Kalle Kärhä

Prof. Dr. Kalle Kärhä

Stora Enso Wood Supply Finland, P.O. Box 309, FI-00101 Helsinki, Finland
+1
orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 May 2018 in Forests
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Kalle KärhäKalle Kärhä
Kalle Kärhä
TATuomas Anttonen
Tuomas Anttonen
APAsko Poikela
Asko Poikela
Teijo PalanderTeijo Palander
Teijo Palander
ALAnnamari (Ari) Laurén
Annamari (Ari) Laurén
YNYrjö Nuutinen
Yrjö Nuutinen
Different abiotic and biotic disturbances are expected to become more common in the future due to a warming climate. Globally, post-disturbance salvage logging is becoming more predominant to recover economic value from timber in disturbed forests. This study collected comparative time-study data and analyzed the productivity of cutting for windfalls in clear cuttings and determined the cutting costs of windfalls. Furthermore, the logging (i.e., cutting and forwarding) costs of wind-damaged trees and those of undamaged standing Norway spruce (Picea abies (L.) Karst.) trees in clear cuts were calculated in Finland. The results revealed that the cutting productivity of windfalls was 19–33% lower than that of undamaged stems. The cutting costs of windthrown stems with a volume of 0.3–1.5 m3 were 35–64% higher and the logging costs of windfalls were 10–30% higher than those of undamaged standing stems. The study provided new understanding regarding the productivity and costs of salvage logging operations under Finnish conditions. Even if the logging of windfalls is expensive and laborious, salvage logging operations are important for forest stands and their health to minimize post-disaster damage outbreaks in coniferous forests, such as the damage caused by bark beetles—mainly Ips typographus L.

2 December 2020 in European Journal of Forest Research
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NMNatascia Magagnotti
Natascia Magagnotti
Raffaele SpinelliRaffaele Spinelli
Raffaele Spinelli
Kalle KärhäKalle Kärhä
Kalle Kärhä
Piotr S. MederskiPiotr S. Mederski
Piotr S. Mederski
Small tree size represents the main challenge when designing a cost-effective harvesting system for European short-rotation plantations. This challenge is further complicated by the need to obtain 4-m logs for high-end products, which rules out the possibility of deploying whole-tree chipping. Both challenges can be met through mass or multi-tree handling (MTH), which must begin at the time of felling and continue uninterrupted along the whole supply chain. The objective was to: (1) gauge the productivity and the cost of CTL harvesting applied to these plantations; (2) assess log yield and capacity to match dimensional specifications; (3) determine if MTH applied to CTL technology offers a real benefit compared with conventional single-tree handling. The authors conducted a time study using a block design with a two-machine cut-to-length harvesting system (i.e. harvester and forwarder) in single- and multi-tree handling operations on the clear cutting of a hybrid poplar plantation in Poland, as well as we manually measured the produced volumes of the study. Higher productivity (+ 8%) was achieved under the multi-stem handling mode. The MTH system proved capable of containing harvesting costs below € 15 per green ton, while fulfilling set timber quality requirements in terms of value recovery and log quality specifications. A new, software-based, MTH system is recommended to be used in short-rotation poplar plantation for logs and biomass harvesting. When the coppicing season is over, the system can be deployed for the conventional thinning operations.

10 November 2021 in Croatian journal of forest engineering
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HHHanna Haavikko
Hanna Haavikko
Kalle KärhäKalle Kärhä
Kalle Kärhä
APAsko Poikela
Asko Poikela
MKMika Korvenranta
Mika Korvenranta
Teijo PalanderTeijo Palander
Teijo Palander
The EU’s climate and energy framework and Energy Efficiency Directive drive European companies to improve their energy efficiency. In Finland, the aim is to achieve carbon neutrality by 2035. Stora Enso Wood Supply Finland (WSF) had a target, by 2020, to improve its energy efficiency by 4% from the 2015 level. This case study researches the use of the forest machine fleet contracted to Stora Enso WSF. The aims were to 1) clarify the forest machine fleet energy-efficiency as related to the engine power; 2) determine the fuel consumption and greenhouse gas (GHG) emissions from wood-harvesting operations, including relocations of forest machines by trucks; and 3) investigate the energy efficiency of wood-harvesting operations. The study data consisted of Stora Enso WSF’s industrial roundwood harvest of 8.9 million m3 (solid over bark) in 2016. The results illustrated that forest machinery was not allocated to the different cutting methods (thinning or final felling) based on the engine power. The calculated fuel consumption totalled 14.2 million litres (ML) for harvesting 8.9 million m3, and the calculated fuel consumption of relocations totalled 1.2 ML, for a total of 15.4 ML. The share of fuel consumption was 52.5% for harvesters (cutting), 39.5% for forwarders (forest haulage), and 8.0% for forest machine relocations. The average calculated cubic-based fuel consumption of wood harvesting was 1.6 L/m3, ranging from the lowest of 1.2 L/m3 for final fellings to the highest of 2.8 L/m3 in first thinnings. The calculated fuel consumption from machine relocations was, on average, 0.13 L/m3. The calculated carbon dioxide equivalent (CO2 eq.) emissions totalled 40,872 tonnes (t), of which 21,676 t were from cutting, 16,295 t were from forwarding, and 2,901 t from relocation trucks. By cutting method, the highest calculated CO2 eq. emissions were recorded in first thinnings (7340 g CO2 eq./m3) and the lowest in final fellings (3140 g CO2 eq./m3). The calculated CO2 eq. emissions in the forest machine relocations averaged 325 g CO2 eq./m3. The results underlined that there is a remarkable gap between the actual and optimal allocation of forest machine fleets. Minimizing the gap could result in higher work productivity, lower fuel consumption and GHG emissions, and higher energy efficiency in wood-harvesting operations in the future.

12 November 2020 in Forests
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Teijo PalanderTeijo Palander
Teijo Palander
HHHanna Haavikko
Hanna Haavikko
EKEmma Kortelainen
Emma Kortelainen
Kalle KärhäKalle Kärhä
Kalle Kärhä
Stelian Alexandru BorzStelian Alexandru Borz
Stelian Alexandru Borz
Wood transportation is an important source of greenhouse gas emissions, which should be considered when the carbon neutrality of the forest industry is of concern. The EU is dedicated to improving technology for a carbon-neutral development. This study investigates carbon neutrality by improving road freight transportation fleets consisting of various vehicle size combinations. The environmental emission and energy efficiency of a transportation fleet were analyzed in selected wood procurement regions of Stora Enso corporation (Finland). Based on the enterprise resource planning (ERP) data (2018–2020), the environmental emission efficiency increased by 11% via 76 t-vehicles compared 64 t vehicles. The maximum reduction in fuel consumption was 26% for 92 t vehicles, though this was achieved when operations were fully adjusted to the maximum weight limit. The wood-based energy efficiency measure (wood energy/transport energy) was a useful development indicator. It showed that the adapted fleets of transportation companies support a positive development for a carbon-neutral forestry. In respect to the current legal fleet (64, 68 and 76 t), the use of 76 t vehicles increased energy efficiency most effectively, by 50%, compared to 64 t vehicles in the best region. Currently, transportation service providers and their clients are using ERP information to tailor their energy efficiency metric and to implement them locally in the transportation monitoring systems. A three-year sensitivity analysis demonstrates that the technological development of management tools to improve transportation efficiency is essential for larger and heavier vehicle utilization. In the future, the whole wood supply chain from forest to factory will also be optimized with respect to energy efficiency criterion to ensure a low-carbon forest industry.

31 March 2020 in Sustainability
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Teijo PalanderTeijo Palander
Teijo Palander
HHHanna Haavikko
Hanna Haavikko
EKEmma Kortelainen
Emma Kortelainen
Kalle KärhäKalle Kärhä
Kalle Kärhä
The Finnish forest industry is committed to applying novel technologies for increasing carbon-neutral development and environmental sustainability in “green” circular industry. This study compares the energy efficiency indicators of road freight transportation. Additionally, effects of four mass limits of vehicle combinations are analyzed after a three-year adaptation process that took place in a wood procurement region of 100% renewable resources. The wood-based energy efficiency model (load’s wood energy/fossil transport energy) was the most accurate and precise measure as the development indicator. The indicator showed that the transportation systems (60, 64, 68, and 76 t) and (64, 68, and 76 t) were carbon negative (122, 133, 144, and 108) (142, 147, and 133) in 2014 and 2016, respectively. The numbers reveal positive energy ratio of renewable wood and fossil fuels. In comparison to 60 t, the use of 68 t vehicles increased energy efficiency most effectively in the systems, by 18.0% and 20.5%, respectively. The indicator robustly revealed the energy efficiency of a partial system in the smaller supply region, which depended on the region’s transportation conditions. This novel knowledge can be applied for advancing the adaptation toward carbon-neutral supply networks. There is also the development potential of an industrial ecosystem model for optimizing the environmental sustainability of “green” circular industry.

10 November 2023 in Croatian journal of forest engineering
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Journal Article
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Kalle KärhäKalle Kärhä
Kalle Kärhä
MSMilla Seuri
Milla Seuri
ABAllan Bradley
Allan Bradley
DRDominik Roser
Dominik Roser
CPCristian Pinto
Cristian Pinto
TKTihomir Krumov
Tihomir Krumov
The aim of the study was to provide a comprehensive overview of global long-distance road transportation of industrial roundwood. The study focused on the maximum gross vehicle weight (GVW) limits allowed with different timber truck configurations, typical payloads in timber trucking, the road transportation share of the total industrial roundwood long-distance transportation volume, and the average long-distance transportation distances and costs of industrial roundwood. The study was carried out as a questionnaire survey. The questionnaire was sent to timber transportation logistics experts and research scientists in the 30 countries with the largest industrial roundwood removals in Europe, as well as selected major forestry countries in the world (Argentina, Australia, Brazil, Canada, Chile, China, Japan, New Zealand, South Africa, Türkiye, the United States of America and Uruguay) in February 2022, and closed in May 2022. A total of 31 countries took part in the survey. The survey illustrated that timber trucking was the main long-distance transportation method of industrial roundwood in almost every country surveyed. Road transportation averaged 89% of the total industrial roundwood long-distance transportation volume. Timber truck configurations of 4 to 9 axles with GVW limits of around 30 tonnes to over 70 tonnes were most commonly used. The results indicated that higher GVW limits allowed significantly higher payloads in timber trucking, with the lowest payloads at less than 25 tonnes, and the highest payloads more than 45 tonnes. The average road transportation distance with industrial roundwood was 128 km, and the average long-distance transportation cost in timber trucking was €11.1 per tonne of timber transported. In the entire survey material, there was a direct relationship between transportation distance and transportation costs and an inverse relationship between maximum GVW limits and transportation costs. Consequently, in order to reduce transportation costs, it is essential to maximise payloads (within legal limits) and minimise haul distances. Several measures to increase cost- and energy-efficiency, and to reduce greenhouse gas emissions in road transportation logistics, are discussed in the paper. On the basis of the survey, it is recommended that up-to-date statistical data and novel research studies on the long-distance transportation of industrial roundwood be conducted in some countries in the future.