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Harri Mäkinen - One of the best experts on this subject based on the ideXlab platform.

  • Stem Form and branchiness of norway spruce as a sawn timber predicted by a process based model
    Forest Ecology and Management, 2007
    Co-Authors: Anu Kantola, Harri Mäkinen, Annikki Makela
    Abstract:

    A process-based growth model, PipeQual was adapted to Norway spruce (Picea abies [L.] Karst.) for describing stand development and timber properties (Stem taper, heartwood Formation and branchiness). PipeQual predictions on timber properties were tested against (1) the data set used for estimating the structural and metabolic parameters of the growth model, and (2) an independent data set. Both data sets consist of two stands located in southern and central Finland. Parameter values of the PipeQual model related to tree structure were estimated on the basis of measurements of tree characteristics. The metabolic parameters of the model were calibrated on the basis of stand-level predictions of basal area, dominant height, and Stem volume. In addition, statistical models for branch characteristics were incorporated in the model. The predictions of Stem taper, heartwood content and branchiness were consistent with measurements. However, the model slightly overestimated Stem taper curve in the upper half of the Stem in thinned stands. In addition, branch diameters were underestimated in the upper half of the Stem in thinned and untreated stands, while branch diameters in the lower Stem were somewhat overestimated. Overall, the results suggest that the PipeQual model has potential for simulating growth and properties of a Norway spruce stand.

  • Thinning intensity and long-term changes in increment and Stem Form of Scots pine trees
    Forest Ecology and Management, 2004
    Co-Authors: Harri Mäkinen, Antti Isomäki
    Abstract:

    Abstract The effects of thinning intensity on the basal area and volume increment, as well as on the Stem Form and crown height, of Scots pine trees ( Pinus sylvestris L.) were investigated in 37 long-term (on the average 25 years) thinning experiments in Finland. The intensity of the thinnings from below ranged from heavy thinning (42% of basal area removed) to no thinning. Basal area increment of the trees increased with increasing thinning intensity, but the absolute thinning effect decreased with decreasing tree size. Thinning increased the relative basal area increment of smaller trees somewhat more than that of larger ones. Depending on the stand age at the time of establishment of the experiments, it was possible to produce 400–800 larger trees per ha on the heavily and moderately thinned plots compared to the unthinned and lightly thinned plots. The average Stem diameter of the standing and removed trees remained lower on the heavily thinned plots because of the early removal of trees in thinning. Thus, heavy thinning results in a higher number of larger-sized Stems at the expense of somewhat poorer Stem Form and lower average Stem diameter of all the trees (standing and removed combined).

  • thinning intensity and long term changes in increment and Stem Form of norway spruce trees
    Forest Ecology and Management, 2004
    Co-Authors: Harri Mäkinen, Antti Isomäki
    Abstract:

    Abstract The effects of thinning intensity on the basal area and volume increment, as well as on the Stem Form and crown height, of individual Norway spruce ( Picea abies (L.) Karst.) trees were investigated in 21 long-term thinning experiments in southern and central Finland. The measurement period was on average 28 years and the thinning intensity ranged from heavy thinning (45% of basal area removed) to no thinning. Basal area increment of the trees increased with increasing thinning intensity, but the absolute thinning effect decreased with decreasing tree size within the same plot. In contrast, thinning increased the relative basal area increment of smaller somewhat more than that of larger diameter trees. Thinnings increased the volume of the largest trees. During stand rotation it was possible to produce 400–600 larger trees ha −1 on the heavily thinned plots compared to the unthinned plots. On the other hand, the average Stem diameter of the standing and removed trees remained lower on the heavily thinned plots because of the early removal of thinned trees. Height/diameter ratio decreased with increasing thinning intensity, but the differences in Stem taper were also related to tree age. In addition, lower stand density slowed down the rate of crown rise. The stand age at the time of establishment of the experiments had no major effect on the growth reactions. Thus, heavy thinning results in a higher number of larger-sized Stems at the expense of poorer Stem Form and lower average Stem diameter of all the trees (standing and removed combined).

Antti Isomäki - One of the best experts on this subject based on the ideXlab platform.

  • Thinning intensity and long-term changes in increment and Stem Form of Scots pine trees
    Forest Ecology and Management, 2004
    Co-Authors: Harri Mäkinen, Antti Isomäki
    Abstract:

    Abstract The effects of thinning intensity on the basal area and volume increment, as well as on the Stem Form and crown height, of Scots pine trees ( Pinus sylvestris L.) were investigated in 37 long-term (on the average 25 years) thinning experiments in Finland. The intensity of the thinnings from below ranged from heavy thinning (42% of basal area removed) to no thinning. Basal area increment of the trees increased with increasing thinning intensity, but the absolute thinning effect decreased with decreasing tree size. Thinning increased the relative basal area increment of smaller trees somewhat more than that of larger ones. Depending on the stand age at the time of establishment of the experiments, it was possible to produce 400–800 larger trees per ha on the heavily and moderately thinned plots compared to the unthinned and lightly thinned plots. The average Stem diameter of the standing and removed trees remained lower on the heavily thinned plots because of the early removal of trees in thinning. Thus, heavy thinning results in a higher number of larger-sized Stems at the expense of somewhat poorer Stem Form and lower average Stem diameter of all the trees (standing and removed combined).

  • thinning intensity and long term changes in increment and Stem Form of norway spruce trees
    Forest Ecology and Management, 2004
    Co-Authors: Harri Mäkinen, Antti Isomäki
    Abstract:

    Abstract The effects of thinning intensity on the basal area and volume increment, as well as on the Stem Form and crown height, of individual Norway spruce ( Picea abies (L.) Karst.) trees were investigated in 21 long-term thinning experiments in southern and central Finland. The measurement period was on average 28 years and the thinning intensity ranged from heavy thinning (45% of basal area removed) to no thinning. Basal area increment of the trees increased with increasing thinning intensity, but the absolute thinning effect decreased with decreasing tree size within the same plot. In contrast, thinning increased the relative basal area increment of smaller somewhat more than that of larger diameter trees. Thinnings increased the volume of the largest trees. During stand rotation it was possible to produce 400–600 larger trees ha −1 on the heavily thinned plots compared to the unthinned plots. On the other hand, the average Stem diameter of the standing and removed trees remained lower on the heavily thinned plots because of the early removal of thinned trees. Height/diameter ratio decreased with increasing thinning intensity, but the differences in Stem taper were also related to tree age. In addition, lower stand density slowed down the rate of crown rise. The stand age at the time of establishment of the experiments had no major effect on the growth reactions. Thus, heavy thinning results in a higher number of larger-sized Stems at the expense of poorer Stem Form and lower average Stem diameter of all the trees (standing and removed combined).

John Trinder - One of the best experts on this subject based on the ideXlab platform.

  • IGARSS - Estimating taper diameter and Stem Form of Pinus radiata in Australia by terrestrial laser scanning
    2012 IEEE International Geoscience and Remote Sensing Symposium, 2012
    Co-Authors: Fadhillah Norzahari, Russell Turner, John Trinder
    Abstract:

    Predicting the taper diameter and Stem Form of trees has been explored in several recent studies. In this paper, the use of terrestrial laser scanning technology along with the trigonometric variable-Form taper equation is explored as a possibility to detect the change of diameter at breast height, taper diameter and Stem Form of Pinus radiata in a plantation in New South Wales, Australia. This paper is presented in threefold: firstly, the possibility of detecting the change in Stem diameter is addressed. Secondly, a comparison of destructive sampling versus lidar is provided. Thirdly, the change in Stem Form of the Pinus radiata plantation over a 13-month period based on the measurements by terrestrial lidar, total station and destructive sampling is presented.

  • Estimating taper diameter and Stem Form of Pinus radiata in Australia by terrestrial laser scanning
    International Geoscience and Remote Sensing Symposium (IGARSS), 2012
    Co-Authors: Fadhillah Norzahari, Samsung Lim, Russell Turner, John Trinder
    Abstract:

    Predicting the taper diameter and Stem Form of trees has been explored in several recent studies. In this paper, the use of terrestrial laser scanning technology along with the trigonometric variable-Form taper equation is explored as a possibility to detect the change of diameter at breast height, taper diameter and Stem Form of Pinus radiata in a plantation in New South Wales, Australia. This paper is presented in threefold: firstly, the possibility of detecting the change in Stem diameter is addressed. Secondly, a comparison of destructive sampling versus lidar is provided. Thirdly, the change in Stem Form of the Pinus radiata plantation over a 13-month period based on the measurements by terrestrial lidar, total station and destructive sampling is presented. © 2012 IEEE.

Jason Cook - One of the best experts on this subject based on the ideXlab platform.

Huiquan Bi - One of the best experts on this subject based on the ideXlab platform.

  • Trigonometric variable-Form taper equations for Australian eucalypts.
    Forest Science, 2000
    Co-Authors: Huiquan Bi
    Abstract:

    This article introduces a new variable-Form taper model that is stable in specification yet flexible in its ability to fit data for species and trees with different Stem Forms. The base function is constructed from trigonometric volume-ratio equations following the geometry of a tree Stem. The specification for the exponent includes variables for depicting changes in Stem Form along a Stem and variables for taking into account differences in Stem Form among trees of different sizes. This model is fitted to data from 25 species of Australian eucalypts and is compared with Kozak's taper model to demonstrate its characteristics: stability in specification, flexibility in fitting data for species and trees with varying Stem Forms and accurate predictions of taper and merchantable height.

  • Competition in mixed stands of Pinus radiata and Eucalyptus obliqua
    Journal of Applied Ecology, 1996
    Co-Authors: Huiquan Bi, Nigel D. Turvey
    Abstract:

    1. Relative growth rate, mortality and Stem Form of individual trees in mixed stands of planted P. radiata and naturally regenerated E. obliqua over 5 years were examined in relation to their sizes and the density and leaf area index of their neighbours. 2. Relative growth rate increased with tree size and decreased with increasing neighbourhood leaf area index for both species, but it increased with increasing neighbourhood density as a result of a release from competition due to mortality in the neighbourhood. 3. Mortality affected smaller E. obliqua. The probability of death decreased with increasing tree size. 4. Height to diameter ratio, an indicator of Stem Form, decreased with tree size and increased with neighbourhood leaf area index for both species. 5. The growth, mortality and changes in Stem Form of individual trees led to changes in density-dependent stand level characteristics such as mean height to diameter ratio and size distribution patterns.

  • Long-term effects of superphosphate fertilization on Stem Form, taper and Stem volume estimation of Pinus radiata
    Forest Ecology and Management, 1994
    Co-Authors: Huiquan Bi, John Turner
    Abstract:

    Abstract The long term effects of superphosphate fertilization on Stem Form, taper and Stem volume estimation of Pinus radiata on a phosphorus-deficient site was examined using data from a fertilizer experiment which had been maintained for 30 years. The application of superphosphate resulted in long term and statistically significant changes in Stem Form. Mean cylindrical Form factor ranged from 0.33 for the control trees up to 0.40 for trees fertilized with 100 kg P ha−1. Stem Form was also examined through taper curves which provided detailed depiction of average relative Stem profiles. The increase in cylindrical Form factor of fertilized trees was largely attributed to a significantly broader profile of the lower third of the Stem. In comparison with the control trees, the fertilized trees also had a broader, although not statistically significant, profile of upper and middle Stem which could also contribute to the increase in their cylindrical Form factor. With increased Form factor a greater proportion of the Stem became merchantable because of increased log length to tree height ratio. Mean average taper of trees did not show a consistent trend with increasing lelevels of superphosphate application. It largely reflected the differential response of DBH and height growth to the treatments. The volume equation based on control trees underestimated the underbark Stem volume of fertilized trees by 5–12% on average. Developing separate volume equations for the fertilized trees is warranted.

  • Improving Stem volume estimation of regrowth Eucalyptus fastigata with a lower Stem Form quotient
    Australian Forestry, 1994
    Co-Authors: Huiquan Bi
    Abstract:

    Summary Stem volume equations were developed and validated using data from 877 sample trees. Initially, three commonly used models were compared. The least biased and most precise estimates of underbark Stem volume was obtained using equations based on the combined variable model. A lower Stem Form quotient, calculated as the ratio of diameter at 4.5m above ground to diameter at breast height, was subsequently included resulting in a substantial improvement in precision.