scholarly journals Principles and methods of developing a map “Geographical patterns of natural regeneration and forest stand productivity”

2020 ◽  
Vol 26 (4) ◽  
pp. 73-89
Author(s):  
Nadezda Kiseleva
Keyword(s):  
Natural Regeneration ◽  
Thermal Conditions ◽  
Forest Stand ◽  
Forest Growth ◽  
General Idea ◽  
Small Scale ◽  
Central Siberia ◽  
Geographical Patterns ◽  
Stand Productivity ◽  
Air Temperatures

A special series of small-scale maps (approximate scale 1 : 7 500 000–1 : 8 000 000) is necessary for more effective forestry management in Russia and ensuring the stable functioning of this sector of the economy to create. These maps should give a holistic spatial representation of the object of forestry activity, they will allow to give a realistic assessment of the forest resource potential of the country. One of the maps in the series is “Geographical patterns of natural regeneration and forest stand productivity”. The basic principles of the map constructing are: general geographical patterns of main forest-forming species natural regeneration on clearings and general geographical patterns of productivity of the stand of all forest-forming species (in bonitet); the idea of V.V. Dokuchaev about the similarity of altitudinal mountain zonation to natural zones and subzones of plains. Zonal, subzonal, and altitudinal-zonal natural complexes, the formation of which is determined by the climate, serve as units of mapping. The methodology for constructing the map was verified using the example of the thermal conditions of forest growth in Central Siberia. Four indicators from 147 weather stations were used for this (calculated for the period from 1881 to 1980). Three indicators — the average monthly air temperatures in January and July and the average annual air temperature give a general idea of the thermal conditions of forest growth in Central Siberia. The sum of the average daily air temperatures above 10°C, which is the fourth indicator, characterizes the period of the most active vegetation of tree species. These indicators are summarized in a table constructed on the basis of the similarity of altitudinal zonation of natural complexes to zonal and subzonal. The article presents construction methodology, a fragment and the map legend.

Carbon sequestration in mixed deciduous forests: The importance of mid-storey trees for forest productivity

2021 ◽  
Author(s):  
Anne Holtmann ◽  
Andreas Huth ◽  
Felix Pohl ◽  
Corinna Rebmann ◽  
Rico Fischer
Keyword(s):  
Carbon Sequestration ◽  
Species Composition ◽  
Primary Productivity ◽  
Stand Structure ◽  
Forest Productivity ◽  
Forest Stand ◽  
Gross Primary Productivity ◽  
Small Scale ◽  
Stand Productivity ◽  
Simulation Results

<p>Forests play an important role in climate regulation due to carbon sequestration. However, a deeper understanding of forest carbon flux dynamics are often missing due to a lack of information about forest structure and species composition, especially for non-even-aged and mixed forests. In this study, we combined field inventory data of a mixed deciduous forest in Germany with an individual-based forest gap model to investigate daily carbon fluxes and to examine the role of tree size and species composition for the overall stand productivity. Simulation results show that the forest model is capable to reproduce daily eddy covariance measurements (R<sup>2</sup> of 0.73 for gross primary productivity and of 0.65 for ecosystem respiration). The simulation results showed that the forest act as a carbon sink with a net uptake of 3.2 t<sub>C</sub> ha<sup>-1</sup> yr<sup>-1</sup>  (net ecosystem productivity) and an overall gross primary productivity of 18.2  t<sub>C</sub> ha<sup>-1</sup> yr<sup>-1</sup>. At the study site, medium sized trees (30-60cm) account for the largest share (66%) of the total productivity. Small (0-30cm) and large trees (>60cm) contribute less with 8.5% and 25.5% respectively. Simulation experiments showed, that species composition showed less effect on forest productivity. Stand productivity therefore is highly depended on vertical stand structure and light climate. Hence, it is important to incorporate small scale information’s about forest stand structure into modelling studies to decrease uncertainties of carbon dynamic predictions. Experiments with such a modelling approach might help to investigate large scale mitigation strategies for climate change that takes local forest stand characteristics into account.</p>

ON THE THERMAL REGIME OF THE SURFACE AIR LAYER IN THE DEBED RIVER BASIN (ARMENIA)

2021 ◽  
Vol 1 (1) ◽  
pp. 31-44
Author(s):  
MARGARYAN V.G. ◽  
Keyword(s):  
River Basin ◽  
Air Temperature ◽  
Thermal Regime ◽  
Time Course ◽  
Temporal Distribution ◽  
Thermal Conditions ◽  
High Mountain ◽  
Air Temperatures ◽  
Using Data ◽  
Surface Air Layer

The features of the thermal regime of the surface air layer in the Debed river basin are considered. A statistical analysis of the average annual and average seasonal values of air temperature from 1964 to 2018 was carried out, two periods were identified, their time course was shown. The analysis was carried out using data from six meteorological stations representing the lowland, mountain and high-mountain climatic zones of the Debed river basin. A correlation was obtained between the absolute altitude and the monthly average values of air temperature for January and July, which can be used to assess the thermal conditions of unexplored or poorly studied territories and for cartography. The time course of average values of air temperatures for the seasonal period has been studied. Analysis of trend lines of temporal changes in air temperatures shows that in all situations on the territory of the basin as a whole, there is a tendency of temperature growth. Moreover, with a range of interannual fluctuations, a break in the course of temperatures in the early to mid 1990 is clearly visible, after which their significant increase began. It turned out that a significant increase in seasonal temperatures is observed especially over the period 1993-2018, which means that the annual warming after the mid 1990 occurred primarily due to summer and spring seasons. The regular dynamics indicates that in the studied area in terms of temperatures, a tendency of softening winters, a decrease in the water content of rivers, aridization of the climate. The results obtained can be used to assess the regularities of the spatial-temporal distribution of the temperature of the study area, to clarify the thermal balance, for the rational use of heat resources, as well as in the development of strategic programs for longterm analysis.

scholarly journals Algorithm for assessing forest stand productivity index using leaf area index

2019 ◽  
Vol 16 (3) ◽  
pp. 1311
Author(s):  
Faid Abdul Manan ◽  
Muhammad Buce Saleh ◽  
I Nengah Surati Jaya ◽  
Uus Saepul Mukarom
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Basal Area ◽  
Forest Stand ◽  
Productivity Index ◽  
Estimation Model ◽  
Area Index ◽  
Study Objective ◽  
Stand Productivity ◽  
Variable Combination

This paper describes a development of an algorithm for assessing stand productivity by considering the stand variables. Forest stand productivity is one of the crucial information that required to establish the business plan for unit management at the beginning of forest planning activity. The main study objective is to find out the most significant and accurate variable combination to be used for assessing the forest stand productivity, as well as to develop productivity estimation model based on leaf area index. The study found the best stand variable combination in assessing stand productivity were density of poles (X2), volume of commercial tree having diameter at breast height (dbh) 20-40 cm (X16), basal area of commercial tree of dbh >40 cm (X20) with Kappa Accuracy of 90.56% for classifying into 5 stand productivity classes. It was recognized that the examined algorithm provides excellent accuracy of 100% when the stand productivity was classified into only 3 classes. The best model for assessing the stand productivity index with leaf area index is y = 0.6214x - 0.9928 with R2= 0.71, where y is productivity index and x is leaf area index.

Small and Full-Scale Modeling for the Application of Wall Solar Chimneys

2016 ◽  
Author(s):  
David Park ◽  
Francine Battaglia
Keyword(s):  
Natural Ventilation ◽  
Velocity Ratio ◽  
Thermal Conditions ◽  
Ambient Air ◽  
Full Scale ◽  
Scale Model ◽  
Small Scale ◽  
Solar Chimney ◽  
Window Position ◽  
Pi Theorem

A solar chimney is a natural ventilation technique that has a potential to save energy consumption as well as to maintain the air quality in the building. However, studies of buildings are often challenging due to their large sizes. The objective of the current study was to determine relationships between small- and full-scale solar chimney system models. In the current work, computational fluid dynamics (CFD) was utilized to model different building sizes with a solar chimney system, where the computational model was validated with the experimental study of Mathur et al. The window, which controls entrainment of ambient air, was also studied to determine the effects of window position. Correlations for average velocity ratio and non-dimensional temperature were consistent regardless of window position. Buckingham pi theorem was employed to further non-dimensionalize the important variables. Regression analysis was conducted to develop a mathematical model to predict a relationship among all of the variables, where the model agreed well with simulation results with an error of 2.33%. The study demonstrated that the flow and thermal conditions in larger buildings can be predicted from the small-scale model.

Development of a Predictive Equation for Ventilation in a Wall-Solar Chimney System

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
David Park ◽  
Francine Battaglia
Keyword(s):  
Mathematical Model ◽  
Relative Error ◽  
Natural Ventilation ◽  
Thermal Conditions ◽  
Ambient Air ◽  
Maximum Error ◽  
Scale Model ◽  
Small Scale ◽  
Maximum Relative Error ◽  
Solar Chimney

A solar chimney is a natural ventilation technique that has potential to save energy consumption as well as to maintain the air quality in a building. However, studies of buildings are often challenging due to their large sizes. The objective of this study was to determine the relationships between small- and full-scale solar chimney system models. Computational fluid dynamics (CFD) was employed to model different building sizes with a wall-solar chimney utilizing a validated model. The window, which controls entrainment of ambient air for ventilation, was also studied to determine the effects of window position. A set of nondimensional parameters were identified to describe the important features of the chimney configuration, window configuration, temperature changes, and solar radiation. Regression analysis was employed to develop a mathematical model to predict velocity and air changes per hour, where the model agreed well with CFD results yielding a maximum relative error of 1.2% and with experiments for a maximum error of 3.1%. Additional wall-solar chimney data were tested using the mathematical model based on random conditions (e.g., geometry, solar intensity), and the overall relative error was less than 6%. The study demonstrated that the flow and thermal conditions in larger buildings can be predicted from the small-scale model, and that the newly developed mathematical equation can be used to predict ventilation conditions for a wall-solar chimney.

scholarly journals Independent and interactive effects of thermal stress and mental fatigue on manual dexterity

2020 ◽  
Vol 319 (6) ◽  
pp. R703-R711
Author(s):  
Alessandro Valenza ◽  
Harry Charlier ◽  
Antonino Bianco ◽  
Davide Filingeri
Keyword(s):  
Thermal Stress ◽  
Reaction Time ◽  
Interactive Effect ◽  
Thermal Conditions ◽  
Mental Fatigue ◽  
Manual Dexterity ◽  
Interactive Effects ◽  
Manual Task ◽  
Air Temperatures ◽  
Manual Tasks

Many occupations and sports require high levels of manual dexterity under thermal stress and mental fatigue. Yet, multistressor studies remain scarce. We quantified the interactive effects of thermal stress and mental fatigue on manual dexterity. Seven males (21.1 ± 1.3 yr) underwent six separate 60-min trials characterized by a combination of three air temperatures (hot, 37°C; neutral, 21°C; cold, 7°C) and two mental fatigue states (MF, mental fatigue induced by a 35-min cognitive battery; no-MF, no mental fatigue). Participants performed complex (O’Connor test) and simple (hand-tool test) manual tasks pre- and posttrial to determine stressor-induced performance changes. We monitored participants’ rectal temperature and hand skin temperature (Thand) continuously and assessed the reaction time (hand-click test) and subjective mental fatigue (5-point scale). Thermal stress ( P < 0.0001), but not mental fatigue ( P = 0.290), modulated Thand (heat, +3.3°C [95% CI: +0.2, +6.5]; cold, −7.5°C [−10.7, −4.4]). Mental fatigue ( P = 0.021), but not thermal stress ( P = 0.646), slowed the reaction time (∼10%) and increased subjective fatigue. Thermal stress and mental fatigue had an interactive effect on the complex manual task ( P = 0.040), with cold-no-MF decreasing the performance by −22% [−39, −5], whereas neutral-MF, cold-MF, and heat-MF by −36% [−53, −19], −34% [−52, −17], and −36% [−53, −19], respectively. Only mental fatigue decreased the performance in the simple manual task (−30% [−43, −16] across all thermal conditions; P = 0.002). Cold stress-induced impairments in complex manipulation increase with mental fatigue; yet combined stressors’ effects are no greater than those of mental fatigue alone, which also impairs simple manipulation. Mental fatigue poses a greater challenge to manual dexterity than thermal stress.

scholarly journals Microtopographic control on the ground thermal regime in ice wedge polygons

2018 ◽  
Vol 12 (6) ◽  
pp. 1957-1968 ◽  
Author(s):  
Charles J. Abolt ◽  
Michael H. Young ◽  
Adam L. Atchley ◽  
Dylan R. Harp
Keyword(s):  
Thermal Conditions ◽  
Ground Temperature ◽  
The Arctic ◽  
Near Surface ◽  
Hydrologic Processes ◽  
Ground Temperatures ◽  
Air Temperatures ◽  
Winter Temperatures ◽  
Ice Wedge ◽  
Prudhoe Bay

Abstract. The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 ∘C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.

scholarly journals Estimation of sensible and latent heat based on measurements for non-typical large room

2019 ◽  
Vol 116 ◽  
pp. 00085
Author(s):  
Sylwia Szczęśniak ◽  
Juliusz Walaszczyk
Keyword(s):  
Latent Heat ◽  
Air Temperature ◽  
Historical Data ◽  
Operation Mode ◽  
Ventilation System ◽  
Thermal Conditions ◽  
Existing Building ◽  
Heating And Cooling ◽  
Air Temperatures ◽  
Heating And Cooling Load

The knowledge about dynamic changing heating and cooling load in existing building is essential for proper energy management. Whenever existing building is analyzed or ventilation system is going optimized, it’s essential to estimate temporary sensible and latent heat based on historical data. The basic conditions for heat calculations are quasi-stable thermal conditions. If supply air temperature significantly varies in short time, what happens very often, the calculations can give untrue results. The procedure described in this article improves usability of measured data affected by rapid supply air temperature changing. Therefore real sensible and latent heat can be calculated, what it is important for future optimization process. Specified, on the basis of varying supply and exhaust air temperatures, thermal loads range from -55.8 kW to 40.7 kW was substitute to more authentic range from -14.1 kW to 51.2 kW received from the conducted simulations. In addition, the data obtained from the simulation showed that latent heat gains were associated with the air temperature in the room, and not with the operation mode of the ventilation unit (day/night) as observed on the basis of historical data.

scholarly journals White Spruce Regeneration on a Blade-Scarified Alaskan Loess Soil1

1990 ◽  
Vol 7 (3) ◽  
pp. 121-123 ◽  
Author(s):  
Edmond C. Packee
Keyword(s):  
Natural Regeneration ◽  
Mineral Soil ◽  
White Spruce ◽  
Site Preparation ◽  
Forest Stand ◽  
Aspen Forest

Abstract Following hardwood removal from a mixed spruce-birch-aspen forest stand, portions of the stand were blade-scarified to encourage natural white spruce regeneration. Six years after treatment the number and height of white spruce seedlings were significantly greater on scarified than on unscarified plots. Whereas 100% of scarified sample plots contained five or more seedlings, 73% of unscarified plots contained no seedlings. Exposure of mineral soil and removal of grass competition are essential for the satisfactory natural regeneration of white spruce. Detailed regeneration surveys should not be considered for white spruce until seedlings are 15 cm tall, typically the fifth or sixth year after site preparation. North. J. Appl. For. 7:121-123, September 1990.

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