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Silva Fennica 1926-1997
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Articles containing the keyword 'gap'

Category: Article

article id 5593, category Article
Malle Mandre, Jaan Klõseiko, Vaike Reisner, Hardi Tullus. (1996). Assessment of CO2 fluxes and effects of possible climate changes on forests in Estonia. Silva Fennica vol. 30 no. 2–3 article id 5593. https://doi.org/10.14214/sf.a9238
Keywords: climate change; CO2; forestry; Estonia; carbon dioxide; forest composition; Forest Gap model
Abstract | View details | Full text in PDF | Author Info

The present study is the first attempt to carry out an inventory of greenhouse gas (GHG) fluxes in the forests of Estonia. The emission and uptake of CO2 as a result of forest management, forest conversion and abandonment of cultivated lands in Estonia was estimated. The removal of GHG by Estonian forests in 1990 exceeded the release about 3.3 times. Changes in the species composition and productivity of forest sites under various simulated climate change scenarios have been predicted by using the Forest Gap Model for the central and coastal areas of Estonia. The computational examples showed that the changes in forest community would be essential.

  • Mandre, E-mail: mm@mm.unknown (email)
  • Klõseiko, E-mail: jk@mm.unknown
  • Reisner, E-mail: vr@mm.unknown
  • Tullus, E-mail: ht@mm.unknown
article id 5592, category Article
Ari Talkkari. (1996). Regional predictions concerning the effects of climate change on forests in southern Finland. Silva Fennica vol. 30 no. 2–3 article id 5592. https://doi.org/10.14214/sf.a9237
Keywords: climate change; Finland; simulation; growing stock; wood production; Gap model; regional predictions; cutting yield
Abstract | View details | Full text in PDF | Author Info

A gap-model was used with forest inventory data in taking ground-true site, soil and tree characteristics into account in predicting the effects of climate change on forests. A total of 910 permanent sample plots established in the course of national forest inventory (NFI) in Finland and located on mineral soil sites in southern Finland were selected as the input data. The climatological input used in the simulations consisted of interpolated means of and deviations from long-term local temperature and precipitation records. The policy-oriented climate scenarios of SILMU (Finnish Research Programme on Climate Change) were used to describe the climate change. The temperature changes in the climate scenarios were increases of ca. +1.1 °C (low), +4.4 °C (medium) and +6.6 °C (high) compared to the current climate in 110 years. The simulation period was 110 years covering the time years 1990–2100.

Southern Finland, divided into fifteen forestry board districts, was used as the study region. Regional development of stand volume, cutting yield, and total wood production of forests under different climate scenarios were examined. The annual average growth in simulations under current climate was close to that observed in NFL Forests benefited from a modest temperature increase (Scenario 2), but under Scenario 1 the growing stock remained at a lower level than under the current climate in all parts of the study region. In wood production and cutting yield there were regional differences. In the southern part of the study regional wood production under Scenario 1 was ca. 10% lower than under the current climate, but in the eastern and western parts wood production was 5–15% higher under Scenario 1 than under the current climate. The relative values of total wood production and cutting yield indicated that the response of forests to climate change varied by geographical location and the magnitude of climate change. This may be a consequence of not just varying climatic (e.g. temperature and precipitation) and site conditions, but of varying responses by different kind of forests (e.g. forests differing in tree species composition and age).

  • Talkkari, E-mail: at@mm.unknown (email)
article id 5590, category Article
Heikki Hänninen, Seppo Kellomäki, Ilkka Leinonen, Tapani Repo. (1996). Overwintering and productivity of Scots pine in a changing climate. Silva Fennica vol. 30 no. 2–3 article id 5590. https://doi.org/10.14214/sf.a9235
Keywords: Pinus sylvestris; climate change; ecosystems; frost damage; phenology; forest ecology; gap-type model; model accuracy; model realism; overvintering
Abstract | View details | Full text in PDF | Author Info

The productivity of Scots pine (Pinus sylvestris L.) under changing climatic conditions in the southern part of Finland was studied by scenario analysis with a gap-type forest ecosystem model. Standard simulations with the model predicted an increased rate of growth and hence increased productivity as a result of climatic warming. The gap-type model was refined by introducing an overwintering sub-model describing the annual growth cycle, frost hardiness, and frost damage of the trees. Simulations with the refined gap-type model produced results conflicting with those of the standard simulation, i.e., drastically decreased productivity caused by mortality and growth-reducing damage due to premature dehardening in the changing climate. The overwintering sub-model was tested with frost hardiness data from Scots pine saplings growing at their natural site 1) under natural conditions and 2) under elevated temperature condition, both in open-top chambers. The model predicted the frost hardiness dynamics quite accurately for the natural conditions while underestimating the frost hardiness of the saplings for the elevated temperature conditions. These findings show that 1) the overwintering sub-model requires further development, and 2) the possible reduction of productivity caused by frost damage in a changing climate is less drastic than predicted in the scenario analysis. The results as a whole demonstrated the need to consider the overwintering of trees in scenario analysis carried out with ecosystem model for boreal conditions. More generally, the results revealed a problem that exists in scenario analysis with ecological models: the accuracy of a model in predicting the ecosystem functioning under present climatic condition does not guarantee the realism of the model, nor for this reason the accuracy for predicting the ecosystem functioning under changing climatic conditions. This finding calls for the continuous rigorous experimental testing of ecological models used for assessing the ecological implications of climatic change.

  • Hänninen, E-mail: hh@mm.unknown (email)
  • Kellomäki, E-mail: sk@mm.unknown
  • Leinonen, E-mail: il@mm.unknown
  • Repo, E-mail: tr@mm.unknown
article id 5468, category Article
Seppo Kellomäki, Heikki Hänninen, Taneli Kolström, Risto Lauhanen, Ulla Mattila, Brita Pajari, Hannu Väisänen. (1992). A simulation model for the succession of the boreal forest ecosystem. Silva Fennica vol. 26 no. 1 article id 5468. https://doi.org/10.14214/sf.a15626
Keywords: succession; gap dynamics; ecosystems; simulation models; forest ecology
Abstract | View details | Full text in PDF | Author Info

A model for the succession of the forest ecosystem is described. The growth and development of trees and ground cover are controlled by temperature and light conditions and the availability of nitrogen and water. In addition, the effects of the annual cycle of trees including the risk of frost damage, wild fire, and wind damages are contained in the model as factors which control the survival and productivity of trees. The model also makes it possible to evaluated the risk of insect attack assuming that this risk is inversely related to the growth efficiency of trees.

The PDF includes an abstract in Finnish.

  • Kellomäki, E-mail: sk@mm.unknown (email)
  • Hänninen, E-mail: hh@mm.unknown
  • Kolström, E-mail: tk@mm.unknown
  • Lauhanen, E-mail: rl@mm.unknown
  • Mattila, E-mail: um@mm.unknown
  • Pajari, E-mail: bp@mm.unknown
  • Väisänen, E-mail: hv@mm.unknown

Category: Research article

article id 7748, category Research article
Dominik Bayer, Hans Pretzsch. (2017). Reactions to gap emergence: Norway spruce increases growth while European beech features horizontal space occupation – evidence by repeated 3D TLS measurements. Silva Fennica vol. 51 no. 5 article id 7748. https://doi.org/10.14214/sf.7748
Keywords: Picea abies; gap dynamics; Fagus sylvatica; crown expansion; crown allometry; TLS; growing area competition; growing space efficiency
Highlights: Analysis of the closure dynamics of a Norway spruce, a European beech and a mixed forest gap by repeated TLS measurements; Norway spruce allocated additional resources predominantly into DBH growth and displayed stronger resilience against mechanical crown damage; European beech allocated resources towards space occupation and displayed higher crown plasticity; Species mixture had no significant effect.
Abstract | Full text in HTML | Full text in PDF | Author Info

The reach of different tree species’ crowns and the velocity of gap closure during the occupation of canopy gaps resulting from mortality and thinning during stand development determine species-specific competition and productivity within forest stands. However, classical dendrometric methods are rather inaccurate or even incapable of time- and cost-effectively measuring 3D tree structure, crown dynamics and space occupation non-destructively. Therefore, we applied terrestrial laser scanning (TLS) in order to measure the structural dynamics at tree and stand level from gap cutting in 2006 until 2012 in pure and mixed stands of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.). In conclusion, our results suggest that Norway spruce invests newly available above-ground resources primarily into DBH as well as biomass growth and indicate a stronger resilience against loss of crown mass induced by mechanical damage. European beech showed a vastly different reaction, investing gains from additional above-ground resources primarily into faster occupation of canopy space. Whether our sample trees were located in pure or mixed groups around the gaps had no significant impact on their behavior during the years after gap cutting.

  • Bayer, Address Technical University of Munich (TUM), Chair for Forest Growth and Yield Science, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany ORCID http://orcid.org/0000-0002-2084-3019 E-mail: dominik.bayer@lrz.tu-muenchen.de (email)
  • Pretzsch, Address Technical University of Munich (TUM), Chair for Forest Growth and Yield Science, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany E-mail: hans.pretzsch@lrz.tu-muenchen.de
article id 1219, category Research article
Thomas P. Sullivan, Druscilla S. Sullivan. (2014). Diversifying clearcuts with green-tree retention and woody debris structures: conservation of mammals across forest ecological zones. Silva Fennica vol. 48 no. 5 article id 1219. https://doi.org/10.14214/sf.1219
Keywords: clearcutting; green-tree retention; small mammals; coniferous forests; ecological zones; Myodes gapperi; population dynamics; red-backed voles; woody debris structures
Highlights: Species diversity of small mammals increased with structural complexity left on clearcut sites; Productivity of red-backed vole populations was higher in sites with green-tree retention (GTR) and windrows of woody debris; GTR and windrows may provide additive effect for providing habitat to conserve mammals on clearcuts.
Abstract | Full text in HTML | Full text in PDF | Author Info
We tested the hypotheses (H) that on newly clearcut-harvested sites, (H1) abundance and species diversity of the forest-floor small mammal community, and (H2) abundance, reproduction, and recruitment of red-backed voles (Myodes gapperi Vigors), would increase with higher levels of structural retention via green-tree retention (GTR) and woody debris (dispersed and constructed into windrows). Study areas were located in three forest ecological zones in southern British Columbia, Canada. For H1, mean total abundance did generally increase with the gradient of retained habitat structure. Mean species richness and diversity were similar among treatment sites but did show an increasing gradient with structural compexity. For H2, mean abundance, reproduction, and recruitment of M. gapperi were higher in GTR and windrow sites than those without retained structures. There was a positive relationship between mean abundance of M. gapperi and total volume of woody debris across treatments. This study is the first investigation of the responses of forest-floor small mammals to an increasing gradient of retained habitat structure via GTR and woody debris on clearcuts. Our assessment of a combination of these two interventions suggested a potentially strong additive effect that could be cautiously extrapolated across three forest ecological zones. With the advent of low levels of GTR on clearcuts, woody debris structures should help provide some habitat to conserve forest mammals on harvest openings.
  • Sullivan, Department of Forest and Conservation Sciences, Faculty of Forestry, University of BC, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4 E-mail: tom.sullivan@ubc.ca (email)
  • Sullivan, Applied Mammal Research Institute, 11010 Mitchell Avenue, Summerland, BC, Canada V0H 1Z8 E-mail: dru.sullivan@appliedmammal.com
article id 1192, category Research article
Hannu Hökkä, Hanna Mäkelä. (2015). Post-harvest height growth of Norway spruce seedlings in northern Finland peatland forest canopy gaps and comparison to partial and complete canopy removals and plantations. Silva Fennica vol. 48 no. 5 article id 1192. https://doi.org/10.14214/sf.1192
Keywords: Picea abies; height growth; peatlands; growth models; advance growth; canopy gap
Highlights: Norway spruce seedlings’ height growth recovered within four years after the cutting of canopy gaps; Growth was linearly related to tree height, being highest for tallest seedlings; Seedlings in the 20 m diameter gap and in the central and northern parts in the 15 m diameter gap showed the best growth; In gaps early height growth was 60% of that in peatland spruce plantations but 2–3 times higher than in uneven-aged cut forests.
Abstract | Full text in HTML | Full text in PDF | Author Info
Recent studies have shown the establishment of Norway spruce (Picea abies (L.) Karst.) to be successful in small canopy gaps cut in drained spruce mire stands in northern Finland. The aim of this study was to quantify seedling height growth in gaps and compare it to that observed in other canopy cuttings and plantations. We sampled spruce crop seedlings (maximum density ca. 3000 ha–1) in the spring of 2013 in a field experiment in which canopy gaps of 10, 15 and 20 m in diameter had been cut in winter 2004. The total seedling height in 2013 and the length of annual shoots over the past five years (2012–2008) were recorded in the survey. Seedling height varied from 20 cm to 2.7 m, with an average of 65 cm. The average annual height growth was 7.1 cm. A mixed linear model analysis was carried out to investigate seedling height growth variation. Seedling height was linearly and positively related to growth. Height growth started to increase in the fifth growing season after cutting. Seedling height growth in the 20 m gap was slightly better than in the smaller ones. In the 15 m gap, both the centrally located seedlings and those located at the northern edge grew best. In the 20 m gap, southerly located seedlings grew more slowly than seedlings in all other locations. The average seedling height growth in this study was about 60% of that in peatland plantations, but comparable to that in mineral soil gaps, and 2–3 times higher than in uneven-age cut stands.
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: hannu.hokka@metla.fi (email)
  • Mäkelä, Lapland University of Applied Sciences, Jokiväylä 11 C, FI-96300 Rovaniemi, Finland E-mail: hanna.makela@edu.ramk.fi
article id 920, category Research article
Hannu Hökkä, Jaakko Repola, Mikko Moilanen, Markku Saarinen. (2012). Seedling establishment on small cutting areas with or without site preparation in a drained spruce mire – a case study in northern Finland. Silva Fennica vol. 46 no. 5 article id 920. https://doi.org/10.14214/sf.920
Keywords: Picea abies; site preparation; canopy gaps; natural regeneration; drained peatlands; seedling establishment; clear-cut
Abstract | View details | Full text in PDF | Author Info
A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. We studied the effect of cutting – small canopy openings (78, 177, and 314 m2) and small clear-cuts (0.25–0.37 ha) – with or without site preparation (scalping) on the establishment of natural Norway spruce seedlings in one experimental drained spruce mire stand in northern Finland. The cuttings were made in winter 2004–2005 and site preparation with scalping in early June 2005. The experimental design was composed of four blocks with altogether four clear-cuts and 33 canopy openings. The seedling establishment was surveyed annually (2006, 2008–2010) from five circular sample plots (one 10 m2 and four 5 m2 plots in size) located within the canopy openings and from 18 circular 5 m2 sample plots systematically located in the scalped and untreated halves of the clear-cuts. Site preparation was found unnecessary, because it resulted in a clearly lower number of seedlings in the openings. A slight negative effect was also found in the clear-cuts. In the two years following the cuttings, the number of seedlings increased quickly in the canopy openings, but more gradually in the clear-cut areas. In 2010, on average 15 500 new seedlings were observed in the canopy openings and 6700 in the clear-cut areas, of which 5050 and 1200, respectively, were >0.1 m tall spruces. The proportion of birch increased in the last two years, being ca. 22% in the openings and 45% in the clear-cuts in 2010. The spatial distribution of seedlings was more uneven in the clear-cuts than in the openings, with 41% and 20% of survey plots empty, respectively.
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: hannu.hokka@metla.fi (email)
  • Repola, Finnish Forest Research Institute, Rovaniemi Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: jaakko.repola@metla.fi
  • Moilanen, Finnish Forest Research Institute, Oulu Unit, P.O. Box 413, FI-90014 University of Oulu, Finland E-mail: mikko.moilanen@metla.fi
  • Saarinen, Finnish Forest Research Institute, Parkano Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: markku.saarinen@metla.fi
article id 65, category Research article
Kristóf Kelemen, Barbara Mihók, László Gálhidy, Tibor Standovár. (2012). Dynamic response of herbaceous vegetation to gap opening in a Central European beech stand. Silva Fennica vol. 46 no. 1 article id 65. https://doi.org/10.14214/sf.65
Keywords: continuous cover forestry; dispersal; gap colonization; herbs; seed bank type; species richness
Abstract | View details | Full text in PDF | Author Info
Herbaceous ground vegetation in artificially-created gaps was studied in a managed beech (Fagus sylvatica L.) forest over a period of eight years in Northern Hungary, Central Europe. These gaps were being used as an alternative to the regular shelterwood system to create uneven-aged stands. The effects of gap size (15 and 40 m diameter) and canopy openness on herbaceous species colonization and persistence were assessed in a systematic grid of 5 5 m. Overall, herbaceous cover was low before gap creation, increased soon afterwards, and continued to rise over time. The number of herb species increased in the gaps and, to a lesser extent, in adjacent areas under the remaining tree canopy. Colonization of gaps was rapid and there was substantial turnover of species i.e. various species disappeared from the gaps over time whilst others colonized. Species with both long-term persistent seed banks and long distance dispersal abilities were the most successful types colonizing gaps. Six species occurred preferentially in large gaps, while only one species was found to prefer small gaps. Species present before gap creation survived in both gap sizes. Smaller gaps with a diameter of half the height of canopy trees also tended to remain free of common weed species, whereas large cover of Rubus fruticosus L. and Calamagrostis epigejos (L.) Roth could hamper natural regeneration in larger gaps. For the successful regeneration of beech we recommend the use of small gaps complemented by few large gaps.
  • Kelemen, Loránd Eötvös University, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: kk@nn.hu
  • Mihók, Loránd Eötvös University, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: bm@nn.hu
  • Gálhidy, Loránd Eötvös University, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: lg@nn.hu
  • Standovár, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: standy@ludens.elte.hu (email)
article id 82, category Research article
Nicole J. Fenton, Yves Bergeron. (2011). Dynamic old-growth forests? A case study of boreal black spruce forest bryophytes. Silva Fennica vol. 45 no. 5 article id 82. https://doi.org/10.14214/sf.82
Keywords: disturbances; old-growth forest; succession; boreal; bryophytes; climax; gap dynamics
Abstract | View details | Full text in PDF | Author Info
Old-growth forests have sparked significant interest over the last twenty years and definitions have evolved from structure based to process based, acknowledging the diversity of forests that could be considered old growth. However studies frequently group all forests over a certain age into a single type, negating the dynamic processes that create old growth. In this study we examine a 2350-year chronosequence in boreal black spruce forests in northwestern Quebec to determine whether continued community change can be observed in the bryophyte layer. Bryophytes dominate the understory of boreal forests and influence ecosystem functioning, particularly in paludified forests where production exceeds decomposition in the organic layer. Community composition and richness changed throughout the chronosequence with no evidence of a steady state associated with an old-growth phase. In contrast the bryophyte community continued to evolve with multiple phases being evident. These results suggest that old-growth forests on the Clay Belt of northwestern Quebec and northeastern Ontario, Canada, should be regarded as part of the continuous gradient in forest development rather than a single state. This complicates conservation of these forests as multiple phases should be considered when planning forest reserves.
  • Fenton, Université du Québec en Abitibi-Témiscamingue, 445 Boulevard de l’Université, Rouyn-Noranda, Québec, Canada J9X 4E5 E-mail: nicole.fenton@uqat.ca (email)
  • Bergeron, Université du Québec en Abitibi-Témiscamingue, 445 Boulevard de l’Université, Rouyn-Noranda, Québec, Canada J9X 4E5 E-mail: yb@nn.ca
article id 76, category Research article
Alessandra Bottero, Matteo Garbarino, Vojislav Dukic, Zoran Govedar, Emanuele Lingua, Thomas A. Nagel, Renzo Motta. (2011). Gap-phase dynamics in the old-growth forest of Lom, Bosnia and Herzegovina. Silva Fennica vol. 45 no. 5 article id 76. https://doi.org/10.14214/sf.76
Keywords: disturbance regime; Lom; old-growth forest; canopy gaps; beech-spruce-fir; small-scale
Abstract | View details | Full text in PDF | Author Info
We investigated forest canopy gaps in the mixed beech (Fagus sylvatica L.), silver fir (Abies alba Miller), and Norway spruce (Picea abies (L.) Karst.) old-growth forest of Lom in the Dinaric Mountains of Bosnia and Herzegovina. Gap size, age, gap fraction, gapmaker characteristics and the structure and composition of gapfillers were documented to investigate gap dynamics. The percentages of forest area in canopy and expanded gaps were 19% and 41%, respectively. The median canopy gap size was 77 m2, and ranged from 11 to 708 m2. Although there were many single tree-fall gaps, the majority had multiple gapmakers that were often in different stages of decay, suggesting gap expansion is important at the study site. Of the gapmakers recorded, 14% were uprooted stems, 60% snapped stems, and 26% were standing dead trees. Dendroecological analysis suggests that gap formation varied in time. The density of gapfillers was not correlated to gap size, and the species composition of gapfillers varied between seedling, sapling, and tree life stages. The results suggest that gaps are mainly formed by endogenous senescence of single canopy trees. Exogenous disturbance agents, most likely related to wind and snow, act mainly as secondary agents in breaking weakened trees and in expanding previously established gaps. Although the findings are partially consistent with other studies of gap disturbance processes in similar old-growth forests in central Europe, the observed gap dynamic places the Lom core area at the end of a gradient that ranges from forests controlled by very small-scale processes to those where large, stand replacing disturbances predominate.
  • Bottero, University of Turin, Department Agroselviter, Via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy E-mail: alessandra.bottero@unito.it (email)
  • Garbarino, University of Turin, Department Agroselviter, Via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy E-mail: mg@nn.it
  • Dukic, University of Banja Luka, Faculty of Forestry, Banja Luka, Bosnia and Herzegovina E-mail: vd@nn.ba
  • Govedar, University of Banja Luka, Faculty of Forestry, Banja Luka, Bosnia and Herzegovina E-mail: zg@nn.ba
  • Lingua, University of Padua, Department of TeSAF, Legnaro (PD), Italy E-mail: el@nn.it
  • Nagel, University of Ljubljana, Department of Forestry and Renewable Forest Resources, Ljubljana, Slovenia E-mail: tan@nn.si
  • Motta, University of Turin, Department Agroselviter, Via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy E-mail: rm@nn.it
article id 97, category Research article
Hannu Hökkä, Jaakko Repola, Mikko Moilanen, Markku Saarinen. (2011). Seedling survival and establishment in small canopy openings in drained spruce mires in Northern Finland. Silva Fennica vol. 45 no. 4 article id 97. https://doi.org/10.14214/sf.97
Keywords: Picea abies; canopy gaps; natural regeneration; drained peatlands; seedling establishment
Abstract | View details | Full text in PDF | Author Info
A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. Traditional regeneration methods with effective site preparation and planting generally result in satisfactory seedling stands also in spruce mires. However, natural regeneration methods may be more appropriate in protecting watercourses and minimizing regeneration costs. We studied the survival of advance growth and establishment of new seedlings in small canopy openings that were cut at three different diameters in two experimental drained spruce mire stands in Northern Finland (Tervola and Oulu) in 2004. The number of seedlings was repeatedly surveyed from five small circular plots (one 10 m2 and four 5 m2 plots in size) located within the opening. Advance growth which survived the cutting and new seedlings were separated in the surveys. The density of advance growth was on average 9000 ha–1 after cutting, and it decreased by 30% during the five-year monitoring period (2006–2010) due to natural mortality. The number of new seedlings increased rapidly within the three years after cutting the openings. In 2010, 11 000–26 000 new seedlings ha–1 in Tervola and 12 000–16 000 ha–1 in Oulu on average were observed. The size of the opening had no clear effect on the regeneration result. The proportion of birch of the new seedlings increased with time and opening size in Tervola. The results show that Norway spruce regenerates naturally in small canopy openings cut in mature drained spruce mire stands.
  • Hökkä, Finnish Forest Research Institute, Rovaniemi Research Unit, FI-96301 Rovaniemi, Finland E-mail: hannu.hokka@metla.fi (email)
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, FI-96301 Rovaniemi, Finland E-mail: jr@nn.fi
  • Moilanen, Finnish Forest Research Institute, Muhos Research Unit, Muhos, Finland E-mail: mm@nn.fi
  • Saarinen, Finnish Forest Research Institute, Parkano Research Unit, Parkano, Finland E-mail: ms@nn.fi
article id 144, category Research article
Markku Oikari, Kalle Kärhä, Teijo Palander, Heikki Pajuoja, Heikki Ovaskainen. (2010). Analyzing the views of wood harvesting professionals related to the approaches for increasing the cost-efficiency of wood harvesting from young stands. Silva Fennica vol. 44 no. 3 article id 144. https://doi.org/10.14214/sf.144
Keywords: cost-efficiency; energy wood; early thinnings; industrial roundwood; costs; gap analysis; opinion survey
Abstract | View details | Full text in PDF | Author Info
A lot of viable guidelines are currently available for more cost-effective harvesting of energy wood and industrial roundwood (i.e. pulpwood) from young stands. The study ranked the proposed potential approaches for increasing the cost-efficiency of small-diameter (d1.3 < 10 cm) energy wood and industrial roundwood harvesting from early thinnings. Research data, based on a total of 40 personal interviews, was collected in early 2008. The interviewees were divided into four wood harvesting professional groups: 1) Managers in wood procurement organizations, 2) Forest machine contractors, 3) Forest machine manufacturers and vendors, and 4) Wood harvesting researchers. In the opinion of the respondents, there is great potential to increase the cost-efficiency of wood harvesting through improving harvesting conditions (i.e. effective tending of seedling stands, delaying harvesting operations, and pre-clearance of dense undergrowth). The interviewees also underlined that harvesting methods can be rationalized, e.g. multiple-tree handling in industrial roundwood cuttings, crane scale measurement, integrated wood harvesting, and careful selection of stands for harvesting. The strong message given by the interviewees was that the education of forest machine operators must be made more effective in the future. There would be significant possibilities for cost savings in young stands, if methods and techniques with the most potential were utilized completely in wood harvesting.
  • Oikari, Karelwood, Kontiolahti, Finland E-mail: markku.oikari@karelwood.com (email)
  • Kärhä, Metsäteho Oy, Helsinki, Finland E-mail: kk@nn.fi
  • Palander, University of Eastern Finland, Faculty of Science and Forestry, Joensuu, Finland E-mail: tp@nn.fi
  • Pajuoja, Metsäteho Oy, Helsinki, Finland E-mail: hp@nn.fi
  • Ovaskainen, University of Eastern Finland, Faculty of Science and Forestry, Joensuu, Finland E-mail: ho@nn.fi
article id 339, category Research article
John W. McCarthy, Gordon Weetman. (2006). Age and size structure of gap-dynamic, old-growth boreal forest stands in Newfoundland. Silva Fennica vol. 40 no. 2 article id 339. https://doi.org/10.14214/sf.339
Keywords: boreal forests; old-growth forests; gap dynamics; age and size structure; rotated sigmoid; Newfoundland
Abstract | View details | Full text in PDF | Author Info
The age and size structure of trees in old Abies-Picea-Betula forests on Newfoundland’s Great Northern Peninsula were examined. It was hypothesized that the size and age structure of both the tree and regeneration “strata” of these stands display the complex structural heterogeneity characteristic of classic, self-regenerating, uneven-aged old-growth stands, and that the development and dynamics of such structures occur over long periods of time. With all tree species combined, dbh (diameter at breast height) and height distributions exhibited a strong reverse-J character, with well-defined, semi-logarithmic rotated sigmoid height and size frequencies. Seedling height and basal diameter frequency distributions were reverse-J in character. Live tree ages for all species, except white birch (Betula papyrifera Marsh), ranged from 25 to 269 years, and were characterized by all-age frequency distributions. Tree age and size were poorly correlated. On average, balsam fir (Abies balsamea (L.) Mill.) required 62 years to reach breast height (1.3 m), with black spruce (Picea mariana (Mill.) B.S.P.) and white spruce (Picea glauca (Moench) Voss) requiring 40 and 48 years, respectively. Total age of dead standing trees ranged from 45 to 232 years. Reverse-J age frequencies characterized the seedling bank, with balsam fir seedlings present in nearly all age classes up to 110, 120 and 85 years in three sample stands. Seedling size (height and basal diameter)-age relationships were characteristic of decades-long suppression. The combination of tree and seedling bank size and age structure provide strong evidence of quasi-equilibrium, small-scale, gap dynamic old-growth boreal forest stands.
  • McCarthy, University of British Columbia, Forest Sciences Department, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 E-mail: jmccarthy@jesuits.ca (email)
  • Weetman, University of British Columbia, Forest Sciences Department, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 E-mail: gw@n.ca

Category: Review article

article id 73, category Review article
Timo Kuuluvainen, Tuomas Aakala. (2011). Natural forest dynamics in boreal Fennoscandia: a review and classification. Silva Fennica vol. 45 no. 5 article id 73. https://doi.org/10.14214/sf.73
Keywords: disturbance; age structure; stand replacement; cohort; gap; patch; natural disturbance emulation
Abstract | View details | Full text in PDF | Author Info
The aim here was to review and summarize the findings of scientific studies concerning the types of forest dynamics which occur in natural forests (i.e. forests with negligible human impact) of boreal Fennoscandia. We conducted a systematic search for relevant studies from selected reference databases, using search terms describing the location, structure and processes, and degree of naturalness of the forest. The studies resulting from these searches were supplemented with other known works that were not indexed in the databases. This procedure yielded a total of 43 studies. The studies were grouped into four types of forest dynamics according to the information presented on the characteristics of the native disturbance-succession cycle: 1) even-aged stand dynamics driven by stand-replacing disturbances, 2) cohort dynamics driven by partial disturbances, 3) patch dynamics driven by tree mortality at intermediate scales (> 200 m2) and 4) gap dynamics driven by tree mortality at fine scales (< 200 m2). All four dynamic types were reported from both spruce and pine dominated forests, but their commonness differed. Gap dynamics was most commonly reported in spruce forests, and cohort dynamics in pine forests. The studies reviewed provide the best obtainable overall picture of scientific findings concerning the characteristics and variability of the unmanaged boreal forest dynamics in Fennoscandia. The results demonstrate that the unmanaged Fennoscandian forests are characterized by more diverse and complex dynamics than has traditionally been acknowledged.
  • Kuuluvainen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: timo.kuuluvainen@helsinki.fi (email)
  • Aakala, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ta@nn.fi

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