Silva Fennica vol. 26 no. 4 | 1992
Category : Article
Ten trails, one kilometre each, were evaluated by 15 persons for scenic beauty, recreational value and variety. All trails passed through commercially managed forests dominated by conifers. The trails were first evaluated by viewing computer simulations based on a series of graphical illustrations of forest landscapes, then from a slide show, and finally in the field. In the computer simulation and slide show, landscape pictures along the trail at an interval of 35–40 m were presented for 3–4 seconds. The ranks between slide show and field were slightly more similar than those between simulation and field. The mean correlation of 12 persons between the field ranking and assessment of either computer simulations or slide shows or graphics than scenic beauty or recreational value. Spearman’s rank correlations computed from median scores of a group of 12 peers were clearly better than the average of individual persons varying from 0.6 to 0.9.
The PDF includes an abstract in Finnish
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Nousiainen,
E-mail:
in@mm.unknown
- Pukkala, E-mail: tp@mm.unknown
Models for estimating the upper diameter of trees were constructed using sample tree data measured in the 7th National Forest Inventory in Finland. Calibration of the models was tested with data from the 8th National Forest Inventory. The results showed that using mixed estimation for combining the two data sets improves the reliability of the models. Models and methods used in this study can be recommended for use in forest inventories.
The PDF includes an abstract in Finnish.
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Korhonen,
E-mail:
kk@mm.unknown
The model predicts the base diameter of the thickest living branch of a tree growing in a planted or naturally regenerated even-aged stand. A mixed model type was used in which the residual variation was divided into within-stand and between-stand components. The study material consisted of 779 trees measured in 12 plots located in 20 to 35 years old Scots pine (Pinus sylvestris L.) stands (breast height age 10 to 20 years). Branch diameter was closely connected to the breast height diameter of the stem. In a stand of a certain age, competition by close neighbours slightly decreased branch diameter in a given diameter class. According to the model, the greatest difference is between trees subjected to very little competition and those subjected to normal competition. The model was used in simulated stands with varying age, density, and tree arrangement. The simulations showed that trees with rapid diameter growth at young age had thicker branches at a given breast height diameter than trees with slower diameter growth. However, a very slow growth rate did not produce trees with branches thinner than those possessing a medium growth rate.
The PDF includes an abstract in Finnish.
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Pukkala,
E-mail:
tp@mm.unknown
- Karsikko, E-mail: jk@mm.unknown
- Kolström, E-mail: tk@mm.unknown
The profitability of jointly owned forest holdings in the two northernmost forest board districts of Finland was studied by means of ratio analysis. A time series of profit and loss statements and balance sheets from 33 holdings covering the fiscal years ending 1981–1990 served as the database. The studied area was 348,038 ha, the allowable cut 304,300 m3 per year and the average turnover, deflated by the wholesale price index, FIM 57.6 million per year. The key result obtained was that the average annual profit was FIM 107 per hectare and FIM 110 per m3. The time series showed that the ratios had increased significantly over the calculation period.
The PDF includes an abstract in Finnish.
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Penttinen,
E-mail:
mp@mm.unknown
- Kinnunen, E-mail: mk@mm.unknown
A simulation approach was applied to study the pattern of environmental variability and the relative statistical efficiency of 14 different plot types. The study material consisted of two nine-year-old field tests of Scots pine (Pinus sylvestris L.). The area of the test sites was 1.57 and 0.67 hectares. The efficiency was measured as the error variance attached to the estimate of family mean and the total size of a test needed to detect a given, least significant difference between two family means. The statistical efficiency tended to decline along with increasing plot size. The importance of plot shape was negligible compared to plot size. The highest efficiency was obtained with single-tree plots. Non-contiguous plots appeared to be considerably more efficient than block plots of equal size. The effects of intergenotypic competition on the choice of plot type are discussed.
The PDF includes an abstract in Finnish
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Haapanen,
E-mail:
mh@mm.unknown
The ability of Lygus bugs to cause growth disorders in permethrin-treated Scots pine (Pinus sylvestris L.) seedlings after planting was studied in two regeneration areas. There were three treatments: exposure of the seedlings to Lygus, mechanical protection of the seedlings from insects, and control seedlings. There were no significant differences in the rate of growth disorders between the treatments. The permethrin application protected the seedlings against Lygus bugs in the early summer, as well as when the bug abundance was low. The development of these seedlings, as well as the multiple-leadered and bushy seedlings on a third regeneration area, was followed for two years. Multiple leaders reduced height growth and bud number of a seedling, but caused marked losses in growth only when the seedlings still had multiple leaders the following year, or when they formed several, equally developed stems.
The PDF includes an abstract in Finnish.
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Kytö,
E-mail:
mk@mm.unknown