Predicting tree crown ratio for unthinned and thinned Scots pine stands

1995 ◽  
Vol 25 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Jari Hynynen
Keyword(s):  
Scots Pine ◽  
Basal Area ◽  
Tree Height ◽  
Tree Crown ◽  
Thinning Intensity ◽  
Tree Diameter ◽  
Dominant Height ◽  
The Difference ◽  
Thinning Effect ◽  
Experimental Plots

A nonlinear model that yields logical predictions for tree crown ratio is presented. The model is based on data from permanent experimental plots located in even-aged Scots pine (Pinussylvestris L.) stands in southern and central Finland. Regressor variables in the model are stand dominant height, stand basal area, tree diameter, and tree height. The effect of thinning on tree crown ratio is modelled by incorporating a thinning response variable into the model. Thinning effect is dependent on thinning intensity and time elapsed from thinning, the latter of which is represented by the difference between current stand dominant height and dominant height at the time of thinning.

Incorporating intertree competition into an ecosystem model

1995 ◽  
Vol 25 (3) ◽  
pp. 413-424 ◽  
Author(s):  
R.L. Korol ◽  
S.W. Running ◽  
K.S. Milner
Keyword(s):  
Process Model ◽  
Basal Area ◽  
Stand Density ◽  
Tree Height ◽  
Ecosystem Model ◽  
Growth And Yield ◽  
Maintenance Respiration ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Individual Trees

Current research suggests that projected climate change may influence the growth of individual trees. Therefore, growth and yield models that can respond to potential changes in climate must be developed, TREE-BGC, a variant of the ecosystem process model FOREST-BGC, calculates the cycling of carbon, water, and nitrogen in and through forested ecosystems. TREE-BGC allocates stand-level estimates of photosynthesis to "each tree using a competition algorithm that incorporates tree height, relative radiation-use efficiency, and absorbed photosynthetically active radiation, TREE-BGC simulated the growth of trees grown in a dense and an open stand of interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) near Kamloops, B.C. The competition algorithm dynamically allocated stand estimates of photosynthesis to individual trees, and the trees were grown using an allometric relationship between biomass increment and height and diameter increment. Asymptotic height growth and the changes in the height–diameter relationship with competition were also incorporated in the model algorithms. Sapwood and phloem volume were used to calculate maintenance respiration. Predicted reductions in diameter growth with stand density were similar to those observed in the study stands. Although the carbon balance of individual trees was not tested, simulated tree diameter increments and height increments were correlated with the actual measurements of tree diameter increment (r2 = 0.89) and tree height increment (r2 = 0.78) for the 5-year period (n = 352). Although the model did not work well with trees that had diameters <5 cm, the model would be appropriate for a user who required an accuracy of ± 0.03 m3•ha−1 for volume, ± 0.02 m2•ha−1 for basal area, or ± 0.4 m for tree height over a 5-year period.

Crown efficiency in a loblolly pine (Pinus taeda) spacing experiment

1998 ◽  
Vol 28 (9) ◽  
pp. 1344-1351 ◽  
Author(s):  
Hubert Sterba ◽  
Ralph L Amateis
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Basal Area ◽  
Tree Height ◽  
Projection Area ◽  
Individual Tree ◽  
Dominant Height ◽  
Crown Projection Area ◽  
Pinus Taeda L ◽  
Crown Closure

Crown efficiency was first defined by Assmann (1961. Waldertragskunde. BLV, München) as individual tree volume increment per unit of crown projection area. He hypothesized that within a given crown class, smaller crowns are more efficient because their ratio between crown surface and horizontal crown projection is higher. Data from a loblolly pine (Pinus taeda L.) spacing experiment were used to test if this hypothesis also holds in young loblolly pine stands and, if so, to determine if it explains the increment differences between spacings in the spacing experiment. Using individual tree height relative to plot dominant height to describe crown class, within-plot regression showed that crown efficiency decreased with crown size for trees below dominant height. This relationship was much less pronounced than indicated from Assmann's examples, although the crown surface to crown projection ratio behaved in the same way as Assmann had hypothesized. Crown efficiency as well as the crown surface to crown projection area ratio decreased with increasing density. Basal area increment per hectare increased until total crown closure approached 130% and then stayed constant. This major impact of total crown coverage brings into question the usefullness of crown efficiency as an indicator for unit area growth.

scholarly journals Modeling Early Responses of Loblolly Pine Growth to Thinning in the Western Gulf Coastal Plain Region

2020 ◽  
Vol 66 (5) ◽  
pp. 623-633
Author(s):  
Y H Weng ◽  
J Grogan ◽  
D W Coble
Keyword(s):  
Loblolly Pine ◽  
Basal Area ◽  
Tree Height ◽  
Height Growth ◽  
Growth Responses ◽  
Individual Tree ◽  
Large Trees ◽  
The Difference ◽  
Pinus Taeda L ◽  
Stand Basal Area

Abstract Growth response to thinning has long been a research topic of interest in forest science. This study presents the first 3–4 years of response of loblolly pine (Pinus taeda L.) growth to thinning at different intensities. Data were collected from the East Texas Pine Research Project’s region-wide loblolly pine thinning study, which covers a wide variety of stand conditions. Four treatments, light, moderate, and heavy thinning, respectively having 370, 555, and 740 residual trees per hectare after thinning, and an unthinned control, were included. Individual tree diameter at breast height (dbh) and total height were recorded annually for the first 3–4 years after thinning. Results indicate significant differences between treatments in dbh growth in each year after thinning, as well as for all years combined. Each thinning treatment had significantly greater dbh growth than the control in the first growing season with this positive response being more evident in the case of the heavier thinning or at the later years post-thinning. Conversely, the thinning effect on tree height growth was initially negligibly negative, then becoming positive after 2–4 years, with the heavier thinning becoming positive sooner. Tree size class, assigned based on prethinning dbh, had a significant effect on both dbh and height growth responses. Compared to the control, small trees had a greater response both in dbh and in height growth than the medium and large trees over the measurement period. At the stand level, the heavier thinning had significantly less stand basal area per hectare, but the difference in stand basal area per hectare between the thinned and the unthinned plots decreased with years post-thinning. Results from this study can improve our understanding in thinning effects and help forest managers make accurate decisions on silvicultural regimes.

scholarly journals Spatial distribution of losses in growth of trees caused by the feeding of pine shoot beetles Tomicus piniperda and T. minor (Col., Scolytidae) in Scots pine stands growing within range of the influence of a timber yard in southern Poland

2012 ◽  
Vol 52 (No. 3) ◽  
pp. 130-135 ◽  
Author(s):  
A. Borkowski
Keyword(s):  
Spatial Distribution ◽  
Scots Pine ◽  
Basal Area ◽  
Tomicus Piniperda ◽  
Pine Trees ◽  
Pine Stands ◽  
The Difference ◽  
High Level ◽  
Pine Shoot Beetles ◽  
Scots Pine Stands

This study deals with the assessment of increment losses in Scots pine trees caused by the maturation feeding of pine shoot beetles Tomicus piniperda (L.) and T. minor (Hart.) (Col., Scolytidae) in even-aged stands growing during their entire life span within range of the influence of a sawmill and its timber yard. In spring 2004, on three sample plots, 0.2 ha in size, situated 60, 200, and 500 m from the yard, height and dbh of all trees were measured and increment cores were taken from randomly selected sample trees. An agreement between the spatial distribution of losses in tree increments and the distribution of damage to crowns of investigated stands indicated that the losses resulted from the maturation feeding of pine shoot beetles migrating from the sawmill timber yard. Divergence of growth in the about 25-years-old stand indicated the beginning of intensive feeding of beetles in pine shoots with a high level of probability. In comparison with the control stand the basal area losses in stands growing 60 and 200 m from the beetle source amounted to 57% and 46%, respectively. The difference in the height of trees was as large as almost 100%.

scholarly journals Influence of thinning intensity and canopy type on Scots pine stand and growth dynamics in a mixed managed forest

2016 ◽  
Vol 25 (2) ◽  
pp. e057 ◽  
Author(s):  
Irantzu Primicia ◽  
Rubén Artázcoz ◽  
Juan-Bosco Imbert ◽  
Fernando Puertas ◽  
María-del-Carmen Traver ◽  
...  
Keyword(s):  
Scots Pine ◽  
Tree Growth ◽  
Growth Rates ◽  
Stand Structure ◽  
Growth Dynamics ◽  
Basal Area ◽  
Beech Forest ◽  
Annual Increment ◽  
Thinning Intensity ◽  
Canopy Type

Aim of the study: We analysed the effects of thinning intensity and canopy type on Scots pine growth and stand dynamics in a mixed Scots pine-beech forest. Area of the study: Western Pyrenees. Material and methods: Three thinning intensities were applied in 1999 (0, 20 and 30% basal area removed) and 2009 (0, 20 and 40%) on 9 plots. Within each plot, pure pine and mixed pine-beech patches are distinguished. All pine trees were inventoried in 1999, 2009 and 2014. The effects of treatments on the tree and stand structure variables (density, basal area, stand and tree volume), on the periodic annual increment in basal area and stand and tree volume, and on mortality rates, were analysed using linear mixed effects models. Main Results: The enhancement of tree growth was mainly noticeable after the second thinning. Growth rates following thinning were similar or higher in the moderate than in the severe thinning. Periodic stand volume annual increments were higher in the thinned than in the unthinned plots, but no differences were observed between the thinned treatments. We observed an increase in the differences of the Tree volume annual increment between canopy types (mixed < pure) over time in the unthinned plots, as beech crowns developed. Research highlights: Moderate thinning is suggested as an appropriate forest practice at early pine age in these mixed forests, since it produced higher tree growth rates than the severe thinning and it counteracted the negative effect of beech on pine growth observed in the unthinned plots.Keywords: competition; Fagus sylvatica L.; Pinus sylvestris L.; forest management; mortality; Mediterranean forest.

Modeling relative error in stem basal area estimates

1990 ◽  
Vol 20 (5) ◽  
pp. 496-502 ◽  
Author(s):  
T. G. Gregoire ◽  
S. M. Zedaker ◽  
N. S. Nicholas
Keyword(s):  
Basal Area ◽  
Field Measurements ◽  
Mean Square ◽  
Interval Estimates ◽  
Tree Diameter ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
The Mean ◽  
The Difference ◽  
Relative Errors

The computed estimate of basal area was the focus of this investigation into the accuracy of tree diameter measurements. Diameter at breast height was measured on 101 trees, the breast height disc was removed from the stem, and each disc outline was then digitized to determine its actual area. Actual areas were compared with the basal areas computed with the field measurements of diameter by expressing the deviations as a proportion of the actual areas. These relative errors averaged 3.1% when basal area was computed with a taped diameter at breast height, and they averaged −2.5% when the mean of two calipered, perpendicular diameter at breast height measurements were used. Noncircularity accounted for about 2.6% of the bias, on average, in basal areas from taped diameters. Root mean square error of relative basal area errors ranged from 7.3 to 7.9% among these methods. The difference between basal areas computed with a taped diameter at breast height and with calipered diameter at breast height was computed and expressed as a proportion of the actual basal area. On average, a difference of 5% was observed. Interval estimates for these differences are presented.

scholarly journals Diameter increment distribution along the stem of narrow-leaved ash in response to thinning intensity

2019 ◽  
Vol 143 (1-2) ◽  
pp. 45-51
Author(s):  
Ali Kemal Özbayram
Keyword(s):  
Rapid Development ◽  
Basal Area ◽  
Cross Sectional ◽  
Thinning Intensity ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Breast Height ◽  
Sample Tree ◽  
Fraxinus Angustifolia ◽  
Different Parts

Narrow-leaved ash (NLA, Fraxinus angustifolia) is an important tree species due to its rapid development and valuable wood. In the pure NLA plantations in Turkey, little is known about the effects of thinning intensity on the diameter increment of different parts of the tree stem. In 2005, a thinning experiment with three thinning intensities (control: 0%; moderate: 19%; heavy: 28% of basal area removed) was established in an NLA plantation in Sakarya, Turkey. Seven years after thinning, a total of 25 sample trees representing dominant and co-dominant trees were felled, and cross-sectional stem samples were taken for analysis. The diameter at breast height (d<sub>1.30</sub>) and d<sub>1.30</sub> increments of the co-dominant trees with the moderate and heavy treatments were similar to each other and greater than in the controls. The seven-year d<sub>1.30</sub> increments of the dominant trees in the heavy-treatment plot were approximately 20% greater than in the other treatments plots. The highest diameter increments in both dominant and co-dominant trees for all treatments were determined at the 0.30 m and 17.30 m section heights. The sample tree diameter increments of between 1.30 m and 13.30 m were similar within their classes. In conclusion, heavy-intensity thinning of up to 28% did not cause tapering in the NLA plantation stems, and thus, heavy thinning can be recommended for NLA trees.

scholarly journals Significance of Mangroves in the Arid Environment of the Sultanate of Oman

1996 ◽  
Vol 1 ◽  
pp. 41 ◽  
Author(s):  
M.M. Fouda ◽  
M.A. AI-Muharrami
Keyword(s):  
Soil Texture ◽  
Basal Area ◽  
Tree Height ◽  
Arid Environment ◽  
Available Phosphorus ◽  
Physical Habitat ◽  
Tree Diameter ◽  
Hypersaline Water ◽  
Mangrove Trees

Little is known of the ecological role of the only species of mangrove, Avicemnia marina, in Oman. This study provides information on the physical habitat of three mangrove areas( Qurm, Mahout and Shinas) in relation to the main features of each area ( i.e. community structure, soil and water analysis and biota). The climate of three mangrove areas and surrounding regions is hot and arid; all have very low rainfall (less than 100mm yr), high air temperature (mean 27”C), relative humidity (57.8% at Qurm and 72% at Mahout and Shinas) , solar radiation ( more than 500 MVH cm2) and evaporation rates (more than 3000 mm yr2). Mangrove trees folowered during January-March, fruits matured during April- May, seedlings fell in June , seeds germinated in July-August and leaves were produced in September. Difference among sites included areal  extent ( 162 ha in Mabout, 74 ha in Quran and 53 ha in Shinas) and high variability in mangrove structure within and between sites . The most obvious differences between sites related to tree height diameter , density and basal area. The increase in tree diameter was associated with increase in tree height and basal area, but an impressive relationship existed between tree diameter and density. Significant differences in soil texture and chemical analysis were found  within and between the three mangrove sites. Soil texture wasdominated by sand; however, site( highest at Qurm,, 32%) and clay ( highest at Mahout , 10.1%) were present in considerable amounts. Soils of Mhout had the highest organic matter (10.2%) – totall nitrogeon ( 0.2% ), available phosphorus ( 56.2ppm) and sulphate ( 17.1 meq 100g) contents compared to those from Qurm and Shinas. Water temperature ranged 22-38C and salinity showed small variations at Mahout ( 37-40 ) and Shinas ( 37-40) but at Qurm, salinity showed remarkable variation from fresh and brackish water (10) to hypersaline  water ( more than 100). Dissolved oxygen averaged 8.1( 4.8-12.7) mg and PH was  7.8 ( 6.9-8.9). Mangrove communicate included a faunal assemblage of many species of birds ( more than 200 species ), fish ( 54 species) , crustaceans ( 31 species) and mollusks ( 51 species ) . Some group exhibited clear pattern ( e.g, crabs and oysters), others were just visitors ( fish and birds ), but the majority were resident in the mangroves.

scholarly journals The influence of different thinning methods on dominance coefficients of future crop trees in even-aged Scots pine stands

2014 ◽  
Vol 75 (1) ◽  
pp. 31-45
Author(s):  
Tadeusz Zachara
Keyword(s):  
Scots Pine ◽  
Average Diameter ◽  
Long Term Effect ◽  
Pine Stands ◽  
The Difference ◽  
1960S And 1970S ◽  
Poor Site ◽  
Thinning Effect ◽  
Scots Pine Stands

Abstract The research aim was to evaluate the influence of different thinning methods on future crop tree growth. Investigations were conducted on permanent Scots-pine experimental plots, established in 1960s and 1970s in Kozienice, Łąck, Parciaki and Janów Lubelski Forest Districts. To assess the response to thinning of future crop trees, their dominance coefficients were used. These are defined as quotients for each given future crop tree diameter and average stand diameter (WP1), the average dominant layer diameter (WP2) and the average diameter of 100 thickest trees per hectare (WP3). The difference between each coefficient value at the beginning and at the end of the measurement period was used as a measure of the thinning effect. On Kozienice, Łąck and Parciaki plots the differences between treatments were significant, especially in the period after first thinning. The increase of WP3 coefficient occurred in a case of strong thinning - TS1 and TS2. On plot Parciaki also the moderate thinning TU1 and TU2 had a significant influence on change of this coefficient. On plot Janów Lubelski the influence of treatment has not been stated in the first 5-year period but in the next one. Analyses of changes in the dominance coefficients confirmed the hypothesis that the WP3 coefficient is very useful as it is the most stable indicator of future crop-tree position in a stand. On Kozienice, Łąck and Parciaki plots the significant differences between treatments were stated, especially in the period after first thinning. The influence of thinning treatment on the plot Janów Lubelski was not considered for the first 5-year period but in the next one. All reactions to thinning were slower on this plot, possibly because of the relatively poor site conditions. This was a long-term effect. The results obtained suggest that very intense thinning of Scots pine stands should only be implemented under a restricted set of conditions - in healthy, not neglected, forest stands. Classical moderately-selective thinning is preferable to intense thinning and is the most convenient option for pine stands

Sign in / Sign up

Export Citation Format

Share Document