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Articles by Jari Ala-Ilomäki

Category: Research article

article id 10134, category Research article
Matti Sirén, Jari Ala-Ilomäki, Harri Lindeman, Jori Uusitalo, Kalle E.K. Kiilo, Aura Salmivaara, Ari Ryynänen. (2019). Soil disturbance by cut-to-length machinery on mid-grained soils. Silva Fennica vol. 53 no. 2 article id 10134. https://doi.org/10.14214/sf.10134
Highlights: The number of machine passes, volumetric water content in the mineral soil and the depth of the organic layer were the controlling factors for rut formation; The harvester rut depth was a good predictor of the forwarder rut formation; Changes in the penetration resistance were highest at depths of 20–40 cm.

Factors affecting soil disturbance caused by harvester and forwarder were studied on mid-grained soils in Finland. Sample plots were harvested using a one-grip harvester. The harvester operator processed the trees outside the strip roads, and the remaining residues were removed to exclude the covering effect of residues. Thereafter, a loaded forwarder made up to 5 passes over the sample plots. The average rut depth after four machine passes was positively correlated to the volumetric water content at a depth of 0–10 cm in mineral soil, as well as the thickness of the organic layer and the harvester rut depth, and negatively correlated with penetration resistance at depths of both 0–20 cm and 5–40 cm. We present 5 models to predict forwarder rut depth. Four include the cumulative mass driven over a measurement point and combinations of penetration resistance, water content and the depth of organic layer. The fifth model includes harvester rut depth and the cumulative overpassed mass and provided the best fit. Changes in the penetration resistance (PR) were highest at depths of 20–40 cm. Increase in BD and VWC decreased PR, which increased with total overdriven mass. After four to five machine passes PR values started to stabilize.

  • Sirén, Natural Resources Institute Finland (Luke) c/o Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland ORCID ID:E-mail: matti.siren@luke.fi (email)
  • Ala-Ilomäki, Natural Resources Institute Finland (Luke) c/o Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland ORCID ID: http://orcid.org/0000-0002-6671-7624 E-mail: jari.ala-ilomaki@luke.fi
  • Lindeman, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland ORCID ID:E-mail: harri.lindeman@luke.fi
  • Uusitalo, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland ORCID ID: http://orcid.org/0000-0003-3793-1215 E-mail: jori.uusitalo@luke.fi
  • Kiilo, Versowood, Teollisuuskatu 1, FI-11130 Riihimäki, Finland ORCID ID:E-mail: kalle.kiilo@versowood.fi
  • Salmivaara, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00791 Helsinki, Finland ORCID ID:E-mail: aura.salmivaara@luke.fi
  • Ryynänen, Natural Resources Institute Finland (Luke), Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: ari.ryynanen@luke.fi
article id 10050, category Research article
Jori Uusitalo, Jari Ala-Ilomäki, Harri Lindeman, Jenny Toivio, Matti Siren. (2019). Modelling soil moisture – soil strength relationship of fine-grained upland forest soils. Silva Fennica vol. 53 no. 1 article id 10050. https://doi.org/10.14214/sf.10050
Highlights: Penetration resistance (PR) is best predicted with moisture content (MC), bulk density and clay content; In fully saturated silty or clayey soils PR range from 600 to 800 kPa; The models can be linked with mobility models predicting rutting of forest machines.

The strength of soil is known to be dependent on water content but the relationship is strongly affected by the type of soil. Accurate moisture content – soil strength models will provide forest managers with the improved ability to reduce soil disturbances and increase annual forest machine utilization rates. The aim of this study was to examine soil strength and how it is connected to the physical properties of fine-grained forest soils; and develop models that could be applied in practical forestry to make predictions on rutting induced by forest machines. Field studies were conducted on two separate forests in Southern Finland. The data consisted of parallel measurements of dry soil bulk density (BD), volumetric water content (VWC) and penetration resistance (PR). The model performance was logical, and the results were in harmony with earlier findings. The accuracy of the models created was tested with independent data. The models may be regarded rather trustworthy, since no significant bias was found. Mean absolute error of roughly 20% was found which may be regarded as acceptable taken into account the character of the penetrometer tool. The models can be linked with mobility models predicting either risks of rutting, compaction or rolling resistance.

  • Uusitalo, Natural Resources Institute Finland (Luke), Production systems, Korkeakoulunkatu 7, FI-33720 Tampere, Finland ORCID ID:E-mail: jori.uusitalo@luke.fi (email)
  • Ala-Ilomäki, Natural Resources Institute Finland (Luke), Production systems Maarintie 6, FI-02150 Espoo, Finland ORCID ID:E-mail: jari.ala-ilomaki@luke.fi
  • Lindeman, Natural Resources Institute Finland (Luke), Production systems, Korkeakoulunkatu 7, FI-33720 Tampere, Finland ORCID ID:E-mail: harri.lindeman@luke.fi
  • Toivio, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: toiviojenny@gmail.com
  • Siren, Natural Resources Institute Finland (Luke), Production systems Maarintie 6, FI-02150 Espoo, Finland ORCID ID:E-mail: matti.siren@luke.fi
article id 1687, category Research article
Hannu Hökkä, Jori Uusitalo, Harri Lindeman, Jari Ala-Ilomäki. (2016). Performance of weather parameters in predicting growing season water table depth variations on drained forested peatlands – a case study from southern Finland. Silva Fennica vol. 50 no. 4 article id 1687. https://doi.org/10.14214/sf.1687
Highlights: Four-week precipitation and evapotranspiration explain much of drained peatland water table depth variation during a growing season.

The amount of water in peat soil is one factor affecting its bearing capacity, which is a crucial aspect in planning peatland timber harvesting operations. We studied the influence of weather variables on the variation of drained peatland growing season water conditions, here the ground water table depth (WTD). WTD was manually monitored four times in 2014 and three times in 2015 in 10–30 sample plots located in four drained peatland forests in south-western Finland. For each peatland, precipitation and evapotranspiration were calculated from the records of the nearest Finnish Meteorological Institute field stations covering periods from one day to four weeks preceding the WTD monitoring date. A mixed linear model was constructed to investigate the impact of the weather parameters on WTD. Precipitation of the previous four–week period was the most important explanatory variable. The four-week evapotranspiration amount was interacting with the Julian day showing a greater effect in late summer. Other variables influencing WTD were stand volume within the three-metre radius sample plot and distance from nearest ditch. Our results show the potential of weather parameters, specifically that of the previous four-week precipitation and evapotranspiration, for predicting drained peatland water table depth variation and subsequently, the possibility to develop a more general empirical model to assist planning of harvesting operations on drained peatlands.

  • Hökkä, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Paavo Havaksen tie 3, FI-90014 Oulun yliopisto, Finland ORCID ID:E-mail: hannu.hokka@luke.fi (email)
  • Uusitalo, Natural Resources Institute Finland (Luke), Green Technology, Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: jori.uusitalo@luke.fi
  • Lindeman, Natural Resources Institute Finland (Luke), Green Technology, Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: harri.lindeman@luke.fi
  • Ala-Ilomäki, Natural Resources Institute Finland (Luke), Green Technology, Jokiniemenkuja 1, FI-01370 Vantaa, Finland ORCID ID:E-mail: jari.ala-ilomaki@luke.fi
article id 993, category Research article
Jori Uusitalo, Jari Ala-Ilomäki. (2013). The significance of above-ground biomass, moisture content and mechanical properties of peat layer on the bearing capacity of ditched pine bogs. Silva Fennica vol. 47 no. 3 article id 993. https://doi.org/10.14214/sf.993
Intensive utilisation of peatland forests calls for logging activities to be increasingly carried out in conditions other than those in harsh winter. The low bearing capacity of peatlands forms a severe obstacle for the prevailing harvesting machinery. The aim of this study was to clarify and quantify the significance of above-ground biomass, brash mat, moisture content and mechanical properties of peat layer on the bearing capacity of pine bogs. In-situ driving tests were conducted in Western Finland on a pine bog covering a large variation of growing stock. Portable tools were tested for measuring strength properties of the top layer of peat. According to the results, shear modulus of top layer of peat, volume of trees and the existence of cutting debris are the most important factors affecting bearing capacity. Spiked shear vane was shown to be a promising tool in predicting the strength properties of peat soil.
  • Uusitalo, Finnish Forest Research Institute, Parkano Unit, Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: jori.uusitalo@metla.fi (email)
  • Ala-Ilomäki, Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jari.ala-ilomaki@metla.fi

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