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1.
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.  相似文献   

2.
Modern forestry management has reduced the amount of dead wood in forest ecosystems and this has become a serious threat to flora and fauna. Efforts are therefore being made to reverse this trend but one problem is that we still lack detailed knowledge regarding the substrate requirements of many saproxylic species. In a field experiment, conducted in three forest types (forest reserve, mature managed forest and clear-cut), we evaluated the value, from a conservation perspective, of different substrate types (logs, snags and tops) of Norway Spruce, Picea abies, and if the quality of spruce logs as saproxylic habitats can be improved by simple log treatments (scorching and shading). We collected 9982 individuals representing 262 saproxylic beetle species in window traps. Both substrate type and, to a lesser extent, log treatment had a significant effect on the abundance and species richness of saproxylic beetles attracted to the different dead wood substrates. However, more importantly, the composition of the beetle assemblages differed significantly between both substrates and log treatments. Snags, logs and tops all attracted significantly different beetle assemblages and scorched logs differed from untreated control logs. Sixteen red listed species were trapped, with the highest number (11 species) being found on scorched logs. We found strong evidence that some species preferred a specific substrate type, mainly logs, in some cases treated logs (scorched or shaded), but not snags, the substrate commonly provided for conservation purposes on e.g. clear-cuts. This stresses the importance of conducting forestry in such a way that a multitude of both forest habitats and dead wood substrates are available continuously in the forest landscape to maintain biodiversity.  相似文献   

3.
Species belonging to higher trophic levels are particularly vulnerable to habitat loss and consequential host population declines, but detection of effects depends on observation scale. We investigated the effects of habitat and host availability at multiple scales on parasitoids of early successional saproxylic beetles in middle boreal Sweden, where forestry has led to habitat fragmentation and coarse woody debris (CWD) loss. Parasitoid wasps and beetle hosts were collected from nine locations, each containing three spruce-dominated stand types (clear-cut, mature managed and unmanaged stands), using emergence traps on experimental CWD. We measured local CWD volumes and determined the availability of forests of a suitable age within the landscape. We tested parasitoid responses to stand type, CWD volume, abundance of known and probable hosts and longitude. Additionally, we tested whether parasitoids responded to the area of habitat of a suitable age within radii from 0.2 to 10 km. Stand type appeared in best-fit models for all common species, suggesting that wasps respond strongly to habitat at local scales. Longitude (largely climate) featured commonly, but CWD volume was never significant. Host abundance appeared in best-fit models for three of five common species, proving significant only for Bracon obscurator, the abundance of which correlated with that of Orthotomicus laricis at both trap and site levels. Rhimphoctona spp. also correlated significantly with its known host Tetropium castaneum at the trap level. B. obscurator responded to habitat area at scales of 0.6–1 km and Cosmophorus regius responded at radii greater than 7 km, while the larger species did not respond strongly to habitat area. The role of habitat area at greater scales thus varied greatly amongst species, but our data suggest that dispersal of these common early successional species may not be strongly restricted at the current scale of fragmentation of their boreal habitats.  相似文献   

4.
  1. A 2‐year study of litter dwelling beetles was conducted in different mature pine stands and clear‐cuts in Lithuania using the litter sifting method. We hypothesized that clear‐cutting and subsequent ploughing would increase species diversity and the abundance of beetles, and also would encourage the immediate appearance of early‐successional beetle species replacing late successional species in the clear‐cuts.
  2. We did not confirm a hypothesis regarding increase in the number of species and abundance of beetles in clear‐cuts.
  3. Our hypothesis regarding the immediate appearance of early successional species and disappearance of late‐successional species in clear‐cuts was confirmed.
  4. We also revealed that subsequent soil ploughing in clear‐cuts did not accelerate this process, which was linked to the possibility of late successional species surviving in the undisturbed spaces between the strips of ploughed soil.
  5. The present study shows that late‐successional forest litter‐dwelling coleopteran species of old pine forests have a better chance of survival in a ploughed clear‐cut, at least in northern Europe, than has been reported in other studies.
  相似文献   

5.
1 Saproxylic insects, a functional group dominated by beetles, are dependent on dead or moribund trees as habitat elements. 2 Although there are few studies of saproxylic insects from the North American boreal zone, European studies demonstrate that forest harvest can lead to a biologically significant decrease in saproxylic beetle diversity. 3 We studied saproxylic beetles in the North American boreal mixedwood forest using flight intercept traps established on naturally dead and girdled trembling aspen and spruce trees along a successional gradient of undisturbed stands from deciduous to coniferous overstory trees. 4 Composition and diversity of beetle assemblages differed among forest successional types. 5 Snag age class was an important determinant of composition for saproxylic beetle assemblages. 6 Multivariate regression analysis of these data indicated that saproxylic beetles are responding to changes in coarse woody debris, and not to the relative densities of canopy tree species, although these variables are strongly correlated. 7 Coarse woody debris management should be a primary concern in forest management plans seeking to conserve saproxylic organisms and the critical ecosystem functions (i.e. nutrient cycling) in which they participate.  相似文献   

6.
The increasing demand for biofuels from logging residues require serious attention on the importance of dead wood substrates on clear-cuts for the many forestry-intolerant saproxylic (wood-inhabiting) species. In particular, the emerging harvest of low stumps motivates further study of these substrates. On ten clear-cuts we compared the species richness, abundance and species composition of saproxylic beetles hatching from four to nine year old low stumps, high stumps and logs of Norway spruce. By using emergence traps we collected a total of 2,670 saproxylic beetles among 195 species during the summers of 2006, 2007 and 2009. We found that the species assemblages differed significantly between high stumps and logs all three years. The species assemblages of low stumps, on the other hand, were intermediate to those found in logs and high stumps. There were also significant difference in species richness between the three examined years, and we found significant effect of substrate type on richness of predators and fungivores. As shown in previous studies of low stumps on clear-cuts they can sustain large numbers of different saproxylic beetles, including red-listed species. Our study does, in addition to this fact, highlight a possible problem in creating just one type of substrate as a tool for conservation in forestry. Species assemblages in high stumps did not differ significantly from those found in low stumps. Instead logs, which constitute a scarcer substrate type on clear-cuts, provided habitat for a more distinct assemblage of saproxylic species than high stumps. It can therefore be questioned whether high stumps are an optimal tool for nature conservation in clear-cutting forestry. Our results also indicate that low stumps constitute an equally important substrate as high stumps and logs, and we therefore suggest that stump harvesting is done after carefully evaluating measures to provide habitat for saproxylic organisms.  相似文献   

7.
8.
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.  相似文献   

9.
Many protected areas have a long history of human intervention before being protected. In protected forests, the past land use has reduced the amount of natural structures, which are crucial substrates for thousands of species. We evaluate the short-term ecological effect of forest restoration (dead wood creation) on conifer-associated saproxylic (dead-wood dependent) beetles. More specifically, we analyze the effect of dead wood creation on the number of beetle species and individuals 1 and 5 years after restoration in spruce and pine forests, using a large-scale monitoring network over Finland. The number of saproxylic beetle species and individuals was larger at restored than at control plots both 1 and 5 years after restoration in both spruce and pine forests. Community composition in restored plots was different from control plots 1 year after restoration, but had returned towards the control plot composition 5 years after restoration, while control plots remained largely unchanged. Both in spruce and pine forests, there were more red-listed and rare saproxylic beetles in restored than in control plots 1 and 5 years after restoration. Our results indicate that restoration has an overall positive influence on saproxylic beetle diversity immediately after dead wood creation, but this effect is rather short-lived. Long term monitoring of restored dead wood is crucial in investigating successional pathways as well as biotic communities in advanced decay stages, and in fully evaluating the ecological effect of dead wood creation as a forest restoration measure.  相似文献   

10.
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.  相似文献   

11.
Abstract

The fundamental ecological significance of deadwood decomposition in forests has been highlighted in several reviews, some conclusions regarding silviculture being drawn. Old‐growth forests are natural centres of biodiversity. Saproxylic fungi and beetles, which are vital components of these ecosystems, occupy a variety of spatial and trophic niches. Fungal and beetle diversity on coarse woody debris (CWD) was analysed in 36 forest sites in the Cilento and Vallo di Diano National Park, Italy. The data were analysed by DCA and Spearman’s rank correlation. The results provide empirical evidence of the existence of a pattern of joint colonization of the woody substrate by fungi and beetles, which includes an assemblage of reciprocal trophic roles within fungal/beetle communities. These organisms act together to form a dynamic taxonomical and functional ecosystem component within the complex set of processes involved in wood decay. The variables most predictive of correlations between management‐related structural attributes and fungal/beetle species richness and their trophic roles for old‐growth forest are: number of logs, number of decay classes and CWD total volume. Deadwood spatio‐temporal continuity should be the main objective of forest planning to stop the loss of saproxylic fungal and insect biodiversity.  相似文献   

12.
吴捷  潘卉  杨淑贞  牛晓玲 《昆虫学报》2013,56(2):173-185
不合理的森林管理是导致腐木甲虫多样性丧失的重要原因。在中国亚热带地区, 多样性较高的天然林已被大面积的人工种植林取代, 然而, 这些人工林对腐木甲虫多样性的影响还研究甚少。本研究对浙江天目山自然保护区人工幼龄林(30~40年)、 人工老熟林(80~100年)和半天然混合林(>200年)中柳杉枯立木上的腐木甲虫群落及多样性进行比较。结果表明: 半天然混合林腐木甲虫个体数量(97.4±66.7)显著高于幼龄林(39.9±16.3)和老熟林(21.9±5.9), 但半天然林混合林(27.9±11.2)与幼龄林(24.1±3.7)腐木甲虫物种数差异并不显著(P>0.05), 而幼龄林的腐木甲虫物种数和个体数量则显著高于老熟林(P<0.05)。腐木甲虫物种数和个体数量与样地粗死木残体体积相关性显著(P<0.05)。典范对应分析和多响应置换过程分析表明腐木甲虫群落特征在不同林型间差异显著(P<0.001)。柳杉枯立木直径、 粗死木残体的直径和数量以及林冠盖度均对腐木甲虫物种组成具有显著影响(P<0.05)。腐木甲虫营养级组成分析也表明, 半天然混合林菌食性甲虫数量显著高于种植林(P<0.001)。结果提示, 提高种植林粗死木残体的数量和质量可以增加腐木甲虫的物种丰富度, 但种植林腐木甲虫多样性可能在随后的演替阶段有所下降, 而且种植林与天然林在腐木甲虫群落组成上差异十分明显。  相似文献   

13.
Artificially created high-stumps (snags) are created regularly during forest felling operations in Swedish coniferous production forests. The saproxylic beetle fauna in high-stumps of spruce and birch, on 20 clearcuts in Southern Sweden, were sampled by bark sieving. Ten of the clearcuts were located in hotspot areas with documented occurrence of many red-listed saproxylic beetle species. The other ten clearcuts were located in a typical production forest landscape (i.e. the matrix). Our aim was to investigate whether the benefit of creating high-stumps differs if the clearcuts is located in a hotspot area or in the matrix. In total 4,179 saproxylic beetles were found, belonging to 66 species, 9 of which were red-listed. Birch high-stumps hosted more species, on average, than spruce high-stumps. In an ordination analysis, tree species had the strongest explanatory effect among the environmental variables. No difference in beetle fauna could be found between the hotspot and matrix clearcuts, for neither birch nor spruce, according to all parameters: species numbers, species composition and red-listed species. The study does not indicate that conservation efforts in coniferous production forests should be concentrated to hotspot areas.  相似文献   

14.
Deadwood is widely recognized to be an important issue for biodiversity conservation in forest ecosystems. Establishing guidelines for its management requires a better understanding of relationships between woody debris characteristics and associated species assemblages. Although deadwood diameter has been identified as an important factor predicting occurrence of many saproxylic species, the boundary between small and large diameter has not yet been precisely defined. In commercial forests, it is also of critical importance to know which diameter is large enough to host the beetle species associated with large logs in order to ensure cost-effectiveness of biodiversity conservation measures. We investigated the differences in saproxylic beetle assemblages among four different diameter classes of downed woody oak and maritime pine debris, in France. Beetles were sampled using in situ emergence traps. The diameter of deadwood pieces ranged from 1 to 40 cm. No patterns of nestedness associated with the gradient of diameter size were identified for either tree species. More indicator saproxylic species were observed in large logs and branches than in small logs. A clear distinction appeared in assemblage composition around the 5-cm diameter threshold whereas no similar pattern occurred around the 10 cm value, i.e. the classical threshold used in forestry to distinguish fine woody debris from coarse woody debris. For both tree species, the mean body length of beetles increased with the diameter of deadwood suggesting that the quantity of available resources per piece may constitute a limiting factor for large beetle species. This study confirms that not only large deadwood pieces are relevant for saproxylic biodiversity conservation but also the smallest pieces. Therefore, forest managers would be well advised to maintain a high diversity of deadwoods to maintain saproxylic biodiversity.  相似文献   

15.
Dead wood is a habitat for many insects and other small animals, some of which may be rare or endangered and in need of effective protection. In this paper, saproxylic beetle assemblages associated with different host trees in the subtropical forests in southwestern China were investigated. A total of 277 species (1 439 specimens) in 36 beetle families were collected from 117 dead wood samples, of which 101 samples were identified and respectively belonged to 12 tree genera. The number of saproxylic beetle species varied greatly among logs of different tree genera, with the highest diversity on logs of Juglans. Generally, broad‐leaved trees had a higher richness and abundance of saproxylic species than coniferous trees. Cluster analysis revealed that assemblages from broad‐leaved tree genera were generally similar (except for Betula) and assemblages from coniferous trees formed another distinct cluster. The subsequent indicator analysis proposed that there are different characteristic species for different cluster groups of host tree genera. In our study, log diameter has no positive influence on beetle species density. Conversely, comparisons of individual‐based rarefaction curves suggested that beetle species richness was highest in the small diameter class both in coniferous and broad‐leaved tree genera. With increased wood decay, proportion of habitat specialists (saproxylic beetles living on one tree genus) decreased, whereas proportion of habitat generalists (living on more than three tree genera) increased. The beetle species density was found to be higher in early stages, and decreased in later stages as well. A negative influence of altitude on saproxylic beetle species richness and abundance was detected. It was indicated that different tree genera and altitudes possibly display cross effects in modulating the altitudinal distribution and host preference of the beetles.  相似文献   

16.
The decrease of old deciduous trees in northern Europe is a threat to the saproxylic fauna. In northern Europe, oak sustains the highest richness of saproxylic invertebrates, among which beetles is a large group. In order to preserve species associated with old trees, it has become common practice in commercial forestry to retain such trees at final felling. However, to create beneficial conditions for species associated with retained trees, the surrounding plantation has to be managed with regard to their specific demands. In the case of oak-associated species, including many red-listed species, several studies have shown that light is an important factor. The aim of this study was to analyze the effects of increased openness around oaks (Quercus robur) in spruce plantations (Picea abies) on species richness and abundance of oak-associated saproxylic beetles. The study was performed in nine spruce plantations located in southern Sweden, with mature oaks standing in a gradient of canopy openness. Beetles were collected from 54 oaks from May to September during two seasons, using window traps. The analyses revealed that increased openness around oaks increases species richness and abundance of oak-associated beetles. By including insolation angle in the analysis, we found that it is mainly the degree of openness directed south from the oak that has positive effects on beetle richness. These findings imply that it is desirable to maintain an open area around retained oaks, and that this area should be placed on the southern side of the oak to maximize the biodiversity benefit in relation to costs for the forest owner.  相似文献   

17.
Effective fire suppression in combination with intensive forestry has caused a large number of dead wood‐dependent (saproxylic) species to become threatened in Fennoscandia. In order to return the fire disturbance dynamics and to increase the amount of dead wood, restoration actions are urgently needed. We studied the effects of restoring young (under 30 years old) pine‐dominated (Pinus sylvestris L.) forest stands on saproxylic beetle assemblages in eastern Finland, focusing especially on rare, red‐listed, and pyrophilous (RRLP) species. Our experiment included a restoration treatment including two tree felling levels for fuel load (10 or 20 m3/ha) followed by burning, and an untreated control. We sampled beetles before restoration in 2005, during the year of restoration in 2006, and in two post‐treatment years in 2007 and 2011. Both restoration treatments increased the number of saproxylic and RRLP species. The species richness increased most in the year of restoration in 2006 and this trend continued in the following year 2007, but no differences in species assemblages were detected between the two fuel load levels. By 2011, however, the species richness and abundance had declined back to the pre‐treatment level. We suggest that restoration burning can also be directed to young forests where biodiversity values are initially low. On the basis of the observed decline in the species richness, we suggest that fire could be introduced in neighboring areas in approximately 5‐year intervals to maintain populations of the most demanding pyrophilous species .  相似文献   

18.
19.
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.  相似文献   

20.
Many paddy fields in the mountainous rural areas of Japan have been abandoned since the 1960s, and forests have regenerated on these sites. In a mountainous area on Sado Island, a large number of abandoned paddies were converted into wetlands and open terrestrial vegetation. In this study, we used pitfall traps to examine the effects of the creation of open vegetation on carabid beetle assemblages by investigating 14 sites spanning five vegetation types: six sites in secondary forests (three coppice forests and three 40‐year‐old regenerating forests on abandoned paddies), three each in clear‐cuts and paddy levees, and two in grasslands. The 14 study sites were clearly separated into two groups different in the species composition of carabid beetles: secondary forest and grassland‐levee groups. The species composition of two clear‐cut sites was similar to that of secondary forests, whereas that of the remaining one clear‐cut site was similar to that of grasslands. Analyses of species responses showed various habitat preferences, e.g., for only coppice forests, for two types of secondary forests, for secondary forests and clear‐cuts, for clear‐cuts and grasslands, and for grasslands or levees, or no clear preference. There were no characteristic species in the regenerating forests. These results suggest that the 40‐year‐old regenerating forests may sustain only a limited subset of the carabid fauna found in coppice forests and that the creation of open vegetation in the abandoned paddies enhances carabid diversity at the landscape level by raising β diversity among the different vegetation types.  相似文献   

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