Economic result of forest regeneration chains, based either on spot mounding or on disc trenching and planting of Norway spruce (Picea abies [L.] Karst.) seedlings, were clarified and compared to each other. First, effects of soil preparation method on early development of Norway spruce stands were measured from field experiments. Second, the effects of soil preparation method on stand level management programs were modelled. The modelling was based on growth simulation and investment calculations. The soil preparation methods substantially affected early development of a stand. The density of the removed trees in early cleaning was 56% higher on the disc-trenched area compared to the spot-mounded area. The difference was especially high (120%), close by (<25 cm) the remained spruce seedlings. There was also a difference between the methods in the growth of crop spruces; at biological age of 8 years, the mean height of spruce was 110 cm on the spot-mounded area and 68 cm on the disc-trenched area. The differences led to divergent management programs between the areas. The disc-trenched area needed three young stand management operations whereas two was enough at the spot-mounded area. Although disc trenching is a less expensive method than spot mounding, the total management costs were higher in disc trenching than in spot mounding. Furthermore, incomes from the first commercial thinning were higher when regeneration based on spot mounding. At the interest rate of 3%, the investment in spot mounding had 329 € ha -1 higher net present value than the investment in disc trenching.
The purpose of this thesis was to develop the concept of cost-efficient Juvenile Stand Management (JSM) for planted Norway spruce (Picea abies L. Karst) stands. The principles of time based management were followed, by integrating regeneration activities as a cost-efficient value chain and by minimizing non-value-adding work with straightforward decision making based on forest management plan data.The effects of soil preparation and Early Cleaning (EC) on further development of the stands were studied in intensive field experiments. Extensive survey data were used to develop methods applicable for efficient decision making in JSM, such as estimating need for EC or labor time consumption of PreCommercial Thinning (PCT).Timing of JSM had major effect on its costs; a delay in PCT increased the labor time needed to manage a stand by 8.3% annually. Moreover, 61-70% of the saplings in a typical Norway spruce stand were considered to need EC years before PCT was appropriate to be done. EC was also found to be an effective release treatment as it subsequently increased the diameter growth of crop trees by 21-32%. However, a two-stage management regimen, which included EC and PCT, appeared to be somewhat more labor consuming than the PCT only option. Soil preparation method had a major effect on emergence and growth of non-crop trees, and thus, on overall costs of JSM-program. The results showed that understanding the interactions in regeneration chain activities is important for productive forestry.Furthermore, a priori information can have practical implications in decision making for JSM. Several site or stand attributes were found to explain labor consumption of PCT or the need for EC. However, decision making in daily forestry requires more reliable models. The modelling data should go beyond the data of traditional forest management planning in further research. Big data offers promising opportunities. Foremost, I'm grateful to Timo Saksa who supported me in every situation necessary during this work and encouraged me to finally gain this achievement. I'm very grateful to Juho Rantala for his help, guidance and encouragement, which was invaluable for me as a researcher and for this thesis. Without these two people this work would not have been happened. I'm thankful also to my other supervisors, valuable comments from Pasi Puttonen and Lauri Valsta gave much content for the thesis and made it more coherent. I like to express my gratitude to Juha Lappi, a good colleague next to my room who has been eager to help me with statistics in any moment I've needed it. I'm grateful to my co-authors Pertti Harstela and Nuutti Kiljunen for their help in planning the research and commenting the articles. I'm thankful to Pekka Rossi, Pekka Voipio, Mervi Seppänen, Jussi Nuutinen, and Mikko Nykänen for assisting with field experiments, and to Alisdair McLean and Michael Hardman for revising the English language. I would also like to express my thanks to pre-examiners Doug Pitt and Kari Mielikäinen for their valuable comments.I'm g...
, Kiljunen N. (2014). Labour consumption models applied to motor-manual pre-commercial thinning in Finland. Silva Fennica vol. 48 no. 2 article id 982. 14 p. Highlights• When a young stand grows and gets older, the work time needed to make pre-commercial thinning increases. The stands of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and hardwoods (Betula spp.) required an additional 8.2%, 5.2%, and 3.3% work-time per year, respectively. AbstractLabour models were developed to estimate the time required to Pre-Commercially Thin (PCT) with a clearing saw 4-to 20-year-old stands of the main commercial tree species in Finland. Labour (i.e., work-time consumption) was estimated from the density and stem diameter of the removal of 448 stands via an existing work productivity function. The removal based estimator attained was used as the basis for a priori mixed linear regression models. The main finding was that when a young stand grows and gets older, the work time needed to make a PCT increases. The stands of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and hardwoods (Betula spp.) required an additional 8.2%, 5.2%, and 3.3% work-time per year, respectively. Site fertility also played a role in that the most fertile site (mesic OMT) had an estimated labour requirement 114% higher than that for dryish VT. We also note that, per unit area, small stands require less labour than large ones and soil preparation method had a minor effect on the labour estimate. The stands which had previously gone through PCT were separately analysed. In those stands, the only significant variable concerning the labour estimate was age. The a priori models described here can help foresters to develop economic management programmes and issue quotes for forestry services.
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.
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