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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'spatial variation'

Category : Article

article id 5561, category Article
Jari Liski. (1995). Variation in soil organic carbon and thickness of soil horizons within a boreal forest stand – effect of trees and implications for sampling. Silva Fennica vol. 29 no. 4 article id 5561.
Keywords: Pinus sylvestris; soil carbon; spatial variation; soil formation; soil morphology; tree effects; soil sampling; geostatics
Abstract | View details | Full text in PDF | Author Info

Spatial variation in the density of soil organic carbon (kg/m2) and the thickness of soil horizons (F/H, E) were investigated in a 6 m x 8 m area in Scots pine (Pinus sylvestris L.) stand in Southern Finland for designing an effective sampling for the C density and studying the effect of trees on the variation. The horizon thickness of the podzolized soil were measured on a total of 126 soil cores (50 cm deep) and the C density of the organic F/H and 0–10 cm, 10–20 cm and 20–40 cm mineral soil layers was analysed.

The C density varied 3–5 fold within the layers and the coefficients of variation ranged from 22 % to 40%. Considering the gain in confidence per sample, 8–10 samples were suggested for estimating the mean C density in the F/H and 0–40 cm layers, although about 30 samples are needed for 10% confidence in the mean. The C densities and horizon thicknesses were spatially dependent within the distances of 1–8 m, the spatial dependence accounting for 43–86% of the total variance. The F/H layer was thicker and contained more C within 1–3 m radius from trees. In the 10–20 cm and 20–40 cm layers (B horizon) the C density also increased towards the trees, but more pronouncedly in the immediate vicinity of the stems. Because the spatial patterning of the E horizon thickness was similar, the increase was attributed to stemflow and precipitation of organic compounds in the podzol B horizon.

  • Liski, E-mail: jl@mm.unknown (email)
article id 5482, category Article
Heljä-Sisko Helmisaari. (1992). Spatial and age-related variation in nutrient concentrations of Pinus sylvestris needles. Silva Fennica vol. 26 no. 3 article id 5482.
Keywords: Pinus sylvestris; spatial variation; nutrients; sampling; nutrient concentration; conifer needles
Abstract | View details | Full text in PDF | Author Info

Spatial and age-related variation in nutrient concentrations of Scots pine (Pinus sylvestris L.) needles was studied during 1984–86 in three stands of different stages of development. The dry weight of current needles was significantly (p < 0.05) higher in the tree top than in a composite sample representing the whole crown. However, there were no significant differences in the concentrations of nutrients in needles between upper and lower crown levels. The concentrations of mobile nutrients N, P, K and Mg decreased with increasing needle age whereas the concentrations of poorly mobile nutrients Ca, Mn and Fe increased during needle ageing. The coefficient of variation for nutrient concentrations varied irregularly when only a few trees were sampled but stabilized when tree number was ten or more.
The PDF includes an abstract in Finnish.

  • Helmisaari, E-mail: hh@mm.unknown (email)
article id 5379, category Article
Timo Kuuluvainen, Timo Pukkala. (1989). Effect of Scots pine seed trees on the density of ground vegetation and tree seedlings. Silva Fennica vol. 23 no. 2 article id 5379.
Keywords: Pinus sylvestris; natural regeneration; spatial variation; ground vegetation; seedlings; seed trees; regeneration models; ecological fields; resource consumption; competitive interface
Abstract | View details | Full text in PDF | Author Info

The study uses the methodology of ecological field theory to model the effect of Scots pine (Pinus sylvestris L.) seed trees on the density of tree seedlings and other plants in the field layer. The seed trees had a clear effect on the expected value of the amount and distribution of the ground vegetation. The vicinity of seed trees had an adverse effect on the growth of grasses, herbs and seedlings, while mosses were most abundant near the trees. Models based on the ecological field approach were derived to describe the effect of seed trees on the ground vegetation.

The PDF includes an abstract in Finnish.

  • Kuuluvainen, E-mail: tk@mm.unknown (email)
  • Pukkala, E-mail: tp@mm.unknown

Category : Article

article id 7643, category Article
Pauline Oker-Blom. (1986). Photosynthetic radiation regime and canopy structure in modeled forest stands. Acta Forestalia Fennica no. 197 article id 7643.
Keywords: spatial variation; radiation models; penumbra; grouping effect; photosynthetic radiation
Abstract | View details | Full text in PDF | Author Info

The relationship between canopy structure and photosynthetic radiation regime are studied in a theoretical basis. In modelling the canopy structure, a statistical approach is applied and the radiation field inside a stand is described in terms of random variables and their distribution. A comparison is made between horizontally homogenous stands and grouped forest stands in order to assess the influence of grouping of foliage on the irradiance distribution in a forest stand. Results show that grouping considerably reduces the interception of radiation and causes a large spatial variation. In coniferous stands the grouping of needles into shoots and the effect of penumbra are shown to have an important influence on the distribution of radiation on the needle area.

The PDF includes a summary in Finnish.

  • Oker-Blom, E-mail: po@mm.unknown (email)

Category : Research article

article id 233, category Research article
Raija Laiho, Sakari Sarkkola, Seppo Kaunisto, Jukka Laine, Kari Minkkinen. (2008). Macroscale variation in peat element concentrations in drained boreal peatland forests. Silva Fennica vol. 42 no. 4 article id 233.
Keywords: drainage; peat soil; nutrient deficiencies; spatial variation; soil nutrients
Abstract | View details | Full text in PDF | Author Info
Information on the variation in soil element concentrations at different spatial scales is needed for, e.g., designing efficient sampling strategies, upscaling the processes related to carbon cycling, and planning land use and management. In spite of intensive land use, such information concerning peat soils is still scarce. We analyzed the variation in peat mineral element concentrations in boreal peatland forests drained 50–60 years earlier. We wanted to quantify the proportions of variation deriving from differences between regions and peatland basins and from within-peatland heterogeneity, and to model the variation using relatively easily measurable site and soil characteristics. We utilized 878 peat samples representing the 0–20 cm layer and collected from 289 sites in 79 peatland basins. The sites represented three different drained peatland forest site types. The two strongest gradients in the element composition captured by principal component analysis were correlated with both the North-South gradient and the site type variation, and the East-West gradient. In general, most of the variation in the element concentrations was contributed by differences among peatland basins, and variation within the floristically determined sites. Most of the element concentrations were best modeled when either the bulk density or the ash content of the peat, or both, were used in addition to site type and geographical location. The explanatory power remained modest for most element concentrations. As for the P concentrations in soil, however, our models provide means for estimating a large part of the variation among drained pine mire sites.
  • Laiho, University of Helsinki, Department of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: (email)
  • Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail:
  • Kaunisto, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail:
  • Laine, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail:
  • Minkkinen, University of Helsinki, Department of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail:
article id 433, category Research article
Raija Laiho, Timo Penttilä, Jukka Laine. (2004). Variation in soil nutrient concentrations and bulk density within peatland forest sites. Silva Fennica vol. 38 no. 1 article id 433.
Keywords: thinning; drainage; peat soil; spatial variation; nutrients; bulk density; sampling; variance components
Abstract | View details | Full text in PDF | Author Info
The within-site variability of soil characteristics on sites with different soil types remains poorly quantified, although this information is crucial for the success of research on soil properties, and especially for monitoring soil properties over time. We used coefficients of variation and multilevel variance component models to examine the within-site variation of soil (0–30 cm) mineral nutrient concentrations (P, K, Ca, Mg, Fe, mg g–1; Mn, Zn, mg g–1) and bulk density (kg m–3) on boreal deep-peat sites. We then evaluated the reliability of the site-level estimates (sample means) obtained using different sampling intensities (numbers of samples per site). Our 11 sites represented a single original site type within the oligotrophic nutrient level. Two of the sites were undrained while the rest had been drained for forestry at different points in time. Overall, P concentrations showed the smallest and Mn concentrations the largest within-site variation. The sampling depth contributed more than 50% of the total variance in all other characteristics except the concentrations of P and Fe, and bulk density. The variance proportions of peatland basin, site (within basin), and sampling location (within site) varied by sampling depth for most soil characteristics. The estimates obtained when using a certain number of samples per site were always more reliable for the 0–30 cm layer’s composite samples than for any single 10-cm layer at any depth sampled. On average, it was found that between 4 (P) and some 200 (Mn) samples per site would be needed for the estimates to have a theoretical 10% maximum deviation.
  • Laiho, Univ. of Helsinki, Dept. of Forest Ecology, Peatland Ecology Group, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: (email)
  • Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail:
  • Laine, Univ. of Helsinki, Dept. of Forest Ecology, Peatland Ecology Group, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail:

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