Current issue: 58(5)
This study forms part of a project designed to elucidate the total nutrient budget of a Scots pine (Pinus sylvestris L.) stand in Central Finland during the 1974 growing period. Precipitation has been divided up into precipitation, throughfall and stemflow.
The acidity of the rainwater was found to increase in the order – Precipitation, throughfall and stemflow. The electrolyte content of the rain water from throughfall and stemflow was higher than that of precipitation. The nutrient contents of precipitation were rather low. Throughfall and stemflow were found to leach some nutrient from the trees. This was most clear in the case of potassium. The total amounts of nutrients reaching the ground in throughfall were found to be smaller than those in precipitation. On the other hand, the amounts of potassium, calcium and magnesium in stemflow were clearly greater than those in precipitation.
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The significance of water budget in June and July for forest and peatland vegetation, and consequent effects on fauna, climate and agriculture has been studied.
In June, the difference between evaporation and precipitation is greater than it is later in the summer. North of the line zero difference of evaporation and precipitation, coinciding with a line of sharp change in forest vegetation, the uppermost part of podsol remains wet throughout the summer. During July, the line of zero difference moves from north to south over the greater part of Finland, run-off being minute and podsol at the driest in this month. This line, indicating the length of the period with evaporation greater than precipitation and causing a sharp change in forest vegetation, in frequency of peatlands, amount of growing stock productive capacity of forests etc. This line is significant also for cultivation: because of the lower evaporation north of this line, night temperature below the freezing point often appear in summer.
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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 calculation of the annual financial performance of a forest district and a county.
Silva Fennica Issue 39 includes presentations held in professional development courses in 1935 that were arranged for foresters working in public administration. 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 the peparation of national budget in forestry administration.
Because the ‘rental cut method’ is rather arduous and based partly on subjective analysis, new forms for a cutting budget has been developed. One of them is a method called stock development forecast, and another method will be described in this paper. The main characteristics of the present growing stock affecting the allowable cut are the forest area, site quality, forest composition by age and development classes, volume, and increment.
In the method described in this paper an analysis of the desirable stock is necessary. The allowable cut is a function of the current and desirable stock and the increment during the budget period. The budget is based on information about the forest area, site quality, growing stock and its structure, collected from an inventory. The desirable stock is described in the same sub-groups as is the current stock. An increment forecast is prepared by compound and an interest formulae and increment percentages are presented as a function of the stock age. The allowable cut shows the average amount of the cut during the management plan period.
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Two lines can be defined in the management planning for the State Forests of Finland: 1) general planning for regions and inspectional sub-regions based on forest inventory, and 2) management plans for individual districts based on the revision of each district after 10–15 years. Long-term planning is has recently been alleviated by several new methods, such as stock-development forecast and yield tables.
A stock-development forecast and cutting budget were prepared separately for each State Forest region. The present growing stock was based on the data collected in the inventory in 1951–1955. Desirable stock for each region was calculated. The methods to calculate total cut during near future, allowable cut, allowable cut by timber products, the long-term development of the allowable cut, and conditions for realizing the allowable cut are presented in the paper.
The development of the growing stock towards a desirable condition requires also realization of a silvicultural program. Because the Finnish forest industry is expanding vigorously, the amount of the allowable cut on a sustained basis must be estimated carefully. Otherwise the demand for wood may exceed the supply. Though there are many sources of error in preparing a long-term cutting budget, it was considered necessary for State Forestry. An approximate estimate of the largest cut on a sustained basis and a program of silvicultural measures necessary to increase the yield gradually has been worked out.
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An estimate of value of a forest holding is needed, for instance, when the holding is sold. There is, however, no standard method for forest valuation. This paper describes a method based on yield in terms of value that is estimated on the basis of cutting budget. The first, mensurational part of the investigation concentrates on calculation of cutting budget that can be used in forest valuation. Second part studies how chronological order of fellings changes allowable cut in forests that differ by age-class distribution and other structural properties. Structure and variation in the structure of silviculturally different forests are determined for the forests that form the data for the investigation.
According to the study, even if the forests studied in the investigation included forests which structure differed in their age-class distribution from normal forests, they could be managed in a such way that in 5-6 decades the age-class distribution resemble that of a normal forest, and have growing stock that correspond the stock of forests in Southern Finland, about 80-110 m3/ha. Based on this, the cutting budgets of the later decades of the first rotation can be assumed to be nearly even. The original age-class distribution of the forest affects, however, allowable cut of the forests during the first decade. The revenues of the first decade have small impact on the value, the later decades strong. Consequently, development of the most valuable part of the allowable cut, timber trees, has big impact on the value. The results show that in young forests the planned cut including the proportion of timber trees increases, in middle-aged forest it is relatively even, and in old forest declining. The results indicate the order of magnitude the planned cut can be in near future in diferent kinds of forests, and when different felling regimes are used to reach different goals.
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The purpose of this study was to clarify increment forecast methods in connection with the cutting budget. The emphasis is laid on the Finnish increment per cent methods. A tentative attempt is made to carry out a passage calculation. Increment forecasts are accomplished for diameter class distribution of a 60 years old Scots pine (Pinus sylvestris L.) stand. The increment data for the growing stock are taken from the domestic increment calculating tables.
When comparing the results of the two methods, the increment values are expressed in rabatt per cent in which the forecasted annual increment is in proportion to the initial value of the growing stock. It will be emphasized that the weak point in the domestic budgets is in the relation between the increment of the developable stock and the increment of the exploitable stock. Almost all the Finnish increment data are from the developable trees and the estimates of the increment of the exploitable trees have not been on sufficient facts.
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The aim of the study was to develop a method for calculating a cutting budget that is adapted to the present forest management practices. The cutting budget determines the volume of annual cuttings for a forest holding in a certain period of time. Effect of fellings on the cutting budget depends on the cutting methods used. The study aimed at proving that growth of the forest can be estimated based on growing stock and structure of the forests for a certain time period. Accordingly, adequate drain can be defined in advance. The cutting budget is based on age-class distribution of the forest holding, which is most applicable for even-aged forestry. Calculation is based on area of the forest land and estimated volume of the growing stock. Also, the quality of the forest soil can be taken into account when age-class distribution is used. A suitable period for estimating a cutting budget is suggested to be 20 years, which is divided in two 10-year periods. The cutting budget it is included in a forestry plan. An example of a cutting plan based on the method is presented.
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A theoretical framework to analyse the growth of Scots pine (Pinus sylvestris L.) is presented. Material exchange processes and internal processes that transport, transform and consume materials are identified as the components of growth. Hierarchical system is lined out. Momentary uptake of material at a single exchange site depends on the environmental condition next to the exchange site, the internal state of the biochemical system of the plant and the structure of the plant. The internal state depends on the exchange flows over period of time and the structural growth depends on the internal state. The response of these processes to the fluxes is controlled by the genetic composition of the plant.
The theoretical framework is formulated into a mathematical model. A concept of balanced internal state was applied to describe the poorly known internal processes. Internal substrate concentrations were assumed to remain constant but tissue-specific. A linear relationship between the quantity of foliage and wood cross-sectional area was assumed to describe balanced formation of structure. The exchange processes were thus described as a function of external conditions. The stand level interactions were derived from shading and effects of root density on nutrient uptake.
The approach was tested at different levels of hierarchy. Field measurements indicated that the hypothesis of the linear relationship described well the regularities between foliage and sapwood of a tree within a stand when measured at functionally corresponding height. There was considerable variation in the observed regularities in the range of geographic occurrence of Scots pine. Model simulations gave a realistic description of stand development in Southern Finland. The same model was also able to describe growth differences in Lapland after considering the effect of growing season length in the parameter values. Simulations to South Russia indicate stronger deviation from the observed patterns.
The simulations suggest interesting features of stand development. They indicate strong variability in the distribution of carbohydrates between tree parts during stand development. Internal circulation of nutrients and the reuse of the same transport structure by various needle generations had a strong influence on the simulation results.
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The paper is the final report of a study on the estimation of value increment and inherent variables of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands. The main aim was to obtain improved criteria for decision-making concerning the priority of stands for regeneration.
The construction of various estimation models and their reliability are discussed in detail. The study, together with some previous papers, has resulted in a system which on the basis of a number of easily assessed stand variables gives for the stands concerned the volume of stems, percentages of timber assortments, stumpage value, volume increment and value increment.
The following examples are given with regard to the practical application of the results, in addition to the determination of the relative maturity of stands: 1) The study of various trends in stand development; the comparison between the volume and value variables. 2) The estimation of timber assortments needed for a cutting budget, trees marked for felling etc. 3) The calculation of the value of forests.
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The aim of the study was to discover a model by which the determination of the discount value of a woodlot can be simplified so as to make it possible to avoid both the computation of a cutting budget and the customary discount procedure itself. The regression analysis of the cutting budget data that indicates the discounted amount of the fellings to be expected and the assortment composition can be discovered rather accurately as a function of the measured stand characteristics only.
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The aim of this study was to develop cutting budget methods for a forest undertaking. Cutting budget provides information on the future income from the forest undertaking, and on the development of the forest.
Two cutting budget models have been developed, by the application of simulation and linear programming. Both of the models are deterministic in nature, i.e. there is only one possible outcome once the stated input information has been given. To make the models simpler, it has been assumed that thinning and clear cutting with reforestation are the only activities that can occur in the forest. The models are directly applicable only to forests consisting of even-aged Scots pine stands at three different forest types. However, they can easily be extended to cover forests comprising several tree species and more sites.
In the light of this study, simulation seems today to be more appropriate than linear programming in the preparation of cutting budgets. However, the increasing capacity of computers may even in the near future make linear programming quite competitive, especially as if it is borne in mind that the theoretical basis of linear programming is much firmer than that of simulation. The most advisable cutting budget method might consist of a combination of simulation and linear programming. Simulation could be employed to find a rough cutting schedule, and linear programming to test and improve the solution.
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Silver birch (Betula pendula Roth.) is one of the main pioneer tree species occupying large areas of abandoned agricultural lands under natural succession in Estonia. We estimated aboveground biomass (AGB) dynamics during 17 growing seasons, and analysed soil nitrogen (N) and carbon (C) dynamics for 10 year period in a silver birch stand growing on former arable land. Main N fluxes were estimated and nitrogen budget for 10-year-old stand was compiled. The leafless AGB and stem mass of the stand at the age of 17-years were 94 and 76 Mg ha–1 respectively. The current annual increment (CAI) of stemwood fluctuated, peaking at 10 Mg ha–1 yr–1 at the age of 15 years; the mean annual increment (MAI) fluctuated at around 4–5 Mg ha–1. The annual leaf mass of the stand stabilised at around 3 Mg ha–1 yr–1. The stand density decreased from 11600 to 2700 trees ha–1 in the 8- and 17-year-old stand, respectively. The largest fluxes in N budget were net nitrogen mineralization and gaseous N2-N emission. The estimated fluxes of N2O and N2 were 0.12 and 83 kg ha–1 yr–1, respectively; N leaching was negligible. Nitrogen retranslocation from senescing leaves was approximately 45 kg ha–1, N was mainly retranslocated into stembark. The N content in the upper 0–10 cm soil layer increased significantly (145 kg ha–1) from 2004 to 2014; soil C content remained stable. Both the woody biomass dynamics and the N cycling of the stand witness the potential for bioenergetics of such ecosystems.