scholarly journals Practical approaches to determining the dynamics of the stability of stands of breeding objects

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
V. I. Blystiv ◽  
V. M. Malyuga ◽  
V. V. Minder ◽  
O. P. Syrota
Keyword(s):  
Genetic Diversity ◽  
Forest Stand ◽  
Loss Of Stability ◽  
Forest Types ◽  
Forest Stands ◽  
Ecological Stability ◽  
Forest Environment ◽  
Forest Genetic ◽  
The Stability ◽  
Sanitary State

The article analyzes the indicators that can be used to assess the biotic and ecological stability of forest stands. For breeding facilities, this issue is of relevance when prescribing reforestation measures in forest genetic reserves, assessing the stability when selecting plus stands, assessing selected permanent forest-seed plots to determine the volumes of their formation and tending activities in them and, in the future, their transfer to plus stands, as well as, in general, for isolation of a reserve fund from the forest environment. The methods for assessing the stability of forest stands are based on determining the indicators of forest stand stability, calculated on the basis of tree mensuration in the study area (based on a trial plot) and the sanitary state of the trees. The basis for the determination is the complete tree enumeration and the scale of sanitary state used in production operations (SanitaryForestsReg.Ukraine). The assessment of stand stability is based on the method of calculating the loss of stability (BC)), which was proposed to determine the stability of secondary spruce forests in fertile beech forest types (BlystivV. I. 2006) and later adapted to assess the formation of the stability of hornbeam-beech stands (Blystiv V. I., 2012). The issue of assessing the tension of a stand, using the growing space of the forest is addressed in the methods section of the dissertation work by V.M.Malyuga, 2020. Using the values of the above indicators (KC, ВбС, ВеС), stands can be divided into 3 categories of stability: stable, conditionally stable and unstable. Appropriate forestry activities are proposed according to the categories. They require a special numeric-expressed substantiation, both in relation to the economic group of forest types, forest category, and for targeted activities or research areas - in this case, loss of stability of breeding facilities. Tension studies have shown that by using factors of environmental impact, the conditions are assessed as normal, non-tensioned and tensioned. To assess the indicator values of normal and weakened states, the basic scale of the assessment of biotic stability by stand indexes will be used. For the weakened state, three indexes are identified for the purpose of detailed planning of possible activities. In forest breeding, the selection and formation of forest stands for stability will require parameter-defined indicators, in this case, the forest stand stability coefficient is used. The protective properties of the forest environment, identified with the preservation of genetic diversity, determined by the amount and quality of natural regeneration and associated with ecological stability, can be effectively assessed by its loss according to the above method. The studies on the stand tension, using the factors of environmental impact, have shown that stands growing under tension are those that are somewhat overstocked ones. Pine stands grow optimally when they have a density range of 0.7-1.0. The rest of the stands grow without tension, but they do not make full use of growing space due to varying degrees of stand density. Such medium-stocked stands can be effectively used as selected and appropriately formed permanent forest-seed plots. Assessment of the stand state by impact factors makes it possible to record quantitative changes. The dynamics of areas in accordance with the changes of these indicators by periods characterizes the ecosystem changes (stages of development by successive process) and is important for the facilities of preservation of genetic diversity - especially forest genetic reserves.

Modelling growing stock volume of forest stands with various ALS area-based approaches

2021 ◽  
Author(s):  
Karolina Parkitna ◽  
Grzegorz Krok ◽  
Stanisław Miścicki ◽  
Krzysztof Ukalski ◽  
Marek Lisańczuk ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Mean Squared Error ◽  
Prediction Method ◽  
Forest Stand ◽  
Boosted Regression Trees ◽  
Forest Stands ◽  
Individual Tree ◽  
Growing Stock ◽  
Modelling Techniques ◽  
Stock Volume

Abstract Airborne laser scanning (ALS) is one of the most innovative remote sensing tools with a recognized important utility for characterizing forest stands. Currently, the most common ALS-based method applied in the estimation of forest stand characteristics is the area-based approach (ABA). The aim of this study was to analyse how three ABA methods affect growing stock volume (GSV) estimates at the sample plot and forest stand levels. We examined (1) an ABA with point cloud metrics, (2) an ABA with canopy height model (CHM) metrics and (3) an ABA with aggregated individual tree CHM-based metrics. What is more, three different modelling techniques: multiple linear regression, boosted regression trees and random forest, were applied to all ABA methods, which yielded a total of nine combinations to report. An important element of this work is also the empirical verification of the methods for estimating the GSV error for individual forest stand. All nine combinations of the ABA methods and different modelling techniques yielded very similar predictions of GSV for both sample plots and forest stands. The root mean squared error (RMSE) of estimated GSV ranged from 75 to 85 m3 ha−1 (RMSE% = 20.5–23.4 per cent) and from 57 to 64 m3 ha−1 (RMSE% = 16.4–18.3 per cent) for plots and stands, respectively. As a result of the research, it can be concluded that GSV modelling with the use of different ALS processing approaches and statistical methods leads to very similar results. Therefore, the choice of a GSV prediction method may be more determined by the availability of data and competences than by the requirement to use a particular method.

The optimal rotation of a flammable forest stand

1980 ◽  
Vol 10 (1) ◽  
pp. 30-34 ◽  
Author(s):  
D. L. Martell
Keyword(s):  
Stochastic Model ◽  
Fire Management ◽  
Jack Pine ◽  
Forest Stand ◽  
Timber Production ◽  
Forest Stands ◽  
Rotation Interval ◽  
Optimal Rotation

The author describes a stochastic model of forest stand rotation which can be used to determine the optimal planned rotation interval for flammable forest stands. The model can also be used to estimate the value of fire management activities in terms of the potential enhanced value of timber production. The use of the model is illustrated by applying it to a simplified case of jack pine (Pinusbanksiana, Lamb.) management.

Nonstationary Response of a Two-Degrees-of-Freedom Nonlinear Ship Model Under Modulated Excitation

1995 ◽  
Author(s):  
Ruigui Pan ◽  
Huw G. Davies
Keyword(s):  
Degrees Of Freedom ◽  
Stability Boundary ◽  
Period Doubling ◽  
Approximate Solutions ◽  
Loss Of Stability ◽  
Two Degrees Of Freedom ◽  
Ship Model ◽  
Nonstationary Response ◽  
Period 2 ◽  
The Stability

Abstract Nonstationary response of a two-degrees-of-freedom system with quadratic coupling under a time varying modulated amplitude sinusoidal excitation is studied. The nonlinearly coupled pitch and roll ship model is based on Nayfeh, Mook and Marshall’s work for the case of stationary excitation. The ship model has a 2:1 internal resonance and is excited near the resonance of the pitch mode. The modulated excitation (F0 + F1 cos ωt) cosQt is used to model a narrow band sea-wave excitation. The response demonstrates a variety of bifurcations, loss of stability, and chaos phenomena that are not present in the stationary case. We consider here the periodically modulated response. Chaotic response of the system is discussed in a separate paper. Several approximate solutions, under both small and large modulating amplitudes F1, are obtained and compared with the exact one. The stability of an exact solution with one mode having zero amplitude is studied. Loss of stability in this case involves either a rapid transition from one of two stable (in the stationary sense) branches to another, or a period doubling bifurcation. From Floquet theory, various stability boundary diagrams are obtained in F1 and F0 parameter space which can be used to predict the various transition phenomena and the period-2 bifurcations. The study shows that both the modulation parameters F1 and ω (the modulating frequency) have great effect on the stability boundaries. Because of the modulation, the stable area is greatly expanded, and the stationary bifurcation point can be exceeded without loss of stability. Decreasing ω can make the stability boundary very complicated. For very small ω the response can make periodic transitions between the two (pseudo) stable solutions.

scholarly journals Conservation and directed utilization of forest genetic resources

2007 ◽  
pp. 7-21 ◽  
Author(s):  
Mirjana Sijacic-Nikolic ◽  
Jelena Milovanovic
Keyword(s):  
Genetic Diversity ◽  
Genetic Resources ◽  
Genetic Resource ◽  
Environmental Changes ◽  
Future Generations ◽  
Forest Trees ◽  
The Earth ◽  
Forest Genetic ◽  
Forest Genetic Resources ◽  
Defensive Mechanism

Forest genetic resources represent the genetic diversity contained in the thousands of species of forest trees on the earth. their conservation is a set of activities and strategies, which are performed in the aim of ensuring the continued existence, evolution and availability of these resources for the present and future generations. the aim of genetic resource management is the enhancement of conditions for the continual evolution of the species which is the defensive mechanism of the organisms in the struggle with environmental changes.

scholarly journals SANITARY CONDITION OF PICEA ABIES (L. ) KARST. YOUNG FOREST STANDS DEPENDING ON THE SPATIAL SPECIFICITY

AGROFOR ◽  
2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Jelena RUBA ◽  
Olga MIEZITE ◽  
Imants LIEPA
Keyword(s):  
Risk Factors ◽  
Picea Abies ◽  
Tree Height ◽  
Impact Factors ◽  
Forest Stands ◽  
Sanitary Condition ◽  
Young Forest ◽  
Young Forests ◽  
Spatial Specificity ◽  
Sanitary State

As a result of nature resources intensive use, most of ecosystems have beenconverted. Anthropogenic impact includes changes of forest stands structure andtheir spatial specificity in the forest area. Accordingly the sanitary state of Norwayspruce young forest stands can be affected by different risk impact factors ofmanagement. The aim of the research was to analyze the spruce Picea abies (L. )Karst. young forest stands sanitary condition depending on forest plots spatialspecificity and location in the forest areas. The data were collected in 4 regions ofLatvia in spruce young forest stands (1 - 40 years old). The research was conductedin young natural and artificial stands (pure – 44, mixed – 42). In total 502 sampleplots with a total area of 28250 mwere installed. The particular plot size (25, 50,100 and 200 m) were selected depending on the stand average tree height, whiletheir number depended on the forest stand area. A total area of investigated foreststands were 127. 5 hectares. Results showed that the expression of spatial specificsdepended on risk factors and their intensity, as well as the environmentalcharacteristics. Damages caused by abiotic risk factors at different forest standswere not the same regarding intensity, nature and volume, but more or less closelywere related to all site conditions. Spatial specificity of forest stands area (regularand irregular), as well as their location in the forest massif significantly affects thespruce young forests sanitary status (respectively p=0. 027 and p=0. 002). Differentrisk factors damage to forests, bordering with spruce or pine young growths,cutovers and various types of infrastructure, were identified as much moreimportant.

scholarly journals ALGORITHM AND SOFTWARE FOR CALCULATING THE STABILITY OF THE FORM OF EQUILIBRIUM OF DISCRETE SYSTEMS

2019 ◽  
Vol 13 (3) ◽  
pp. 44-49
Author(s):  
A.A. SHKURUPIY ◽  
A.N. PASCHENKO ◽  
P.B. MYTROFANOV
Keyword(s):  
Discrete Systems ◽  
Stability Loss ◽  
Transcendental Equation ◽  
Loss Of Stability ◽  
Displacement Method ◽  
Software Complex ◽  
Complex Functions ◽  
Transcendental Functions ◽  
The Stability ◽  
Theoretical Mechanics

The paper presents an algorithm for calculating the stability of the form of equilibrium of the first kind of compressed discrete systems by the method of displacements in combination with themethods of iterations and bisection. The use of the displacement method in combination with the iteration and bisection methods makes it possible to effectively determine the minimum critical stress or strain at the first bifurcation and their corresponding form of loss of stability, both for statically determined and statically undetectable systems. This approach, using matrixforms, makes it possible to significantly simplify the calculations of the analytical condition for the loss of stability of compressed discrete systems (the stability loss equation), which has high orders, as well as to construct the form of loss of stability corresponding to a critical load, that is, to solve the problem of loss of stability of equilibrium. The calculation of the compressed discrete system on the stability of the form of equilibrium actually reduces to the solution of the difficultly described nonlinear transcendental equation, which is the equation of loss of stability. The difficulty lies in the absence of an analytical solution of such an equation due to the presence of complex functions of Zhukovsky, which have transcendental functions in their structure. Such solution can be performed only with the use of numerical methods. This algorithm for calculating the loss of equilibrium of the first kind of compressed discrete systems by displacement in combination with the methods of iteration and bisection is implemented in the software complex "Persist" for a PC in Windows OS. The program was approbated and implemented in theeducational process at the Department of Structural and Theoretical Mechanics of the Poltava National Technical Yuri Kondratyuk University during the training of specialists in engineering specialties.

scholarly journals Production potential and ecological stability of mixed forest stands in uplands – V. A mixed spruce/beech stand on a nutrient-rich site of the Křtiny Training Forest Enterprise

2012 ◽  
Vol 49 (No. 11) ◽  
pp. 502-514 ◽  
Author(s):  
P. Kantor ◽  
V. Hurt
Keyword(s):  
Mixed Forest ◽  
Health Condition ◽  
Forest Stands ◽  
Ecological Stability ◽  
Production Potential ◽  
Dominant Position ◽  
Beech Stand ◽  
The Given ◽  
Young Growth

The study is already the 5<sup>th </sup>account on the production potential and stability of mixed forest stands in uplands. A spruce/beech stand established in the mid-30s of the 20<sup>th</sup>century is assessed. The stand is situated at an altitude of 470 m and since 1960, it is left to its spontaneous development. At that time, the stand was characterized as a silviculturally neglected dense spruce young growth to a small pole-stage stand with an admixture of beech (spruce 71%, beech 13%). In the course of 41 years, spruce proportion in the stand without intentional thinning measures decreased from 71 to 56% and, vice versa, beech proportion increased from 13 to 31%. Present dominant and co-dominant position of spruce in the stand, its health condition and development in recent years indicate that the ecosystem under evaluation is stabilized fulfilling all functions on the given site at an age of 65 years. The stand is permanently fully stocked and its initial standing volume of 109 m<sup>3</sup>/ha at an age of 24 years in 1960 increased to 560 m<sup>3</sup>/ha at an age of 65 years in 2001.

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