Seppo Rouvinen, Jari Kouki. (2011). Tree regeneration in artificial canopy gaps established for restoring natural structural variability in a Scots pine stand. Silva Fennica vol. 45 no. 5 article id 88. https://doi.org/10.14214/sf.88

Keywords: ecosystems; diversity; restoration

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In Finland and elsewhere in Europe, many protected forest areas include also stands that were previously managed and that lack several naturally occurring stand characteristics. In these areas, ecosystem restoration can be used to facilitate and accelerate the formation of structural and habitat features resembling those of natural forests. For example, by creating small gaps it could be possible to diversify forest structure and tree species composition and to produce dead wood while still maintaining mostly continous canopy coverage. We examined experimentally the effects of artificial gap formation on post-disturbance tree regeneration in the gaps in a young protected, but formerly commercially managed pine (Pinus sylvestris L.) dominated forest. In the experimental sites, gap size and the portion of girdled trees out of all treated trees (girdled and felled trees combined) in the gaps varied. Natural and artificial (direct seeding of silver birch Betula pendula Roth) tree regeneration and development was monitored both on disturbed (scarified soil patches) and undisturbed forest floor during three growing seasons. Results show that gaps can be valuable in diversifying stand structure but to be successful and rapid, tree regeneration needs disturbed forest floor. Pine regenerated numerously, but birch had clearly lower regeneration, especially on small-sized gaps. In conclusion, increasing tree diversity in young pine-dominated forests seems to be difficult when only small artificial gaps are used. But even small gaps can be used to create and maintain diverse cohort structure of the dominant species and thus they can contribute to restoration goals.

Rouvinen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: seppo.rouvinen@uef.fi
Kouki, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: jk@nn.fi

article id 393, category Research article

Seppo Rouvinen, Anne Rautiainen, Jari Kouki. (2005). A relation between historical forest use and current dead woody material in a boreal protected old-growth forest in Finland. Silva Fennica vol. 39 no. 1 article id 393. https://doi.org/10.14214/sf.393

Keywords: Populus tremula; Pinus sylvestris; Picea abies; coarse woody debris; forest utilization; historical ecology; land-use history; nature conservation; spatial pattern analysis

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Assessing the human impact on the naturalness and vegetation characteristics of protected areas is one of the key issues when designing forest conservation networks in Fennoscandia. We studied the small-scale, detailed relationship between forest utilization history and the current availability of dead woody material in a protected old-growth forest area in North Karelia, eastern Finland. From the study area of 32.4 ha, all the stumps (diameter ≥ 5 cm and height < 1.3 m, classified as natural, man-made and of undetermined origin) were measured using 25 x 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 x 50 m plots in an area of 7.8 ha. The average number of stumps was 130 per ha, and over half of the stumps were classified as man-made. However, the historical documents since the 1910s showed no logging in the area: some of the largest man-made stumps probably originated from an earlier time, but most of those stumps were made considerably later. The variation in the total number of stumps (per ha) was great (range 0–560/ha, 0–16 m2/ha), with no clear clustering in space. However, clustering of man-made stumps was detected. The average volume of pooled standing and fallen trees was 84 m3/ha, with a range of 37–146 m3/ha. The other noticeable man-made disturbance besides logging was notching of aspens, which has a scatteredly significant influence on the amount of dead trees. In conclusion, the protected old-growth forest was not as a whole in a natural state but showed different degrees of human impact from virtually untouched patches to quite heavily managed patches. The results suggest that the number of man-made stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.

Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: seppo.rouvinen@joensuu.fi
Rautiainen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ar@nn.fi
Kouki, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jk@nn.fi

article id 554, category Research article

Seppo Rouvinen, Timo Kuuluvainen, Juha Siitonen. (2002). Tree mortality in a Pinus sylvestris dominated boreal forest landscape in Vienansalo wilderness, eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 554. https://doi.org/10.14214/sf.554

Keywords: dead wood; disturbance dynamics; spatial pattern analysis; mortality agent; forest structure; temporal variation

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Tree mortality and its causes and spatial pattern were examined along four transects (width 40 m, length 2550–3960 m), with a total length of 12 190 m and area of 48.8 ha, in a Pinus sylvestris L. dominated, boreal forest landscape. Tree mortality was determined within a time window of 3 years by identifying those trees (dbh ≥ 10 cm) along the transects that fitted into one of the three categories: 1) current mortality: trees that had died during the year of survey (1998), 2) recent mortality: trees that had died during the year (1997) before the survey year, and 3) predicted mortality: trees that were expected to die during the year (1999) following the survey year. Long-term tree mortality was studied on 10 plots (20 m x 100 m) by dating 87 dead trees using dendrochronological methods. The mean current mortality was 1.4 m3 ha–1 (3.7 trees ha–1). Both the recent and predicted mortalities were also 1.4 m3 ha–1. Mortality was, on the average, higher on peatlands than on mineral soils. The highest mortality was found within an area recently flooded by beavers. Over half of the examined trees (52%) were judged to die without any visible signs of an external abiotic cause. At the landscape scale, tree mortality was continuous although somewhat aggregated in space. Of the 66 dated standing dead Pinus trees, 23 (35%) had died during the 19th century and two during the 18th century, demonstrating that dead Pinus can remain standing for long periods of time before falling. Our results show that autogenic mortality of individual trees or small groups of trees was the predominant mode of disturbance in this Pinus dominated landscape.

Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: seppo.rouvinen@forest.joensuu.fi
Kuuluvainen, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: tk@nn.fi
Siitonen, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: juha.siitonen@metla.fi

Category : Discussion article

article id 270, category Discussion article

Seppo Rouvinen, Jari Kouki. (2008). The natural northern European boreal forests: unifying the concepts, terminologies, and their application. Silva Fennica vol. 42 no. 1 article id 270. https://doi.org/10.14214/sf.270

Keywords: human influence; biodiversity; natural ecosystems; natural forests; protection; terminology

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Recent emphasis on conserving the biodiversity has stressed the value of natural ecosystems in saving the species from extinction. In the Fennoscandian region the conifer-dominated boreal forests form the largest single ecosystem. The forests have been under varying intensity of human influence for decades or centuries. Recent attempts have tried to seek the last remaining natural forests to be included in the protection programmes. However, due to long and widespread human influence, finding and defining the natural forests has proven to be extremely difficult, not only because they are so rare but also because the concept of natural forest is vague. These difficulties are partly seen through the diverse terminology used. We first review the varying terminology as seen in recent studies. Secondly, we propose the basis for defining the natural forest and show some intriguing and challenging difficulties are involved in the concept. These difficulties are at least partly related to inherent strong and long-term dynamic component in boreal forest ecosystems that is manifested over several temporal and spatial scales. Finally, we outline a more general terminology with associated indicators and measurements that might be used in the classification and terminology. Conceptual clarification is necessary, for example, to compile ecologically justified and representative global, national and regional forest statistics. Many currently applied definitions of “forest” and “natural” that are applied in the context of forest statistics overlook ecologically important components of natural forests, and thus provide quite misleading or inadequate data of existing diversity patterns in these ecosystems.

Rouvinen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: sr@nn.fi
Kouki, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jari.kouki@joensuu.fi

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