Esko Hyvärinen

Prescribed fires and retention trees help to conserve beetle diversity in managed boreal forests despite their transient negative effects on some beetle groups.

Abstract. 1 Controlled burning and green‐tree retention have been suggested to alleviate the negative effects of forestry on species diversity in boreal forests, but the ecological impacts of these measures are poorly known. 2 We studied experimentally the response of four ecological groups of beetles – saproxylics, herbivores, species on ephemeral resources, and litter‐dwelling species – to different harvesting intensities and controlled burning in Scots pine‐dominated forests. The study included four levels of green‐tree retention (0, 10, 50 m3 ha−1, and no harvesting) with burning on 12 of the 24 study sites, covering ~4 ha each. A beetle data of 153 334 individuals representing 1142 species were collected during one pre‐treatment (2000) and two post‐treatment years (2001–2002), using window traps. 3 Species richness increased in all four groups after harvesting, with and without burning, and there were major community‐level changes. The species richness of saproxylics and herbivores continued to increase in the second post‐treatment year on burned sites, whereas it decreased on many unburned sites. The assemblages were strongly affected by the treatments, but higher volumes of green‐tree retention maintained them closer to the pre‐treatment structure. 4 Although some ecological groups, such as species on ephemeral resources, experienced substantial turnover as a result of burning, populations of species that initially declined recovered. Since the increase in the saproxylics was evident, and the population reductions of other species were transient, we recommend the controlled burning with reasonable volumes of green‐tree retention to reduce negative effects of forestry on insect diversity.

Effects of green tree retention and prescribed burning on the crown damage caused by the pine shoot beetles (Tomicus spp.) in pine-dominated timber harvest areas

Abstract:  We explored how two recently introduced methods to promote biodiversity during the timber harvest in boreal forests – green tree retention and use of fire – may affect damages caused by pine shoot beetles (Tomicus piniperda and Tomicus minor; Col., Scolytinae) in the surrounding pine forests. The experimental design included 24 separate study sites, 3–5 ha each, which were assigned to different treatments according to factorial design. Retention levels included 0, 10, 50 m3/ha and uncut controls. Twelve of the sites were burned and thus there were three replicates of each treatment combination. Old and new fallen pine shoots were counted from transects in adjacent pine‐dominated forests 2 and 3 years after the treatments. Populations of Tomicus spp. in the sites were monitored using window traps before and after the treatments, and by examining felled sample trees. Numbers of fallen shoots returned to background levels around unburned and burned clearcuts with no retention trees in 3 years after the treatments, but remained still at increased level in burned harvested sites with 10 and 50 m3 of retained trees per hectare. Numbers of fallen shoots in burned uncut forests increased in one site only, where the fire was intense enough to kill large pine trees, but the damage did not extend outside the burned area. Shoot numbers remained at such low levels (<18 000 shoots/ha) in all treatment combinations that growth losses were not likely. Numbers of egg galleries of Tomicus spp. in trees killed by fire were low, indicating that burnings that take place after the swarming of Tomicus beetles create dead wood that is not optimal for the breeding of these pests. We conclude that green tree retention and prescribed use of fire do not automatically affect populations of Tomicus spp. more than traditional forestry operations (thinnings and clearcuttings) do.

Application of the Red-List Index at a National Level for Multiple Species Groups

The International Union for Conservation of Nature (IUCN) Red List Index (RLI) is recognized as one of the key indicators of trends in the status of species. The red-list assessment done by Finnish authorities of species in Finland is taxonomically one of the most extensive national assessments. We used the Finnish Red Lists from 2000 and 2010 to calculate for the first time the national RLIs for 11 taxonomic groups at different trophic levels and with different life cycles. The red-list index is calculated on the basis of changes in red-list categories and indicates trends in the status of biological diversity of sets of species. The RLI value ranges from 0 to 1. The lower the value the faster the set of species is heading toward extinction. If the value is 1, all species in the set are least concern and if the value is 0, all species are (regionally) extinct. The overall RLI of Finnish species decreased. This means that, in Finland, these taxonomic groups were heading toward extinction faster in 2010 than in 2000. Of the analyzed groups of organisms, RLIs of 5 decreased and RLIs of 6 increased. At the national level, the RLIs and status trends varied markedly between species groups. Thus, we concluded that generalizations on the basis of RLIs of a few taxa only may yield a biased view of ongoing trends in the status of biological diversity at the species level. In addition, one overall RLI that includes many different species groups may also be misleading if variation in RLI among species groups is not considered and if RLI values are not presented separately for each group.