Field Measurement of Effective Leaf Area Index using Optical Device in Vegetation Canopy

Leaf area index (LAI) is an essential canopy variable describing the amount of foliage in an ecosystem. The parameter serves as the interface between green components of plants and the atmosphere, and many physiological processes occur there, primarily photosynthetic uptake, respiration, and transpiration. LAI is also an input parameter for many models involving carbon, water, and the energy cycle. Moreover, ground-based in situ measurements serve as the calibration method for LAI obtained from remote sensing products. Therefore, straightforward indirect optical methods are necessary for making precise and rapid LAI estimates. The methodological approach, advantages, controversies, and future perspectives of the newly developed LP 110 optical device based on the relation between radiation transmitted through the vegetation canopy and canopy gaps were discussed in the protocol. Furthermore, the instrument was compared to the world standard LAI-2200 Plant Canopy Analyzer. The LP 110 enables more rapid and more straightforward processing of data acquired in the field, and it is more affordable than the Plant Canopy Analyzer. The new instrument is characterized by its ease of use for both above- and below-canopy readings due to its greater sensor sensitivity, in-built digital inclinometer, and automatic logging of readings at the correct position. Therefore, the hand-held LP 110 device is a suitable gadget for performing LAI estimation in forestry, ecology, horticulture, and agriculture based on the representative results. Moreover, the same device also enables the user to take accurate measurements of incident photosynthetically active radiation (PAR) intensity.Postprin

Accumulating energy wood head

Tato bakalářšká práce pojednává o návrhu a vlastní koncepci kácecí hlavice pro odstraňování drobných náletových dřevin umístěné na nakládací jeřáb lesního stroje. Zařízení je řešeno jako nástavba obslužného stroje, přičemž nakládací jeřáb s kácecí hlavicí je součástí lesního těžebního nebo vyvážecího stroje. Práce je zaměřena na konstrukční zpracování vybraného celku.This bachelor thesis deals with the design and custom concept of a cutting head for the removal of small seeding trees located on the loading crane of a forestry machine. The device is designed as an extension of the service machine while the loading crane with the cutting head is part of lumber mining machinery or a forwarder. The work is focused on the design of the selected unit.

Impact of Different Pruning Practices on Height Growth of Paulownia Clon in Vitro 112(R)

We focused on the ability of one-year-old and two-year-old plants of Paulownia Clon in vitro 112(R) to sprout and grow branches, and on their pruning for their best possible growth on a plantation in Střelice u Brna. Furthermore, we carried out pruning on selected parts that comprised: spring pruning; reduction in the angle between the stem axis and one new growing sprout; and year-long pruning. The sprouting capacity of Paulownia was high-up to 56% (one-year-old plants) and 50% (two-year-old plants). Branches grew on 34% of all one-year-old plants and on 57% of all two-year-old plants. The best possible spring pruning method seems to be the keeping of one stem sprout or one stump sprout for one-year-old plants and one stem sprout for two-year-old plants. The newly growing stem sprout should be formed by bandaging it to the stem, and, as a result of this, the angle between the stem and the sprout can be reduced to 20o in contrast to 50o when the sprout is not bandaged. Our results suggest that it is best to take off the lower ⅓ of the branches and leaves, which leads to faster height growth of the plant.O

Comparison of the Biomass and Dendrometric Parameters of Norway Spruce with Its Different Representations in Young Stands at Lower Altitudes in the Czech Republic

In forestry, it is still common to plant the seedlings of and cultivate Norway spruce (Picea abies L. Karst) at lower altitudes; however, the climatic change that has been occurring increases evaporative demands in these areas. As a result, the spruce evidently suffers from drought, withers and loses its power to grow, thus, influencing stem thickness and tree-height growth, as well as biomass production. Therefore, the growth and biomass production of young (5-, 15- and 25-year-old) Norway spruce stands at these altitudes (i.e., from 200 to 500 m a.s.l.) was surveyed, as a case study, across the Training Forest Enterprise "Masaryk Forest" Křtiny. There, 48 stands with a varied representation of spruce (i.e., up to 30%, 31%-60%, 61%-90% and over 91%) were analyzed. In each stand, 12 trees were sampled across all social status classes (i.e., sub-dominant, co-dominant and dominant) in detail. Basic dendrometric parameters (such as the total tree height, height of the crown base and stem diameter at breast height) and the amount of the above-ground tree organ biomass (i.e., stem, branches and needles) were investigated. Based on the trends found in the biomass production here and climate change predictions, we recommend that Norway spruce be cultivated only in zones from an altitude of ca 400 m a.s.l., with an annual precipitation of 700 mm and an average annual temperature of 7 oC, and its percentage representation in the stand be no more than 30%.O

Testing the Production Potential of Paulownia Clon In Vitro 112(R) in the Czech Republic

Paulownia is a deciduous fast-growing tree with intensive sprouting ability and is well adapted to various climatic and soil conditions. Its native area extends from the middle to the lower section of the Yangtze River. The aim of our research was to test the potential of Paulownia Clon in vitro 112(R) for production of saw timber in the conditions of the Czech Republic. In 2016, three private plantations were established-Střelice, Vlčatín and Vorel. The parameters that were measured were the total height, the height of the live above-ground part of each plant after the winter, the stem thickness at 10 cm above the ground, and the stem thickness at breast height. The measurements were taken from 2016 to 2021. At all plantations, the plants achieved very small mean annual increments in height (under 1 m) and thickness (under 1 cm). On average, 39% of the upper above-ground part of each plant was damaged by frost each winter and the cumulative mortality was 28% to 53%.O

Fire Behaviour Test of Brick Masonry Columns Reinforced with High-strength Carbon Fibres (CFRP)

Článek se zabývá problematikou chování zděných tlačených konstrukcí zpevněných či stabilizovaných kompozity tvořenými tkaninami na bázi vysokopevnostních uhlíkových vláken a epoxidovou pryskyřicí (CFRP - z angl. Carbon Fibre Reinforced Polymer) v podmínkách normového požáru. V článku je popsána požární zkouška zesílených cihelných zděných pilířů provedená v rámci výzkumného úkolu NAKI DF12P01OVV037 ve sloupové požární peci ve zkušebně PAVUS ve Veselí nad Lužnicí a její vyhodnocení. Zkouška byla provedena na 3 různých cihelných pilířích: (1) zesílený zděný pilíř bez povrchové úpravy zatížený osovou silnou; (2) nezatížený zesílený zděný pilíř opatřený vápennou omítkou; (3) nezatížený zesílený zděný pilíř opatřený vápennou omítkou a požárním intumescentním (zpěňujícím) nátěrem.The article deals with the behavior of compressed masonry structures reinforced or stabilized with composite fabrics based on high-strength carbon fi bers and epoxy resin (CFRP) during standard fi re. The article describes the fi re test of reinforced brick masonry columns performed within the research project NAKI DF12P01OVV037 in the fi re furnace in PAVUS (Veselí nad Lužnicí) and its evaluation. The test was performed on 3 different masonry columns: reinforced masonry column without any fi re protection or plaster loaded by axial force; unloaded reinforced masonry column with lime plaster; unloaded reinforced masonry column with lime plaster and intumescent (swelling) paint

Transpiration and water potential of young Quercus petraea (M.) Liebl. coppice sprouts and seedlings during favourable and drought conditions

Increased frequency and intensity of drought events consequently affect oak high forests with the process of further decline, compromised growth and questionable natural regeneration. To overcome such difficulties, new adaptive strategies are required. Coppicing, as the oldest way of forest management, might provide some solutions. In our study two contrasting management systems, sessile oak coppice and high forest, were compared at the initial stages of regeneration and forest development. The transpiration of young oak sprouts and seedlings was monitored using sap flow systems during the 2015 growing season. The study of transpiration also included leaf water potential measurements during three measurement campaigns with contrasting weather conditions. Coppice sprouts transpired significantly more than seedlings on the individual tree and stand level during the entire growing season 2015; particularly large differences were observed during drought conditions. Coppice sprouts experienced lower water limitations due to the voluminous and deeper root system as indicated by leaf water potential results. Presented results attribute young coppices as one of the promising adaptable forest management types with a better adaptive strategy at the extreme sites under water limiting conditions.O

Sap flow and growth response of Norway spruce under long-term partial rainfall exclusion at low altitude

Introduction: Under ongoing climate change, more frequent and severe drought periods accompanied by heat waves are expected in the future. Under these conditions, the tree’s survival is conditioned by fast recovery of functions after drought release. Therefore, in the presented study, we evaluated the effect of long-term water reduction in soil on tree water use and growth dynamics of Norway spruce. Methods: The experiment was conducted in two young Norway spruce plots located on suboptimal sites at a low altitude of 440 m a.s.l. In the first plot (PE), 25% of precipitation throughfall was excluded since 2007, and the second one represented the control treatment with ambient conditions (PC). Tree sap flow, stem radial increment, and tree water deficit were monitored in two consecutive growing seasons: 2015-2016, with contrasting hydro-climatic conditions. Results: Trees in both treatments showed relatively isohydric behavior reflected in a strong reduction of sap flow under the exceptional drought of 2015. Nevertheless, trees from PE treatment reduced sap flow faster than PC under decreasing soil water potential, exhibiting faster stomatal response. This led to a significantly lower sap flow of PE, compared to PC in 2015. The maximal sap flow rates were also lower for PE treatment, compared to PC. Both treatments experienced minimal radial growth during the 2015 drought and subsequent recovery of radial growth under the more the humid year of 2016. However, treatments did not differ significantly in stem radial increments within respective years. Discussion: Precipitation exclusion treatment, therefore, led to water loss adjustment, but did not affect growth response to intense drought and growth recovery in the year after drought

Comparison of LiDAR-based Models for True Leaf Area Index and Effective Leaf Area Index Estimation in Young Beech Forests

The leaf area index (LAI) is one of the most common leaf area and canopy structure quantifiers. Direct LAI measurement and determination of canopy characteristics in larger areas is unrealistic due to the large number of measurements required to create the distribution model. This study compares the regression models for the ALS-based calculation of LAI, where the effective leaf area index (eLAI) determined by optical methods and the LAI determined by the direct destructive method and developed by allometric equations were used as response variables. LiDAR metrics and the laser penetration index (LPI) were used as predictor variables. The regression models of LPI and eLAI dependency and the LiDAR metrics and eLAI dependency showed coefficients of determination (R2) of 0.75 and 0.92, respectively; the advantage of using LiDAR metrics for more accurate modelling is demonstrated. The model for true LAI estimation reached a R2of 0.88.O

Effect of infill density of the printed PET-G structures containing iron oxides on magnetic properties

This work aims to characterize printing structures with various infill densities composed of a thermoplastic material containing magnetic particles composed of mainly Iron(III) oxides with regard to their possible processing with the additive technology of Fused Filament Fabrication. A polyethylene terephthalate glycol (PET-G) structural thermoplastic with the addition of Iron(III)) oxides has been selected, and correct processing temperatures have been determined using thermal analysis. The paramagnetic properties of printed products consisting of different filling densities have been tested. Relative permeability has been identified to be strongly dependent on the printed internal structures of tested products. The samples composed of the densest structure have shown relative permeability higher by 18% with respect to the sample printed with the least dense structure. Finite Element Modelling (FEM) simulations have been applied to determine magnetic field distributions and, moreover, to calculate the holding forces of all printed samples. The performed simulations confirmed that produced composites might be utilized as magnetic switches and sensors or as more advanced components for homogenizing electric motors’ magnetic fields. Moreover, magnetic properties might be tuned according to the specific needs printing structure with the suitable density.Web of Science91art. no.