Total Dead Wood Volume Research Articles

Естественное возобновление на валежной древесине в реликтовом лесу Янь Республики Сербской

The paper investigates the natural regeneration of downed deadwood in the Janj primeval forest. The old-growth forest is located in the southwestern part of the Republic of Srpska, which is dominated by dolomite geological base on which cambial soils were formed. The climate is perhumid and mountainous and the plantation belongs to the Piceo-Abieti-Fagetum community. The hectare contains 517 live trees with a total basal area of 53.0 m2/ha and a volume of 876 m3/ha. Twenty six downed deadwoods classified into three different degrees of decay were included in the study, where fir and spruce seedlings were found to be predominant and beech seedlings were rarely represented. The first degree of decay includes 7 (26.9 %), the second 8 (30.7 %), and the third 11 (42.3 %). The total volume of deadwood is 110.82 m3/ha with an average volume per tree of 4.2 m3/ha. The total number of seedlings on fallen dead trees is 836 seedlings (Abies alba – 89.59 %, Picea abies – 10.17 %, Fagus silvatica – 0.24 %). Fir seedlings are found on 25 fallen trees, spruce on 18 fallen trees, and beech on 2 fallen trees. Regarding quality, on average fir seedlings are better than spruce seedlings, but both species show a lot of senescence and very small size of current height increment. Most seedlings belong to the third quality class (fir – 46.2 %, spruce – 61.1 %), followed by second class (fir – 34.6 %, spruce – 22.2 %) and third class (fir – 19.2 %, spruce – 16.7 %). The total number of seedlings was found to have a statistically significant difference in the amount of downed deadwood depending on the degree of decay, and the number of seedlings depended on the degree of tree decay. The number of seedlings increased with increasing volume and length of rotten trees. For citation: Govedar Z., Prokhorova N., Babić V., Dukić V., Kanjevac B., Bilić S. Natural Regeneration on Deadwood in the Primeval Forest Janj. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 90–102. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-90-102

Comparison of four alternative survey methods in assessing dead wood at the stand level

ABSTRACT Many forestry practitioners need information on the amount of dead wood for various purposes, often at the level of individual stands. Our aim was to compare four simple dead-wood inventory methods of which systematic circular plot inventory is a well-known method, while relascope plot inventory (using the ordinary horizontal angle relascope also for downed trees), diameter class counting and total inventory are new methods. Seven surveyors tested the methods in four stands in southern Finland. All the methods produced rather accurate volume estimates. Mean percent error was the smallest (−5.7%) in total inventory and the largest (−12.4%) in diameter class counting. Precision differed significantly between the methods. Variation among individual measurements, expressed as percentage SD, was 15.9% in total inventory, 24.8% in diameter counting, 36.6% in relascope inventory and 43.0% in circular plot inventory. Diameter counting was by far the fastest method. Relascope inventory and circular plot inventory took about twice as much time, and total inventory over three times as much time as diameter counting. In conclusion, diameter class counting is a cost-effective dead-wood assessment method, if the purpose is to get an estimate of the total volume of dead wood within a forest stand with a reasonable precision.

Characteristics of deadwood and implications for biodiversity in Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) planted forests in Italy

The aim of the present study is to define a set of indicators to measure the stand diversity of Douglas fir planted forests with special regard to deadwood attributes related to biodiversity conservation. The set of quantitative and qualitative indicators was implemented in a Douglas fir stand in Central Italy (Rincine forest, Tuscany region) realized on degraded Sweet chestnut stands and abandoned agricultural lands from late ‘60s to first ‘80s. The identified indicators include two stand indicators (trees species composition and horizontal stand structure) and five deadwood indicators (total deadwood volume divided in coarse woody debris and fine woody debris, deadwood diversity by species and decay class, and number of habitat trees). The results show that the Douglas fir stand in the Rincine forest is characterized by a high number of Douglas fir trees (88.6% of stem density, 94.0% of basal area) with some young broadleaved trees and ancient Sweet chestnut trees prior to reforestation (Shannon index of 0.2 ± 0.34 and Diameter differentiation index of 0.20 ± 0.09). The deadwood indicators highlight a total volume of 62.0 m3 ha−1 mainly consisting of coarse woody debris (86.4% of total volume) and a diversified distribution by species (Shannon index of 0.29 ± 0.33) and decay class (Shannon index of 1.30 ± 0.10). The set of indicators proposed in this study can be implemented in other planted forests with the aim to monitor changes in stand diversity over time by forest managers.

Ecological assessment of dead woodvolume in hornbeam-oak forest in «Medobory» Nature Reserve

The volume of coarse woody detritus in the 139year-old hornbeam-oak forest stand of natural origin on the territory of the «Medobory» Nature Reserve have been studied. The study of dead wood was carried out on a sample plot (0.24 ha) by the method of continuous accounting. It was found that the volume of woody detritus in the forest ecosystem is 108.8 m3∙ha–1 and consists of fallen (32.1%) and standing (67.9%) deadwood. The main part of the dead wood volume is formed by two tree species — common oak (Quercus robur L.) (49.1%) and wychelm (Ulmus glabra Huds.) (48.4%). In general, woody detritus is characterized by I–V classes of decomposition, while detritus of decomposition stage II prevails (40.9%), shares of other stages are slightly smaller: I (27.8%), III (18.6%) and IV (11. 1%). The share of detritus of the last (V) decomposition stage is insignificant (1.6%). The volume of standing dead wood is 73.9 m3∙ha–1 and is formed by whole and broken dead trees. In terms of tree species composition, common oak has a significant advantage (65.4%), wychelm has a much smaller share (33.7%), and the share of hornbeam (Carpinus betulus L.) and small-leaved linden is insignificant (Tilia cordata Mill) (less than 1.0%). In the total standing dead wood volume, wood of decomposition stage IIsignificantly predominates (43.6 m3∙ha–1, 59.0%), compared with stage I (30.3 m3∙ha–1, 41.0%). Volume of fallen dead wood is 35.0 m3∙ha–1 and is formed by whole fallen trees, fragments of felled trees (trunks) and rough branches. In terms of species composition, woody detritus of which elm predominates (27.8 m3∙ha–1, 79.7%), much less common oak wood (5.1 m3∙ha–1, 14.6%) and common hornbeam (2.0 m∙ha–1, 5.7%). Fallen dead wood is represented by four stages of decomposition (II–V). In terms of volume, decomposition stage III has an absolute advantage (20.2 m3∙ha–1, 57.9%), detritus of stage II is much less (12.1 m3∙ha–1, 34.7%), and the shares of other stages are insignificant. The predominance of standing dead wood in the total dead wood volume, as well as the dominance of detritus of I and II decomposition stages due to the relatively short period of strict regime of nature conservation, during which the forest ecosystem developed without human intervention, and the impact of forestry activities (selective sanitary cuttings and fallen dead wood removal) in the past.

A Permanent Research Platform for Ecological Studies in Intact Temperate Mountainous Forests from Slătioara UNESCO Site and Its Surroundings, Romania

This paper describes a permanent research platform (PRP) designed and implemented in “Codrul secular Slătioara” and its surroundings (2205.85 ha), having also the role of introductory paper for future research articles based on data collected from this platform. “Codrul secular Slătioara” is known as one of the largest temperate mountainous intact forests of Europe and, in 2017, it was included in UNESCO World Heritage List, as part of the “Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe”. Moreover, the PRP overlaps other three scientific reserves, the share of strictly protected forests exceeding 70%. This platform has a multiple role, being developed for research, conservation and educational activities. The PRP was designed for an ecological analysis of the intact forest ecosystems. It contains 193 circular sample plots, each of them of 500 m2, and it is structured on two levels. The first level contains 58 sample plots corresponding to a square grid of 500 × 500 m, stretching over the entire forested area, and the second level contains 135 plots, placed according to a square grid of 100 × 100 m, covering 136 ha within the core area of the UNESCO site. We measured the characteristics of 8296 living trees, 1743 standing dead trees, 1900 dead wood trunks, 3214 saplings, and the abundance–dominance indices of flora species. Thus, we identified 14 tree species, 17 shrub species, and 248 other cormophyte species forming the herbaceous layer. In terms of volume, the main tree species are Norway spruce, silver fir and European beech. The tallest species are Norway spruce (56 m) and silver fir (51 m). The average volume of living trees is 659 m3·ha−1, with a maximum of 1441 m3·ha−1. The mean total dead wood volume is about 158 m3·ha−1, with sample plots where the total dead wood volume exceeds 600 m3·ha−1. After presenting the results of preliminary data processing, the paper describes the main research topics to be further considered, based on the PRP, and the foresights related to the PRP’s monitoring and development.

Ecological assessment of dead wood volume in natural deciduous forests in the Vita river valley in Holosiivskyi National Nature Park

The volume of dead wood by fractions, components, species composition and decay stages in natural lime-ash-oak forest in Vita river valley within the protected zone of the Holosiivskyi National Nature Park in northern part of forest-steppe of Ukraine is studied and presented. The study was conducted on permanent sample plot by identifying and measuring components of standing dead wood (standing dead trees, snags) and lying (fallen dead trees, logs and tree branches) dead wood. Total volume of deadwood is 94.2 m3 ·ha–1, and consists of standing dead wood (23.9 m3 ·ha–1) and lying deadwood (70.3 m3 ·ha–1). Common ash (Fraxinus excelsior L.) has the highest proportion of total dead wood volume – 43.2% (40.7 m3 ·ha–1) followed by common oak (Quercus robur L.) with 32.0% (30.1 m3 ·ha–1). Hornbeam (Carpinus betulus L.) and linden (Tilia cordata Mill.) have 10.1 and 8.8 % respectively of total dead wood volume. The relative sharing of wych elm (Ulmus glabra Huds.) and black alder (Alnus glutinosa (L.) Gaerth.) is low. Common ash has the highest proportion of standing dead wood volume – 59.4%, the proportion of hornbeam is much lower – 23.8%. Standing dead wood mainly belongs to decay stage I (81.6%). The volume of lying dead wood consists mainly of common oak (40.8%) and common ash (37.7%). In general lying dead wood belongs to decay stages I–V, although decay stages III and IV dominate. Among tree species only common ash has lying dead wood of all five decay stages, although dead wood of III and IV decay stages dominates with proportions 35.2% and 29.3% respectively. Lying dead wood of other tree species belongs to one-three decay stages with domination one decay stage. Dead wood displayed a wide range of variation in fractions and components, tree species and decay stages may have an important role in creating a high diversity of habitats and substrates for wildlife organisms in studied forest ecosystems

Optimal Continuous Cover Forest Management with a Lower Bound Constraint on Dead Wood

AbstractWe analyze economically optimal continuous cover forestry with dead wood as a biodiversity indicator. We study mixed-species stands consisting of Norway spruce (Picea abies [L.] Karst.), birch (Betula pendula Roth.), and other broadleaves (e.g., oak [Quercus sp.], maple [Acer sp.]). The analysis is based on an economic description of continuous cover forest management using an empirically estimated size-structured transition matrix model. We use size-specific decomposition rates for dead wood, with the lower limit on total dead wood volume varying between 0 and 40 m3 ha–1. The optimization problem is solved in its general dynamic form using gradient-based interior point methods. Increasing the dead wood volume requirement affects total stand density only slightly, but increases stand heterogeneity as other broadleaves are grown in higher numbers. In addition, increasing the dead wood requirement has only a minor effect on the total felled volume, but harvests shift from timber harvests to biodiversity fellings to maintain the required dead wood volume. In the optimal steady state with a high dead wood requirement, two harvesting cohorts emerge: one for timber harvests and the other for biodiversity fellings. Increasing the dead wood requirement decreases steady-state net timber income by up to 30 percent compared to the unconstrained solution.

Necromass Carbon Stock in a Secondary Atlantic Forest Fragment in Brazil

Necromass has a relevant role to play in the carbon stock of forest ecosystems, especially with the increase of tree mortality due to climate change. Despite this importance, its quantification is often neglected in tropical forests. The objective of this study was to quantify the carbon storage in a secondary Atlantic Forest fragment in Viçosa, Minas Gerais, Brazil. Coarse Woody Debris (CWD), standing dead trees (snags), and litter were quantified in twenty 10 m x 50 m plots randomly positioned throughout the forest area (simple random sampling). Data were collected during 2015, from July to December. The CWD and snags volumes were determined by the Smalian method and by allometric equations, respectively. The necromass of these components was estimated by multiplying the volume by the apparent density at each decomposition classes. The litter necromass was estimated by the proportionality method and the average of the extrapolated estimates per hectare. The carbon stock of the three components was quantified by multiplying the necromass and the carbon wood content. The total volume of dead wood, including CWD and snag, was 23.6 ± 0.9 m3 ha−1, being produced mainly by the competition for resources, senescence, and anthropic and climatic disturbances. The total necromass was 16.3 ± 0.4 Mg ha−1. The total carbon stock in necromass was 7.3 ± 0.2 MgC ha−1. The CWD, snag and litter stocked 3.0 ± 0.1, 1.8 ± 0.1, and 2.5 ± 0.1 MgC ha−1, respectively. These results demonstrate that although necromass has a lower carbon stock compared to biomass, neglecting its quantification may lead to underestimation of the carbon balance of forest ecosystems and their potential to mitigate climate change.

Protection against rockfall along a maturity gradient in mountain forests

When harvesting activities stop, forest stands become steadily richer in very large trees and deadwood, maturity attributes that are crucial for forest dwelling species. On the other hand, the maturation process, associated with large trees and large gaps between trees, has traditionally been thought to be detrimental to the protective function of the forest against gravitational hazards such as rockfall. However, the findings of recent studies have contested this belief, first because they showed that natural dynamics in aging stands is rather gradual in space and time, and second because they highlighted that deadwood may play an important role in protection forests.In this study, we assessed the protection efficiency of the forest along a maturity gradient in uneven aged stands, using a network of permanent sample plots in the French Alps. Plots were selected according to management plans to represent four successive stages along the maturity gradient: young stands, adult stands just after logging, post-adult stands that escaped one to two rotations, and mature stands. We checked that stands gradually matured using the total number of very large trees (dbh>77.5cm), the total volume of deadwood, and the total volume of degraded large logs.We then developed a specific module to integrate deadwood into the Rockyfor3D rockfall simulation model and assessed the rockfall protection of the plots. Mature stands, although not having reached the protection efficiency of young and dense stands, can provide adequate protection against rockfall. First, because mature stands are rather dense (more than 500stemsha−1). Second, because large logs increase the surface roughness of the forest floor and act as additional obstacles to the propagation of rocks.Consequently, mature stands originating from aging irregular stands play a fitting role in protection forests, thereby reconciling biodiversity conservation objectives with protective functions. When mature stands originate from aging regular stands dominated by a cohort of very large trees, a cautious approach to management will better initiate a progressive irregularization process before promoting patches of mature stands.

Value of old forest attributes related to cryptogam species richness in temperate forests: A quantitative assessment

Changes in temperate forest ecosystems resulting from a long history of forest exploitation may severely impact current cryptogam diversity. We documented the distribution of cryptogams in representative forest types between 200 and 1000m a.s.l. in central Europe, in managed and unmanaged stands. This survey included one-time inventories of lichens and bryophytes, 2 years of regular monitoring of macrofungi, and a detailed description of forest structure (live trees and dead woody debris) in 96 sampling plots (2500m2 each) in six study areas in the Czech Republic. On this basis, we attempted to identify the quantitative limits of forest structural attributes that affect cryptogam diversity along a gradient of forest management practices in central Europe. In total, we recorded 1387, 173 and 103 species of macrofungi, lichens and bryophytes, respectively, of which 149, 99 and 4 were red-listed species. Species richness was correlated among observed taxa at the plot scale, and rare and red-listed species made higher contributions in species-rich communities. Cryptogam species richness showed both common and taxa-specific patterns in relation to forest structure, tree species composition, age of the oldest tree strata and elevation. We found a positive influence of the largest-diameter tree classes (stem diameter >80cm) on the species richness of all cryptogam taxa, whereas the contribution of dead wood to the fit of a linear mixed effect model was minimal. Nevertheless, the magnitude of total and red-listed species richness was remarkably high in plots in which at least one large tree or woody object occurred compared to plots lacking these attributes. The effect of large dead wood debris (diameter >80cm and unit volume >1m3) was not replaced by total dead wood volume, even though it was relatively high (>40m3ha−1). Hence, both large live trees and woody debris compartments are probably important for the species richness of cryptogam communities. However, the spatial pattern of cryptogam communities at a given time point (i.e., the time of our survey) was associated with the spatial and temporal heterogeneity of live tree structures, but less with that of dead wood substrates. Large tree and woody debris characterize forests that have been unmanaged for at least several decades and occasionally occur in the oldest of moderately managed forests. The importance of these cryptogam refuges in managed forests should not be underestimated because their continuing disappearance will probably result in the impoverishment of cryptogam richness at regional scales.

Dead wood as an indicator of forest naturalness: A comparison of methods

Several measures related to dead wood have been used as indicators of forest naturalness, but their general applicability and comparability is unclear. We compared five dead wood related measures: volume of dead wood, dead wood diversity index, number of cut stumps, dead wood continuity profile and number of kelo trees (specific type of dead pine trees). Furthermore, we studied if these indicators provide similar relative ranking of forest sites. Study sites were located on 40 islands of the Archipelago Sea in southwestern Finland in the hemiboreal zone. Islands included sites that apparently varied in their naturalness. The total volume of dead wood was on average 16.6m3ha−1 (range 4.1–42.9m3ha−1). The dead wood diversity index varied from 4.4 to 56.2 (median 23.6), and the number of cut stumps from 0 to 173.3stumpsha−1 (median 33.0). The dead wood continuity profiles indicated four patterns: strong continuity (5 islands), weak continuity (13 islands), old continuity gap (15 islands) and low abundance (4 islands). The number of kelo trees varied between 0 and 42.9kelosha−1. The dead wood diversity index and the number of cut stumps were significantly related to the volume of dead wood. The volume of dead wood and the dead wood diversity index varied significantly along with the continuity patterns. The number of kelos was negatively correlated with the number of cut stumps, but not with other measures. Ranking order of the study sites according to the three indicators (volume of dead wood, dead wood diversity index, number of cut stumps) showed significant similarity. The volume of dead wood provided the best overall agreement with other indicators but requires considerable effort to measure. The number of cut stumps, however, provides direct information on human activity. The indicators of naturalness provide data for many purposes, like conservation priorization. Based on our results, the selected indicator can affect the output of the assessment considerably. Therefore, it important to consider these differences when interpreting assessments that are based on different indicators.

Quantifying the effect of sampling plot size on the estimation of structural indicators in old-growth forest stands

There is increasing awareness that structure-based indicators should be considered for assessing the biological value of late successional forests. In order to increase the unique habitat features critical for old-growth associated species, it is important to identify and rank candidate potential forest sites on the basis of their distinctive structural features. Data on living and deadwood components for the identification of old-growth condition are usually acquired in the considered forest stands by two sampling survey: (i) census performed in relatively large monitoring sites; (ii) network of small sampling units, on which inventory practices are usually based. Several authors argued that choosing between these survey strategies might have substantial effects on the values of common indicators of old-growth condition. Our study aims at (i) assessing the total estimate differences among old-growth structural indicators measured in field plots with different sizes, and (ii) defining the optimal sample size for the reliable assessment of such indicators. The study was carried out in six beech dominated forest stands on the Apennines range in Italy. In each stand, living and deadwood components were surveyed and geocoded in 1-ha square areas. Based on these dataset, circular plots with radii ranging from 4m up to 20m were then considered in order to quantify the effect of sampling plot size on the estimation of four structural indicators: (1) number of living trees; (2) number of large trees (dbh⩾50cm); (3) total deadwood volume; (4) number of deadwood elements (snags, dead standing trees; lying dead trees, lying deadwood) with dbh (or average diameter for lying deadwood) ⩾ 30cm. We found that the size of the sampling plots should be at least 500 m2 in order to establish a database for the assessment of the investigated indicators. The census approach should be preferred to the sampling plot approach for old-growth forest stands smaller than 3–5ha. The achieved results contribute to define assessment protocols for characterizing and ranking the degree to which forest stands approximate old-growth condition based on standardized indicators.

Pattern and process in the largest primeval beech forest of Europe (Ukrainian Carpathians)

AbstractQuestionsAre the structural characteristics of natural beech forests predominant on small monitoring plots representative of the large‐scale features of these forests? Do the findings of our large‐scale investigation support the hypothesis that this primeval beech forest is shaped by fine‐scale processes, or is there evidence that high‐severity disturbance events have affected its structure?LocationUkrainian Carpathians, Uholka‐Shyrokyi Luh, the largest primeval beech forest in Europe, covering 102.8 km2.MethodsOn 314 (500 m2) circular plots, systematically distributed across the forest, all living and dead trees with a DBH ≥6 cm were assessed. Lying deadwood, tree regeneration, the size of canopy gaps and the number of canopy layers were recorded. Spatial analyses were conducted using Moran's I. Dendrochronological analysis was used to reconstruct tree ages and growth patterns.ResultsThe forest is characterized overall by a density of 435.0 ± 12.2 ha−1 (mean ± SE) living trees, a basal area of 36.6 ± 0.8 m2·ha−1, a volume of living trees of 582.1 ± 13.5 m3·ha−1 and a total deadwood volume of 162.5 ± 8.4 m3·ha−1. Beech is the dominant species (97.3 ± 0.7%, by basal area), interspersed with mostly deciduous species with moderate shade tolerance. The forest canopy is multi‐layered, with a high abundance of old trees, and with canopy gaps rarely larger than the crown projection area of a few trees.ConclusionsThe results lend support to findings from small monitoring plots, but our landscape approach allows a reliable estimation of key forest characteristics such as basal area and standing volume, which tend to be overestimated in studies on subjectively placed small monitoring plots. We conclude that disturbance events of moderate or higher severity have left only few discernible traces in forest structure or species composition. All findings suggest that this forest is characterized by a mainly small‐scale disturbance regime, leading to a homogeneity of forest characteristics of the living stand at larger spatial scales and causing only minor fluctuations around the average values of forest parameters observed.

Dead wood and stand structure - relationships for forest plots across Europe

Dead wood and stand structural parameters were sampled in eleven countries using standardized methods at about 90 intensive forest monitoring sites across large parts of Europe. Besides descriptions and correlation analyses of dead wood and stand structure parameters, a joint evaluation of both fields was performed by principal component analysis (PCA). The extracted principal components were subsequently regressed against important numerical and categorical site-related parameters like soil pH, altitude, or forest type. Dead wood volumes varied largely across plots, however, 77 percent of them had volumes below 25 cubic meter per hectare. While all fractions of dead wood - except cut stumps - reveal high intercorrelation, different aspects of stand structure varied more independently. Clark-Evans index, number of tree species and standard deviation of tree trunk diameters revealed as most self-contained. The 1st PCA axis covered 46 percent of the total variance and was mostly loaded by total dead wood volume denoting it as the feature differentiating forests most. The 2nd axis was primarily loaded by tree species diversity together with stem density and the Clark-Evans index. On the 3rd axis diameter differentiation of trees together with the volume of cut stumps prevailed, while the 4th was mainly related to the decay class of woody debris. Bivariate ex post analyses revealed country as a significant predictor of all PCA axes, underlining national forest legislations and management rules as crucial for all investigated structural features of forests. Forest type was related only to the 3rd and 2nd axis. Only the 3rd axis revealed significant relationships with some ecological site factors (age, number of tree layers, latitude, altitude). The outcome underlines the significance of nationally enacted forest legislations for both important structural and biodiversity-relevant features of forest ecosystems and encourages similar approaches with data from national forest inventories or monitoring systems.

Effects of restoration fire on dead wood heterogeneity and availability in three <i>Pinus sylvestris</i> forests in Sweden

Restoration fires are increasingly used as a conservation tool in Sweden to recreate forests with characteristics of previous forests that were periodically disturbed by fires and promote fire-dependent species. Restoration fires can result in large inputs of fresh dead wood, but there are risks of losing some of the existing, pre-fire dead wood. To assess these counteracting effects we studied the heterogeneity and availability of dead wood before and after three restoration fires in boreal Scots pine forests. Specifically, we studied volumes of stumps, high stumps, snags and logs. The fires decreased the total volume of pre-fire dead wood (23-41%) and consumed logs in late decay stages (26-54%) to a higher extent than logs in earlier stages. The input of new fresh dead wood after the fires exceeded losses of pre-fire dead wood and resulted in a net increase of dead wood in all three sites. The added dead wood consisted of fresh snags killed by the fires. Fire also affected log characteristics: reducing their vegetation coverage (60-98%), decreasing their ground contact (4-50%) and increasing their surface area of charred wood (>50%). Such changes have important consequences for the micro environmental conditions inside logs, but have been rarely studied in relation to restoration fires. Our results show that restoration fire causes changes in dead wood availability and characteristics of logs. The results imply that ideally stands with low abundance of rare and heavily decayed wood substrates should be burned to optimize dead wood values. Alternatively, management practices should include protection of these substrates during restoration fires.

Le volume de bois mort, indicateur indirect de biodiversité : une approche critique

Le volume local total de bois mort est actuellement utilisé pour évaluer la durabilité de la gestion des forêts en Europe et en France, comme indicateur structurel indirect d’une des composantes de la biodiversité forestière, à savoir la biodiversité dite saproxylique. Ce descripteur du stock de bois mort est en lien avec les pressions de gestion, directement connectable à un objectif-cible de gestion forestière, mesurable au moyen de protocoles standardisés, et aisément communicable. C’est pourquoi sa pertinence écologique est remise en cause par de récentes investigations. La méta-analyse d’une trentaine de jeux de données européens a montré que la corrélation linéaire entre volume local de bois mort et nombre local d’espèces saproxyliques (coléoptères ou champignons) était globalement significative mais faible, notamment dans les forêts tempérées et feuillues. De même, la relation logarithmique entre le volume local de bois mort et le nombre d’espèces de coléoptères saproxyliques ne montre pas de tendance significative dans différentes forêts tempérées feuillues et résineuses en Europe de l’Ouest. C’est pourquoi d’autres indicateurs indirects de la biodiversité saproxylique sont à explorer, qui auraient une meilleure pertinence écologique tout en préservant leur facilité opérationnelle : volume de bois mort estimé non plus localement mais dans le paysage environnant, diversité (plutôt que quantité) de bois mort local, densité et diversité d’autres niches écologiques du cortège saproxylique (micro-habitats portés par les arbres). Nous présentons ici des premiers résultats qui montrent qu'un indicateur concurrent – la diversité de pièces de bois mort – semble un bien meilleur candidat comme indicateur de la diversité saproxylique, à une échelle plus paysagère que locale.

Impact of silviculture on dead wood and on the distribution and frequency of tree microhabitats in montane beech-fir forests of the Pyrenees

In forest ecosystems, the level of biodiversity is strongly linked to dead wood and tree microhabitats. To evaluate the influence of current forest management on the availability of dead wood and on the abundance and distribution of microhabitats, we studied the volume and diversity of dead wood objects and the distribution and frequency of cavities, dendrothelms, cracks, bark losses and sporophores of saproxylic fungi in montane beech-fir stands. We compared stands unmanaged for 50 or 100 years with continuously managed stands. A total of 1,204 live trees and 460 dead wood objects were observed. Total dead wood volume, snag volume and microhabitat diversity were lower in the managed stands, but the total number of microhabitats per ha was not significantly different between managed and unmanaged stands. Cavities were always the most frequent microhabitat and cracks the least frequent. Dendrothelm and bark loss were favored by management. Beech (Fagus sylvatica) carried many more microhabitats than silver fir (Abies alba), especially cavities, dendrothelms and bark losses. Fir very scarcely formed dendrothelms. Secondary tree species played an important role by providing cracks and bark losses. The proportion of microhabitat-bearing trees increased dramatically above circumference thresholds of 225 cm for beech and 215 cm for fir. Firs with a circumference of less than 135 cm did not carry microhabitats. In order to conserve microhabitat-providing trees and to increase the volume of dead wood in managed stands, we recommend conserving trees that finish their natural cycle over 10–20% of the surface area.

Effect of deadwood position on saproxylic beetles in temperate forests and conservation interest of oak snags

Abstract.1. Intensive forestry has drastically reduced the volume of standing deadwood, even more than total deadwood volume. It has been demonstrated in boreal forests that snags have a high conservation value for many saproxylic species and that the lying or standing aspect of the deadwood makes a difference. The conservation of saproxylic beetles in the changing deadwood landscape of temperate managed forests depends on a deeper understanding of the ecological value of forest stand legacies.2. Our study questioned whether the retention of oak snags is an important conservation concern in European temperate forests. We analysed the differences in saproxylic beetle fauna between oak snags and logs and explored the diameter effect on log–snag differences. We compared the species composition and richness of saproxylic beetle assemblages in a temperate deciduous forest. Emergence traps were set in a balanced sampling design of 22 ground‐lying logs and 22 oak snags with a range of intermediate decay stages and 2 diameter classes.3. Oak snags yielded more individuals per volume unit and supported more species than logs, and exhibited significantly dissimilar assemblages from logs and hosted original species. Snags, especially large snags, were more interesting for rare beetle species conservation than logs. The feeding guild structure slightly differed between snags and logs. Overall, log–snag differences depended on the diameter class.4. We confirm that saproxylic biodiversity would significantly benefit from forestry measures favouring oak snag retention (especially large snags), even though further multi‐scale studies are necessary to develop quantitative retention guidelines.

Managed vs. unmanaged. Structure of beech forest stands (Fagus sylvatica L.) after 50 years of development, Central Bohemia

In this study, the structure and spatial patterns of adjacent beech (Fagus sylvatica L.) forest stands, both those having undergone intensive management and those without management intervention over the last 50 years were analyzed. Data was collected from six 1ha permanent research plots. Four plots were established in varying parts of the reserve, comprising entirely of even-aged managed forest stands; two 1-ha permanent plots were located in a non-interventional stand. For each woody stem, basic dendrometrical data and coordinates were measured. The total volume of dead wood (standing and fallen) and its classes of decay were recorded. The structure and species diversity of forest stands were analyzed using skewness and the coefficient of variation of dbh distribution, the Gini index, the Shannon index, the mingling index, the Pielou index of segregation and the Hopkins-Skellam, Pielou-Mountford, Clark-Evans aggregation indices, the diameter differentiation index and Ripley K function. The diameter distribution of the managed stands was generally normal, albeit with a large diameter range and with a typical flat diameter curve. A general lack of giant trees, lower rates of coarse woody debris (from 0.2 to 0.5% of the total living volume) and random tree distribution were also confirmed. Within the investigated area, the diameter differentiation and Gini indices along with the degree of skewness and the coefficient of variation made it possible to monitor the shift from even-aged forest management to spontaneous forest development. In general, spontaneous development was marked mainly by aggregated tree distribution in the middle and lower layer, and a shift from normal to reversed J-shaped dbh distribution. The total volume of deadwood in one of the unmanaged plots amounted to 48.10 m3/ha (9.5% of living wood volume). The use of adequate structural and spatial analysis as indicators of natural forest development are discussed.

Critical length sampling: a method to estimate the volume of downed coarse woody debris

In this paper, critical length sampling for estimating the volume of downed coarse woody debris is presented. Using this method, the volume of downed wood in a stand can be estimated by summing the critical lengths of down logs included in a sample obtained using a relascope or wedge prism; typically, the instrument should be tilted 90° from its usual orientation in sampling live trees. The critical length of a downed tree is the length of the log section large enough in diameter to be counted from the selected sample point. A simulation study was conducted to compare critical length sampling with diameter relascope sampling and perpendicular distance sampling. For the population studied, diameter relascope sampling tended to have the smallest variance but exhibited a small design-bias. By combining critical length sampling with critical height sampling—a method previously described for estimating the volume of standing trees—the total volume of dead wood in a stand can be estimated using the same basic principle. One use of the combined method might be in rapid in-place inventories where a quick estimate of the volume of dead wood is needed for biodiversity management purposes. The combined critical length/height method provides a relatively simple means for obtaining such estimates.