Karri Uotila, Timo Saksa. (2021). Cost-efficient pre-commercial thinning: effects of method and season of early cleaning. Silva Fennica vol. 55 no. 4 article id 10507. https://doi.org/10.14214/sf.10507

Keywords: productivity; young stand management; cost-effectiveness; release treatment

Highlights: The first stage of multistage pre-commercial thinning, early cleaning, took 27–30% less time when carried out in the spring instead of the summer; The two stage pre-commercial thinning program was 11% less expensive to apply when early cleaning had been applied in the spring instead of the summer.

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This study’s aim was to identify how the application season and the method of early cleaning (EC), the first stage of multistage pre-commercial thinning (PCT), affected the time consumption in EC and in the subsequent second PCT operation. The worktime in EC was recorded in the spring, summer, and autumn in 22 sites, which were either totally cleaned or point cleaned. Later, these sites were measured at the time of the second PCT. Time consumption was estimated in PCT, based on the removal of the sites. The time consumption in EC was 5.3 productive work hours (pwh) ha^–1, 7.3 pwh ha^–1, and 6.2 pwh ha^–1 respectively in the spring, summer, and autumn. EC in the spring instead of the summer saved 27–30% of working time, depending on the cleaning method. Point cleaning was 0.8 pwh ha^–1 quicker than total cleaning, but the difference was statistically insignificant. The second stage, PCT, was 1 pwh ha^–1 slower to conduct in sites which had been early cleaned in the spring instead of the summer. However, at the entire management program level, EC applied in the spring or autumn instead of the summer saved 11% or 5% respectively of the total discounted costs (3% interest rate) of multistage pre-commercial thinning. Today, the commonest time to conduct EC is in the summer, which was the most expensive of the analyzed management alternatives here. We can expect savings in juvenile stand management in forestry throughout boreal conifer forests by rethinking the seasonal workforce allocation.

Uotila, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: karri.uotila@luke.fi
Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi

article id 919, category Research article

Karri Uotila, Juho Rantala, Timo Saksa. (2012). Estimating the need for early cleaning in Norway spruce plantations in Finland. Silva Fennica vol. 46 no. 5 article id 919. https://doi.org/10.14214/sf.919

Keywords: cleaning; conifer release; cost-effectiveness; forest vegetation management; early cleaning

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Effective management of Norway spruce (Picea abies (L.) Karst.) plantations requires detailed information on stand development, which is costly to measure. However, estimating the need for early stand management from site attributes that persists stabile after ones measured, may provide an inexpensive alternative. This study compared hardwood competition in spruce plantations of varying ages and tested the usability of this information in estimating the need for early cleaning. The data included 197 spruce plantations (4–7 years old) inventoried in southern Finland in 2007. The level (Low, Substantial, High) of need for early cleaning was subjectively determined by contrasting location and size of competing hardwoods to a conifer crop tree. Then the stage of the need for early cleaning was modelled according to site and stand attributes. Nearly 60% of the conifer crop trees in the plantations were subjectively judged to require early cleaning (Substantial 37.2%, High 21.2%), but only 10 per cent of the evaluated area was cleaned. Need for cleaning was intense on peatlands or damp soils, whereas it was mild on unprepared soils or cleaned sites. Traditional site characteristics used in forest management planning can be useful for recognising the peripheral cases, where need for cleaning is probably high or low. However, on a typical mineral soil plantation (uncleaned, soil prepared) the model indicates the differences in the need for early cleaning weakly. The need for early cleaning was already high in 4-year-old plantations, why stand age did not have significant effect on development of the need. Thus, the timing of an operation can not be predicted with the model. Nonetheless, early cleaning very likely opens growth space of crop trees in a 4–7-year-old spruce plantation. Therefore, from an aspect of crop growth, an uncleaned Norway spruce plantation in this age group is quite consistently worth cleaning.

Uotila, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: karri.uotila@metla.fi
Rantala, Metsä Group, Tampere, Finland E-mail: juho.rantala@metsagroup.com
Saksa, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@metla.fi

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