cm pieces of logs, fallen branches and stumps, in the 1st, 2nd and 3rd decay classes. Fungal communities were analysed using high throughput Illumina MiSeq sequencing of fungal rDNA internal transcribed spacer. From a total of 80 076 OTUs from 34 samples, 58 436 (72.98%) were of culturable fungi and 21 640 (27.02%) were of non-culturable fungi and other organisms. Fungi from Glomeromycota, Zygomycota, Ascomycota and Basidiomycota were detected. In the unmanaged stand the frequency of Glomeromycota was 0–0.2%, of Zygomycota 0.01–0.29%, of Ascomycota 30.47–79.08%, of Basidiomycota 1.56–16.45%, and of non-culturable fungi 7.28–65.51%. In the managed stand the frequency of Glomeromycota was 0–0.12%, of Zygomycota 0.04–1.48%, of Ascomycota 52.25–68.33%, of Basidiomycota 8.01–18.05%, and of non-culturable fungi 10.54–26.09%. Fungal communities in coarse dead wood were shown to be huge complexes which include many previously undifferentiated taxa that often occupy specific ecological niches. Samples were colonized by at least 260 taxa of fungi. Fungi were most abundant and fungal communities most species-rich in the managed stand and in the initial stages of wood decay. Known wood-decay species were most abundant in the less decayed wood. Management practice influenced density and diversity of fungal communities in decayed wood. Illumina technology proved to be more effective in detection of fungi than analysis based on fungal morphology in culture or Sanger DNA sequencing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Saproxylic species from different taxonomic groups often occur only on certain types of deadwood with specific qualitative characteristics. The various types of deadwood are very dynamic elements of ...forest ecosystems, associated with many site and stand features, as well as with the type of forest management. Using a pool of 29,098 sample plots spread across Poland, we analyzed 30 different deadwood types defined on the basis of three characteristics: position (standing, lying), degree of decomposition, and size. Statistical hurdle models were used to assess changes in the volume of individual deadwood types based on a broad range of independent variables. Depending on the type of management, terrain, site fertility, stand volume, tree density, and stand age, the models revealed substantial differences in the volume of different deadwood types, ranging from 0 to approx. 4 m3 ha−1. It was found that the volume of most deadwood types (except for a few, mostly with diameters under 15 cm) increases with stand age or stand volume. In managed forests at all stages of stand development there is a deficiency of thick deadwood. Both standing and lying deadwood at different decay stages is available continuously, irrespective of the values of individual independent variables, but considerable differences exist. While most lying deadwood exhibits higher levels of decomposition, in standing deadwood the proportions of different decay stages are strongly associated with tree diameter at breast height. The developed models make it possible to predict the volume of individual deadwood types for a broad range of independent variables. The current work presents several examples, with the results showing extremely complex relationships between deadwood diversity and site and stand features at every stage of forest development, with continuous changes in the volume and proportions of different deadwood types. In general, at the landscape level Polish forests contain both standing and lying deadwood at all decay stages in more or less equal proportions. However, in forest management one should pay special attention to the dimensions of retained deadwood. The absence of thick deadwood is particularly conspicuous in lowland managed forests.
•The total deadwood volume consists of many deadwood types with very different characteristics.•Statistical models based on stand features describe the diversity of dead wood with high accuracy.•The diversity of the deadwood changes with the age of the stand, the method of management and habitat conditions.•Some types of deadwood are not found in all forests, especially thick deadwood is completely removed.•Management of deadwood resources should be largely based on its diversity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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