Current issue: 55(2)
In this study an attempt was made to use manometric Warburg technique in studying the growing season variations in the respiration rates of the roots of 1–3-year-old seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.). The respiration rates in both short-roots and long-roots have also been investigated.
According to the results, respiration intensity was the greatest in Scots pine and Norway spruce short-roots but also considerable in the long-root tips at the points of elongation. When the oxygen uptake rate per weight unit in the pine short-roots is given value of 100, the rate in the long-root tips is 61 and in the basal area 36. The corresponding values for spruce are 100, 69 and 43. The relative carbon dioxide release rates are different for the basal parts of the long-roots: pine 53 and spruce 57, when the CO2 release from the short-roots is 100. The CO2 release rate in the basal parts of the long-roots is relatively greater than the oxygen uptake. The respiration rate of the root systems of pine was larger than that of spruce due to the larger size of the root system.
The respiration rate per unit weight of pine roots of the 1- to 3-year-old seedlings decreases significantly with the increasing age. In spruce, the decrease was smaller. The result could have been different if only the short-roots of the same growing season were studied from all seedlings.
During the first growing season the root respiration rate decreased from the middle of the summer towards autumn. An experiment with pine seedlings grown in the mineral soil showed a very rapid increase in respiration rate in the spring. The rate, especially oxygen uptake, is at its greatest in the roots at the time of fastest growth.
Dilution plate method was used in studying the density and composition of the microfungal populations of the organic layer of Scots pine forests, and the soil-plate method in studying the part of these populations decomposing cellulose. The media used were rose bengal agar (Martin’s medium for fungi) and cellulose medium.
The microfungal density depended to a considerable extent on the moisture content and temperature of the organic layer. Only the combination of relatively high moisture content and temperature, but neither of these factors alone, influenced considerably the microfungal population density. The correlation of the populations to the changes in this combined factor was stronger than the correlation to the seasonal variations of spring, summer and autumn.
The microfungal population consisted of only a few species. Mucor, Mortierella and Penicillium were the most common genera isolated from the rose bengal agar. The first and the last of these comprised almost 90% of the total population. For the Mucor fungi, increases in the moisture content up to the maximum values found (75%) were favourable; the Penicillium fungi, on the contrary, were intolerant of high moisture content.
Among the cellulose decomposing microfungi grown on cellulose medium, Trichoderma sp. was the most common; also, it formed the most colonies, tolerated the lowest temperatures, and was most efficient. The others were of the genera Pullularia, Verticillium, Scopulariopsis and Penicillium. In addition, there were some unidentified Phycomycetes fungi. Only the two first-mentioned caused observable changes in cellulose.
The objective of this project was to determine the amount of gas exchange in peat samples collected from several swamps, using the Warburg method in the laboratory measurements. Special attention was directed on the influence of the lowering of the ground water level through drainage, on oxidation-reduction conditions in the samples from both forested and treeless peatlands, by measuring oxygen uptake and CO2 release. The biological activity in situ was determined by the cellulose decomposition rate in the sample plots. The six areas examined were both in drained peatlands and peatlands in natural condition.
The results show that in the sample plots in open swamps there was no consistent differences in the CO2 release rate in peat samples taken from different depths. However, in the sample plots on forested swamps rapid decrease is seen with increasing depth. The decreased biological activity of peat is caused by the oxidation-reduction conditions. The CO2 release rate may also be due to the respiration of tree roots, which are very shallow in peatlands.
The rate of in situ cellulose decomposition experiment and CO2 release indicated by the Warburg measurements appear to be correlated. The results indicate improved conditions for cellulose-decomposing microbes after draining. It is also possible that the biological activity of peat after draining increases to a considerable depth until the decrease of easily decomposable substances limit the activity in an old drainage area. The cellulose decomposition rate would still increase as the oxidation-reduction conditions improve.
Examination of stands developed under natural conditions can be used to provide basis for comparison for study of the development and yield of stands treated with intermediate fellings. In Finland, the first investigation and the yield and the structure of natural normal stands were published in 1920. This investigation on development and yield of the natural forests of Kainuu in southeastern Northern Finland is based on 92 sample plots on three forest types; Empetrum-Vaccinium type (EVT), Empetrum-Calluna type (ECT) and Vaccinium-Myrtillus type (VMT).
The Scots pine (Pinus sylvestris L.) sample plots represented variation of age classes for construction of mean development series. The Norway spruce (Picea abies (L.) H. Karst.) of the region are so old that development series could be obtained only for dominant trees based on stem analysis.
The average development of Scots pine stand on EMT type within the region is on average more rapid and the yield in cubic volume quantitatively larger and structurally better than that on ECT type. Self-thinning during the early decades of EVT is slower. The pine stands are denser in the age of 70 in Kainuu compared to Central Northern Finland, but the development and yield are similar.
The development, yield and structure of natural Norway spruce stand on VMT proved considerably inferior to the average level of pine stands on EVT, and to a major part on ECT. The mixed pines on spruce sample plots have developed better than spruces of equal age. Spruce stands on VMT in the area developed markedly better than Geranium-Dryopteris-Myrtillus (GDMT) in Central Northern Finland.
It seems that a spruce stand seems to require more fertile site type in north than in the southern part of Finland. These fertile types are relative rare in the north. In the region, the best results are received with pine. As a rule, also the yield of birch (Betula sp.) is poor in the region.
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This paper reports on tests made for the study of alternative methods in forest survey. Data were acquired by measurements in five areas in Finland and in Mexico, varying in size from 20 to 900 ha. The principal characteristics used in the analysis was the entire volume. By the combination of neighbouring plots, the variation could be studied for different plot sizes and survey strips. Variable (relascope) plots could be compared.
A starting point for the comparison of different sampling methods, calculations were made of the coefficients of variation for each plot type; total and within the strata. The amount of decrease of variation with an increasing plot size could be established. Comparisons have been made of the following sampling methods: simple random, stratified random, simple systematic, and stratified systematic sampling.
On comparisons of the standard error of sample mean it was found that in both stratified sampling and different types of systematic sampling there is, with increasing size and diminishing interval of sample plots, an increase in the relative improvement of the result against simple random sampling. Only in exceptional cases did systematic surveys give results which were less precise than those derived by other methods.
In discussion of some methods for determination of the precision of systematic sampling, possibilities of theoretical determination of the degree of precision was considered. An empirical study was made of the behaviour of some equations based on the sample itself. The larger the plot size and the shorter the plot interval, the more the equations overestimated in general the variance of sample mean.
As none of the equations studied gave reliable results, regression equations were calculated for the relative standard error on the basis of the data measured. The independent variables were plot size, plot or strip interval, area of survey unit and mean volume. The results arrived at are based mainly on the complete measurement of one area only. To enable extension of the scope of application, more material is needed with a complete enumeration of trees.
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Highest degree of precision in determining the areas of different strata in forest survey is achieved when the areas are measured from a map. However, in practice the stratum-areas usually need to be determined on the basis of samples taken in the field or from aerial photographs. The goal of the present investigation was to determine the precision in stratum-area estimation on the application of different sampling methods.
Three sampling methods were used: 1. sampling with random plots, 2. uniform systematic plot sampling, and 3. sampling with equidistant lines.
The dependence of the standard error of stratum-areas in systematic line and plot sampling was examined by regression analysis. The models for regression equations were derived from random sampling formulae. It appears that the characteristics of these formulae were applicable as variables in the regression equations for systematic samples. Also, some characteristics of the distribution of the stratum was found, which seem to influence the error in sampling with equidistant lines.
The results as regards uniform systematic plot sampling indicate that the use of random sampling formulae leads to considerable over-estimation of the standard error. Nonetheless, unless relatively short intervals between sample plots are used in the forest survey made on the ground, it is of advantage to study the division of the area into strata by measuring the distribution of the survey lines in these strata.
The results can be used in two ways: for estimation of the precision in a survey already made, or to predetermine the sample size in a survey to be made. The results may be applicable to areas ranging from 100 to 1,000 ha in size, as well as to larger areas.
The objective of the present investigation was to clarify the profitability of pruning silver birch (Betula verrucosa, now Betula pendula Roth) in the growing of raw material for veneer industry. Calculations were made on the grade, value, and price of pruned and untreated butt logs as well as on costs of pruning and the development of pruned trees.
The grade distribution of unpruned veneer butt logs, the grade distribution of the veneer yield, and consequently, the value of veneer yield and log prices at the plant are considerably better than those of average logs. The grade, value and price increased with increasing diameter. The value and price of pruned butt logs depended primarily on the difference between the turning pruning diameters, and their increase with decreasing pruning diameter and increasing turning diameter. The value of pruned butt logs is always considerably higher than that of unpruned logs. The increase in the value correlates to the pruning and turning diameters, and is, for example, in rotary-cut logs which have been pruned when 10 cm in diameter 80–130%.
Pruning increases the stumpage in naturally regenerated silver birch stands on Oxalis-Myrtillus site by 2,000–3,000 Fmk/ha when employed at 20 years of stand age and rotary cutting at 60–80 years of age respectively. The average pruning costs on Oxalis-Myrtillus site are 51–57 Fmk/ha.
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Growth-promoting effects of enhanced caron dioxide levels upon forest tree seedlings grown in plastic houses was studied in 1964 and 1965 in the Forest Breeding Foundation in Haapastensyrjä near Loppi in Southern Finland. In both years more vigorous height and weight growth, and development of root system was achieved when the CO2 concentration was increased to 0.2% than in the normal conditions (CO2 0.03%). The CO2 concentration was increased by burning propane in the plastic houses. Burning continued for four hours per day either at 8–10 and 14–16 a clock or 6–10 a clock. Growth was not affected by the time of the treatment, and it was equally high in 0.1% and 0.2% concentrations.
Treatment of the seedlings with 100–200 ppm gibberellic acid (GA) increased the height growth of healthy, well-rooted seedlings. Treatment with a concentrated (600 ppm) dosage, as well as treatment with a combination of GA and 1-naphtyl acetic acid (NAA) caused serious defects in grafts of Scots pine (Pinus sylvestris L.). GA treatments did not induce flower formation in pine. Red light during the night seemed to enhance growth of grafts of silver birch (Betula pendula Roth) and Norway spruce (Picea abies (L.) H. Karst.).
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