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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'cone'

Category: Article

article id 5451, category Article
Maija Salemaa, Eeva-Liisa Jukola-Sulonen, Martti Lindgren. (1991). Forest condition in Finland, 1986-1990. Silva Fennica vol. 25 no. 3 article id 5451.
Keywords: needle age; Finland; defoliation; discolouration; cones; needle cast; air pollution; leaves
Abstract | View details | Full text in PDF | Author Info

The results of the Finnish forest condition survey carried out during 1986–90 in background areas are presented. The same 3,388 forest trees (1,897 Scots pines (Pinus sylvestris L.), 1,289 Norway spruces (Picea abies (L.) H. Karst. And 202 broadleaves) on 450 mineral soil sample plots were examined annually. Growth characteristics (defoliation, the number of needle age classes, branch damage and needle discolouration), fertility and abiotic and biotic damage express the general vitality of the trees and are not specific for air pollutants. A correlative approach was applied in analysing the factors which may explain the regional pattern and changes in defoliation.

Average tree-specific degree of defoliation was 9% in pine, 21% in spruce and 12% in broadleaves in 1990. Altogether 11% of the pines, 42% of the spruces and 16% of the broadleaves have lost over 20% of their needles or leaves. Defoliation in spruce was the same as in the previous year, but in pine and broadleaves it had slightly decreased. Defoliation had increased by 5 %-units in pine, 16 %-units in spruce and 7 %-units in broadleaves during the whole study period 1986–90.

High stand age and different weather and climatic factors greatly affected forest defoliation in background areas in Finland. Pine cancer (Ascocalyx abietina) has enhanced defoliation in pine in the western part of the country. Air pollutants have evidently contributed to the increase of defoliation in the most polluted parts of Southern Finland. In pine a significant positive correlation was found between modelled sulphur deposition and the average stand-specific degree of defoliation as well as with the increase in average 5-year defoliation in Southern Finland. It is suspected that green algae growing on needles of spruce in Southern Finland indicates elevated nitrogen deposition levels.

The PDF includes an abstract in Finnish.

  • Salemaa, E-mail: ms@mm.unknown (email)
  • Jukola-Sulonen, E-mail: ej@mm.unknown
  • Lindgren, E-mail: ml@mm.unknown
article id 5442, category Article
Erkki Annila, Kari Heliövaara. (1991). Chemical control of cone pests in a Norway spruce seed orchard. Silva Fennica vol. 25 no. 2 article id 5442.
Keywords: Norway spruce; Picea abies; seed orchards; seed quality; pollen; chemical control; pesticides; cone pests; cone rust; pest control
Abstract | View details | Full text in PDF | Author Info

The effect of three pesticides containing either dimethoate (0.5% a.i.), permitrin (0.5%) or triadimephon (0.5%) on the cone pests and flowering biology of Norway spruce (Picea abies (L.) H. Karst.) was tested in a seed orchard in mid-May or in the beginning of June. The pesticide treatments significantly reduced infestation by Laspeyresia strobiella and Kaltenbachiella strobi only. Variation in the number of cones infested by both insects and cone rusts was high between the spruce clones. Generally, the pesticides did not affect flower viability, seed quality or seed germination, but reduced drastically the germination capacity of pollen in vitro. In practice, sufficient control cannot be achieved with concentrations or methods used in the present study.

The PDF includes an abstract in Finnish.

  • Annila, E-mail: ea@mm.unknown (email)
  • Heliövaara, E-mail: kh@mm.unknown
article id 5262, category Article
Markku Nygren. (1986). Männyn siementen syyskeräys. Silva Fennica vol. 20 no. 1 article id 5262.
English title: Autumn harvested Scots pine seeds: the effect of cone storage and germination conditions on germination capacity.
Original keywords: mänty; itävyys; dormanssi; siemenkeräys; lepotila; käpyjen varastointi
English keywords: Pinus sylvestris; Scots pine; germination capacity; seed dormancy; cone storage
Abstract | View details | Full text in PDF | Author Info

Six seed collections were made in September–December 1984 in a natural Scots pine (Pinus sylvestris L.) stand in Southern Finland. The seeds were germinated immediately after the cone collection and three photoperiods (0.8 and 24 hours) were used in germination tests.

The seeds collected in September and October possessed relative dormancy, i.e. they did not germinate in darkness and at 10°C. Later in November and December the seeds were capable to germinate in darkness and at low temperature also. The gradual change in germination capacity is attributed to chilling temperatures in natural environments or in cone storage.

The PDF includes a summary in English.

  • Nygren, E-mail: mn@mm.unknown (email)
article id 5066, category Article
J. P. Efimov. (1980). Some results on the regularities of seed crops in Scots pine seed orchards. Silva Fennica vol. 14 no. 1 article id 5066.
Keywords: Pinus sylvestris; Scots pine; tree breeding; seed orchards; Symposiums; Soviet Union; USSR; seed crop; cone yield
Abstract | View details | Full text in PDF | Author Info

Establishment of seed orchards to produce genetically improved seed started in the USSR in the 1960’s. The aim is that within 10–15 years the total seed production will reach 50% of the seed used. The paper describes seed production in seed orchards of Scots pine (Pinus sylvestris L.) in the forest-steppe of the European part of the USSR. The orchards have been established either by grafting or by planting of seedlings originating from plus trees. The grafts begin flowering relatively early, however, only at the age of 8–10 years seed crops become relatively regular and abundant. The cone yield in young seed orchards have great variability, and the yield of cones varies between clones. Cone yield does not always correlate with a good seed yield. One of the reasons for high amount of empty seeds is the difference in the periods of flowering between the clones.

The seed crops can be improved by establishing optimal conditions for the growth of the trees. Also, when a seed orchard is founded, the peculiarities of the generative activities of the clones and their reactions to changes in the environmental conditions must be taken account by taking an individual and selective measure approach to improvement measures. The orchards can be established with clones for their genetic combining ability and their requirements for the stimulation of seed-bearing.

The PDF includes a summary in Finnish.

  • Efimov, E-mail: je@mm.unknown (email)
article id 4868, category Article
Mikko Tormilainen. (1972). Havaintoja Oitin siemenviljelyksen mäntykloonien kukinnasta ja käpysadosta. Silva Fennica vol. 6 no. 2 article id 4868.
English title: Studies of flowering and cone crop in a seed orchard of Scots pine.
Original keywords: Etelä-Suomi; mänty; kloonit; siemenviljelmä; siemenviljely; kukinta; käpysato; geneettinen vaihtelu
English keywords: Pinus sylvestris; Scots pine; flowering; genetic variation; seed orchards; clones; Southern Finland; cone production
Abstract | View details | Full text in PDF | Author Info

Male and female flowering, cone crop, and some vegetative characteristics were studied in grafts 10 to 16 years of age in a clonal seed orchard of Scots pine (Pinus sylvestris L.). Genetic variation was found between clones in flowering as well as in cone production. Clone evaluation resulted in similar classifications of clones in different years. A regression analysis showed that crown size clearly increased but previous height growth slightly decreased flowering and cone production. The percentage of pollinated female strobili did not differ between clones.

The PDF includes a summary in English.

  • Tormilainen, E-mail: mt@mm.unknown (email)
article id 4810, category Article
Pentti Solin. (1970). Kuusen käpyjen säilyttäminen jäähdyttämössä ja sen vaikutus niistä saatavan siemenen itävyyteen. Silva Fennica vol. 4 no. 1 article id 4810.
English title: Cold storage of Norway spruce cones and its effect on seed viability.
Original keywords: kuusi; varastointi; siemenet; itävyys; kävyt; kylmävarasto
English keywords: Norway spruce; Picea abies; germination; storage; viability; seeds; cones; cold storage
Abstract | View details | Full text in PDF | Author Info

The aim of the study was to establish how the cold storage of cones of Norway spruce (Picea abies (L.) H. Karst.) affects the viability of the seeds and the percentage ratio in 7 days. A parallel study was made of the longevity of seed in barn-stored cones subject to weather fluctuations and the longevity of seed extracted immediately and stored in the conventional way in an air-tight container. The cones were collected near Kuopio in Central Finland and near Tampere.

The viability and germination rate of the control sample was constant throughout the storage period. This storage method proved the best. The viability of seeds kept in cones declined in cold storage after 3 ½ months. The cones collected in Tampere were damaged by Laspeyresia strobilella, which affected the viability of the seeds.

The viability of seeds stored in cones in a barn had not weakened by the end of May, however, they deteriorated during the summer, as did the seeds stored in cones in the cold storage. Viability of the seeds was still 94% in October. The germination rate was constant in each lot up to the end of May, after which it decreased to 81.7–86.1% in October.

The results show that healthy spruce cones can be stored in paper sacks in a single layer in cold storage and in an ordinary barn for several months without it affecting the viability of the seeds.

The PDF includes a summary in English.

  • Solin, E-mail: ps@mm.unknown (email)

Category: Article

article id 7158, category Article
Olavi Huuri. (1965). Männyn- ja kuusenkäpyjen varastoinnin vaikutus niistä saatavan siemenen itävyyteen. Acta Forestalia Fennica vol. 78 no. 5 article id 7158.
English title: The effects of storage in cones on the viability of pine and spruce seeds.
Original keywords: kuusi; mänty; itävyys; kävyt; siemenkeräys; käpyjen varastointi; metsäpuiden siemenet; siementen varastointi; karistus; itämiskyky
English keywords: Pinus sylvestris; Norway spruce; Picea abies; Scots pine; cones; seeds of forest trees; seed extraction; storage of cones; storage of seeds; germinative capacity
Abstract | View details | Full text in PDF | Author Info

Seed storing experiments with cones of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) were conducted in Oitti seed extracting plant in Southern Finland from February to December 1955. The pine cones were stores for 267 and the spruce coned for 304 days. In four of the storage methods the cones were packed in sacks and another four in wooden boxes. Sample of cones were taken once a month, seeds were extracted and the germinative capacity was tested. The remaining extracted seeds were placed in storage, and in January 1956 moved to cold seed cellar until 1962, when the viability of the seeds was tested.

According to the results, cleaned pine cones can be stores for at least nine months using almost all methods of storage which are commonly used at our seed traction plants, without hazarding the usability of the seeds. The seeds in spruce cones, however, seemed to be more sensitive to conditions during the storage. The germinative capacity of the spruce seeds began to decrease after the beginning of May. Later the seeds were infected with mould, which increased towards the end of the experiment.

Thus, preservation of the germinative capacity of the seeds of pine and spruce requires storage in different conditions. The results suggest that extraction of spruce seeds should be finished during the cold winter months. It seems that seed in the cones of pine and spruce endure storage in piles of paper or cloth sacks at least as well as in wooden boxes. Occasional warming of the storage, snow and foreign material among the cones and an over meter thick cone layer decreased the germinative capacity of spruce seeds during spring and summer. Spruce seeds that had been extracted immediately after collecting of the cones preserved their germinative capacity well during an eight years storage period.

The PDF includes a summary in English.

  • Huuri, E-mail: oh@mm.unknown (email)
article id 7432, category Article
Ukko Rummukainen. (1954). Männyn ja kuusen käpysadosta ja sen arvioinnista vuosina 1950-1953. Acta Forestalia Fennica vol. 61 no. 20 article id 7432.
English title: Estimation of Scots pine and Norway spruce cone crop in 1950-1953.
Original keywords: kuusi; mänty; käpysato; siemenkeräys; käpykeräys; arviointimenetelmä
English keywords: Pinus sylvestris; Norway spruce; Picea abies; Scots pine; seed collection; cone crop; cone collection; assessment method
Abstract | View details | Full text in PDF | Author Info

The cone crop of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) has been assessed in Finland since 1930 annually by sending a questionnaire to forest professionals around the country. Based on the result it is decided if the crop is good enough for collection of the cones next winter. This article presents the results of cone surveys in 1950-1953, and suggest improvements in the method of the investigation.

According to the survey, Scots pine crop was best in 1952, when the crop was intermediate in the whole country, and relatively abundant in the county of Lapland. Norway spruce crop was best in 1951, when the crop was better than in average in the whole country. The evaluators had variable opinions whether the crop was good enough for cone collection or not. They assessed the pine cone collection more often as profitable than the spruce cone collection. Usual reasons to regard spruce cone collection as unprofitable were seed damages and the sites being too far away. To make the results more uniform and accurate, a suggestion to change the evaluation method is presented. The evaluation should be focused on the cone crop of mature stands.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
The PDF includes a summary in German.

  • Rummukainen, E-mail: ur@mm.unknown (email)
article id 7360, category Article
Viljo Kujala. (1942). Morphologic interpretation of a spruce cone based on fertilization. Acta Forestalia Fennica vol. 50 no. 7 article id 7360.
Keywords: fertilization; spruce; morphology; cone
Abstract | View details | Full text in PDF | Author Info

Article presents some rare cone formations found from a small spruce in region of Punkaharju, Finland. In this case all the scales have developed into perfect, green needle leaves. Instead of a normal scale of a cone there are formations of buds that on the basal part of a cone resemble a normal bud, and hence develop into a branch. On the upper part of the cone formation the bud develops into scale of a cone.

The morphological form of the cones has been interpreted many ways. These anomalies resemble earlier observations and hence support the former theory of inflorescence. According the theory, the scales and scales of a cone are separate leaves, the scale corresponding to one leaf, the scale of a cone corresponding to two leaves. A cone is hence rather to be compared with a branching inflorescence than only one flower.

The PDF contains a summary in Finnish. 

  • Kujala, E-mail: vk@mm.unknown (email)
article id 7036, category Article
I. Lassila. (1920). Tutkimuksia mäntymetsien synnystä ja kehityksestä pohjoisen napapiirin pohjoispuolella. Acta Forestalia Fennica vol. 14 no. 3 article id 7036.
English title: Studies on the regeneration and development of Scots pine forests north of the arctic circle.
Original keywords: luontainen uudistuminen; mänty; Pinus sylvestris; siemensato; käpy
English keywords: natural regeneration; cone; seed yield
Abstract | View details | Full text in PDF | Author Info

The frequency of years when Scots pine (Pinus sylvestris L.) produces cones and seeds affects its reproduction in the north. The study area covered most of the pine lands in Northern Finland. Scots pine seems to be able to produce cones relatively often in the north. The amount of seeds produced in one year was, however, not sufficient to produce a dense seedling stand. Thus, the natural pine stands contain usually trees in different ages-classes, which have germinated in different years. The cone production is highest in 150-170 years old trees. Pine also needs warm summers to produce viable seeds. Brush fires avail the growth of seedlings, because they clear of ground vegetation that hinders germination of seeds. The seedlings need also moisture to survive; good regeneration years have often had rainy summers.

The PDF includes a summary in German.

  • Lassila, E-mail: il@mm.unknown (email)
article id 7527, category Article
August Renvall. (1913). The periodic variation of the regeneration of pine (Pinus sylvestris) at the polar tree line. Acta Forestalia Fennica vol. 1 no. 2 article id 7527.
Keywords: Pinus sylvestris; seed production; reproduction of pine; polar tree line; cone formation
Abstract | View details | Full text in PDF | Author Info

The study deals with the preconditions for natural regeneration of the pine at the polar tree line in northern Finland and Sweden. The data has been collected in three summers from 1909 to 1911 in areas of Inari and Utsjoki in Finland and Kaaresuvanto, Jukkasjärvi und Pajala in Sweden. The yearly variation of seed production of pine is studied and compared with the age of the stand, site factors and weather conditions.

Intensity of reproduction is dependent on different preconditions for pistils and stamens and hence the total reproduction (formation of cones) can vary very much depending on the weather.

According the study, the formation of cones varies yearly and is particularly strong every three to four years.  Supposedly the same model applies to whole polar tree line of the Fennoscandia. There seem to be no difference between northern and southern parts of Scandinavia when it comes to frequency of good cone years though they not always occur in the same years.
  • Renvall, E-mail: ar@mm.unknown (email)

Category: Research article

article id 10422, category Research article
Juha Kaitera, Jouni Karhu. (2020). Temperature range for germination of Thekopsora areolata aeciospores from Finnish Norway spruce seed orchards. Silva Fennica vol. 55 no. 1 article id 10422.
Keywords: Picea abies; cherry-spruce rust; cones; epidemics; rust diseases
Highlights: Cherry-spruce rust was able to germinate at very low temperature (6 °C) close to the temperature when thermal growth starts; Optimum spore germination occurred between 15–24 °C; High temperature of 30 °C drastically reduced germination; Temperature had the most significant effect on germination, while spore source had less significant effect and agar media a non-significant effect on germination in a Fixed Effects model.
Abstract | Full text in HTML | Full text in PDF | Author Info

Cherry-spruce rust caused by Thekopsora areolata (Fr.) Magnus is a serious cone pathogen of Norway spruce [Picea abies (L.) Karst.]. The rust causes great economical losses in seed orchards specialized in the production of high quality seeds. Germination range of T. areolata aeciospores from rust populations (spore sources) in seven Finnish Norway spruce seed orchards was tested on water agar and malt agar at nine temperatures varying between 6–30 °C. The temperature range of spore germination was high varying between 6 °C and 27 °C, while germination was retarded at 30 °C. The peak in germination rate of all spore sources occurred between 15–24 °C. In a model with fixed effects of agar media, temperature and spore source, temperature had the most significant effect on germination. Spore source had a less significant effect, while agar media had a non-significant effect on germination. The rust was able to germinate at low temperatures corresponding to temperatures when the thermal growing season starts at 5 °C in the spring. As spores from cones from both the spruce canopy and the ground showed very similar germination ranges, it indicated the great capacity of all spores of the rust to germinate early in the spring. Hot temperatures with over 30 °C drastically reduced germination of the rust.

  • Kaitera, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, Paavo Havaksentie 3, FI-90014 University of Oulu, Finland E-mail: (email)
  • Karhu, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, Paavo Havaksentie 3, FI-90014 University of Oulu, Finland E-mail:
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.
Keywords: cone index; penetration resistance; shear strength; soil bulk density; VWC
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.
Abstract | Full text in HTML | Full text in PDF | Author Info

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 E-mail: (email)
  • Ala-Ilomäki, Natural Resources Institute Finland (Luke), Production systems Maarintie 6, FI-02150 Espoo, Finland E-mail:
  • Lindeman, Natural Resources Institute Finland (Luke), Production systems, Korkeakoulunkatu 7, FI-33720 Tampere, Finland E-mail:
  • Toivio, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail:
  • Siren, Natural Resources Institute Finland (Luke), Production systems Maarintie 6, FI-02150 Espoo, Finland E-mail:
article id 1239, category Research article
Tomi Kaakkurivaara, Nuutti Vuorimies, Pauli Kolisoja, Jori Uusitalo. (2015). Applicability of portable tools in assessing the bearing capacity of forest roads. Silva Fennica vol. 49 no. 2 article id 1239.
Keywords: stiffness; light weight deflectometer; dynamic cone penetrometer; falling weight deflectometer; elastic modulus
Highlights: The dynamic cone penetrometer (DCP) and light falling weight deflectometer (LFWD) are useful tools for measuring bearing capacity; The measurement results are not same as with the falling weight deflectometer (FWD), but comparable.
Abstract | Full text in HTML | Full text in PDF | Author Info
Forest roads provide access to logging sites and enable transportation of timber from forest to mills. Efficient forest management and forest industry are impossible without a proper forest road network. The bearing capacity of forest roads varies significantly by weather conditions and seasons since they are generally made of poor materials and the constructed layers may be mixed with subgrade. A bearing capacity assessment is valuable information when trafficability is uncertain and rutting is obvious. In this study, bearing capacity measurements were carried out using the light falling weight deflectometer (LFWD), the dynamic cone penetrometer (DCP) and the conventional falling weight deflectometer (FWD). The aim was to compare their measurement results in relation to road characteristics and moisture conditions. Data were collected from 35 test road sections in four consecutive springs and during one summer. The test road sections had measurement points both on the wheel path and the centre line. The data show logical correlations between measured quantities, and the study presents reliable regression models between measuring devices. The results indicate that light portable tools, the DCP and the LFWD, can in most cases be used instead of the expensive falling weight deflectometer on forest roads.
  • Kaakkurivaara, Natural Resources Institute Finland, Green technology, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: (email)
  • Vuorimies, Tampere University of Technology, P.O.Box 600, FI-33101 Tampere, Finland E-mail:
  • Kolisoja, Tampere University of Technology, P.O.Box 600, FI-33101 Tampere, Finland E-mail:
  • Uusitalo, Natural Resources Institute Finland, Green technology, Kaironiementie 15, FI-39700 Parkano, Finland E-mail:
article id 131, category Research article
Timo Pukkala, Tatu Hokkanen, Teijo Nikkanen. (2010). Prediction models for the annual seed crop of Norway spruce and Scots pine in Finland. Silva Fennica vol. 44 no. 4 article id 131.
Keywords: flowering; cone crops; seed years; mixed model
Abstract | View details | Full text in PDF | Author Info
Many studies indicate that the flowering abundance of boreal trees strongly correlates with the weather conditions of the previous summer. This study developed prediction models for the seed crops of Norway spruce and Scots pine using weather variables one and two years prior to flowering year as predictors. Weather data, systematically recorded at many weather stations, were obtained from the Finnish Meteorological Institute. Seed crop monitoring data came from 22 spruce stands and 44 pine stands. In every stand, seed crop has been monitored for many years, the longest continuous period being 45 years. Monthly mean temperatures, monthly rainfalls, and periodical temperature sums were used as predictors in the seed crop models. Generally, both tree species flowered abundantly one year after a warm summer and two years after a cool summer. While the models only explained about 45% of the variation in the annual seed crop, they accurately predicted good and bad seed years: when the models predicted good seed crops the likelihood to have at least a medium seed crop was very high and when the models predicted small seed crops, the likelihood to obtain medium or good seed crop was very low. Therefore, the models reliably predict if a particular year will be a good seed year or a poor seed year. These predictions can be used in forestry practice for proper timing of natural regeneration activities, and when activities in seed orchards are planned.
  • Pukkala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: (email)
  • Hokkanen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail:
  • Nikkanen, Finnish Forest Research Institute, Finlandiantie 18, FI-58450 Punkaharju, Finland E-mail:
article id 366, category Research article
Lars Eliasson. (2005). Effects of forwarder tyre pressure on rut formation and soil compaction. Silva Fennica vol. 39 no. 4 article id 366.
Keywords: soil density; cone penetrometer; final felling; till soil
Abstract | View details | Full text in PDF | Author Info
In Swedish forestry, final felling is usually done by a harvester and a forwarder. These machines are heavy and the risk for rutting and soil compaction can be considerable under unfavourable soil conditions. The aim of this study was to evaluate effects of forwarder tyre inflation pressure on rutting and soil compaction after final felling. Three levels of forwarder tyre pressure were studied, 300, 450 and 600 kPa, after 2 and 5 machine passages. The first passage was driven with a 19.7 Mg harvester, and the second to fifth passages with a fully loaded forwarder totalling 37.8 Mg. Rut depths were not significant affected by tyre pressures but increased significantly with the number of machine passages. Soil density was significantly increased by 0.075 Mg m–3 by the harvester passage. Soil density increased significantly with increasing number of forwarder passages, and tyre pressure did not significantly influence this increase but the interaction between number of forwarder passages and tyre pressure was almost significant. Data suggest that density increases occur earlier in the 600 kPa treatment than in the other treatments. Only parts of an area harvested are trafficked in a normal harvesting operation. Outside the research area approximately 12.5 per cent of the area harvested was covered with ruts. On primary strip roads, which are heavily trafficked, soil compaction cannot be avoided by reducing the tyre pressure. On secondary strip roads, not passed more than once by the forwarder, a low forwarder tyre pressure may reduce soil compaction.
  • Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: (email)

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