Martti Varmola

Timing and intensity of precommercial thinning in Pinus sylvestris stands

The effects of timing and intensity of precommercial thinning were studied in three Scots pine artificially regenerated stands on Vaccinium forest sites in southern Finland. A two-level factorial design (3×3) was used in each stand: thinning at dominant height of 3, 6 and 9 m to 1000, 1600 and 2200 stems ha−1. The effects of the treatments were analysed after a period of 23–25 yrs when the dominant height was 14–15 m. Early thinning resulted in the highest standing volume and amount of merchantable wood, and also in slightly accelerated height development. Thinning to 1000 stems ha−1 caused a considerable production loss, but there were no differences between the densities of 1600 and 2200 stems ha−1. Branches became thicker after early thinning, but the differences between the treatments were negligible for crop trees. Crown ratio was lowest as the result of early or moderate thinning (2200 stems ha−1).

Use of decision analysis interviews to support the sustainable use of the forests in Finnish Upper Lapland

Controversy between alternative uses of forests in Finnish Upper Lapland has been going on for decades, and in recent years it has been escalated to a serious conflict. The core of the conflict is the adverse impacts of forestry on old forests which are important grazing areas for reindeer and which are regarded as intact nature and wilderness areas. This paper describes the experiences of applying multi-criteria decision analysis interview approach on this conflict. The approach provides tools for structuring the problem and preferences of the stakeholders as well as for analyzing the effects of different alternatives in a common framework. We focus on the practical experiences gained from the application of this approach in this context. Multi-criteria decision analysis was found to be a useful approach to evaluate the economic, ecological and cultural aspects of this intense conflict. The obtained experiences also support the view that the approach works best when tightly integrated into the planning process.

Forest Management and Regeneration Success in Protection Forests near the Timberline in Finnish Lapland

Sustainable forestry is practised in Finnish Lapland north of latitude 69°, i.e. farther north than anywhere else in the world. The Protection Forests Act was passed in 1922 to guarantee the stability of timberline forests in this climatically extreme, unique area. This review, based on earlier studies, covers forest and climate statistics, and legislation, regulations and recommendations of forest management, and the effects of management practices and climatic trends on the results of natural and artificial regeneration of conifer forests, as well as on shifts in the timberline. The review is mainly based on Finnish research, but references from the other Fennoscandian countries have also been used. Temperature plays the main role in forest regeneration success, and the effective temperature sum has been found to express well the location of the Scots pine (Pinus sylvestris L.) timberline. Natural regeneration of pine has been satisfactory, especially when combined with soil preparation. In many cases the pine forests regenerate in the form of advance growth without any silvicultural action. The success of artificial regeneration seems to be associated with favourable, warm periods lasting for at least 20 yrs. The effects of cutting, forest fires, reindeer herding, biotic damage and air pollution on forest regeneration and the conifer timberlines are discussed.

The effect of release cutting on the growth and external quality of the dominant trees in a Pinus sylvestris stand established by spot sowing

The effect of the number of Pinus sylvestris trees in seed spots on the growth and external quality of the dominant trees was studied. The trees were monitored during the period between release cutting and the first commercial thinning. The treatments were one, two and four of the tallest seedlings retained per seed spot, and a control. The mean height of the dominant trees was highest in the one‐tree and two‐tree treatments. Diameter at breast height (DBH) increased with increasing spacing. On average, the stump diameter was 1.5–4.7 cm greater in the one‐tree treatment than in the control. Slenderness (height/DBH) was highest in the control treatments. The average living crown limit of the dominant trees was 4.6 m, and was at its highest in the two‐tree treatment. The results indicate that the competition in seed spots decreases the height growth of the dominant trees.

Survival and Early Development of Lodgepole Pine

The effect of site fertility, spacing and mode of regeneration on the survival and stand development of lodgepole pine, Scots pine and Norway spruce was studied in a series of experiments comprising 22 study areas in Finland. After 13-14 yrs, lodgepole pine had a mean survival of 68% in planted and 61% in seeded plots, while Norway spruce had the highest (92%) and Scots pine the second highest survival (82%). The survival of planted lodgepole pine was better the wider the spacing. Best survival was achieved on subdry and dry sites, both with planting and with direct seeding. Dominant height was not affected by spacing, but both basal area and volume at the age of 13-14 yrs were significantly higher the denser the spacing. The average difference in the value of the estimated site index H 50 was slightly under 3 m for the superiority of lodgepole compared with Scots pine. Seeding resulted in site indices almost as high as those of lodgepole planting.

Stability of height positions in young naturally regenerated stands of Scots pine

Abstract The stability of height positions of saplings in young stands of Scots pine (Pinus sylvestris L.) was examined by comparing the height order of trees at successive measurements. The data consisted of six naturally regenerated stands and one planted stand for comparison. The length of the examination period was approximately 20 years, covering the mean height development of stands from 0.5 to 5.5 m. For each stand, a structural equation model was fitted by which the covariance structure occurring in the data could be described. In terms of the stability coefficients between the variables produced by the model, the height position of the saplings was very stable. The height positions had mainly been established during the first 5–10 years of age and at a mean height of less than 0.5–1 m. In the naturally regenerated stands, stability was virtually complete from the stage of 15–20 years and 1.5–2 m onwards. In the planted stand, stability became complete slightly later than in the naturally regenerated stands. According to the results, the height of the sapling can be emphasized as a selection criterion in precommercial thinning.

Dendroclimatological analysis of seeded and thinned Scots pine (Pinus sylvestris L.) stands at the coniferous timberline

Radial growth was examined in two Scots pine stands that were seeded during the 1920s and 1930s due to reforestation and afforestation activity on the timberline of northern Finnish Lapland. Tree-rings of seeded pines were calibrated against the instrumental records of local weather and large-scale atmospheric patterns and further compared to pines of natural origin on the timberline. The studied stands were shown to contain common growth variability that differed from the variability of natural pines. Deviating growth of seeded pines was attributed to their only moderate growth dependence on mid-summer (July) temperatures and, likewise, their strong dependence on the autumn climate in the previous year, and linked to the different genetic origin of artificial stands due to southern seeds. Stands were thinned for different densities in 1985 and 1986. The growth response to thinning was markedly better than could be expected according to previous studies. We found that the positive growth reaction conceivably benefited from the ameliorated winter conditions, expressed as warmed (March) temperatures and the prolonged positive phase of the Arctic Oscillation (February). The results emphasize the determining influence of climatic fluctuations on reforestation and afforestation near the distributional limits of tree species.

Monitavoitearviointi Ylä-Lapin metsien kestävän käytön mahdollisuuksista

Tutkimuksessa tarkasteltiin Ylä-Lapin metsien käytön vaihtoehtoja osallistuvan monitavoitearvioinnin avulla. Eri sidosryhmien arvostukset tuotiin mukaan arviointimalliin henkilökohtaisilla tietokoneavusteisilla päätösanalyysihaastatteluilla. Tavoitteena oli selvittää eri tahojen näkemyksiä vaihtoehtojen mieluisuudesta. Tutkimuksessa muodostettiin viisi erilaista metsien käsittelyvaihtoehtoa, joissa hakkuukertymät vaihtelivat välillä 300 000 m3/v ja 30 000 m3/v. Vaihtoehtoja arvioitiin kuuden kriteerin avulla: 1) bruttotulovaikutukset paikallistaloudessa 2) työllistävyys 3) saamelainen poronhoitokulttuuri 4) paikallinen luonnon virkistyskäyttö 5) luonnon monimuotoisuus ja 6) yhteisymmärrys ja sopeutuminen. Tulosten perusteella voitiin tunnistaa kolme eri ryhmää. Kaksi ensimmäistä ryhmää pitivät parhaimpana vaihtoehtona nykyisen luonnonvarasuunnitelman mukaista hakkuutasoa. Nämä ryhmät poikkesivat toisistaan siten, että ensimmäinen ryhmä asetti toiselle sijalle nykyistä luonnonvarasuunnitelmaa laajemmat hakkuut kun taas toinen ryhmä piti toiseksi parhaana vaihtoehtona tätä suppeampia hakkuita. Kolmas ryhmä piti mieluisimpana vaihtoehtoa, jossa yli 140-vuotiaita metsiä ei hakata lainkaan. Arviointi nosti esille myös vaikutusarvioita koskevia näkemyseroja. Suurimmat erot koskivat saamelainen poronhoitokulttuuri ja porotalouden työllisyys -kriteereitä. Nämä ovat avainkysymyksiä, joista tulisi löytää yhteistä tietopohjaa kiistojen ratkaisemiseksi.