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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'porosity'

Category : Article

article id 5503, category Article
Juha Heiskanen. (1993). Variation in water retention characteristics of peat growth media used in tree nurseries. Silva Fennica vol. 27 no. 2 article id 5503.
Keywords: density; production; water retention; container grown plants; porosity; growth media; substrates; planting stock; hydraulic conductivity; Sphagnum peat media; physical properties
Abstract | View details | Full text in PDF | Author Info

The water retention characteristics and their variation in tree nurseries and related physical properties were determined for commercially produced growth media made of light slightly humified Sphagnum peat. A total of 100 samples of peat media were collected from filled seedling trays in the greenhouses of four Finnish nurseries in 1990. In addition, the physical properties were determined for two growth media made of compressed peat sheets and chips. The variation in water retention characteristics in nurseries was described using linear models with fixed and random effects. The sources of variation in the mixed linear models were producer, grade, batch (greenhouse) and sample (tray).

The water retention of the peat media at different matric potentials was comparable to that given in the literature. The media shrank an average of 0–16% during desorption. The peat grades were finer than the Nordic quality standards for peat growth media. Particles < 1 mm increased and particles 1–5 mm decreased the water retention characteristics measured. The greatest total variation in water retention was at -1 kPa. The water retention of the peat media differed least at -5 and -10 kPa. The water retention characteristics of media from different producers usually differed significantly. The grades, on the other hand, did not differ from each other in their water retention characteristics nor were there significant interactions between producer and grade. The batch effect was marked but was lower than the effect within batches, where the sample (tray) effect was greater than the effect due to random measurement error. At -10 kPa, the measurement error was, however, clearly greater than the sample effect. The random measurement error was comparable to the batch effect. Aeration of the growth media is dependent on the water content retained between saturation and -1 kPa. The water availability to seedlings at the nursery phase is affected mainly by water retention between -1 and -10 kPa.
The PDF includes an abstract in Finnish.

  • Heiskanen, E-mail: jh@mm.unknown (email)
article id 5416, category Article
Carl Johan Westman. (1990). Metsämaan fysikaaliset ja fysikaalis-kemialliset ominaisuudet CT-OMaT kasvupaikkasarjassa. Silva Fennica vol. 24 no. 1 article id 5416.
English title: Soil physical and physio-chemical properties of Finnish upland forest sites.
Original keywords: kasvupaikkatyyppi; ravinteisuus; kationinvaihtokapasiteetti; podzoli
English keywords: pH; fertility; site factors; podzols; porosity; CEC
Abstract | View details | Full text in PDF | Author Info

In soil profiles from a series of uplands of different site types bulk density, density of solids and porosity of soil were clearly related to soil organic matter content and its distribution in the soil profile. Soil organic matter contents were also strongly correlated to effective cation exchange capacity (CEC) and soil acidity. Site fertility was primarily related to the fine fraction (ø<0.06 mm) content in the C horizon and related properties (i.e. CEC). In the humus layer, the content of exchangeable bases and base saturation most strongly related to site fertility.

The PDF includes an abstract in English.

  • Westman, E-mail: cw@mm.unknown (email)

Category : Research article

article id 501, category Research article
Jiaojun Zhu, Yutaka Gonda, Takeshi Matsuzaki, Masashi Yamamoto. (2003). Modeling relative wind speed by optical stratification porosity within the canopy of a coastal protective forest at different stem densities. Silva Fennica vol. 37 no. 2 article id 501.
Keywords: coastal protective forest; optical porosity; Pinus thunbergii; vertical forest structure; wind speed
Abstract | View details | Full text in PDF | Author Info
Wind speed and optical stratification porosity (OSP) were measured at various heights inside a coastal protective forest thinned to different stem densities to assess whether any characteristics of the wind profile in the coastal protective forest could be predicted from OSP. OSP was defined as vertical distribution of the proportion of sky hemisphere not obscured by tree elements inside a forest stand, and was determined for various heights using hemispherical photographic silhouettes on a computer processing system. The distribution of OSP in the coastal forest follows the Lambert-Beer’s law with an extinction coefficient (v). The relative wind speed within the canopy can be described using an exponential form with an attenuation coefficient (a). Variation in relative wind speed was very closely correlated with the distribution of OSP within the canopy. While below the canopy, i.e., in the trunk space, relative wind speed was little correlated with the distribution of OSP because the distribution of OSP was relatively constant there. Therefore, the linear relationships between relative wind speed and OSP and between the two coefficients v and a were established within the canopy. The results suggest that OSP can be used to predict the wind profile in case of the application within the canopy of the coastal forest.
  • Zhu, Qingyuan Station of Forest Ecology, Institute of Applied Ecology, the Chinese Academy of Sciences, No. 72 Wenhua Road, Shenyang 110016, P.R. China; Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail: (email)
  • Gonda, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail:
  • Matsuzaki, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail:
  • Yamamoto, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail:

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