Olalla Díaz-Yáñez, Blas Mola-Yudego, José Ramón González-Olabarria. (2017). What variables make a forest stand vulnerable to browsing damage occurrence? Silva Fennica vol. 51 no. 2 article id 1693. https://doi.org/10.14214/sf.1693

Keywords: moose; forest damage; cervid; machine learning; risk modelling; ungulates

Highlights: Stands more vulnerable to browsing damage are young with lower densities and dominated by birch, pine or mixed species; Stand size could play a role on forest susceptibility to browsing occurrence.

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Ungulate browsing results in important damages on the forests, affecting their structure, composition and development. In the present paper, we examine the occurrence of browsing damage in Norwegian forests, using data provided by the National Forest Inventory along several consecutive measurements (entailing the period 1995–2014). A portfolio of variables describing the stand, site and silvicultural treatments are analyzed using classification trees to retrieve combinations related to browsing damage. Our results indicate that the most vulnerable forest stands are young with densities below 1400 trees ha^–1 and dominated by birch, pine or mixed species. In addition, stand diversity and previous treatments (e.g. thinnings) increase the damage occurrence and other variables, like stand size, could play a role on forest susceptibility to browsing occurrence although the latter is based on weaker evidence. The methods and results of our study can be applied to implement management measures aiming at reducing the browsing damages of forests.

Díaz-Yáñez, School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0003-3829-5759 E-mail: olalla.diaz@gmail.com
Mola-Yudego, Norwegian Institute of Bioenergy Research, P.O. Box, 115, 1431 Ås, Norway; School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
González-Olabarria, Forest Sciences Centre of Catalonia (CTFC-CEMFOR), Ctra. de St. Llorenç de Morunys, km 2, 25280 Solsona, Spain http://orcid.org/0000-0002-5040-712X E-mail: jr.gonzalez@ctfc.es

article id 1342, category Research article

Blas Mola-Yudego, Gianni Picchi, Dominik Röser, Raffaele Spinelli. (2015). Assessing chipper productivity and operator effects in forest biomass operations. Silva Fennica vol. 49 no. 5 article id 1342. https://doi.org/10.14214/sf.1342

Keywords: mixed models; efficiency; comminution; operator effect; raw material supply; wood chippers

Highlights: A model is constructed to assess the productivity in chipping of wood biomass at roadside; The data includes 172 trials and 67 operators in Italy; The operator effect was included in a mixed model approach; The R2 were 0.76 (fixed part) and 0.88 (incl. operator effects).

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The present research focuses on the productivity of energy wood chipping operations at several sites in Italy. The aim was to assess the productivity and specifically the effect attributed to the operator in the chipping of wood biomass. The research included 172 trials involving 67 operators across the country that were analysed using a mixed model approach, in order to assess productivity, and to isolate the operator effect from other potential variables. The model was constructed using different predictors aiming to explain the variability due to the machines and the raw-materials. The final model included the average piece weight of raw material chipped as well as the power of the machine. The coefficients of determination (R²) were 0.76 for the fixed part of the model, and 0.88 when the effects due to the operators were included. The operators’ performance compared to their peers was established, and it was compared to a subjective classification based on the operator’s previous experience. The results of this study can help to the planning and logistics of raw material supply for bioenergy, as well as to a more effective training of future forest operators.

Mola-Yudego, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland; NIBIO Norwegian Institute of Bioeconomy Research, P.O. Box 115, 1431 Ås, Norway http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
Picchi, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy E-mail: picchi@ivalsa.cnr.it
Röser, Forest Feedstocks Group, FPInnovations, Vancouver, British Columbia, Canada E-mail: dominik.roser@fpinnovations.ca
Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy E-mail: spinelli@ivalsa.cnr.it

article id 163, category Research article

Blas Mola-Yudego. (2010). Regional potential yields of short rotation willow plantations on agricultural land in Northern Europe. Silva Fennica vol. 44 no. 1 article id 163. https://doi.org/10.14214/sf.163

Keywords: short rotation forestry; willow; production models; regional biomass supply; energy planning

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The development of short rotation forestry for bioenergy requires accurate and reliable yield estimates. This paper analyses the current, expected and potential regional productivity of short rotation willow plantations for six countries in Northern Europe. The estimations for present productivity are based on empirical models, using data regarding management, and local productivity based on the regional cereal yields. The estimates of expected yield rely on the current trends of yield increase from commercial willow plantations in the region. The estimates for potential yield are based on climatic restrictions. The results show potential average yields of 9.5, 6.8, 7.9, 9.0, 9.3, and 8.0 odt ha–1 yr–1 for Denmark, Finland, Estonia, Latvia, Lithuania and Sweden, respectively. The results of the study also show that there is a wide regional variation between the different countries. In Denmark, Finland and Sweden there is a convergence between the future forecasts and the climatic potential yields in the areas of high productivity. The Baltic countries seem to present lower estimates of present productivity, reflecting possible socio-economic restrictions, although they show a high biomass potential. The methods presented in this study can be further developed in other areas where willow cultivation is considered, and can serve as a basis for future economic considerations.

Mola-Yudego, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: blas.mola@uef.fi

Category : Research note

article id 60, category Research note

Dominik Röser, Blas Mola-Yudego, Robert Prinz, Beatrice Emer, Lauri Sikanen. (2012). Chipping operations and efficiency in different operational environments. Silva Fennica vol. 46 no. 2 article id 60. https://doi.org/10.14214/sf.60

Keywords: wood-fuel logistics; forest machinery; bioenergy supply

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This research analyses the productivity of energy wood chipping operations at several sites in Austria and Finland. The aim of the work is to examine the differences in productivity and the effects of the operational environment for the chipping of bioenergy at the roadside. Furthermore, the study quantifies the effects of different variables such as forest energy assortments, tree species, sieve size and machines on the overall productivity of chipping. The results revealed that there are significant differences in the chipping productivity in Austria and Finland which are largely based on the use of different sieve sizes. Furthermore, the different operational environments in both countries, as well as the characteristics of the raw material also seem to have an effect on productivity. In order to improve the chipping productivity, particularly in Central European conditions, all relevant stakeholders need to work jointly to find solutions that will allow a greater variation of chip size. Furthermore, in the future more consideration has to be given to the close interlinkage between the chipper, crane and grapple. As a result, investments costs can be optimized and operational costs and stress on the machines reduced.

Röser, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: dominik.roser@metla.fi
Mola-Yudego, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: bmy@nn.fi
Prinz, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: rp@nn.fi
Emer, University of Padova, Department of Land, Agriculture and Forest Systems, Legnaro (PD), Italy E-mail: be@nn.it
Sikanen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: ls@nn.fi

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