Articles containing the keyword 'growing stock'
Category : Article
A gap-model was used with forest inventory data in taking ground-true site, soil and tree characteristics into account in predicting the effects of climate change on forests. A total of 910 permanent sample plots established in the course of national forest inventory (NFI) in Finland and located on mineral soil sites in southern Finland were selected as the input data. The climatological input used in the simulations consisted of interpolated means of and deviations from long-term local temperature and precipitation records. The policy-oriented climate scenarios of SILMU (Finnish Research Programme on Climate Change) were used to describe the climate change. The temperature changes in the climate scenarios were increases of ca. +1.1 °C (low), +4.4 °C (medium) and +6.6 °C (high) compared to the current climate in 110 years. The simulation period was 110 years covering the time years 1990–2100.
Southern Finland, divided into fifteen forestry board districts, was used as the study region. Regional development of stand volume, cutting yield, and total wood production of forests under different climate scenarios were examined. The annual average growth in simulations under current climate was close to that observed in NFL Forests benefited from a modest temperature increase (Scenario 2), but under Scenario 1 the growing stock remained at a lower level than under the current climate in all parts of the study region. In wood production and cutting yield there were regional differences. In the southern part of the study regional wood production under Scenario 1 was ca. 10% lower than under the current climate, but in the eastern and western parts wood production was 5–15% higher under Scenario 1 than under the current climate. The relative values of total wood production and cutting yield indicated that the response of forests to climate change varied by geographical location and the magnitude of climate change. This may be a consequence of not just varying climatic (e.g. temperature and precipitation) and site conditions, but of varying responses by different kind of forests (e.g. forests differing in tree species composition and age).
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Talkkari,
E-mail:
at@mm.unknown
Europe’s forest area has increased 5 million ha since the late 1960s. The growing stock has increased 43% and the net annual increment 55% in exploitable forests since 1950. A part of the reported increase is caused by sampling inventories, which have been made in greater part of the countries. Sampling inventories have corrected earlier underestimates of the growing stock and the increment.
The difference between the annual net increment and fellings has increased since 1950. The net increment, 584 million m3, exceeded fellings, 408 million m3, by 176 million m3, in exploitable forests in 1990. If fellings could be increased to equal the increment, Europe would be an exporter of forest products.
A greater increase in the density, in the age and in the mean volume of forests per hectare threaten the biological stability of the growing stock. Degrading of the stock, increasing natural losses and deteriorating environmental qualities of forests can only be prevented by increased fellings and by forest regeneration.
The PDF includes an abstract in Finnish.
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Kuusela,
E-mail:
kk@mm.unknown
This paper is a theoretical study of what is considered to constitute the proper perception of time in forest economics and management. A stumpage appraisal model that recognizes the influence of time is developed within the framework of a national aggregate economy. To demonstrate how a socially optimal land for timber production may be determined in a given nation, a stock-supply model is derived. The stumpage appraisal rule of development determines the market stumpage price that maintains a state of balance between timber production and other land use activities.
The PDF includes an abstract in Finnish.
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Omwami,
E-mail:
ro@mm.unknown
The paper deals with the relationships between macronutrients, ground vegetation and tree crop on a drained peatland area in Central Finland. The former herb-rich spruce swamp was drained in 1930s. The Norway spruce (Picea abies (L.) H. Karst.) stand was established by planting under a nurse crop of birch, which was removed later.
There was a negative correlation between the thickness of the peat layer and the volume and mean height of the growing stock. This was found to depend on the negative correlation prevailing between the potassium content of the topmost peat layer and the thickness of the peat cover. The deficiency of potassium is clearly discernible as deficiency symptoms in the needles, the intensity of which showed a strong correlation with the stand characteristics studied. Among the nutrient characteristics of the topmost peat layer, total potassium and the N/K and P/K ratios showed the closest correlation with the stand characteristics. The communities into which the ground vegetation was divided differed from each other with regard to the calcium content of the peat substrate.
The PDF includes a summary in English.
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Mannerkoski,
E-mail:
hm@mm.unknown
The aim of this paper was that of studying the optimum growing schedules of forest stands, with the classic Faustmann formula as starting point. The study is mainly theoretical in nature. The study shows that the net present-value of the future revenues from a forest stand can be calculated, not only by means of the harvesting revenues, but also by a more theoretical concept, here termed the current gross soil rent. The current gross soil rent represents the difference between the current value growth and the rent of the growing stock.
By use of the concepts described here, it is theoretically possible to find the growing schedule for the stand which maximizes the net present-value of the stand. To make the formulae simpler, a one-year period has been adopted for discussion of the concepts involved in determination of the optimum structure and density of the growing stock, and the financial maturity. However, these concepts can be extended to cover periods of any length.
The method for determination of the optimum growing schedule for a forest stand can be summarized as follows: Thin the stand as the internal rate of return on the marginal increase in ’timber capital’ falls below the guiding rate of interest. Clear-cut and regenerate the stand as the internal rate of return on the sum of the ’timber and soil capital’ falls below the guiding rate of interest.
The PDF includes a summary in Finnish.
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Kilkki,
E-mail:
pk@mm.unknown
Category : Article
The aim of this investigation is to study, for north European conditions, some overall standards of accuracy attainable in the estimation in a number of forest characteristics from aerial photographs. Field data was acquired in three areas, comprising whole stands, fixed and variable size sample plots and sections of survey strips.
The results show that land use classes could be estimated to a rather high degree of precision from aerial photographs. The accuracy of determination of the main tree species (Scots pine, Norway spruce and deciduous trees) was more moderate; three quarters of all stands were interpreted correctly from the present photographs. The estimate of pure stands was noticeable better than those for mixed stands. In general, the agreement between treatment class stratification in the field and from aerial photographs was poor, as only one-third of all cases the class was same. The dominant height was estimated with relative lack of bias for small stands, but systematic underestimation of nearly 2 m existed for high stands.
The emphasis in this investigation was laid on determination of the volume of growing stock. Stand volumes in the small and medium volume classes were overestimated, against clear under-estimate for high volume stands. The standard error of difference, including bias, was ±43 both in m3 and as a percentage.
The variance data available provide a basis for the conclusion that under some conditions photo stratification within the forest land seems to improve the efficiency of volume estimation, whereas in some other cases the stratification is hardly an economic proposition. Alternative computations made from the data of an experimental survey indicated the likelihood that no gain was deprived from the use of aerial photographs for volume class estimation.
The PDF includes a summary in Finnish.
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Nyyssönen,
E-mail:
an@mm.unknown
- Poso, E-mail: sp@mm.unknown
- Keil, E-mail: ck@mm.unknown
The most important fact to consider in attempting to develop an increment forecast method is the great dependency of the increment on the growing stock volume. Although the site (soil and climate) produces the increment and volume, there would be no increment without the volume as an increment capital. The cutting possibilities are still more dependent on the existing growing stock. Thus, the primary characteristics in management planning is the growing stock volume. The methodological starting point in this paper is that the increment is considered dependent variable which can be explained by other growing stock characteristics. The basis of the analysis and the primary object of this investigation is the increment percentage. Using available and measured sample plots the increment percentage will be analysed as a dependent variable by other growing stock characteristics.
The main emphasis will be the methods which can be used in connection with the interacting increment and drain. An increment-drain forecast should give at least approximately the allowable cut in timber products. Thus, it will be attempted to find the stock characteristics determining the amounts of timber products.
The article introduces the theory and basic concepts of the increment-drain process, increment functions and basal area – height method, and discusses estimation of timber products in increment-drain forecast, fluctuations of the increment, mortality in connection with the increment-drain forecast, and the scheme of cutting budget for desirable growing stock. Finally, it gives some proposals, based on the investigation, for preparing an increment-drain forecast for a large forest area.
The PDF includes a summary in Finnish.
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Kuusela,
E-mail:
kk@mm.unknown
In Finland ocular estimation of the growing stock has been made by means of volume tables based on the mean height and density class, or on the dominant height and density class of the stand. The author has observed that if the volume of a stand is estimated by employment of both tables, the results vary markedly from one another. Furthermore, volume of fully stocked stands in the dominant height tables show an approximate correspondence with the volumes of managed normal stands in Southern Finland.
The purpose of this study is therefore to develop volume tables for coniferous trees, based on the density class and the mean height; these tables should give the same volume for a stand as the dominant height tables.
Volume per hectare of 187 Scots pine (Pinus sylvestris L.) stands and 120 Norway spruce (Picea abies (L.) Karst.) stands on different forest types were estimated using the relascope method in Southern Finland. With the volume and the measured mean and dominant heights as a basis, the density classes were extracted from both mean height tables and the dominant height tables. The investigation indicates that the author estimated the dense stands too thinly, and the thin ones too densely, and that the erroneous estimation of the density can be corrected by comparison of the ocular estimations and the corresponding measurements. The density can be measured by means of crown closure, stem number per hectare or the basal area per hectare.
The PDF includes a summary in English.
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Kallio,
E-mail:
kk@mm.unknown
In acquiring land for the population displaced by the Second World War, the forest had to be priced, according to the Land Reclamation Act of 1945, separately for land and timber. Technical defects in the growing stock were to be taken account in the form of a total reduction in the value of the stock. Generally, it was to be 5-15% of the total value. The present investigation aims at checking the reduction percentages.
When the reduction in the felling value of the growing stock caused by the defects is estimated, the reduction is defined for each timber assortment, and the total reduction is calculated from these values. The timber assortments have big variation in prices, therefore defects in the most valuable assortments can have big effect on the total value of the growing stock. According to the study, the decree implementing the Land Reclamation Act did not in some cases allow for price reductions for defects on a sufficiently small scale to correspond to real conditions.
The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
The PDF includes a summary in English.
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Salo,
E-mail:
es@mm.unknown
One of the factors that influence if a peatland is suitable for draining is the time required until fellings bring income, even if it the discounting calculations has uncertainties. This article discusses the factors that affect the economic profitability of draining peatlands.
The profitability of draining increases the more the yield or increase of the yield exceeds the costs of draining. Estimation of the yield is in Finland based on the peatland type, which reflects production capacity of the site. In addition, the growing stock of the site can vary in peatlands within same peatland type. The density and size of ditches affects the draining costs. Thus, productivity based on a peatland type alone does not describe well enough the drainability of a peatland area.
In Finnish classification of site quality of the peatlands, the treeless bogs and rich fens have been given too high a class compared to well stocked spruce swamps and pine swamps. Also, the drainability of two spruce and pine swamps can differ markedly in economic point of view if the tree’s quality, volume and ability to recover differ. The article discusses different methods to assess profitability of draining that have been descibed in the previous studies. It is suggested that the classification of peatlands by their drainability should be more selective.
The PDF includes a summary in German.
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Keltikangas,
E-mail:
vk@mm.unknown
The article discusses use of felling value in determining the value of growing stock. It has been argued that use of felling value to calculate value for a forest holding usually leads to too high values. Consequently, when setting a price for growing stock, felling value should be applied only for such parts of the property that can be sold immediately at a current price.
The article describes in detail assessment of the felling value, first using timber assortments of the stand, and second, by conducting the felling value using parameters affecting the value, such as volume and tree species of the stand. An assessment method was developed to calculate the value by using structure of a cubic metre of timber in a stand. The structure was determined using data of the national forest inventory in Finland. Finally, the article discusses application of the method.
The PDF includes a summary in German.
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Lihtonen,
E-mail:
vl@mm.unknown
The purpose of this study was that of providing a long-term timber production model (Kilkki and Pökkälä 1975) with growing stock models. The paper is divided into two parts; the first is concerned with generation of the stand data through Monte-Carlo simulation. The growing stock of each stand was described by a DBH-height distribution. The necessary information on the relationships between the stand characteristics was derived from sample plots measured in the national forest inventory of Finland. A total of 1,500 Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst), and birch (Betula sp.) stands, each comprising 100 trees were provided by simulation.
In the second part, models predicting the form factor, timber assortment distribution, and value of the growing stock were derived through regression analysis for each species of tree. The predicting variables included the form factor of the basal area median tree, basal area median diameter, and height in the form factor models. In the timber assortment and value models, the only predicting variable was the volume of the basal area median tree. The Matchcurve-technique (Jensen 1973) was employed in derivation of the regression models.
The PDF includes a summary in English.
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Kilkki,
E-mail:
pk@mm.unknown
- Siitonen, E-mail: ms@mm.unknown
Category : Research article
We describe the methodology applied in the 12th national forest inventory of Finland (NFI12) and describe the state of Finland’s forests as well as the development of some key parameters since 1920s. According to the NFI12, the area of forestry land (consisting of productive and poorly productive forest, unproductive land, and other forestry land) is 26.2 M ha. The area of forestry land has decreased from 1920s to 1960s due to expansion of agriculture and built-up land. 20% of the forestry land is not available for wood supply and 13% is only partly available for wood supply. The area of peatlands is 8.8 M ha, which is one third of the forestry land. 53% of the current area of peatlands is drained. The volume of growing stock, 2500 M m3, is 1.7 times the volume estimated in NFI1 in the 1920s for the current territory of Finland. The estimated annual volume increment is 107.8 M m3. The increment estimate has doubled since the estimate of NFI2 implemented in late 1930s. The annual mortality is estimated to 7 M m3, which is 0.5 M m3 more than according to the previous inventory. Serious or complete damage was observed on 2% of the productive forest available for wood supply. The amount of dead wood is on average 5.8 m3 ha–1 in productive forests. Since the NFI9 (1996–2003) the amount of dead wood has increased in South Finland and decreased in North Finland both in protected forests and forests available for wood supply (FAWS). The area of natural or almost natural forests on productive forest is 380 000 ha, out of this, 42 000 ha are in FAWS and 340 000 ha in protected forests.
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Korhonen,
Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland
E-mail:
kari.t.korhonen@luke.fi
- Ahola, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: arto.ahola@luke.fi
- Heikkinen, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: juha.heikkinen@luke.fi
- Henttonen, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: helena.henttonen@luke.fi
- Hotanen, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: juha-pekka.hotanen@luke.fi
- Ihalainen, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: anttivj.ihalainen@elisanet.fi
- Melin, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: markus.melin@luke.fi
- Pitkänen, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: juho.pitkanen@luke.fi
- Räty, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: minna.raty@luke.fi
- Sirviö, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: maria.sirvio@uudenmaanliitto.fi
- Strandström, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: mikael.strandstrom@luke.fi
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Vidal,
Inventaire Forestier National, Château des Barres, Nogent-sur-Vernisson, France
E-mail:
claude.vidal@ifn.fr
- Lanz, WSL/FNP, Abteilung Landschaftsinventuren, Birmensdorf, Switzerland E-mail: al@nn.ch
- Tomppo, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: et@nn.fi
- Schadauer, Bundesamt und Forschungszentrum für Wald, Wien, Austria E-mail: ks@nn.at
- Gschwantner, Bundesamt und Forschungszentrum für Wald, Wien, Austria E-mail: tg@nn.at
- di Cosmo, ISAFA, Villazzano, Italy E-mail: ldc@nn.it
- Robert, Inventaire Forestier National, Ch‰teau des Barres, Nogent-sur-Vernisson, France E-mail: nr@nn.fr
