Stand type is more important than red wood ant abundance for the structure of ground‐dwelling arthropod assemblages in managed boreal forests

• 1 The relationships between red wood ants (Formica rufa group) and other ground‐dwelling arthropods were studied in young managed forests stands in Eastern Finland. The main objectives were: (i) to test the influence of stand type (dominant tree species; age: sapling versus pole stage) and numbers of red wood ants on the occurrence of other ground‐dwelling arthropods and (ii) to study the occurrence of red wood ants versus other arthropods on a distance gradient from ant mounds. We used pitfall traps set in 5–14‐year‐old sapling stands and 30–45‐year‐old pole‐stage stands of Scots pine (Pinus sylvestris L.) and birch (Betula spp.) forests.
• 2 Pitfall trap catches of red wood ants did not vary significantly between the forest stand types, although some groups of other arthropods showed clear responses to stand type (e.g. catches of other Formicinae and Gnaphosidae were higher in sapling stands than in pole‐stage stands). The number of red wood ants clearly explained less of the variation in assemblages of other ground‐dwelling arthropods than the forest stand type.
• 3 Red wood ant numbers decreased significantly with distance from the mounds, but the other ground‐dwelling arthropods were insensitive to this gradient or even showed a preference for proximity to ant mounds and high ant activity.
• 4 The results obtained in the present study suggest that wood ants do not have strong effects on several other ground‐dwelling arthropod groups in young managed forests other than in the immediate vicinity of their mounds.

     

Influence of snag characteristics on saproxylic beetle assemblages in a south Swedish beech forest

Effects of snag characteristics on saproxylic beetles were studied in an area of managed beech forest in southern Sweden. A snag survey was combined with a beetle survey using 30 small window traps directly attached to beech snags. The total number of species was lower in the snags which were most decayed than in the three younger decay classes, while the number of red-listed species remained the same regardless of the stage of decay. The number of fresh wood species declined and the number of rot hole species increased with increasing snag decay. The diversity of fungicolous and decayed wood species peaked at the intermediate stage of decay in the snags. CCA ordination confirmed that the stage of decay in the snags was most important for species composition, followed by sun exposure. There were no general differences in species density and composition between managed and unmanaged stands. Our study suggests that most species are able to find suitable habitat within a radius of a few kilometres and that the total amount of habitat in an unfragmented forest area is more important for species diversity than the spatial distribution of this habitat. Our data also shows that species diversity increases with habitat diversity. Snags formed from giant beech trees seem to be particularly important for rare species living in rot holes. We conclude that for a high species diversity there is a requirement for snags in different stages of decay, size and degree of sun exposure.     

Rainfall and parasitic wasp (Hymenoptera: Ichneumonoidea) activity in successional forest stages at Barro Colorado Nature Monument, Panama, and La Selva Biological Station, Costa Rica

1 In 1997, we ran two Malaise insect traps in each of four stands of wet forest in Costa Rica (two old‐growth and two 20‐year‐old stands) and four stands of moist forest in Panama (old‐growth, 20, 40 and 120‐year‐old stands). 2 Wet forest traps caught 2.32 times as many ichneumonoids as moist forest traps. The average catch per old‐growth trap was 1.89 times greater than the average catch per second‐growth trap. 3 Parasitoids of lepidopteran larvae were caught in higher proportions in the wet forest, while pupal parasitoids were relatively more active in the moist forest. 4 We hypothesize that moisture availability is of key importance in determining parasitoid activity, community composition and trophic interactions.     

Saproxylic beetle assemblages related to silvicultural management intensity and stand structures in a beech forest in Southern Germany

Compared to agricultural land and spruce plantations, central European beech-oak forests are often relatively close to natural conditions. However, forest management may alter these conditions. In Steigerwald, southern Germany, a large beech-dominated forest area, three management intensities were applied during the past 30–70 years. Here, we examined the influence of management intensity on saproxylic beetles in >100-year old mature stands at 69 sampling plots in 2004. We sampled beetles using flight-window traps and time standard direct searches. The community structure based on presence/absence data changed remarkably along the gradient from unmanaged to low-intensity to high-intensity management, but these differences were not evident using abundance data from flight interception traps. Saproxylic species richness decreased in intensively managed forests. Elateridae and threatened species richness peaked in unmanaged forests and in forests under low-intensity management. Saproxylic species richness was dependent on certain micro-habitat factors. These factors were (1) the amount of dead wood for Elateridae, overall and threatened saproxylic beetle richness; (2) the amount of flowering plants for Cerambycidae; (3) the richness of wood-inhabiting fungi for Staphylinidae, Melandryidae and overall saproxylic beetle richness; and (4) the frequency of Fomes fomentarius for threatened species. Species richness was better explained by plot factors, such as dead wood or fungi, than by management intensity. These results suggest that the natural variation of dead wood niches (decay stages, snag sizes, tree cavities and wood-inhabiting fungi species) must be maintained to efficiently conserve the whole saproxylic beetle fauna of beech forests. Also, intensive management may alter the specialised saproxylic beetle community even if the initial tree-species composition is maintained, which was the case in our study. For monitoring the ecological sustainability of forest management we must focus on threatened species. If structures alone are sampled then the amount of dead wood is the best indicator for a rich saproxylic beetle fauna.     

Evaluation of window flight traps for effectiveness at monitoring dead wood-associated beetles: the effect of ethanol lure under contrasting environmental conditions

1 Subsequent to the diversity of saproxylic beetles being proposed as a management tool in forestry, more explicit knowledge about the efficiency and selective properties of beetle sampling methods is needed.
2 We compared saproxylic beetle assemblages caught by alcohol-baited or unbaited window traps in different forest contexts. Considering that trap attractiveness depends on kairomone concentrations, we appraised whether the trap efficiency was influenced by trap environment (openness and local supply of fresh dead wood).
3 Saproxylic beetles were sampled using 48 cross-vane window flight traps, arranged in paired designs (alcohol-baited/unbaited), in eight ancient and eight recent gaps (open stands), and eight closed-canopy control stands in an upland beech forest in the French Pyrenees.
4 Baited traps were more efficient than unbaited traps in terms of abundance and richness in our deciduous forests. The ethanol lure did not have any repellent effect on the individual response of saproxylic taxa.
5 The influence of local environmental conditions on trap attractiveness was observed. Openness had a significant moderate effect on species richness. Trap attractiveness was slightly reduced in the alcohol-saturated environment of recent gaps probably due to a disruption by local fresh dead-wood concentrations of the kairomonal response of saproxylic beetles to baited traps ('alcohol disruption').
6 Because the ethanol lure enhanced the probability of species detection, it may be useful in early-warning surveillance, monitoring and control of wood borers, despite slight influences of local conditions on baited trap efficiency.     

Deadwood in Relation to Stand Management and Forest Type in Central Apennines (Molise,Italy)

Deadwood is an important component for conserving carbon stock and maintaining species diversity. Scarce information is, at present, available concerning the amount and composition of deadwood in Mediterranean-type ecosystems. In this study, 21 sites were chosen to characterize different forest types among representative managed and unmanaged stands in the Central Apennines (Molise, Italy). Data were collected to assess living tree and deadwood volumes, and the relative abundance of different deadwood components in decay classes. The information gathered was related to human-induced disturbances on a regional scale. There were substantial differences in the deadwood volumes between managed and unmanaged stands, although this was not the case in the living tree volumes. Deadwood volumes were larger in unmanaged than in managed stands. In particular, large amounts of deadwood were found in managed Mediterranean and Anatolian fir forests, probably due to minimal management practices. Dead downed trees were less represented in managed forests as they are normally removed to facilitate logging activities. Logs occurred more frequently in managed stands as logging residues left on site. Most deadwood material belonged to early decay classes. Proportionally larger amounts of deadwood ascribed to class 1 in managed stands correlated with recent cutting activities. The relatively large amounts of deadwood attributed in unmanaged stands to class 3 demonstrate its longer persistence in unmanaged forests. This study represents a first systematic analysis of deadwood occurrence in a typical Mediterranean forest area, and should be useful in defining important objectives for sustainable forest management.     

Diversity of bryophyte vegetation in some forest types in Estonia: a comparison of old unmanaged and managed forests

The bryophyte vegetation of 3 pairs of unmanaged and managed forest stands, representing Oxalis drained peatland, Aegopodium and Oxalis forest site type, were compared. The total number of bryophyte species in unmanaged stands was 74 and that in managed stands 54. Out of the 20 species occurring only in unmanaged forests, 9 grow on decaying wood, and 3 on trunks or bases of big trees; 13 of them were hepatics. In unmanaged forests 11 hemerophobic species were recorded altogether. Although the difference in substrate and species diversity between unmanaged and managed stands is not statistically significant, in unmanaged forests more substrates characteristic for an old-growth stand are available, and the percentage of species preferring dryer habitats or prolonged humidity is a bit higher than in managed forests; the percentage of species associated with better illuminated habitats is higher in managed forests. Analysis of classification structure of the bryophyte layer synusia shows that the number of societies is also higher in unmanaged forests. This is associated with more numerous microhabitats; the average light and humidity indices calculated for every society, confirm this conclusion. The large discrepancy in bryophyte layer classification structure in old-growth and managed forests of the same forest site type is manifested not so much by species content in synusia as by their abundance proportions. The larger diversity of classification units in unmanaged forests is also seen at the synusia facies level; four of nine facies are confined exclusively to unmanaged stands. This is a strong argument for the informativeness of bryophyte layer classification structure for purposes of indication and monitoring as well.     

Saproxylic beetle diversity in a managed boreal forest: importance of stand characteristics and forestry conservation measures

Saproxylic beetles constitute a significant proportion of boreal forest biodiversity. However, the long history of timber production in Fennoscandia has significantly reduced the availability of dead wood and is considered a threat to the conservation of saproxylic beetle assemblages. Therefore, since the mid‐1990s dead wood retention in harvested stands has formed an integral part of silvicultural practices. However, the contribution of this biodiversity‐orientated management approach to conserving saproxylic beetle assemblages in boreal forest landscapes that include production forestry remains largely untested. We examined differences in resident saproxylic beetle assemblages among stands under different management in a boreal forest landscape in Central Sweden, and in particular stands managed according to new conservation‐orientated practices. We also investigated the relationship between beetle diversity and forest stand characteristics. Bark of coarse woody debris (CWD) was sieved for beetles in old managed stands, unmanaged nature reserves, and set‐aside areas, and clear‐cut stands harvested according to certification guidelines [new forestry (NF) clear‐cuts]. All stand types contributed significantly to the total diversity of beetles found. While stand size, position, and distance to nearest reserve were unimportant, both the quality and the quantity of CWD in stands contributed significantly to explaining beetle abundance and species richness. This extends the previous findings for red‐listed invertebrates, and shows that heterogeneous substrate quality and a range of management practices are necessary to maintain saproxylic beetle diversity in boreal forest landscapes that include production forestry. The unique abiotic conditions in combination with the abundant and varied CWD associated with NF clear‐cuts form an important component of forest stand heterogeneity for saproxylic beetles. It is thus essential that sufficient, diverse, CWD is retained in managed boreal landscapes to ensure the conservation of boreal saproxylic beetle assemblages.     

Community structure of Korean fir (Abies koreana) snag‐dwelling arthropods on Hallasan National Park,Jeju Island,Korea

We executed this research to understand the importance of decaying woods as the diverse arthropods' habitat in Abies koreana forests of Mt. Hallasan, Korea, from 2013 April to 2014 July. We discriminated the Abies koreana forests into one live stage and three decay stages in three blocks (Sungpanak, Yeongsil, Donnaeko) with three replicates and collected arthropods using an emergence trap per tree. We also used the different slope, altitude, decay stage and characteristics of dead wood as statistical variables. As A result, a total of six classes 23 orders 99 families 224 species (69,674 individuals) were collected from 282 emergence traps. We found that there were significant differences in abundance among decay stages and study sites. Our research results would be relevant for developing the ecologically sustainable forest management strategies and we expect these results would be used as the basic data for the forest management plans of Abies koreana.     

Linking substrate and habitat requirements of wood‐inhabiting fungi to their regional extinction vulnerability

Loss of old‐growth forests and greatly reduced volumes of coarse dead wood in managed forests are the main reasons for the decline of many wood‐inhabiting species in Europe and elsewhere. To assess the habitat requirements and extinction vulnerability of 13 polypore species associated mainly with spruce, their occurrences were recorded on 96 521 dead‐wood objects in 331 stands along a regional gradient of forest utilization history across southern‐middle boreal Finland. The substrates studied included a variety of tree species and dead‐wood qualities investigated in both unmanaged and managed stands at different successional stages. Hierarchical logistic regression models were constructed to analyze the relationships between the occurrence probability of individual species and variables at the substrate, stand and regional scales. The substrate preferences of the polypore species studied overlapped, since most of them favored large‐diameter spruce logs in mid‐decay stages. However, only a few species were restricted to this substrate. Other species were able to use a wider range of host tree species and qualities of dead wood, including man‐made substrates that are abundant in managed forests (logging residues and stumps). Species confined to logs had a significantly lower occurrence probability in regions with the longest and most intensive forest use history. Species less specialized in their resource use showed no decline or the opposite trend. Loss of threatened species is likely if the preservation of old‐growth forests is not combined with conservation measures in managed forests. Increasing extraction of logging residues and stumps for biofuel may cause non‐threatened species to decline by reducing substrate qualities utilized by them. The hierarchical models predicted a considerable part of the variation in Species' occurrence probabilities, and therefore provide powerful tools for setting quantitative targets for management.     

Re‐forestation restores native dominance in an island beetle fauna

Native re‐forestation is a widely used restoration tool, typically undertaken with the expectation that planting native trees will initiate succession processes (including the re‐establishment of native fauna) that will eventually return the ecosystem to a native‐dominated state. Invertebrate groups can be used to assess restoration progress, as their life history traits enable them to respond more rapidly to environmental change than many other organisms. In this study, we assessed beetle responses to re‐forestation. Using two trapping methods (flight intercept traps and pitfall traps), we compared beetle assemblages in exotic pasture (pre‐restoration state), <10‐year‐old planted native forest (restoration intervention) and approximately 40‐year‐old unmanaged regenerating native forest (reference state). Analysis of the flight intercept‐trapped beetles suggests that re‐forestation has initiated a transition from an exotic‐dominated pasture fauna toward a native‐dominated fauna: in planted forests, 75% of all flight‐intercept‐trapped beetles were native (compared with 22% in pasture and 87% in unmanaged forest). Flight intercept‐trapped beetles also had higher native diversity and abundance in both forest types than in pasture. Pitfall‐trapped beetle species were predominantly native in both forest types, but there were few statistically significant differences between the forests and pasture in the pit‐fall trap data set. Both trapping methods detected significant compositional differences between the beetle assemblages in planted forest and unmanaged forest. Replanting native forest has increased native beetle diversity, abundance, and dominance (compared with the pre‐restoration state), but convergence with the unmanaged reference forest has not yet been achieved.     

Attacks on living spruce trees by the bark beetle Ips typographus (Col. Scolytidae) following a storm-felling: a comparison between stands with and without removal of wind-felled trees

Abstract 1 To maintain biodiversity in forests more wind‐felled trees must be left where they fall. However, there is concern among forest owners that this may result in higher tree mortality caused by the spruce bark beetle, Ips typographus (L.) (Col.: Scolytidae). 2 In the 5 years following a major storm disturbance the number of standing spruces killed by I. typographus was determined in a total of 53 stands. In five of the stands all wind‐thrown trees were left (unmanaged stands) and in 48 of the stands, which were situated at distances of 1.4–10.0 km from each focal unmanaged stand, the wind‐felled trees were removed directly after the storm (managed stands). In the winter preceding the fifth summer new storm‐fellings occurred in the study area. 3 In the 4‐year period between the first and second storm‐fellings, 50–322 standing trees were killed by I. typographus per unmanaged stand. There was a direct linear relationship between the number of storm‐felled spruces colonized by I. typographus and the number of trees subsequently killed in the unmanaged stands. 4 Tree mortality caused by I. typographus in the unmanaged stands was almost nil in the first year, peaked in the second or third year, and decreased markedly to a low level in the fourth and fifth years. 5 In the 4‐year period between the first and second storm‐fellings twice as many trees were killed per ha in the unmanaged stands than in the managed stands: the average difference being 6.2 killed trees per ha, equivalent to 19% of the number of spruce trees felled by the first storm in the unmanaged stands. 6 Much higher numbers of trees were killed per ha in the stand edges than in the interiors of both the unmanaged and the managed stands.     

Micro and macro-habitat associations in saproxylic beetles: implications for biodiversity management

Restoration of habitats is critically important in preventing full realization of the extinction debt owed as a result of anthropogenic habitat destruction. Although much emphasis has been placed on macrohabitats, suitable microhabitats are also vital for the survival of most species. The aim of this large-scale field experiment was to evaluate the relative importance of manipulated microhabitats, i.e., dead wood substrates of spruce (snags, and logs that were burned, inoculated with wood fungi or shaded) and macrohabitats, i.e., stand types (clear-cuts, mature managed forests, and forest reserves) for species richness, abundance and assemblage composition of all saproxylic and red-listed saproxylic beetles. Beetles were collected in emergence traps in 30 forest stands in 2001, 2003, 2004 and 2006. More individuals emerged from snags and untreated logs than from burned and shaded logs, but species richness did not differ among substrates. Assemblage composition differed among substrates for both all saproxylics and red-listed saproxylic species, mainly attributed to different assemblage composition on snags. This suggests that the practise of leaving snags for conservation purposes should be complemented with log supplementation. Clear-cuts supported fewer species and different assemblages from mature managed forests and reserves. Neither abundance, nor species richness or assemblage composition differed between reserves and mature managed forests. This suggests that managed stands subjected to selective cutting, not clear-felling, maintain sufficient old growth characteristics and continuity to maintain more or less intact assemblages of saproxylic beetles. Thus, alternative management methods, e.g., continuity forestry should be considered for some of these stands to maintain continuity and conservation values. Furthermore, the significantly higher estimated abundance per ha of red-listed beetles in reserves underlines the importance of reserves for maintaining viable populations of rare red-listed species and as source areas for saproxylic species in boreal forest landscapes.     

Fungal community dynamics in relation to substrate quality of decaying Norway spruce ( Picea abies [L.] Karst.) logs in boreal forests

Decaying wood plays an important role in forest biodiversity, nutrient cycling and carbon balance. Community structure of wood-inhabiting fungi changes with mass loss of wood, but the relationship between substrate quality and decomposers is poorly understood. This limits the extent to which these ecosystem services can be effectively managed. We studied the fungal community and physico-chemical quality (stage of decay, dimensions, density, moisture, C : N ratio, lignin and water or ethanol extractives) of 543 Norway spruce logs in five unmanaged boreal forest sites of southern Finland. Fungi were identified using denaturing gradient gel electrophoresis and sequencing of DNA extracted directly from wood samples. Macroscopic fruiting bodies were also recorded. Results showed a fungal community succession with decreasing wood density and C : N ratio, and increasing moisture and lignin content. Fungal diversity peaked in the most decayed substrates. Ascomycetes typically colonized recently fallen wood. Brown-rot fungi preferred the intermediate decay stages. White-rot fungi represented approximately one-fifth of sequenced species in all decay phases excluding the final phase, where ectomycorrhizal (ECM) fungi became dominant. Lignin content of logs with white-rot fungi was low, and ECM fungi were associated with substrates containing abundant nitrogen. Macroscopic fruiting bodies were observed for only a small number of species detected with molecular techniques.     

Diversity of saproxylic bryophytes in old‐growth and managed beech forests in the central Balkans

Abstract

The diversity of saproxylic bryophyte species in beech forest stands from the wide region of the central Balkans (i.e. Serbia and Montenegro) was studied, and this study is the first of such a type in SE Europe. Comparison of preserved old‐growth and managed forests were made. Bryophyte species diversity is higher in primeval forest stands where the spectra of dead wood in various decaying stages of its dynamics are present. The ecological group of epixylic specialists is predominant among the bryophytes recorded. Threatened bryophyte species occur in old‐growth beech stands. The dead wood as habitat together with some other factors are extremely important for the surviving of epixylic bryophyte; so these species can be used as bioindicator bryophyte species of old‐growth or managed and structured forest ecosystems.     

A comparison of structural characteristics between old-growth and postfire second-growth hemlock–hardwood forests in Adirondack Park, New York, U. S. A.

1 This study compares the structural characteristics of 12 old‐growth and six postfire second‐growth hemlock–northern hardwood stands in north central Adirondack Park, New York, in order to test the null hypothesis that there are no differences in species composition, size structure, age structure and attributes such as dead wood and canopy gaps between old‐growth stands and this type of second‐growth forest. 2 The second‐growth forests of this study regenerated following widespread logging‐related fires in either 1903 or 1908; the old growth and second growth have similar environmental settings. 3 Estimates of stand ages, derived from an increment core of the oldest tree in each stand, range from 88 to 390 years. 4 Structural attributes are related to stand age (i.e. stage of development). In comparison with the second‐growth forests of this study, older stands are characterized as (a) a larger average diameter of canopy trees; (b) a greater basal area of trees; (c) a lower density of canopy trees and of all trees ≥ 10 cm d.b.h.; (d) a higher density of eastern hemlock (Tsuga canadensis (L.) Carrière) trees; (e) a higher density of large trees (≥ 50 cm d.b.h.); (f) larger canopy gaps; and (g) a greater volume of coarse woody debris (both logs ≥ 20 cm d.b.h. and snags ≥ 10 cm d.b.h.). 5 Despite differences between old growth and second growth, especially in species composition, it appears from observations of the 18 stands that second‐growth forests are developing some structural characteristics of old growth. 6 Structural attributes of the old‐growth forests are similar to characteristics of the same forest type in geographically distant areas in eastern USA.     

Availability of coarse woody debris in a boreal old‐growth Picea abies forest

Abstract. This study reports temporal (based on cross‐dated dead trees) and spatial patterns of availability of coarse woody debris (CWD) from Picea abies in a Swedish boreal landscape with discrete old‐growth forest patches in a wetland matrix. Data were collected from 29 patches ranging in size from 0.3 to 28 ha. A total of 897 dead trees with a minimum diameter of > 15 cm occurred on the 7.2 ha area analysed. The year of death was established for 50% of these trees. CWD volume ranged from 17 to 65 m³/ha for downed logs and from 0.5 to 13 m³/ha for standing snags. CWD of all decay stages and diameter classes occurred abundantly and the probability of finding logs of all decay stages and sizes was very high at the scale of single hectares. Tree mortality differed among 5 yr periods. However, during the last 50 yr no 5 yr period produced less than 3 logs/ha. Decay rates were highly variable among different logs. Logs with soft wood and some wood pieces lost (decay stage 5) died ca. 34 years ago. This suggests a fairly rapid decay in this northern forest. The data indicate a high and continuous availability of CWD of all types. It is likely, therefore, that selection pressures for efficient dispersal among CWD dependent species may not be very high. Consequently, species with narrow habitat demands and/or low dispersal ability may have evolved and this may contribute to the decrease of certain species in the managed landscape.     

It's a long way to the top: Plant species diversity in the transition from managed to old‐growth forests

Questions

Do vascular plant species richness and beta‐diversity differ between managed and structurally complex unmanaged stands? To what extent do species richness and beta‐diversity relate to forest structural attributes and heterogeneity?

Location

Five national parks in central and southern Italy.

Methods

We sampled vascular plant species composition and forest structural attributes in eight unmanaged temperate mesic forest stands dominated or co‐dominated by beech, and in eight comparison stands managed as high forests with similar environmental features. We compared plant species richness, composition and beta‐diversity across pairs of stands (unmanaged vs managed) using GLMM s. Beta‐diversity was quantified both at the scale of each pair of stands using plot‐to‐plot dissimilarity matrices (species turnover), and across the whole data set, considering the distance in the multivariate species space of individual plots from their centroid within the same stand (compositional heterogeneity). We modelled the relationship between species diversity (richness and beta‐diversity) and forest structural heterogeneity and individual structural variables using GLMM s and multiple regression on distance matrices.

Results

Species composition differed significantly between managed and unmanaged stands, but not richness and beta‐diversity. We found weak evidence that plant species richness increased with increasing levels of structural heterogeneity and canopy diversification. At the scale of individual stands, species turnover was explained by different variables in distinct stands, with variables related to deadwood quantity and quality being selected most often. We did not find support for the hypothesis that compositional heterogeneity varies as a function of forest structural characteristics at the scale of the whole data set.

Conclusions

Structurally complex unmanaged stands have a distinct herb layer species composition from that of mature stands in similar environmental conditions. Nevertheless, we did not find significantly higher levels of vascular plant species richness and beta‐diversity in unmanaged stands. Beta‐diversity was related to patterns of deadwood accumulation, while for species richness the evidence that it increases with increasing levels of canopy diversification was weak. These results suggest that emulating natural disturbance, and favouring deadwood accumulation and canopy diversification may benefit some, but not all, facets of plant species diversity in Apennine beech forests.

     

Dendrochronological assessment of the time since death of dead wood in an old growth Magellan's beech forest,Navarino Island (Chile)

The present study investigated the relationship between time since death and the morphological characteristics of fallen dead trees in a Nothofagus betuloides forest stand located on the island of Navarino (Chile). In this unmanaged forest, there were 399 m³ ha^?1 of dead wood, which represented about half of the living tree volume. At the investigation site, 18 living trees were selected and increment cores were collected from them to build master ring‐width chronologies. Cross sections were also collected from 48 fallen dead trees. The samples collected were then assigned to observable decay classes and their death date was determined dendrochronologically. Cross‐dating techniques were used and it was found that the fallen dead trees cross‐dated significantly with standard chronologies. A year of death was successfully determined for 75% of the sampled fallen dead trees. However, this study demonstrated that, in the standard classification, the transition rate from one class of decay to another was highly variable. Furthermore, the inconsistencies found in the decay rates of the fallen dead trees demonstrated that the existing decay classification schemes were unsuitable for this type of forest stand and that the relationship between qualitatively assessed decay classes and the time since death of trees in this extreme environment was rather weak. In addition, the analysis of the time since death, in this old growth forest, was indicative of the persistence of dead wood on the forest floor in austral cold ecosystems and of its contribution to long‐term carbon storage.