Predicting the future diameter of stems in Norway spruce stands subjected to different thinning regimes

2005 ◽  
Vol 35 (6) ◽  
pp. 1331-1341 ◽  
Author(s):  
Kjell Karlsson ◽  
Lennart Norell
Keyword(s):  
Standard Deviation ◽  
Norway Spruce ◽  
Stand Density ◽  
Logistic Function ◽  
Management Regime ◽  
The Future ◽  
The Mean ◽  
Using Data ◽  
Stand Density Management ◽  
Individual Trees

The future diameter of stems in even-aged Norway spruce (Picea abies (L.) Karst.) stands subjected to different thinning regimes was modelled, using data from a thinning experiment established in 25 localities in southern Sweden. Separate models were developed for stands thinned from below, stands thinned from above, and unthinned stands. A bivariate approach was used to construct the models, based on DBH data from the initial stand and from the same trees at future points in time. The approach entails that the dependency between initial and future DBHs can be directly used to predict the future DBH. Also, the modelling used stand and site characteristics together with information about the stand density management regime. The initial stands were assumed to be unthinned, and the dominant height was assumed to be 12–18 m. A logistic function was used to predict which individual trees would remain at future points in time. The mean and standard deviation of the differences between observed and predicted future diameters were used to validate the models. When the prediction period was approximately 33 years, the mean was typically underestimated by 4 mm, and the standard deviation was approximately 40 mm.

scholarly journals Presence of Root Rot Reduces Stability of Norway Spruce (Picea abies): Results of Static Pulling Tests in Latvia

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 416 ◽  
Author(s):  
Oskars Krisans ◽  
Roberts Matisons ◽  
Steffen Rust ◽  
Natalija Burnevica ◽  
Lauma Bruna ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Root Rot ◽  
Rotation Period ◽  
Wind Damage ◽  
Individual Tree ◽  
Study Region ◽  
Secondary Failure ◽  
The Future ◽  
Spruce Stands ◽  
Individual Trees

Storms are the main abiotic disturbance in European forests, effects of which are expected to intensify in the future, hence the importance of forest stand stability is increasing. The predisposition of Norway spruce to wind damage appears to be enhanced by pathogens such as Heterobasidion spp., which reduce stability of individual trees. However, detailed information about the effects of the root rot on the stability of individual trees across diverse soil types is still lacking. The aim of the study was to assess the effect of root rot on the individual tree stability of Norway spruce growing on drained peat and mineral soils. In total, 77 Norway spruce trees (age 50–80 years) growing in four stands were tested under static loading. The presence of Heterobasidion spp. had a significant negative effect on the bending moment at primary and secondary failure of the tested trees irrespectively of soil type. This suggests increased legacy effects (e.g., susceptibility to pathogens and pests due to fractured roots and altered water uptake) of storms. Damaged trees act as weak spots increasing the susceptibility of stands to wind damage, thus forming a negative feedback loop and contributing to an ongoing decline in vitality of Norway spruce stands following storms in the study region in the future. Accordingly, the results support the importance of timely identification of the decayed trees, lowering stand density and/or shortening rotation period as the measures to counteract the increasing effects of storms on Norway spruce stands.

Effects of stand density on outcrossing rate in two Norway spruce (Picea abies) populations

1991 ◽  
Vol 69 (12) ◽  
pp. 2704-2708 ◽  
Author(s):  
M. Morgante ◽  
G. G. Vendramin ◽  
P. Rossi
Keyword(s):  
Picea Abies ◽  
Mating System ◽  
Norway Spruce ◽  
Stand Density ◽  
Major Effect ◽  
Outcrossing Rate ◽  
High Density ◽  
Low Density ◽  
The Mean ◽  
Key Words Mating System

The mating system was investigated in two neighbouring Norway spruce (Picea abies (L.) Karst.) populations with markedly different stand densities. The amount of outcrossing was estimated using open-pollinated array data at four enzyme loci. Multilocus estimates of the proportion of viable progeny owing to outcrossing were 0.956 and 0.955 for the low- and high-density stand, respectively, indicating that the large reduction in stand density had no impact on outcrossing rates. The multilocus estimate was higher than the mean single-locus estimate only for the low-density stand. The lowering of the mean estimate in the low-density stand is probably a consequence of the clustering of related individuals. The regression of pollen allele frequencies on ovule genotype, which is a direct measure of the effective selfing caused by consanguineous matings, had a significant coefficient for the low-density stand and a nonsignificant one for the high-density stand. This obvservation confirms that the major effect of low-stand density in Norway spruce is the occurrence of consanguineous matings. Key words: mating system, outcrossing rate, inbreeding, Norway spruce, stand density.

scholarly journals Stand density management diagrams and their development and utility in black spruce management

1993 ◽  
Vol 69 (4) ◽  
pp. 421-430 ◽  
Author(s):  
P. F. Newton ◽  
G. F. Weetman
Keyword(s):  
Black Spruce ◽  
Basal Area ◽  
Stand Density ◽  
Future Research ◽  
Permanent Sample Plots ◽  
Quadratic Mean Diameter ◽  
Using Data ◽  
Stand Density Management ◽  
Natural Stands ◽  
Stand Density Management Diagram

A stand density management diagram for black spruce (Picea mariana (Mill.) B.S.P.) was developed using data derived from 49 0.081-ha permanent sample plots and 257 open-grown sample trees located throughout central insular Newfoundland. The diagram illustrated the reciprocal equation of the competition-density effect, self-thinning rule, approximate crown closure line, zone of imminent competition-mortality, and isolines for relative density, quadratic mean diameter and merchantability ratio. Mean prediction error for natural stand trajectories over a 30-projection period were 2.5 dm3 for mean volume, 306 stems/ha for density, 16.1 m3/ha for merchantable volume, 14.3 m3/ha for total volume, and 1.9 m2/ha for basal area. Implementation procedures using a combination of monoareal and polyareal sampling methods were described and the potential application of the diagram for evaluating thinning alternatives was demonstrated. Limitations of the diagram and future research directions were identified. Key words: stand density management diagram, black spruce, natural stands, central Newfoundland

scholarly journals Stand Density Management Diagram for Jack Pine Stands in Eastern Canada

2007 ◽  
Vol 24 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Mahadev Sharma ◽  
S.Y. Zhang
Keyword(s):  
Pinus Banksiana ◽  
Stand Density ◽  
Jack Pine ◽  
Eastern Canada ◽  
Permanent Sample Plots ◽  
Quadratic Mean Diameter ◽  
Using Data ◽  
Stand Density Management ◽  
Crown Closure ◽  
Stand Density Management Diagram

Abstract A stand density management diagram was developed for jack pine (Pinus banksiana Lamb.) stands using the data obtained from 125 permanent sample plots (PSPs) established in Ontario and 232 PSPs in Quebec, Canada. The diagram was evaluated using data from 40 PSPs established in Ontario. Recently developed and efficient models have been used in constructing the diagram to estimate diameters and heights for the trees for which no diameters or heights were recorded at the time of stand inventory. Relative density indices of 0.15, 0.40, and 0.55 were used, corresponding to the line of approximate crown closure, the limit of productive zone, and the lower limit of competition-related mortality, respectively. If two stand characteristics are known, including mean total tree volume, quadratic mean diameter, trees per hectare, and average dominant height, the others can be readily obtained using the diagram. The consequences of various thinning scenarios can be plotted and visualized in the field without the need for computer simulation.

Individual-tree diameter growth models for quantifying within-stand response to nitrogen fertilization

1990 ◽  
Vol 20 (8) ◽  
pp. 1149-1155 ◽  
Author(s):  
Bahman Shafii ◽  
James A. Moore ◽  
James D. Newberry
Keyword(s):  
Growth Models ◽  
Stand Density ◽  
Simulation Models ◽  
Diameter Growth ◽  
Individual Tree ◽  
Diameter Increment ◽  
Prognosis Model ◽  
Using Data ◽  
Individual Trees ◽  
Northern Idaho

Diameter-increment models for nitrogen-fertilized stands were developed using data from permanent research plots in northern Idaho. The equations partially resembled PROGNOSIS model diameter growth formulations. Results indicated that both initial tree size and initial stand density produced significant interactions with treatment to explain an individual tree's response to fertilization. Larger trees in a stand showed more fertilization response than smaller trees. Furthermore, individual trees in low-density stands showed more fertilization response than those growing in high-density stands. These diameter increment predictive equations were formulated to be compatible with individual-tree distance-independent simulation models.

scholarly journals The Optimalization of Zakah Distribution During Covid-19 Pandemic Using Data Envelopment Analysis (DEA) Method at Badan Amil Zakat Nasional (BAZNAS) Indonesia

2021 ◽  
Vol 6 (2) ◽  
pp. 180
Author(s):  
Yosi Maytesa ◽  
Mega Ilhamiwati
Keyword(s):  
Data Envelopment Analysis ◽  
Economic Crisis ◽  
Relative Efficiency ◽  
Data Envelopment ◽  
The Future ◽  
The Mean ◽  
Dea Method ◽  
Using Data ◽  
Method Approach

Purpose: The purpose of this paper is to assess the level of optimality of zakat institutions to deal with the economic crisis during the Covid-19 pandemic.Design/Method/Approach: In this research, the measurement of efficiency of zakat distribution during the Covid-19 pandemic at badan amil zakat nasional (BAZNAS) has been carried out using data envelopment analysis (DEA) method.Findings: The result is the mean of zakah distribution relative efficiency are 70 %. Finally, some suggestion for evaluating the distribution of zakat in the future has been discussed. Originality/Values: The contribution of this research is to obtain the efficiency value of zakat distribution during the Covid-19 pandemic. So that with the result, the management of zakat distribution at BAZNAZ can improved and evaluated.

scholarly journals Stand Density Management Diagram for Mixed Balsam Fir-Black Spruce Stands

1998 ◽  
Vol 15 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Brian R. Sturtevant ◽  
John A. Bissonett ◽  
James N. Long
Keyword(s):  
Black Spruce ◽  
Rotation Period ◽  
Stand Density ◽  
Balsam Fir ◽  
Data Set ◽  
Treatment Scenario ◽  
Spruce Stands ◽  
Permanent Sample Plot ◽  
Using Data ◽  
Stand Density Management

Abstract Stand density management diagrams (SDMDs) provide a useful means of predicting the consequences of alternative density management regimes. The specific objectives of this project were to create a SDMD that could (a) be applied to mixed balsam fir-black spruce stands, and (b) allow structural predictions beyond the typical 60 yr pulpwood rotation period. We constructed the SDMD using data from 129 horizontal point samples from 24 stands and 17 permanent sample plot measurements within 9 stands, located in western and central Newfoundland. The model has not been tested with an independent data set, and should therefore be viewed as a first approximation. We further discuss the diagram's applicability, and provide an example of its utility by demonstrating a precommercial thinning treatment versus no treatment scenario. North. J. Appl. For. 15(1):17-22.

Asymmetric, two-sided competition in even-aged monocultures of red pine

1988 ◽  
Vol 18 (7) ◽  
pp. 901-910 ◽  
Author(s):  
David G. Brand ◽  
Steen Magnussen
Keyword(s):  
Stand Density ◽  
Red Pine ◽  
Stem Volume ◽  
Large Trees ◽  
Relative Production ◽  
Competition Process ◽  
Using Data ◽  
The Individual ◽  
Individual Trees ◽  
Relative Production Rate

A framework for analysis of even-aged plant monocultures was developed and used to examine hypotheses on the process of competition, using data obtained from three independently established red pine (Pinusresinosa Ait.) stand-density experiments. Growth rate and relative production rate (a measure of tree vigour) were computed for the individual trees in stands of differing density at points in time when these stands had the same mean stem volume. Competition is shown to be both asymmetric (small trees lose vigour more rapidly than large trees as density increases) and two-sided (not only do larger trees affect smaller trees, but to some degree small trees also cause growth reduction in larger neighbours). Increasing density results in increased size inequality as smaller trees lose vigour and become suppressed. The asymmetric, two-sided competition process in red pine stands is considered ecologically inherent for a species adapted to existence in even-aged monocultures.

Test-Retest Reliability of the Profile of Hearing Aid Performance

1994 ◽  
Vol 37 (5) ◽  
pp. 1211-1215 ◽  
Author(s):  
Charles T. Nelson ◽  
Catherine V. Palmer
Keyword(s):  
Hearing Loss ◽  
Standard Deviation ◽  
Background Noise ◽  
Hearing Aid ◽  
Critical Difference ◽  
Retest Reliability ◽  
Rehabilitative Treatment ◽  
The Mean ◽  
Using Data ◽  
Test Retest Reliability

This study was designed to replicate the test-retest reliability and critical difference components of the Profile of Hearing Aid Performance (PHAP) as established by Cox and Gilmore (1990). Subjects were 18 experienced hearing aid users ranging in age from 62 to 74 years old. The initial and retest administrations of the PHAP were conducted with no rehabilitative treatment pertaining to hearing loss or amplification provided during the intervening period. The interval between the first and second administrations of the profile was 4–5 months. The mean test-retest difference scores obtained in this investigation were small, not unlike those reported by Cox and Gilmore (1990). Critical difference (CD) values closely approximated those of the previous study except for the Background Noise subscale and the Environment C scale. A pooled estimate of each standard deviation of test-retest differences was computed using data from both investigations. This resulted in critical differences considered to be more precise than the CD values derived from either study alone. Findings strongly support the utility of the PHAP as an effective tool for generating reliable information regarding self-perceived hearing aid performance.

scholarly journals Energy Balance at the Surface of the Ice Sheet in the Coastal Area of Adélie Land, Antarctica (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 348
Author(s):  
P.-L Blaix ◽  
D Delaunay ◽  
A Poggi
Keyword(s):  
Heat Flux ◽  
Standard Deviation ◽  
Coastal Area ◽  
Wind Profile ◽  
Potential Temperature ◽  
Net Radiation ◽  
The Mean ◽  
Logarithmic Law ◽  
Flux Layer ◽  
Using Data

Hourly measurements of wind, temperature, and humidity were made between elevations of 1 and 20 m in the coastal area of Adélie Land over a period of 45 d in January and February 1978. About 1000 profiles are available. The height of the constant flux layer is >5 m despite the influence of katabatic winds, the wind profile is logarithmic with a mean standard deviation from the logarithmic law of 15 mm s−1. The potential temperature profile is also logarithmic with a mean standard deviation of 0.04°C. The most important deviation from the logarithmic law appears between -4 and 0°C. Humidity was measured at two points only, between 1 and 20 m; the mean gradient was about 0.01 mbar m−1 and the flux of latent heat was generally negligible. Net radiation was measured for only 10 d because of radiometer failure. All the fluxes are calculated using data for the 5 m layer. For the 10 d period, the heat loss was about 3 Wm−2 with a mean heat flux of -27.5 Wm−2 and mean net radiation of -10.5 Wm−2(the minus sign signifying the flux is towards the surface). In general, the heat flux is towards the surface (92% of the cases) but is away from the surface in the afternoon. The ablation during the 10 d period without snow-fall was about 200 mm of ice.

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