a b s t r a c tTree stumps are being increasingly used for bioenergy purposes, which may have significant effects on pine weevil (Hylobius abietis L.) populations and the level of damage they can cause to seedlings. Pine weevils are attracted by the smell of fresh stumps in clear-cut areas, and have been shown to cause serious damage to planted coniferous seedlings in European forests. This study was conducted to measure the incidence of pine weevil and damage caused to Norway spruce (Picea abies) seedlings in a field experiment including single stump pile plots (SSP), multiple stump pile plots (MSP) and control plots in North Karelia, Finland. Pine weevils were significantly more abundant in MSP stump plots (22% higher) than in SSP plots, and are 23% more abundant compared to the control plots. The extent of seedling damage was significantly lower in the SSP (by 67%) and MSP plots (by 58%) than in the controls. Seedlings damage increased significantly with the distance from the stump pile. Stump harvesting practices should be updated and, in particular, multiple stump piles should be avoided in the clearcut area. However, future studies will be required to explore the environmental and physical factors in the stump-removal area influencing pine weevil abundance.
The aim of this study is to develop a theoretical model by which to demonstrate how taxes and subsidies work as external factors to substitute fossil fuel by a forest-based biofuel. For biofuels, this study predominantly considers solid-form biomass that generates electricity; for fossil fuels, it considers coal. The model results explicated with three states by using various numeric values taken from the literature. Three states are as follows: a situation without a tax and subsidy, a situation with a biofuel subsidy, and a situation with a biofuel subsidy and a fossil fuel tax. The results of the first state exemplify current fuel market situation; those of the second indicate that the aggregate demand for biofuel has shifted upwards by around 15 % and that substitution has increased by around 18 % due to biofuel subsidies being offered. Under the third state, aggregate biofuel demand has shifted upwards by around 19 %, reduced the demand for fossil fuels by around 13 %, and increased substitution by around 31 %. This state relates to a greater sense of social welfare than other two states. It is conceivable that the joint application of taxes and subsidies will succour biofuel to supplant fossil fuel in the near future.
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