Fredrik Stenbacka

Saproxylic and non-saproxylic beetle assemblages in boreal spruce forests of different age and forestry intensity.

Current clear-cutting forestry practices affect many boreal organisms negatively, and those dependent on dead wood (saproxylics) are considered as particularly vulnerable. The succession of species assemblages in managed forest habitats regenerating after clear-cutting is, however, poorly known. We compared beetle assemblages in three successional stages of managed boreal spruce forests established after clear-cutting and two types of older spruce forests that had not been clear-cut. We also assessed whether saproxylic and non-saproxylic beetle assemblages show similar biodiversity patterns among these forest types. Beetles were collected in window traps in nine study areas, each encompassing a protected old-growth forest (mean forest age approximately 160 years, mean dead wood volume 34 m3/ha), an unprotected mature forest (approximately 120 years old, 15 m3/ha), a middle-aged commercially thinned forest (53 years old, 3 m3/ha), a young unthinned forest (30 years old, 4 m3/ha), and a clearcut (5-7 years after harvest, 11 m3/ha). Saproxylic beetles, in particular red-listed species, were more abundant and more species rich in older forest types, whereas no significant differences among forest types in these variables were detected for non-saproxylics. The saproxylic assemblages were clearly differentiated; with increasing forest age, assemblage compositions gradually became more similar to those of protected old-growth forests, but the assemblage composition in thinned forests could not be statistically distinguished from those of the two oldest forest types. Many saproxylic beetles adapted to late-successional stages were present in thinned middle-aged forests but absent from younger unthinned forests. In contrast, non-saproxylics were generally more evenly distributed among the five forest types, and the assemblages were mainly differentiated between clearcuts and forested habitats. The saproxylic beetle assemblages of unprotected mature forests were very similar to those of protected old-growth forests. This indicates a relatively high conservation value of mature boreal forests currently subjected to clear-cutting and raises the question of whether future mature forests will have the same qualities. Our results suggest a high beetle conservation potential of developing managed forests, provided that sufficient amounts and qualities of dead wood are made available (e.g., during thinning operations). Confirming studies of beetle reproduction in dead wood introduced during thinning are, however, lacking.

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.

Responses of eight boreal flat bug (Heteroptera: Aradidae) species to clear-cutting and forest fire

Boreal flat bugs include a high proportion of species that are considered negatively affected by forestry. Knowledge on the biology and habitat demands of individual species is generally limited. We examined the influence on flat bugs of stand-age and clear-cutting, comparing five classes of spruce stands. The five classes were: clear-cut, unthinned, and thinned (all three products of current clear-cutting forestry), mature managed and old-growth stands (these two had never been clear-cut). We also compared unburned and recently burned mature pine forest. Fire, but not stand age, had a pronounced effect on species richness and total abundance. Aradus depressus showed a significant association with older forest stands. Aradus betulae occurred only in clear-cuts and burned forest indicating that this species is favored by disturbance in general. Aradus lugubris, Aradus crenaticollis and Aradus brevicollis were found only in the burned forest. Aradus brevicollis has not previously been shown to be associated with fire.

Saproxylic parasitoid (Hymenoptera, Ichneumonoidea) communities in managed boreal forest landscapes

Abstract.  1. Species of higher trophic levels are predicted to be more vulnerable to disturbances (e.g. by forestry) than their prey because of low population densities, extreme specialisation and reliance on intact trophic chains.

Functional roles affect diversity-succession relationships for boreal beetles.

Species diversity commonly increases with succession and this relationship is an important justification for conserving large areas of old-growth habitats. However, species with different ecological roles respond differently to succession. We examined the relationship between a range of diversity measures and time since disturbance for boreal forest beetles collected over a 285 year forest chronosequence. We compared responses of “functional” groups related to threat status, dependence on dead wood habitats, diet and the type of trap in which they were collected (indicative of the breadth of ecologies of species). We examined fits of commonly used rank-abundance models for each age class and traditional and derived diversity indices. Rank abundance distributions were closest to the Zipf-Mandelbrot distribution, suggesting little role for competition in structuring most assemblages. Diversity measures for most functional groups increased with succession, but differences in slopes were common. Evenness declined with succession; more so for red-listed species than common species. Saproxylic species increased in diversity with succession while non-saproxylic species did not. Slopes for fungivores were steeper than other diet groups, while detritivores were not strongly affected by succession. Species trapped using emergence traps (log specialists) responded more weakly to succession than those trapped using flight intercept traps (representing a broader set of ecologies). Species associated with microhabitats that accumulate with succession (fungi and dead wood) thus showed the strongest diversity responses to succession. These clear differences between functional group responses to forest succession should be considered in planning landscapes for optimum conservation value, particularly functional resilience.

Effective thiafentanil immobilization and physiological responses of free-ranging moose ( Alces alces ) in northern Sweden

OBJECTIVE To evaluate clinical and physiological responses in moose to thiafentanil administration for immobilization. STUDY DESIGN Cross-sectional clinical study. ANIMALS Eleven (six males and five females) free-ranging adult moose (Alces alces). METHODS Each moose was darted from a helicopter with 7.5 mg thiafentanil during March 2014 in northern Sweden. Physiological evaluation included vital signs and blood gases. Arterial blood was collected after induction and again after 10 minutes of intranasal oxygen administration and analyzed immediately with an i-STAT analyzer. A total of 10 mg naltrexone per milligram of thiafentanil was administered to all animals for reversal. Data were analyzed using descriptive statistics. RESULTS All moose were sufficiently immobilized with a single dart injection. Induction occurred within 3 minutes in 10 of 11 moose. One individual became recumbent while crossing a river and naltrexone was immediately administered. Animals maintained sternal recumbency with their head raised and vital signs were stable. Nine of 10 moose were hypoxemic before oxygen administration, with seven becoming markedly hypoxemic [partial pressure of arterial oxygen (PaO2) between 40 and 59 mmHg (5.3-7.9 kPa)]. The PaO2 increased significantly between samples, but six moose remained hypoxemic despite therapy. Hypercapnia was seen in all moose, with eight having marked hypercapnia [partial pressure of arterial carbon dioxide (PaCO2) > 60 mmHg (>8.0 kPa)]. All moose were acidemic, with nine showing marked acidemia (pH < 7.20). The pH increased significantly with time and lactate decreased. Recoveries were rapid and uneventful, and all moose were living 6 months after capture. CONCLUSIONS Thiafentanil provided rapid and sufficient immobilization of moose and its effects were rapidly reversed with naltrexone. As with other opioids, moose showed hypoxemia and varying degrees of respiratory and metabolic acidosis. Arterial oxygenation of moose improved following intranasal oxygen, but hypoxemia was not fully resolved despite therapy. CLINICAL RELEVANCE Thiafentanil (7.5 mg per adult) is effective for immobilization of free-ranging moose. Supplemental oxygen may be of benefit when using this regimen; however, further investigation is required to confirm these results.