Impacts of different forest management scenarios on forestry and reindeer husbandry

In northern Sweden, the forests are used simultaneously for both timber production and reindeer husbandry. During the winter months, lichen is the most important fodder for reindeer. Forest management operations are generally considered having a negative impact on reindeer husbandry as harvesting and dense stands remove or obscure the ground lichen cover. In this study, we simulate three different scenarios for forest management, differing in the intensity and types of harvest operations. The resulting 100-year scenarios are analyzed with respect to their estimated suitability for providing reindeer pasture areas. Suitability is determined by vegetation type, stand density and stand height. The results indicate that the current trend of a decrease in lichen area will continue if existing forestry practice prevails. Implementing continuous cover forestry as a management alternative and carrying out precommercial thinning could halt the decrease in reindeer pasture area and even lead to a future increase in pasture area, with losses of approximately 5% in the net present value of forestry.     

Dissolution and dispersion of spruce wood components into hot water

Summary The dissolution and dispersion of components from Norway spruce (Picea abies) wood were examined in laboratory experiments to determine the factors influencing variations in dissolved and colloidal substances in mechanical pulp suspensions. Finely ground, fresh spruce wood was suspended in water at 90 °C and was agitated intensively for up to 12 h, after which the concentrations of dissolved and dispersed lipophilic extractives, lignans, carbohydrates and lignins were determined. Sapwood and heartwood were studied separately. Effects of pH and added electrolytes on the dissolution and dispersion of wood components were also investigated.Higher amounts of lipophilic extractives, and especially of triglycerides, were dispersed from sapwood than from heartwood. The release of lipophilic extractives continued for up to 3 h, after which the concentrations in the suspensions leveled off. At this stage the composition of the dissolved and dispersed lipophilic extractives equaled that of the wood. The amount of lipophilic extractives in the suspensions increased with increased pH, in the range of 4.5–6.7, but was lower in the presence of electrolytes. The dissolution of carbohydrates continued even beyond 3 h of agitation. The high water temperature induced hydrolytic reactions, thereby releasing especially arabinose. The release of arabinose through the hydrolytic cleavage from polysaccharides was more extensive at pH 4.5 than at pH 5.5 and 6.7. More polysaccharides containing galacturonic acid units (pectins) were dissolved at a higher pH. Much more polysaccharides containing glucose, most probably starch, were present in the sapwood suspensions. The dissolution of lignins also continued throughout the 12 h experiment. The measured UV-absorption, after extraction of lignans, was roughly the same for sapwood and heartwood suspensions. Slightly less lignins were released in the presence of electrolytes. Lignans were released only from heartwood.     

Mortality and F1 production of Rhyzopertha dominica (F.) on wheat treated with diatomaceous earth: impact of biological and environmental parameters on efficacy

A series of experiments were conducted in which label rate (0.3 g per kg of wheat) with diatomaceous earth (DE) formulation Protect-It. Exposure studies were carried out at two levels of relative humiditiy (40% and 55%), two levels of insect density (10 or 20 adults per vial), and three levels of exposure periods. Test insects were placed in vials containing 40 g of soft white winter wheat mixed with either 0 or 0.3 g Protect-It per kg of wheat. After relating exposure periods for both insect density and relative humidity levels, highest mortality was only 16%. Mortality, regardless of the dose rate applied (0 and 0.3 g) were not significantly increased as the exposure period increased. Regardless of relative humidity (r.h.) (40% and 55%r.h.), mortality in control were not significantly increased as the exposure period increased for the same insect density. However, significant differences among the three exposure periods in 10 adults’ density in 0.3 g DE application. Mortality was significantly increased in 10 adults’ density. In this case mortality of R. dominica adults increased with the increasing of the exposure intervals. As for 20 adults’ density, mortality in 0.3 g DE application was not significantly changed along with the exposure intervals. After insects were exposed for 1, 2, or 3 week, dead and live insects were removed, and the wheat in the vial were returned to relating humidity box and kept for 8 week until F₁ adults emerged. Then, the number of F₁ adult was counted. The mean numbers of F₁ adults on untreated wheat at all density and r.h. combinations, regardless of exposure periods were significantly higher than that of 0.3 g DE- treated wheat (Fig. 3). At each density and treatment, the mean number of F₁ adults at 55% r.h. were higher that that of 40%r.h. The comparison between adult densities at each r.h. and treatment showed that adult densities influenced the F₁ production of R. dominica and F₁ adults were always higher at 20 adults’ density. The mean number of F₁ adults at each density, regardless of treatment progressively increased as the exposure period increased. Fewer progeny were produced at 10 adults’ density compared to 20 adults’ density for same exposure periods. The highest reproduction occurred in 3 week of exposure period for both insect densities. Regardless of adult densities, the mean number of F₁ adults was significantly increased as the exposure period increased (Fig. 5) for both control and 0.3 g DE treatment. Reduction of F₁ adults at 0.3 g DE application compared to control were found to be 76.88, 74.78 and 67.63% for 1, 2 and 3 week of exposure period, respectively.     

Development, feeding and reproduction responses of Adalia fasciatopunctata revelierei(Mulsant) (Coleoptera: Coccinellidae) to Hyalopterus pruni(Geoffroy) (Homoptera: Aphididae)

This study was carried out to determine the development, survival and reproduction responses of Adalia fasciatopunctata revelierei (Mulsant) (Coleoptera: Coccinellidae) feeding on Hyalopterus pruni (Geoffroy) (Homoptera: Aphididae), using 20, 40, 80, 160 and 250 prey densities. All experiments were conducted at 25±1°C, 60±5% relative humidity, 16:8 light:dark under laboratory conditions. The average daily prey consumption of A. fasciatopunctata revelierei immatures and adults increased with increasing prey densities. Predation was not different for the larval stages at 80, 160 and 250 prey densities. The longevities of adult females were 35.67, 35.33, 49.00, 58.33 and 57.16 days when 20, 40, 80, 160 and 250 H. pruni were provided, respectively. The mean daily and total fecundity of A. fasciatopunctata revelierei increased with increasing prey densities. Females of A. fasciatopunctata revelierei feeding on H. pruni laid 89 eggs at 20 prey density and 301.67 eggs at 160 prey density. The search rate of females was higher than that of all larval instars; and the search rate of the fourth-instar larvae was higher than that of younger instars. Handling time decreased with development from larval stages to adult.     

Dutch elm disease on the island of Gotland: monitoring disease vector and combat measures

The island of Gotland (Sweden) possesses the largest (more than one million trees) wild population of elms in northern Europe, which until recently was not affected by Dutch elm disease (DED). In 2005, DED was observed for the first time in the northeastern part of Gotland, and in the following years, it rapidly spread in all directions, generally following the major distribution of elms. Implementation of intensive control measures including ground surveys and geographic information system mapping of DED-diseased trees, their felling and destruction, and stump treatment with the herbicide glyphosate allowed reduction of the source of infection and probably suppression of an otherwise very rapid spread of the disease. Monitoring the flying periods of Scolytus multistriatus vector beetles between the years 2007 and 2011 showed that the abundance of trapped beetles in most cases differed significantly among individual years. Over the entire monitoring period, 55.2% of the beetles were trapped in June, 31.2% in July and 13.5% in August (difference among individual months significant at p?S. multistriatus, suggesting that the removal of trees attacked in the previous vegetation period as a combat measure should be completed before the beginning of the flying season of S. multistriatus, and that the application of the integrated DED management has the potential to arrest the development of the disease in a geographically isolated area such as Gotland.