Publikasjoner
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1993
Forfattere
Tron Eid P.A. MoenSammendrag
4 site quality classification methods have been tested in young forest stands; height-age-, intercept-, vegetation- and subjective site quality classification. Two functions are applied for intercept site quality classification. One function where the site quality is based on the intercept (5 years height increment above 2.5 meter off the ground) and the tree species (intercept). And one function where also different characteristics of the growing place are included (extended intercept). Also for site quality classification by means of vegetation two different functions are applied; one which is based on vegetation type and on other characteristics of the growing place (vegetation), and one which in addition use the breast height age to explain the site quality (vegetation with age) (see also Appendix 1). The registrations are carried out on systematically distributed sample plots in 45 stands. The data are described in Table 1, 2 and 3. Table 4 shows that intercept gives significantly higher site quality than extended intercept. The mean difference for all plots is 0.5 meter. It has not been possible to point out any obvious reasons for this difference. Table 5 shows that vegetation with age gives significantly higher site quality than vegetation. The mean difference for all plots is 3.5 meter. The introduction of age as an independent variable has clearly made the site quality higher. Table 6 shows that 100 m2 sample plots give significantly higher site quality than 10 m2 sample plots both for height age and for intercept. The mean differences for all plots are 1.0 meter and 0.7 meter for the two methods. 100 m2 sample plots is recommended in practical inventories. Table 7 shows generally small differences between height-age and intercept. For the best site qualities, however, height-age gives the highest values, while intercept gives highest values for the poorest site qualities. A test, where plots with young trees (T1.3 15 years) have been excluded, does not change the relative relations between the two methods. For both methods there is a certain possibility for an overestimation of the site quality if the soil depth is tiny. Table 7 also shows that vegetation with age gives a significantly higher site quality than height-age for 2 out of 3 sites, and both for spruce and pine. The mean difference for all plots is 1.2 meter. The introduction of age as an independent variable has made the site quality higher. It might be questioned whether it has made the site quality too high. It is not possible based on the present data material, however, to give any appropriate answer to this question. Table 7 further shows that subjective site quality classification gives significantly lower values than height-age, intercept and vegetation with age. Several possible reasons for the differences are pointed out. It is also quite likely to perform person-dependent systematic errors when subjective classification methods are applied. The results of this study basically point out two possible correct site quality levels in young forest stands. One possibility is that the methods height-age, intercept and vegetation with age all give an approximately correct level. The other possibility is that vegetation (without age) and subjective site quality classification give an approximately correct level. According to the discussion it is quite possible that the correct level is somewhat lower than the level indicated by height-age, vegetation with age and intercept. It is, however, less likely that the level is as low as vegetation (without age) and subjective site quality classification are indicating. Subjective site quality classification has so fare been recommended for young forest stands. This method has also been applied for practical inventories. We know that person-dependent systematic errors are usual when subjective classification methods are applied. Because of this, and based on the results of this study, it is quite likely that site quality classification in young forest stands will be done more accurate if some of the three other methods were applied.
Forfattere
Gry Kolsrud BjerketvedtSammendrag
Det er ikke registrert sammendrag
Forfattere
Oddvar SkreSammendrag
Det er ikke registrert sammendrag
Forfattere
Jarle BerganSammendrag
The main objection of the investigation was to study survival, height growth and injuries to plant material originating from different localities in the central pine forests of Troms and Finnmark (Fig. 1). The distance between the most northern and southern central pine forests in Troms and Finnmark is about 110 to 120 kilometres. On the other hand, the corresponding distance west to east is 400 to 450 kilometres.Previous investigations and experiences have shown that provenances from the inner parts of Troms have achieved good results as regards survival and height development when planted or sown in fjord districts and inner parts of Finnmark (Bergan 1988, 1989a). However, comparative studies of plants originating from all the main districts of pine forests have not been made before the present investigation.In the years 1974 to 1985, 21 test fields of Scots pine were laid out at different localities in the central districts of pine forests in Troms and Finnmark (Table 1). The seed was collected in Febr. - April 1973 from ten selected trees in different stands situated in eight of the most important districts of pine forests in this northern part of the country (Table 2, Fig. 1). The germination percentage of the seed was 90 to 97 per cent, except for the localities Bollo (80 %) and Slepelvli (75 %).The plots are divided into three groups. Group 1 includes plots where all or nearly all the localities of seed collection are represented (named \"main plots\"). Group 2 includes a section of the localities. The plots in Group 2 are situated at lower altitudes, while most of the plots in Group 3 are laid out at high altitudes. All plots have been frequently examined and heights measured until the autumn in 1991 or 1992.The Tables present the relative heights and survival percentages in the last year of inspection (Heikamelen, Nordreisa=100). The results of the main plots (Group 1) are shown in the Tables 3 to 5. As an average of the eight main plots, Table 6 shows the relative mean heights of all living trees (Htot) and a section of the highest trees (H20=889 trees per ha) together with the relative survival percentages.Analyses of variance and rangetests (Student-Newman-Keul = SNK) show that plants of seed from the smaller and most isolated districts of pine forests - Trany, Skibotn and Kvenangen - have less height growth and/or lower survival than plants from the larger districts: Mlselv, Nordreisa, Karasjok and Pasvik. The difference seems to increase at the frosty sites. The results of the plots in Groups 2 and 3 confirm the results of the main plots.Slepelvli in Mlselv has relatively small heights and low survival percentage, too. The locality of Slepelvli is relatively isolated from the rest of the pine forests in Mlselv. One outstanding feature of the climate at Skibotn and Slepelvli is the snow conditions, which are characterized by very little snow in the winter.One of the most frequent causes of a large decrease in plant survival of some of the seed collections at the plots has been attack from fungal diseases as Phacidium infestans and Gremmeniella abietina on the plants. Decrease in plant survival, especially in the first 5-6 years after cultivation, has been caused by physiological response due to extremely bad climatic conditions in some years. Injuries by frost, elk and hare have to a certain degree influenced the height development at some of the plots.The main conclusion of the investigation is as follows: By shortage of local seed in future cultivations in the central districts of pine forests in Troms and Finnmark, equally good survival and height growth will be achieved by using seed from the central pine forests at Mlselv, Nordreisa, Karasjok or Pasvik.
Forfattere
Bjørn TveiteSammendrag
Det er ikke registrert sammendrag
Forfattere
Halvor SolheimSammendrag
Det er ikke registrert sammendrag
Forfattere
Bernt-Håvard ØyenSammendrag
Rapporten beskriver forurensningseffekter i skogvegetasjonen i Mosjøen og omegn, relatert til fluoridutslipp fra et aluminiumverk. Resultatene er sammenholdt med kjemiske analyser av fluorid i plantedeler. Kritisk belastningsgrense er overskredet i et større område rundt aluminiumverket, hvor det er påvist sviskader på arter i skogvegetasjonen. Nærområdene til verket er de mest forurensningsbelastede, og konsentrasjonene av fluorid i blad og nåler avtar med økende avstand fra aluminiumverket. Sviskader forårsaket av fluorid er funnet på liljekonvall opp til 10 km fra aluminiumverket i hovedvindretningen. Utbredelse av sviskader, konsentrasjoner av fluorid i analyserte plantedeler og sammensetning av lav på granstammer viser at forurensninger av fluorid har forårsaket moderate vegetasjonsskader. Analyser viser godt samsvar mellom fluoridopptak i planter og visuell vurdering av skadeomfanget.
Forfattere
Halvor SolheimSammendrag
Det er ikke registrert sammendrag
Forfattere
C. Carter Øystein AustaråSammendrag
Det er ikke registrert sammendrag
Forfattere
Seif S. Madoffe Øystein AustaråSammendrag
Det er ikke registrert sammendrag