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Forest ecosystems are important for biodiversity conservation and human societies, but are under pressure due to climate change and human interventions. This applies to natural forests as well as tree plantations. The latter are globally widespread and therefore gaining increasing importance for biodiversity conservation. However, even after dieback due to increasing disturbance frequencies, such plantations are primarily managed for economic returns, leading to growing conflicts among stakeholders. In particular, the impact of forest management on biodiversity is being discussed. This study investigates the effects of five management approaches in a landscape severely affected by spruce (Picea abies L.) dieback on beetle diversity, conservation, and community composition. We considered direct effects of management and indirect effects of environmental parameters separately in ground-dwelling and flight-active beetles. Beetle diversity was strongly affected by forest management, with non-intervention deadwood stands being most beneficial for beetles. In addition, we show indirect effects of environmental factors. In general, parameters related to salvage logging (e.g. open canopies, tree stumps) influenced beetle diversity and conservation negatively, while positive effects were found for soil nutrient availability and plant species richness. Community composition differed strongly among management categories and indicated a lack of landscape connectivity for open habitat species, as we found only low proportions of such species even on salvage-logged sites. We propose a mixture of management approaches after bark beetle outbreaks, including a substantial proportion of non-intervention deadwood stands, to increase landscape heterogeneity and connectivity. This may increase overall biodiversity while addressing the concerns of both forestry and species conservation.

Background Rapid climate changes lead to an increase in forest disturbance, which in turn lead to growing concerns for biodiversity. While saproxylic beetles are relevant indicators for studying different aspects of biodiversity, most are smaller than 2 ​mm and difficult to sample. This, together with a high number of species and trophic roles, make their study remarkably challenging, time-consuming, and expensive. The Landsat mission provides data since 1984 and represents a powerful tool in this scenario. While we believe that remote sensing data cannot replace on-site sampling and analysis, in this study we aim to prove that the Landsat Time Series (TS) may support the identification of insects’ hotspots and consequently guide the selection of areas where to concentrate field analysis. Methods With this aim, we constructed a Landsat-derived NDVI TS (1984–2020) and we summarised the NDVI trend over time by calculating eight Temporal Metrics (TMs) among which four resulted particularly successful in predicting the amount of saproxylic insects: (i) the slope of the regression line obtained by linear interpolating the NDVI values over time; (ii) the Root Mean Square Error (RMSE) between the regression line and the NDVI TS; (iii) the median, and the (iv) minimum values of the NDVI TS. The study area consists of four monitoring sectors in a Mediterranean-managed beech forest located in the Apennines (Molise, Italy), where 60 window flight traps for flying beetles were installed. First, the saproxylic beetle's biodiversities of monitoring sectors were quantified in terms of species richness and alpha-diversity. Second, the capability of TMs in predicting the richness of saproxylic beetles family and trophic categories was assessed in terms of Pearson's product-moment correlation. Results The alpha diversity and species richness analysis indicate dissimilarities across the four monitored sectors (Shannon and Simpson's index ranging between 0.67 to 2.31 and 0.69 to 0.88, respectively), with Landsat TS resulting in effective predictors for estimating saproxylic beetle richness. The strongest correlation was reached between the Monotomidae family and the RMSE temporal metric (R ​= ​0.66). The mean absolute correlation (r) between the NDVI TMs and the saproxylic community was 0.46 for Monotomidae, 0.31 for Cerambycidae, and 0.25 for Curculionidae. Conclusions Our results suggest that Landsat TS has important implications for studying saproxylic beetle distribution and, by helping the selection of monitoring areas, increasing the amount of information acquired while decreasing the effort required for field analysis. [ABSTRACT FROM AUTHOR]

Highlights • Commercial thinning in planted forests causes a woody necromass resource pulse. • We aimed to document the transition period following thinning-induced resource pulses. • The pulse effect on flying coleopterans faded three years after the treatments. • In parallel, the woody necromass available decayed rapidly. • Thinning-induced pulses are short-lived but longer-term residual effects occur. Abstract Despite the critical role of pulsed resources on the dynamics and conservation of several forest-dwelling species, the transition between the period when the effects of a thinning-induced resource pulse are maximal and the period when only residual effects remain has yet to be documented in forest habitats. In this study, we investigated the occurrence of a transition period after a woody necromass resource pulse produced by commercial thinning operations on flying coleopterans. In a large-scale manipulative study, spruce plantations were subjected to commercial thinning treatments and beetles collected using flight intercept traps during the four years that followed thinning operations. 82,062 beetles from 50 families and 242 species were recovered. For two years after thinning treatments, beetle communities differed in composition between thinned and unthinned plantations, species richness and abundance being higher in thinned areas. By the third and fourth year after thinning treatments, these differences started to fade, indicating that the transition period was occurring. This was associated with a decline in the quality of woody debris found close to or onto thinning trails. These results support our hypothesis that fine woody debris, such as those produced by commercial thinning operations, are attractive to beetles for a short period because they rapidly decay and are rarely colonized by wood-boring species, inhibiting further colonization by fungi and mycophagous beetles. Yet, despite a decline in abundance and species richness in thinned areas during the last two years of the study, thinned plantations still harboured richer and more abundant beetle communities than unthinned plantations, suggesting that thinning trails continue to improve beetle dispersal as the woody necromass resource pulse weakens. [ABSTRACT FROM AUTHOR]

Oases in arid regions of northwestern China are main sites for agriculture and human settlement. Conservation of these important oasis habitats involves establishing shrub shelterbelts around the oases. We investigated how different types of shrub shelterbelts affect the diversity of ground beetles., We sampled carabid and tenebrionid assemblages with pitfall traps in spring and summer and measured key environmental variables in four habitats of the arid region: planted stands of pure and mixed plantations of two long-lived shrubs ( Haloxylon ammodendron and Tamarix ramosissima) and natural grassland ( NG) from which planted systems were converted., Beetle abundance and species richness reduced significantly in the pure plantations but the mixed plantation had similar abundance and higher richness in spring and lower richness in summer relative to NG. We found differences in response between functional groups of beetles. The pure plantations resulted in reduced abundance and richness of herbivores and detritivores and increased predator abundance in spring and reduced predator abundance in summer. The mixed plantation resulted in increased detritivore richness in spring and reduced detritivore richness in summer as well as increased herbivore abundance in spring and reduced herbivore and predator abundance and richness in summer. The beetle community was largely determined by shrub cover and herbaceous plant diversity., We conclude that the pure shrub plantations reduce beetle diversity, whereas the mixed shrub plantation has less adverse effect on beetle diversity. Shrub mixtures can therefore be a practical measure to minimise the negative impacts of shrub shelterbelts on beetles. [ABSTRACT FROM AUTHOR]

Three relict beech forest of central Italy were surveyed by different trap types: pitfall traps, and three different types of windows flight traps. Species richness and similarity of saproxylic beetles among the study areas were compared using Chao's indexes. Species composition and abundance were compared in order to test the influence of two trap factors on the catches of saproxylic beetles: the height effect and the colour effect (transparent or black panels). Redundancy Analysis was used to describe the factors affecting abundance and the occurrence of saproxylic beetles through some selected environmental variables at tree scale (tree diameter, canopy closure, tree cavity) and at plot scale (dead wood typology and decay class). The species richness and composition do not vary among the studied areas. The comparison among traps type showed changes in saproxylic beetle assemblages from the ground level to the canopy closure. On the contrary, trap colour did not influence the species composition. A combination of standardized and replicable pitfall and windows traps is suitable to compare the saproxylic fauna. The analysis performed at tree scale, revealed a different correlation between tree-dependent variables and saproxylic beetle richness and abundance for each trap type. Three dead wood variables at plot scale (the amount of standing dead trees, stumps and large branches on the ground) appeared to be good predictors of saproxylic beetle richness. [ABSTRACT FROM AUTHOR]

Ecological theory predicts that insect assemblages on indigenous plants will be more diverse than those on alien plants. However, this theory refers primarily to herbivores, and its applicability to decomposers is unclear. Here, we compare beetle assemblages from the fallen fruit of the two most common plants producing large fleshy fruit at our study site in Durban, South Africa: one indigenous African plant (the toad tree, Tabernaemontana ventricosa, Apocynaceae) and one invasive tropical American one (the granadilla, Passiflora edulis, Passifloraceae), at various stages of the decomposition process, thus spanning a continuum between herbivory and detritivory. Beetles found on the two plants included both alien (some categorized as pests of stored fruit) and indigenous species (including some localized endemics). We found that the mean diversity and abundance were not significantly different between the two plant species (with nine beetles from four morphospecies in the average sample) and that the beetle assemblages from the two plant species largely overlap. Statistical analyses suggested that other factors such as stage of fruit decomposition and seasonality could have greater influence on diversity and abundance than the provenance of the plant species. We conclude that insect-plant interactions in the emerging ecosystems that include indigenous and alien species in both groups are complex and that the importance of interactions between species of different provenances may have previously been underestimated. [ABSTRACT FROM AUTHOR]

Abstract: Changes in wandering beetle assemblages (Carabidae and Tenebrionidae) of different habitats situated in coastal wetlands of a Mediterranean arid area (Mar Menor, SE Spain) were analysed in 1984, 1992 and 2003 by pitfall trapping. Over two decades, the increase in irrigated lands at watershed scale led to rising water tables in the Mar Menor wetlands, which affected their beetle communities. These hydrological changes caused an increase in the carabid population, particularly in the sites most affected by flooding, where halobionts and halophiles, which were practically absent in 1984 and 1992, had become dominant by 2003. In contrast, tenebrionid assemblages simplified with time and by 2003 were dominated by one or two generalist species. [Copyright &y& Elsevier]

We examined the responses of a beetle assemblage to habitat complexity differences within a single habitat type, Sydney sandstone ridgetop woodland, using pitfall and flight-intercept trapping. Six habitat characters (tree canopy cover, shrub canopy cover, ground herb cover, soil moisture, amount of leaf litter, and amount of logs, rocks and debris) were scored between 0 and 3 using ordinal scales to reflect habitat complexity at survey sites. Pitfall trapped beetles were more species rich and of different composition in high complexity sites, compared with low complexity sites. Species from the Staphylinidae (Aleocharinae sp. 1 and sp. 2), Carabidae (Pamborus alternansLatreille), Corticariidae (CartodereThomson sp. 1) and Anobiidae (MysticephalaFord sp. 1) were most clearly responsible for the compositional differences, preferring high complexity habitat. Affinities between general functional groupings of pitfall-trapped beetles and habitat variables were not clear at a low taxonomic resolution (family level). The composition and species richness of flight-intercept-trapped beetles were similar in high and low complexity sites. Our study demonstrates that discrete responses of the various functional groups of beetles are strongly associated with their feeding habits, indicated by differing habitat components from within overall composite habitat complexity measures. Although habitat preferences by beetle species may often reflect their foraging habits, clarification of the causal mechanisms underpinning the relationships between habitat complexity and beetles are critical for the development of general principles linking habitat, functional roles and diversity. [ABSTRACT FROM AUTHOR]

Urban reserves provide a major opportunity for conservation of indigenous biodiversity in the heavily urbanised landscape of Waitakere City (Auckland), New Zealand. However, there is little documented information on what indigenous fauna survives in these reserves. Beetle (Coleoptera) communities associated with two small, isolated urban reserves and two sites in a larger forest area within the Waitakere Ranges were sampled using pitfall traps and analysed. A total of 887 beetles, from 23 families and 89 recognisable taxonomic units were caught. The urban reserves had a marked reduction in species richness and abundance of beetles compared with the sites within the larger forest areas. Various environmental factors influencing the distribution of beetles across the sites were investigated. The most important factors were size of fragment, local forest cover and soil moisture. ‘Common’ species (>5 specimens in the total dataset) found in the Waitakere Ranges and small urban reserves, were either endemic or indigenous to New Zealand. Therefore, even though these reserves may be isolated from a larger, more continuous forest tract, they have considerable potential as reservoirs of beetle diversity in highly modified landscapes and the contribution of urban reserves to the local sustainability of beetle assemblages emphasises the importance of maintaining ‘green’ areas in and around cities. [ABSTRACT FROM AUTHOR]

Abstract. Herbivorous beetles were sampled in central Slovakia and in the Tatra Mountains of northern Slovakia from seven different Salix species which are partly characterized by smooth leaves containing phenolic glycosides and partly by hairy leaves containing tannins. The collection included about 8000 individuals representing 129 species. Of the 129 species, 77 species are able to use the willows as hosts; the remaining 52 ‘tourist’ species comprise less than 3% of the collected individuals. The data on species richness and abundance did not generally support the ‘feeding specialization’ hypothesis. The proportion of specialized (= monophagous and oligophagous) beetles feeding on willows of both morphological and biochemical groups was in the same range. Host plants of the two groups could support high diversity and high evenness values, even when leaf characteristics and plant chemicals largely influenced species assemblage. The region in which the willow trees grow had a considerable impact on host plant use. Generalist beetle species predominated in central Slovakia. By contrast, in the Tatra Mountains, specialist feeders which are able to use phenolic glycosides to their advantage were predominant. The number of species and the total density of individuals collected from willows containing phenolic glycosides (S. fragilis and S. purpurea ) did not usually vary between the two regions. In contrast, fewer species and individuals were found in the Tatra Mountains when they settled on willow species containing tannins (S. caprea and S. cinerea ). Also, the phylogenetic status of host plants affected species assemblages. In central Slovakia willow species of the subgenus Vetrix (S. purpurea, S. caprea and S. cinerea ) generally showed a higher beetle diversity (Hs ) than species of the subgenus Salix (S. fragilis, S. alba and S. triandra ), although both subgenera comprise species of both morphological and biochemical... [ABSTRACT FROM AUTHOR]

1. Up to 50% or more of the savanna landscapes of northern Australia are burnt each year, but the effects of these fires on savanna faunas are poorly known, especially for arthropods. 2. We investigated the responses of grass-layer beetles to three fire regimes (unburnt — fires excluded; early — annual fires lit early during the dry season; late — annual fires lit late during the dry season) as part of a landscape-scale fire experiment at Kapalga in Australia's Northern Territory, where replicated fire regimes were applied to 15-20-km[sup 2] landscape units over a 5-year period. We also sought to identify beetle species that might act as indicators of particular fire regimes, and examined the extent to which analysis at the family level is sufficient to reveal patterns evident from species-level analysis. 3. Beetles were sampled using sweep nets during February (mid-wet season) and May (end of wet season) each year, from 1989 (18 months prior to the imposition of fire treatments) to 1995 (after 5 years of treatments). 4. A total of 3865 beetles from 233 species was recorded, with the dominant families Chrysomelidae (leaf beetles) and Curculionidae (weevils) contributing 91% of all beetles and 57% of total species. 5. Total beetle abundance, species richness, family richness and the abundances of one of the 10 most common species were significantly affected by fire treatment according to ANOVA. In all cases, beetle abundance and richness were similar in the two burning treatments, but greater than in the unburnt treatment. These differences were only apparent during the second half of the experiment. The responses were mirrored by changes in composition at species, family and guild levels, according to multivariate analysis. 6. According to indicator analysis, five beetle species were significant indicators of late fires, and one of early fires. All these species were infrequently recorded and therefore of limited use for management. However,... [ABSTRACT FROM AUTHOR]

The article presents a study that examines how ground-active beetles respond to savanna fires and how detection of these responses is contingent upon the amount of rain occurring prior to sampling. Also tested is the extent to which family-level responses are taxonomically sufficient to reveal responses detected at the species level. It cites the importance of understanding of the impact of different fire management regimes.

• Forest retention patches aim to provide "lifeboat" areas for animal species. • We assessed the long-term lifeboat effect using a manipulative field experiment. • Retention patches did not host the same species complex than continuous stands. • Retention patches, however, can maintain species diversity within harvest areas. Retention forestry is a silvicultural approach used to retain structural and compositional components of the harvested area, maintain some connectivity throughout the landscape and provide a "lifeboat" area for species as part of a conservation effort. However, no manipulative field experiment has assessed the lifeboat functioning of retention forestry more than a decade post-harvest. In this study, we documented the effects of retention plots 20 years after their establishment on flying Coleoptera assemblages using flight intercept traps. 3414 beetles from 160 different species or genera were recovered during the study. Results demonstrated that beetle abundance and species richness were comparable between retention patches and continuous forests in the vicinity. However, beetle assemblages differed between the treatments because closed-habitat species and fungivorous beetles declined in retention patches and open-habitat species considered as tourists were associated with retention patches. Yet, beetle assemblages varied more in response to interannual effects than treatment effects. With respect to the lifeboat effect of retention forestry, we conclude that retention patches do not host the same species assemblage than continuous stands but are nevertheless effective for the conservation of species abundance and richness within a harvested area. [ABSTRACT FROM AUTHOR]