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Can 'continuity indicator species' predict species richness or red-listed species of saproxylic beetles?
Abstract and Figures
This study investigates the relationship between the abundance of wood-rotting fungus suggested as 'continuity indicator species' and environmental variables for the assemblage of saproxylic (wood-living) beetles associated with Fomitopsis pinicola fruiting bodies in a mature spruce forest in southeastern Norway. The presence of species thought to indicate continuity in old growth is one of the criteria used when finding and delineating small protected areas ('woodland key habitats') in Scandinavian forestry. Although it is clear that remnants of old-growth forest are important for many taxa, documentation as to which entities or species the indicator species indeed indicate is scarce. If stands with a continuous and unbroken input of dead wood have a unique assemblage of wood-rotting fungi, it seems relevant to ask if these stands also have a unique assemblage of rare saproxylic beetles. I find that the indicator species exhibit no significant correlations with beetle species richness or with the presence of red-listed saproxylic beetles as a group. The different characteristics of dead wood conditions are the most important environmental variables that explain both the species richness and the presence of red-listed beetles. Single-species analyses reveal contrasting relationships. The red-listed beetle Atomaria alpina shows a significant and positive association to the abundance of indicator species. Contrary, a group of three red-listed species with similar ecology in the family Cisidae exhibits a significant and negative association to indicator species abundance. This indicates that important patterns are concealed when considering general measures such as overall presence of red-listed beetles. Single-species studies are necessary in order to correctly understand how rare beetles respond to forestry activities and to develop a policy that can secure their continuing existence in the boreal forest.
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... The invertebrate community associated with F. pinicola fruit bodies has traditionally been investigated by rearing (e.g. Jonsell et al., 1999;Lawrence, 1973;Økland, 1995), use of trunk window traps installed in a cut fruit body (Hågvar & Økland, 1997;Kaila et al., 1994;Økland & Hågvar, 1994;Sverdrup-Thygeson, 2001), or by observations of the hymenium layer (Hågvar, 1999;Nikitsky & Schigel, 2004). The trunk window trap method is valuable but you cannot be sure that the trapped insects actually visited the fruit body. ...
... In our study, P. ferruginea and T. limbatus were the most active invertebrates. These are well known as grazers of the hymenium of wood-decay fungi , but have formerly been recorded in low numbers from trunk window traps installed in cut fruit bodies of F. pinicola (Hågvar & Økland, 1997;Sverdrup-Thygeson, 2001) as well as by direct observations (Hågvar, 1999). The discrepancies between these studies and our results might be due to between-year variation in population densities or the grazing behaviour of these beetles, which could inflate the number of observations on images compared with the number of individuals sampled manually or in traps. ...
... These findings match our observations. Several species that have been recorded in earlier studies were missing from our observations; Epuraea variegata, Henoticus serratus and Cis glabratus were among the most common species observed on F. pinicola by Hågvar (1999), of which E. variegata and C. glabratus have also been trapped in high numbers in trunk window traps (Hågvar & Økland, 1997, Sverdrup-Thygeson, 2001 before July (Burner et al., 2022), indicating that the flight period of most forest beetles is indeed early in the season. For fungusvisiting beetles, this seasonal pattern could also be related to the spore production of F. pinicola, which is largest in spring (Norros et al., 2023;Nuss, 1986). ...
Fungi and invertebrates comprise a major part of biodiversity in dead wood ecosystems and invertebrates depend on fungi to utilise the dead wood resource. Many invertebrates also visit the long‐lived fruit bodies of wood‐decay fungi to feed on spores, the hymenium or other invertebrates. However, as traditional sampling methods are labour‐intensive, we know little of these interactions.
In this study, we use time‐lapse cameras to monitor invertebrates visiting the hymenium of a common wood‐decay fungus, Fomitopsis pinicola , and explain their activity in terms of temporal variation, temperature and presence of Gyrophaena boleti , a highly abundant fungivorous beetle living primarily in fruit bodies of F. pinicola .
The most common invertebrates on F. pinicola fruit bodies were Coleoptera, Araneae, Diptera, Gastropoda and Chilopoda. The invertebrate activity exhibited strong temporal variation with higher abundance during night and, for Coleoptera, earlier in the season. We discuss how this might correlate with the sporulation period of F. pinicola . The presence of G. boleti had a positive impact on the predatory Lordithon lunulatus and Ipidia binotata , and a negative impact on the fungivorous Thymalus limbatus and Peltis ferruginea . Chilopoda and L. lunulatus were ephemeral visitors, while the fungivorous Coleoptera and Araneae stayed the longest.
We estimated the invertebrates' visitation frequency and duration, which would be time‐consuming to obtain with traditional methods. We offer improvements to our method and urge future research on invertebrate–fungus interactions to quantify invertebrate visits to fungal fruit bodies.
... This question is important for the planning of wood-necromass management, as the number of saproxylic beetles are known to increase with the amount of deadwood [6,[46][47][48][49][50][51][52] and wood-inhabiting fungi [23,53,54]. The number of large logs in the late stage of decay, and the constant volume per hectare are the variables that best explain the species richness of this group of beetles [55][56][57] and fungi [54]. With each m 3 of deadwood per hectare, the number of saproxylic beetle and fungal species increases on average by an additional 1.2 species [5]. ...
... Normally, trees are felled at a height just above the ground utilizing the lower part of the trunk to produce wood products. The importance of standing deadwood and its greater impact on biodiversity than that of lying logs, especially in endangered species, is illustrated in many cases [56,69,87,102,103]. They carry the highest number of microhabitats per unit area [104]. ...
Due to traditional forest management, the primary goal of which is the production of raw wood material, commercial forest stands are characterized by low biodiversity. At the same time, commercial forests make up the majority of forests in the Central European region, which means a significant impact on the biodiversity of the entire large region. Saproxylic species of organisms are a frequently used criterion of biodiversity in forests. Based upon the analysis of 155 scientific works, this paper defines the fundamental attributes of the active management supporting biodiversity as well as the preservation of the production function. Using these attributes, a model management proposal was created for three tree species, which takes into account the results of research carried out in the territory of the University Forest Enterprise of the Czech University of Life Sciences Prague, since 2019. The optimum constant volume of deadwood in commercial stands was set at 40–60 m3/ha, 20% of which should be standing deadwood. The time framework is scheduled for an average rotation period of the model tree species, while the location of deadwood and frequency of enrichment must comply with the rate of decomposition, the requirement for the bulkiest dimensions of deadwood possible, and the planned time of tending and regeneration operations in accordance with the models used in the Czech Republic. The goal of active management is to maintain the continuity of suitable habitats for sensitive and endangered species. The estimates of the value of retained wood for decomposition can be as high as 45–70 EUR/ha/year for spruce and beech, and about 30 EUR /ha/year for oak.
... In the present study, bark beetles carried viable spores to fresh spruce logs on the exoskeleton but not in the faeces. Thus, these species might not feed on spores, but obtain them passively from the environment, for instance whilst dwelling in the vicinity of F. pinicola sporocarps, like Dryocoetes autographus is known to do (Hågvar and Økland 1997;Sverdrup-Thygeson 2001). This beetle has also been reported to be specifically attracted to wood colonized by F. rosea (Johansson et al., 2006), while similar specificity has been shown for other beetles attracted to beech logs inoculated with different fungal species (Leather et al., 2014). ...
Wood decay fungi are considered to be dispersed by wind, but dispersal by animals may also be important, and more so in managed forests where dead wood is scarce. We investigated whether beetles could disperse spores of the keystone species Fomitopsis pinicola. Beetles were collected on sporocarps and newly felled spruce logs, a favourable habitat for spore deposition. Viable spores (and successful germination) of F. pinicola were detected by dikaryotization of monokaryotic bait mycelium from beetle samples. Viable spores were on the exoskeleton and in the faeces of all beetles collected from sporulating sporocarps. On fresh spruce logs, nine beetle species transported viable spores, of which several bore into the bark. Our results demonstrate that beetles can provide directed dispersal of wood decay fungi. Potentially, it could contribute to a higher persistence of some species in fragmented forests where spore deposition by wind on dead wood is less likely.
... Deadwood is crucial because it contributes enormously to forest biodiversity (Dudley and Vallauri, 2005;Graf et al., 2022). In particular, standing deadwood hosts more saproxylic beetle species than fallen deadwood (Sverdrup-Thygeson, 2001;Bouget et al., 2012). Saproxylic beetles are the most studied forest organisms (Seibold et al., 2015b), as they are considered bioindicators of the state of the forest environment (Zumr and Reme s, 2020) and are dependent on deadwood of any development stage or type (Speight, 1989;Jaworski et al., 2019). ...
The natural composition of forests has undergone significant changes over recent centuries. A closer-to-natural tree species composition has long been perceived as key to a high biodiversity. We investigated the impact on communities of click beetles (Elateridae) caused by changes in the tree species composition of spruce monocultures compared to reference sites of recently unmanaged natural beech forests. To collect data, passive interception traps were distributed within managed spruce stands of different age classes and natural beech forests of various developmental stages. The beetle species richness was slightly but not significantly higher in the beech forests. The saproxylic species group was significantly more common in the spruce stands, whereas the group of nonsaproxylic species was significantly more abundant in the beech stands. In the commercial stands, the significantly highest species richness was in the clearings (0–10-year-old stands), and at this forest age class, the vast majority of the beetle species occurred in the spruce stands. In the developmental stages of the natural forest, a slightly higher beetle richness was found at the disintegration stage. The study results suggested that different tree species compositions and stand structures affect the communities of click beetles and substantially change their species composition and thus their response to external influences. Therefore, management of stands using diverse silvicultural systems is recommended for creating diverse ecological niches in forests.
... Large logs volume has been pointed out as a key parameter for saproxylic species (e.g. Økland et al. 1996, Sverdrup-Thygeson 2001, Lachat et al. 2012) and is a commonly used indicator for sustainable forest management (Forest Europe, UNECE and FAO 2011). stated that the amount and diversity of dead wood are usually correlated and consequently that it may be difficult to disentangle their relative influence. ...
Dans un contexte de changement climatique, des dispositifs sont mis en place par les politiques publiques pour permettre le déplacement de la biodiversité et la recolonisation de nouveaux milieux (TVB, trame de vieux bois. . . ). Ces dispositifs semblent adaptés pour les espèces animales les plus mobiles. Or, les espèces ayant une faible capacité de déplacement représentent un enjeu important pour l'efficacité des dispositifs mis en place. Un grand nombre de ces espèces demeurent aujourd'hui mal connues. En forêt, les coléoptères saproxyliques aptères de litière sont des espèces ayant des capacités de déplacement et de dispersion limitées en raison de leurs petites tailles, de leurs aptérismes et de leurs exigences trophiques. Ces espèces constituent le modèle biologique de cette étude pour comprendre comment des espèces à faible capacité de déplacement peuvent évoluer dans les forêts et les paysages anthropisés, dans l'espace et le temps. L'échantillonnage par tamisage de litière de dix arbres par peuplement en utilisant un Winkler et une extraction par Berlese, a montré une puissance d'échantillonnage moyenne de 97.2% pour six forêts. Des relevés mensuels sur deux ans ont permis de caractériser la phénologie des espèces, à savoir qu'elles sont i/ présentes dans la litière toute l'année, ii/ davantage abondantes au printemps et en automne et iii/ ne présentent pas de variation interannuelle. Nous avons comparé la richesse spécique et la répartition des espèces, entre les forêts subnaturelles et les peuplements exploités des montagnes Pyrénéennes. Ceci a montré que les espèces sont peu impactées par l'exploitation sylvicole traditionnelle, mais présentent une grande variabilité de répartition qui semble liée à l'impact anthropique passé. Le paysage fragmenté des Coteaux de Gascogne s'est avéré être très pauvre en coléoptères saproxyliques aptères. Étonnamment, dans ce territoire, les répartitions des espèces sont mieux expliquées par les caractéristiques des paysages que celles des forêts. Pour la moitié des espèces, leurs répartitions sont mieux expliquées par la composition du paysage en 1850 que celle d'aujourd'hui. Un seuil critique de 15% de proportion de forêts dans le paysage en 1850 a pu être mis en évidence pour une espèce (Dienerella clathrata). Nous avons montré que les espèces sont capables (au moins) de se déplacer à travers les haies, quelles que soient les caractéristiques de ces dernières. Si les espèces étaient présentes dans la forêt connectée à la haie, elles ont été échantillonnées dans cette dernière. Les capacités de déplacement de trois espèces ont été étudiées en laboratoire et montrent une vitesse moyenne de 1,6m.h-1. Ces deux éléments conrment le fait que ces espèces sont mobiles dans le paysage. L'ensemble de ces résultats, ainsi que le fait que les territoires les moins anthropisés soient les plus riches en coléoptères saproxyliques aptères, nous amènent à conclure que ce groupe taxonomique supporte bien les impacts humains de faible amplitude spatiale et temporelle, mais qu'ils sont peu résilients à une anthropisation importante dans le temps et dans l'espace.
... Advanced-decay deadwood volume also favours the local diversity of small mammals (Fauteux et al., 2013). The availability of large logs in advanced decay is known to affect many rare species of saproxylic beetles (Sverdrup-Thygeson, 2001). ...
In this study we analysed a dataset of 8661 logs of silver fir (Abies alba Mill.) and Norway spruce (Picea abies L., Karst) in mixed fir-spruce-beech stands in primeval and natural forests in four sites separated into the two macroclimatic categories according to mean annual temperature ("cold" and "warmer") and according to mean annual precipitation ("mesic" and "humid"). We used "Bayesian Survival Trajectory Analysis" on a more than 40-year long time series (1972-2015), focusing on differences in the residence time of deadwood in different macroclimatic categories and two DBH classes. We also evaluated two qualitative characteristics of the downed logs: mortality mode and log position during decomposition. We calculated residence time and the time needed to reach the advanced decay stage. Our analyses confirmed the influence temperature and precipitation on modelled residence time. The residence time for silver fir logs in the DBH class 55+ cm in the "cold" site was 106 years, while in the "warmer" sites was 78 years. The residence time in the "mesic" site was 57 years, while in the "humid" sites was 90 years. It took 81 years for Norway spruce logs in the DBH class 55+ cm to completely decompose in the "cold" site. Suspended logs 11 took years longer to decay than those in contact with the ground. The modelled residence time of logs on wet sites was the same as that of logs at sites unaffected by water. These results can be utilised in biodiversity oriented forest management, as well as in modelling future amounts of deadwood. In order to maintain the continuous presence of silver fir and Norway spruce deadwood for those organisms that depend on it, it is necessary to supply deadwood at least once every 25-40 years (depending on climatic category and DBH class). During this time, approximately 50% of logs become completely decomposed and 50% remain in the last decay stage.
... With a dependency on the same habitat type it would be expectable to find less deviating patterns in species composition and richness among saproxylic organisms, and it would ease management of dead wood for biodiversity, if this appears to be the case, so that a single easily surveyed group of organism could guide conservation initiatives. found species richness of wood decaying fungi and saproxylic beetles to be highly correlated in northern Sweden, while Sverdrup-Thygeson (2001) in contrast found that selected, wood rotting fungi suggested to be indicative of forest continuity, were unsuited as indicators of species richness and presence of red-listed species of saproxylic beetles associated with the polypore Fomitopsis pinicola in southern Norway. We know of few studies evaluating similar relations between wood inhabiting fungi and bryophytes. ...
... The cause for higher species richness and larger variety of specialists may also be the emergence of special microhabitat types confined to late successional phases or larger diversity of different microhabitats. This is due to the absence of large-scale disturbances, which promotes the time-demanding development of these resources (Tibell, 1992;Sverdrup-Thygeson, 2001;Winter and Möller, 2008). Landscape level continuity, on the other hand, refers to a network of available habitat patches within a given region or landscape over time (Fritz et al., 2008;Hanski, 2005;Nordén et al., 2014). ...
Human-induced fragmentation affects forest continuity, i.e. availability of a suitable habitat for the target species over a time period. The dependence of wood-inhabiting fungi on landscape level continuity has been well demonstrated, but the importance of local continuity has remained controversial. In this study, we explored the effects of local forest continuity (microhabitat and stand level) on the diversity of wood-inhabiting fungi on standing dead trunks of Scots pine (Pinus sylvestris L.). We studied species richness and community composition of decomposers and Micarea lichens on 70 trunks in 14 forests in central Finland that differed in their state of continuity. We used dendrochronological methods to assess the detailed history of each study trunk, i.e. the microhabitat continuity. The stand continuity was estimated as dead wood diversity and past management intensity (number of stumps). We recorded 107 species (91 decomposers, 16 Micarea lichens), with a total of 510 occurrences. Using generalized linear mixed models, we found that none of the variables explained decomposer species richness, but that Micarea species richness was positively dependent on the time since tree death. Dead wood diversity was the most important variable determining the composition of decomposer communities. For Micarea lichens, the community composition was best explained by the combined effect of years from death, site and dead wood diversity. However, these effects were rather tentative. The results are in line with those of previous studies suggesting the restricted significance of local forest continuity for wood-inhabiting fungi. However, standing dead pines that have been available continuously over long periods seem to be important for species-rich communities of Micarea lichens. Rare specialists (e.g. on veteran trees) may be more sensitive to local continuity, and should be at the center of future research.
ABSTRACT: Ericulture once confined to the hilly, tribal districts of North Eastern Region of India
has spread to several other states including the state of Telangana. The size of land holdings
possessed by small and marginal farmers in the state of Telangana is much below the minimum
economically viable sizes. Hence, rainfed castor farming in Telangana has been diversified into eri
silkworm cocoon production which ensures additional income and family employment during crop
leisure period. In this regard, eight castor genotypes were subjected to four defoliation levels viz.,
30%, 40% and 50% along with control (no defoliation). Significantly no deviation was observed in
seed yield from non defoliation plot and 30% defoliated plants. At 50% defoliation on an average,
the yield gap was more than 15% in all most all the genotypes. The batch of eri silkworms reared
on the leaves of PCH-111 recorded significantly the highest shell yield of 15.5 kg/ha followed by
GCH-4 (14.9 kg/ha) and PCH-222 (14.8 kg/ha). If the castor crop is grown for the seed purpose
alone, the gross returns and net profit was highest with PCH-111 (Rs. 45,600 and 30,640/-)
followed by PCH-222 (Rs. 44,832 and 29,872/-). By utilizing the 30% defoliated leaf for eri silkworm
rearing, significantly more gross returns and net profit was recorded with PCH-111 (Rs. 8525 and
6007.5/-), GCH-4 (Rs. 8195 and 5867.5/-) and PCH-222 (Rs. 8140 and 5765/-). That means, these
genotypes are suitable both for seed production and eri silkworm rearing. On an average all most
all the genotypes recorded Rs. 5,500/- per hectare in addition to the regular seed yield. Significantly
higher CB ratio was observed with PCH-111 (1:3.95), PCH-222 (1:3.72) and GCH-4 (1:3.05) while
the CB ratio was least with DCH-177 (1:2.32). Hence, from the above results it is very clear that
castor plants were able to completely regrow its leaf area when the 30% defoliation occurred during
the crop stage without any influence on the seed yield and defoliation beyond this level caused a
reduction in the seed yield. That 30% defoliated leaf can be utilized for growing eri silkworms and
can get an additional income of Rs. 3000/- acre. However, by utilizing PCH-111, PCH-222 and
GCH-4 genotypes farmers can reap higher gross and net returns with more CB ratio.
The massive diversity of insects in forests reflects the elaborate structure of the environment, the persistence and complexity of these botanically diverse systems, and long histories of evolutionary associations. Quantifying that diversity and the patterns of its variation, series of surveys in several parts of the world have confirmed both high insect species richness and the difficulties of ecological interpretation, not least because of taxonomic inadequacy with many species undescribed. The roles of locally trained parataxonomists for inventory surveys of forest insects (Basset et al. 2004) may be important contributions to increasing understanding of diversity and its trajectories in relation to forest condition and management. Those surveys have progressively enabled extrapolations from limited samples to incorporate the full range of host tree species present, as the template that could in due course lead to estimations of impacts from forest changes. Comparisons between intact forest and forests modified in various ways provide evidence of impacts of imposed changes, as bases for conservation concern and possible reaction by changed management or level of protection.
A trapping method for collecting quantitative samples of insects, especially beetles (Coleoptera) associated with decaying wood or wood fungi, is described. The trap is a modification of the window flight trap, attached to dead tree trunks, preferably close to the basidiocarps of polypores. Sampling during the summer of 1990 in southern Finland showed that large numbers of insects living in decaying wood or polypores can be caught with this method without destroying the habitat. Several threatened species were found during this sampling.
Rearing yielded 23 species. Few species were reared from more than one of the stages, indicating a pronounced fauna succession in the carpophores. Highest diversity was found in the dead carpophores. Four species seem to be clearly associated with F. pinicola, while the majority is described from other habitats. Four Diptera and three Hymenoptera species are new to Norway. The long species list in the carpophore traps indicate a high activity of insects close to the carpophores. Gyrophaena boleti was exclusively observed under living carpophores with opened hymenium, and moisture of between 28-100%, while this restriction was not demonstrated in the carpophore traps, in which this species also occurred in the other stages of the carpophores. Thus, stimuli from direct or close contact with the substrate appears to be a major factor in host selection. -from Authors
A high trapping efficiency was found both for window traps and trunk-window traps, while the efficiency of extraction cylinders was low. Trunk-window traps are suitable for comparison of different substrates within the same forest environment, while comparative studies of different forest environments are more difficult, due to baiting effects. Window trap captures are more suitable for comparing different forest environments, but are related to ecological conditions over wide areas, and are almost unaffected by substrate conditions in the near surroundings of the traps.
We studied the spatial distribution pattern of Bolitophagus reticulatus L. Coleoptera, Tenebrionidae) in a boreal forest in south-eastern Norway. The beetle is monophagous and lives in basidiocarps of Fomes fomentarius (L.) Kickx. We collected 900 basidiocarps from all of the 452 birch trees infected with tinder fungus in the 225 ha study area. We then used logistic regression analyses to relate trees with and without beetle occurrence to patch size, isolation and other habitat characteristics. To understand why the beetle had disappeared from certain trees, we also did similar analyses on trees without present occurrence but with signs of earlier beetle presence versus trees with present occurrence of the beetle. The probability of B. reticulatus presence increased with tree diameter and with the number of dead basidiocarps on the tree. We interpret these variables as indicating the habitat patch size. The probability of beetle presence decreased as the distance to surrounding inhabited trees increased, even on a scale of less than one hundred meters. The fungus-infected trees were utilized to a much higher degree when they occurred in clusters. We discuss to what degree a metapopulation model is relevant in our case. Several other, less common forest insects depend on wood-rotting fungi or dead wood for their survival. If a similar response to increased isolation of habitat patches can be assumed for some of the rare species, guidelines for an ecologically sustainable forestry should include not only the need for more dead wood in the modern forest, but should also consider the spatial distribution of these key resources.