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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'pipe model'

Category : Article

article id 5632, category Article
Annikki Mäkelä, Veli-Pekka Ikonen, Petteri Vanninen. (1997). An application of process-based modelling to the development of branchiness in Scots pine. Silva Fennica vol. 31 no. 3 article id 5632.
Original keywords: puutavara; mänty; kasvu; hiili; läpimitta; biomassa; oksat; laatu; latvus; simulointi; kasvumallit; mallit; hiilitase; oksaisus
English keywords: Pinus sylvestris; carbon balance; simulation; pipe model; timber quality; growth model; branching; crown structure; whorl
Abstract | View details | Full text in PDF | Author Info

A process-oriented tree and stand growth model is extended to be applicable to the analysis of timber quality, and how it is influenced by silvicultural treatments. The tree-level model is based on the carbon balance and it incorporates the dynamics of five biomass variables as well as tree height, crown base, and breast height diameter. Allocation of carbon is based on the conservation of structural relationships, in particular, the pipe model. The pipe-model relationships are extended to the whorl level, but in order to avoid a 3-dimensional model of entire crown structure, the branch module is largely stochastic and aggregated. In model construction, a top-down hierarchy is used where at each step down, the upper level sets constraints for the lower level. Some advantages of this approach are model consistency and efficiency of calculations, but probably at the cost of reduced flexibility. The detailed structure related with the branching module is preliminary and will be improved when more data becomes available. Model parameters are identified for Scots pine (Pinus sylvestris L.) in Southern Finland, and example simulations are carried out to compare the development of quality characteristics in different stocking densities.

  • Mäkelä, E-mail: am@mm.unknown (email)
  • Ikonen, E-mail: vi@mm.unknown
  • Vanninen, E-mail: pv@mm.unknown

Category : Article

article id 7681, category Article
Eero Nikinmaa. (1992). Analyses of the growth of Scots pine: matching structure with function. Acta Forestalia Fennica no. 235 article id 7681.
Keywords: Pinus sylvestris; Scots pine; pipe model; nutrients; heartwood; growth models; carbon budget; structure; partitioning of growth; growht
Abstract | View details | Full text in PDF | Author Info

A theoretical framework to analyse the growth of Scots pine (Pinus sylvestris L.) is presented. Material exchange processes and internal processes that transport, transform and consume materials are identified as the components of growth. Hierarchical system is lined out. Momentary uptake of material at a single exchange site depends on the environmental condition next to the exchange site, the internal state of the biochemical system of the plant and the structure of the plant. The internal state depends on the exchange flows over period of time and the structural growth depends on the internal state. The response of these processes to the fluxes is controlled by the genetic composition of the plant.

The theoretical framework is formulated into a mathematical model. A concept of balanced internal state was applied to describe the poorly known internal processes. Internal substrate concentrations were assumed to remain constant but tissue-specific. A linear relationship between the quantity of foliage and wood cross-sectional area was assumed to describe balanced formation of structure. The exchange processes were thus described as a function of external conditions. The stand level interactions were derived from shading and effects of root density on nutrient uptake.

The approach was tested at different levels of hierarchy. Field measurements indicated that the hypothesis of the linear relationship described well the regularities between foliage and sapwood of a tree within a stand when measured at functionally corresponding height. There was considerable variation in the observed regularities in the range of geographic occurrence of Scots pine. Model simulations gave a realistic description of stand development in Southern Finland. The same model was also able to describe growth differences in Lapland after considering the effect of growing season length in the parameter values. Simulations to South Russia indicate stronger deviation from the observed patterns.

The simulations suggest interesting features of stand development. They indicate strong variability in the distribution of carbohydrates between tree parts during stand development. Internal circulation of nutrients and the reuse of the same transport structure by various needle generations had a strong influence on the simulation results.

The PDF includes a summary in Finnish.

  • Nikinmaa, E-mail: en@mm.unknown (email)

Category : Research article

article id 174, category Research article
Akihiro Sumida, Taro Nakai, Masahito Yamada, Kiyomi Ono, Shigeru Uemura, Toshihiko Hara. (2009). Ground-based estimation of leaf area index and vertical distribution of leaf area density in a Betula ermanii forest. Silva Fennica vol. 43 no. 5 article id 174.
Keywords: allometry; leaf area density; LAI; leaf inclination angle; MacArthur–Horn method; pipe model; Betula ermanii
Abstract | View details | Full text in PDF | Author Info
We developed a ground-based method for estimating leaf area index (LAI) and vertical distribution of leaf area density (LAD) for two Betula ermanii plots, combining an allometric method for tree leaf area with the MacArthur–Horn (MH) method using a portable laser rangefinder, including a correction for changes in leaf inclination angle along the vertical gradient measured with a portable digital protractor from a canopy access tower in each plot. Vertical distribution of projected leaf area density obtained by the MH method (LADMH) was transformed to relative distribution for allotting fixed LAI to different heights. Hence, we first developed an allometric method for estimating tree leaf area for LAI determination. Trunk cross-sectional area at branching height (AB) was accurately estimated (r2 = 0.97) from ground-based measurements of tree dimensions. We used this method to apply pipe model allometry between tree leaf area and AB, and estimated LAI (4.56 and 4.57 m2 m–2). We then examined how leaf inclination angle affected estimation of the vertical distribution of actual LAD. Leaf inclination angle measurements revealed that actual LAD in the upper canopy was 1.5–1.8-times higher than LADMH, because of steep leaf inclination, while the correction factor was 1.15–1.25 in the lower canopy. Due to the difference among heights, vertical distribution of LAD estimated with correction for vertical change in leaf inclination was more skewed to the upper canopy than that without correction. We also showed that error in LAD distribution can result if horizontal canopy heterogeneity is neglected when applying the MH method.
  • Sumida, Institute of Low Temperature Science, Hokkaido University, N19W8, Sapporo 060-0819, Japan E-mail: (email)
  • Nakai, International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Drive, P.O. Box 757340, Fairbanks, Alaska 99775-7340, USA E-mail:
  • Yamada, International Meteorological & Oceanographic Consultants Co., Ltd. Kawaguchi-cho 2-6528-87, Choshi, Chiba 288-0001, Japan E-mail:
  • Ono, Institute of Low Temperature Science, Hokkaido University, N19W8, Sapporo 060-0819, Japan E-mail:
  • Uemura, Field Science Center for Northern Biosphere, Hokkaido University, Tokuda 250, Nayoro, Hokkaido 096-0071, Japan E-mail:
  • Hara, Institute of Low Temperature Science, Hokkaido University, N19W8, Sapporo 060-0819, Japan E-mail:

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