Articles containing the keyword 'clearing'

Exposure to phenoxy acids and their effect on worker’s health were studied among 35 exposed forest workers. The control group was 47 non-exposed loggers. The both groups were medically examined before and after their working period including such laboratory analyses as B-differential count, B-thrombocytes. In addition, the exposure to eight ULV sprayers and two clearing saw sprayers were measured in breathing zone.

The mean of phenoxy acid concentrations in urine among all the exposed workers after the working period was 6.5 μmol/l being significantly below the hygienic limit value (14 μmol/l). The mean concentrations of ULV sprayer workers was 7.3 μmol/l and of clearing saw sprayer workers 2.7 μmol/l. The mean of air concentrations among ULV sprayers was 0.23 mg/m³ and among clearing saw sprayers 0.06 mg/m³. No statistically significant differences were noticed in the hematologic parameters and in the enzyme activities of the liver, kidney and muscles between the exposed and control groups before or after the working period. So, it seems that these low exposure levels don’t cause sudden changes in health.

The PDF includes an abstract in English.

• Manninen, E-mail: am@mm.unknown
• Heikkinen, E-mail: ph@mm.unknown
• Husman, E-mail: kh@mm.unknown
• Kangas, E-mail: jk@mm.unknown
• Klen, E-mail: tk@mm.unknown
• Mononen, E-mail: im@mm.unknown

The aim of the study was to compare the newly introduced brush cutter to ordinary hand tools in clearing of cutting areas and thinning young birch (Betula sp.) and Scots pine (Pinus Sylvestris L.) stands. Working with a prototype of the brush cutter, Brushmaster, reduced the total working time by 15-20% compared to bush knife and axe, in spite of the cutter’s weight. At rainy weather the advantage of Brushmaster dissapeared because of clogging of the cutter’s air filter. The prototype proved to be more effective when clearing a cutting area, and hand tools seemed to be faster if damage to the remaining trees have to be avoided.

In addition, eight either lighter or more effective motor saws or brush cutters were compared mutually, and the effect of motor effect, weight, handiness, arrangement of suspenders and handles is discussed. With these improved types of the cutter it was possible to shorten the total working time in thinning of stands (mostly clearing of young stands) to 30-40% of the total working time compared to hand tools. The most modern saws appeared to be best adapted in clearing cutting areas.

The article includes an abstract in English.

• Sirén, E-mail: gs@mm.unknown

Silva Fennica issue 46 includes presentations held in professional development courses, arranged for foresters working in public administration in 1937. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service. 
This presentation describes clearing of felling areas. 

• Tertti, E-mail: mt@mm.unknown

An attempt was made in the study to determine the annual periods available for foliage spraying when cleaning Scots pine (Pinus sylvestris L.) dominated seedling stands. The study was made in nine experimental fields which were established in different parts of Finland. The spraying was applied throughout the growing season by DM, MCPA and Roundup. The results were inventoried one year after the treatments.

The results showed that there were big differences both in the destruction of hardwood sprouts and in the survival of pine seedlings due to the time period of the spraying. Threshold points were observed in the range of effect of DM and MCPA. By means of these it is possible to time the spraying treatments in such a way that there remains only slight damage to pine, but hardwood sprouts are destroyed totally. The results varied with Roundup so much, among other things due to rain, that such threshold points could not be determined. This preparation both had a milder effect on the hardwood seedlings and caused slighter damage to pine than the other preparations.

In Sodankylä in Northern Finland, the pines attained a good resistance to arboricides when the efficient temperature sum of the growing season was 550, but in Punkaharju in Central Finland only when it was 850. The seed provenance of the seedlings had an effect on the resistance. The threshold temperature sums of resistance in pine were on the average 70–74% from the long-term average number of degree days at the origin of the seed. The effect on the hardwood trees grew weaker as the long-term average was filled. Resistance of pine followed with a specific lag the lignification of the shoot and the ceasing of the growth of the needles.

The PDF includes a summary in English.

• Pohtila, E-mail: ep@mm.unknown
• Pohjola, E-mail: tp@mm.unknown

• Fernandez-Lacruz, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: raul.fernandez@slu.se
• Di Fulvio, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: fulvio.di.fulvio@slu.se
• Bergström, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: dan.bergstrom@slu.se