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Articles containing the keyword 'tree biomass'.

Category: Research article

article id 1190, category Research article
Jaakko Repola, Kristina Ahnlund Ulvcrona. (2014). Modelling biomass of young and dense Scots pine (Pinus sylvestris L.) dominated mixed forests in northern Sweden. Silva Fennica vol. 48 no. 5 article id 1190. https://doi.org/10.14214/sf.1190
Highlights: The biomass allocation to tree components is different in unmanaged and managed young stands; Higher foliage biomass and lower stem and branch biomass were detected in the unmanaged stands; Models for trees from young and dense stands provide better estimates of biomass in such stands than those based on data from managed stands.
Biomass models for the biomass of above-ground tree components of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] Karst.) and birch (Betula pendula Roth and Betula pubescens Ehrh.) in young dense Scots pine dominated forest stands in northern Sweden were constructed. Destructive above-ground biomass sampling was conducted in naturally generated young, dense, Scots pine dominated mixed stands. Three sampling campaigns were undertaken, the first in 1997 and 1998. The second was six years later (2003), and the last 13 years after the first (2010). In total, 280 trees (126 Scots pine, 68 Norway spruce and 86 birches) were sampled from six different stands in northern Sweden. The sampled trees’ diameter at breast height (dbh) was in the range 1–22 cm (Scots pine), 1–21 cm (Norway spruce) and 1–11 cm (birch). Biomass predictions were tested using our models and the widely used biomass models originally constructed for managed stands. The results showed that the biomass allocation to tree components is different in unmanaged and managed young stands; higher foliage biomass and lower stem and branch biomass were detected in the unmanaged stands. The overall conclusion is that the biomass models for managed stands did not produce satisfactory biomass estimates in unthinned, dense, young stands.
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@metla.fi (email)
  • Ahnlund Ulvcrona, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: kristina.ulvcrona@slu.se
article id 184, category Research article
Jaakko Repola. (2009). Biomass equations for Scots pine and Norway spruce in Finland. Silva Fennica vol. 43 no. 4 article id 184. https://doi.org/10.14214/sf.184
In this study, biomass equations for the above- and below-ground tree components of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies [L.] Karst.) were developed. The models were based on 908 pine trees and 613 spruce trees collected in 77 stands located on mineral soil, and represented a wide range of stand and site conditions in Finland. The whole data set consisted of three sub data sets: 33 temporary sample plots, five thinning experiments, and the control plots of 39 fertilization experiments. The biomass equations were estimated for the individual tree components: stem wood, stem bark, living and dead branches, needles, stump, and roots. In the data analysis, a multivariate procedure was applied in order to take into account the statistical dependence among the equations. Three multivariate models for above-ground biomass and one for below-ground biomass were constructed. The multivariate model (1) was mainly based on tree diameter and height, and additional commonly measured tree variables were used in the multivariate models (2) and (3). Despite the unbalanced data in terms of the response variables, the statistical method generated equations that enable more flexible application of the equations, and ensure better biomass additivity compared to the independently estimated equations. The equations provided logical biomass predictions for a number of tree components, and were comparable with other functions used in Finland and Sweden even though the study material was not an objective, representative sample of the tree stands in Finland.
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@metla.fi (email)
article id 236, category Research article
Jaakko Repola. (2008). Biomass equations for birch in Finland. Silva Fennica vol. 42 no. 4 article id 236. https://doi.org/10.14214/sf.236
Biomass equations were compiled for the above- and below-ground tree components of birch (Betula pendula Roth and Betula pubescens Ehrh.). The equations were based on 127 sample trees in 24 birch stands located on mineral soil sites. The study material consisted of 20 temporary plots and ten plots from four thinning experiments with different thinning intensities (unthinned, moderately and heavily thinned plots). The equations were estimated for the following individual tree components: stem wood, stem bark, living and dead branches, foliage, stump, and roots. In the data analysis, a multivariate procedure was applied in order to take into account the statistical dependency among the equations. Three multivariate variance component models were constructed for the above-ground biomass components, and one for the below-ground biomass components. The multivariate model (1) was mainly based on tree diameter and height, and in the multivariate models (2) and (3) additional commonly measured tree variables were used. The equations provided logical biomass predictions for a number of tree components, and were comparable with other functions used in Finland and Sweden. The applied statistical method generated equations that gave more reliable biomass estimates than the equations presented earlier. Furthermore, the structure of the multivariate models enables more flexible application of the equations, especially for research purposes.
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@metla.fi (email)

Category: Article

article id 7682, category Article
Juha Nurmi. (1993). Heating values of the above ground biomass of small-sized trees. Acta Forestalia Fennica no. 236 article id 7682. https://doi.org/10.14214/aff.7682

The heating values of wood, inner and outer bark, and foliage components of seven small-size tree species (Pinus sylvestris L., Picea abies (L.) H. Karst., Betula pubescens Erhr., B. pendula Roth, Alnus incana (L.) Moench, A. glutinosa (L.) Gaertn., Populus tremula L.) were studied. Significant differences were found between species within each component. However, the differences between species for weighted stem, crown and whole-tree biomass are very small. The weighted heating value of the crown mass is slightly higher than that of the stem in all species. The heating value of stem, crown and whole-tree material was found to increase with increasing latitude.

The effective heating value of wood correlated best with the lignin content, inner bark with carbohydrate, and outer bark with carbohydrates and the extractives soluble in alkalic solvents. It is suggested that the determination of the heating value might be used as an indicator of the cellulose content of coniferous wood.

The PDF includes a summary in Finnish.

  • Nurmi, ORCID ID:E-mail:

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