Heavy Metal Concentrations in Soil Solution, Soil and Needles in a Norway Spruce Stand on an Acid Sulphate Forest Soil

The effects of soil processes, related to the oxidation of sulphide sediments, on heavy metal concentrations in the soil and soil solution were investigated in a Norway spruce stand on a fine-textured, acidic soil rich in sulphates located on the isostatic land-uplift western coast of Finland. The age of the soil is ca. 300–400 years, and the soil texture is silt and till. The chemical properties of the soil and soil solution clearly reflected the formation of acid sulphate (AS) soil. Compared to background reference values for podzolic coniferous forest soil, the pH of the soil solution in the mineral soil (20–40 cm depth) was very low, and the Al, Fe and S concentrations extremely high. The Zn and Ni concentrations in the soil solution were also strongly elevated, and similar to the concentrations reported close to anthropogenic heavy-metal emission sources. The concentrations of Cd and Cu were also frequently elevated. In contrast, the acidity and metal concentrations of the soil solution sampled in the organic layer were not elevated. Similarly, exchangeable Zn and Ni concentrations were also elevated in the mineral soil, but not in the organic layer. Because Norway spruce has a very superficial rooting system and the zone with exceptionally high metal concentrations did not extend up to the topmost soil layers, sulphide-oxidation derived soil acidification is not likely to pose a serious threat to forest ecosystems growing on this type of site. Despite the elevated concentrations of protons and many metals in the mineral soil and soil solution (20–40 cm), the nutrient status of the spruce stand was satisfactory and the general health of the stand has been reported to be relatively good.     

Prolonged persistence of fecally excreted ivermectin from reindeer in a sub-arctic environment

In December 2001 and 2002, feces from reindeer calves treated with ivermectin were distributed on plots established on two types of forested reindeer pasture in northern Finland. The ungrazed plots were on an enclosure that had been fenced to prevent reindeer access for the last 6 years. The grazed plots were on an area that had been heavily stocked by reindeer during the last 5 years. After enclosures had been established, reindeer and large wildlife were prevented from entering by a fence. Topsoil samples (feces, vegetation, and soil) were collected monthly during the summers of the following 2 years, over a period of from 25 to 95 weeks after deposition. The samples were analyzed for ivermectin using HPLC. Although ivermectin degradation rapidly took place during the first spring, considerable residual ivermectin could be measured throughout the sampling time, showing that ivermectin in feces on pasture may not be photodegraded as rapidly as previously believed. The results support the need for further environmental evaluation studies on the use of ivermectin to control reindeer parasites.     

Farmed wild boars exposed to Toxoplasma gondii and Trichinella spp

The meat of wild boar (Sus scrofa L.) can be a source of human infections with zoonotic parasites Toxoplasma gondii and Trichinella spp. We screened 197 wild boar sera collected at slaughter from 25 Finnish farms in 2007-2008 for serological evidence of infections with these parasites. Using a commercial direct agglutination test at a serum dilution of 1:40, T. gondii-specific IgG antibodies were detected in 65 (33.0%) samples, on 14 (56.0%) farms. Females, animals older than 24 months, animals of small herds, and animals originating from south-western parts of Finland were more often T. gondii-seropositive than were males, younger animals, animals of larger herds, and animals originating from the north and east, respectively. Four (2.0%) of the sera, originating from three (12.0%) farms, tested Trichinella-seropositive with an in-house ELISA and a conservative cut-off for seropositivity. One farm had both T. gondii- and Trichinella-seropositive animals. Taken together, an infection source had been present on 16 (64.0%) farms, and 69 (35.0%) of the 197 farmed wild boars intended for human consumption had specific serological evidence of exposure to a zoonotic parasite.     

Impacts of initial stand density and thinning regimes on energy wood production and management-related CO<Subscript>2</Subscript> emissions in boreal ecosystems

An ecosystem model (Sima) was utilised to investigate the impact of forest management (by changing both the initial stand density and basal area thinning thresholds from current recommendations) on energy wood production (at energy wood thinning and final felling) and management-related carbon dioxide (CO₂) emissions for the energy wood production in Finnish boreal conditions (62°39′ N, 29°37′ E). The simultaneous effects of energy wood, timber and C stocks in the forest ecosystem (live and dead biomass) were also assessed. The analyses were carried out at stand level during a rotation period of 80 years for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) growing in different fertility sites. Generally, the results showed that decreased basal area thinning thresholds, compared with current thinning, reduced energy wood (logging residues) and timber production, as well as carbon stocks in the forest ecosystem. Conversely, increased thinning thresholds increased energy wood production (ca. 1–27%) at both energy wood thinning and final felling and reduced CO₂ emissions (ca. 2–6%) related to the production chain (e.g. management operations), depending on the thinning threshold levels, initial stand density, species and site. Increased thinning thresholds also enhanced timber production and carbon stocks in the forest ecosystem. Additionally, increased initial stand density enhanced energy wood production for energy wood thinning for both species, but this reduced energy wood production at final felling for Scots pine and Norway spruce. This study concluded that increases in both initial stand density and thinning thresholds, compared with the current level, could be useful in energy wood, timber and carbon stocks enhancement, as well as reducing management-related CO₂ emissions for energy wood production. Only 2.4–3.3% of input of the produced energy (energy wood) was required during the whole production chain, depending on the management regime, species and sites. However, a comprehensive substitution analysis of wood-based energy, in respect to environmental benefits, would also require the inclusion of CO₂ emissions related to ecosystem processes (e.g. decomposition).     

Cannibalism facilitates gigantism in a nine‐spined stickleback (Pungitius pungitius) population

Cannibalism is a taxonomically widespread phenomenon that can fundamentally affect the structure and stability of aquatic communities, including the emergence of a bimodal size distribution (“dwarfs” and “giants”) in fish populations. Emergence of giants could also be driven or facilitated by parasites that divert host resources from reproduction to growth. We studied the trophic ecology of giant nine‐spined sticklebacks (Pungitius pungitius) in a Finnish pond to evaluate the hypotheses that gigantism in this population would be facilitated by cannibalism and/or parasitic infections by Schistocephalus pungitii cestode. Stomach content analyses revealed an initial ontogenetic dietary shift from small to large benthic invertebrates, followed by cannibalism on 10–20‐mm‐long conspecifics by giant individuals. However, stable nitrogen isotopes (δ¹⁵N) indicated a concave relationship between fish size and trophic position, with relatively low trophic position estimates suggesting only facultative cannibalism among giants. The unexpectedly high trophic position of the intermediate‐sized fish may reflect substantial, but temporary, predation on eggs or young‐of‐the‐year conspecifics, but may also partly result from starvation caused by S. pungitii infection. However, it seems implausible that parasitic infections (i.e. castration) would explain gigantism among nine‐spined sticklebacks because all >100‐mm giants were unparasitised. Hence, the present results suggest that an ontogenetic niche shift from an invertebrate diet to intercohort cannibalism may facilitate the occurrence of gigantism in nine‐spined sticklebacks.     

Stable isotopes and gut contents indicate differential resource use by coexisting asp (Leuciscus aspius) and pikeperch (Sander lucioperca)

Differential use of habitat and prey resources is an important mechanism that may allow coexistence of sympatric species. Unlike interactions between smaller cyprinid and percid fishes, the resource use by coexisting predatory asp (Leuciscus aspius) and pikeperch (Sander lucioperca) is relatively unknown. Here, gut content and stable isotope analyses were used to study ontogenetic dietary shifts and interspecific trophic niche overlap between asp and pikeperch coexisting in two reservoirs. The hypothesis that both species show an ontogenetic dietary shift from small invertebrates to large fish prey, but at the same time use different prey resources to reduce potential competitive interactions, was validated. The isotopic niches of the two predators showed no, or only a moderate, degree of overlap (0%–65%). The ontogenetic changes in the degree of interspecific isotopic niche overlap were different in the two reservoirs, suggesting that trophic segregation can be dynamic and variable among systems. Gut contents revealed that small (<100 mm standard length) asp consumed mostly terrestrial invertebrates and emerged aquatic insects, whereas small pikeperch foraged on zooplankton, larval and pupal stages of aquatic insects and fish. Larger individuals (>100 mm) of both species were predominantly piscivorous, with asp consuming more cyprinid prey and pikeperch more percid prey. Coexisting asp and pikeperch populations are able to utilise different prey resources, thereby reducing potential negative competitive interactions.     

Hydroacoustic assessment of mono‐ and polymorphic Coregonus density and biomass in subarctic lakes

Density and biomass estimates of pelagic fish are essential to understand food web interactions and ecosystem functioning. We conducted surveys of six subarctic lakes for assessing both mono‐ and polymorphic whitefish Coregonus lavaretus (L.) populations. Monomorphic whitefish lakes were inhabited by a habitat and diet generalist, large sparsely rakered (LSR) morph, whereas polymorphic whitefish lakes had a littoral benthivorous LSR morph, a pelagic planktivorous densely rakered (DR) morph and in two cases a benthivorous small sparsely rakered (SSR) morph inhabiting the profundal zone. In addition, an introduced specialist zooplanktivore, vendace Coregonus albula (L.), inhabited one of the monomorphic lakes. Hydroacoustics was found to be an appropriate method for estimating coregonid densities and biomasses in large and deep polymorphic lakes occupied by the planktivorous DR morph or vendace, but only during dark nights in autumn. The suitability of hydroacoustic assessment for benthivorous LSR and SSR morphs was low, especially in polymorphic whitefish lakes due to their preference for near‐bottom habitat or shallow areas not sampled with hydroacoustics. The pelagic density of DR morph varied from 330 to 1780 fish·ha^?1 and biomass from 1.4 to 13.3 kg·ha^?1 in polymorphic whitefish lakes, whereas corresponding estimates for LSR morph were 10–320 fish·ha^?1 and 0.5–8.4 kg·ha^?1 in monomorphic whitefish lakes. In general, polymorphism tended to increase the density and biomass of whitefish in the pelagic area compared with monomorphic systems.     

Efficacy of different treatment regimes against setariosis (Setaria tundra,Nematoda: Filarioidea) and associated peritonitis in reindeer

Background

When a severe peritonitis outbreak in semi-domesticated reindeer was noticed in 2003 in Finland, the concerned industry urged immediate preventive actions in order to avoid detrimental effects of S. tundra and further economical losses. A research programme was swiftly initiated to study S. tundra and its impact on the health and wellbeing of reindeer.

Methods

The ultimate aim of this study was to test the efficacy of different treatment regimes against S. tundra and associated peritonitis in reindeer. The timing of the trials was planned to be compatible with the annual rhythm of the reindeer management; (1) the treatment of calves in midsummer, during routine calf ear marking, with ivermectin injection prophylaxis and deltamethrin pour-on solution as a repellent against insect vectors, (2) the treatment of infected calves in early autumn with ivermectin injection, and (3) ivermectin treatment of breeding reindeer in winter. The results were assessed using the post mortem inspection data and S. tundra detection. Finally, to evaluate on the population level the influence of the annual (late autumn-winter) ivermectin treatment of breeding reindeer on the transmission dynamics of S. tundra, a questionnaire survey was conducted.

Results

In autumn, ivermectin treatment was efficient against peritonitis and in midsummer had a slight negative impact on the degree of peritonitis and positive on the fat layer, but deltamethrin had none. Ivermectin was efficient against adult S. tundra and its smf. All the reindeer herding cooperatives answered the questionnaire and it appeared that antiparasitic treatment of reindeer population was intense during the study period, when 64–90% of the animals were treated. In the southern part of the Finnish reindeer husbandry area, oral administration of ivermectin was commonly used.

Conclusion

Autumn, and to a lesser degree summer, treatment of reindeer calves with injectable ivermectin resulted in decreased severity of peritonitis and perihepatitis in reindeer calves due to setariosis. In the case of necessity for animal welfare reasons, treatment during early autumn round ups should be considered. On the population level, massive and routinely applied antiparasitic treatments can improve the health of breeding reindeer and decrease the mortality and the number of carriers but during the outbreak could not prevent its movement and expansion to the North.     

Predicting lumber grade and by-product yields for Scots pine trees

The purpose of this study was to develop models for estimating yields of lumber grades and by-products of individual Scots pine (Pinus sylvestris L.) trees using stem and crown dimensions as explanatory variables. Two separate data sets were used: (1) one simulated by the process-based growth model, PipeQual, which provides information about stem form and branch properties. The model was used to predict the 3D structure of Scots pine stems from thinning regimes of varying intensity and rotation periods and (2) an empirical data set with detailed 3D measurements of stem structure. The stems were sawn using the WoodCim sawing simulator and the yields and grades of the individual sawn pieces, as well as by-products, were recorded. The sawn timber was classified on A, B, C and D-grades for side and centre boards separately (Nordic Timber grading). By-products were pulpwood, sawmill chips, sawdust and bark.