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Porovnanie rôznych prístupov k stanoveniu indexu listovej plochy
Haninec, Pavel
Leaf area index (LAI) is one of the most important characteristics of forest stand affecting fundamentals of tree physiological processes, biomass production or mechanical stability. The aim of this thesis was to compare three different methods (gravimetrical, optical -- LAI 2000 plant canopy analyzer - and needle method) for estimation of LAI. Additionally, the seasonal development of LAI was measured using the LAI 2000 method. Research was conducted in three European beech (Fagus sylvatica L.) and one sycamore maple (Acer pseudoplatanus L.) stands. The age of forest stands was from 13 to 77 years. Seasonal development of LAI followed general pattern typical for broadleaf stands in central Europe, with fastest rate of leaf growth in the first month following budbreak. Maximal LAI was observed in mid-June and July and it was 4.52 -- 5.08 m2m-2 in beech and 4 m2m-2 in maple stand. LAI 2000 underestimated the gravimetrically measured LAI on average by 15.1 % in beech stands and by 5.8 % in maple stand (these differences were not statistically significant). Needle method underestimated gravimetrical LAI in beech on average by 22 % and in a maple stand by 40 % (this difference was significant in three out of four stands). Overall, gravimetrical method is most laborious but provides most accurate results. LAI 2000 slightly underestimates results (albeit not significantly in broadleaf species) but enables multiple measurements of LAI in the course of growing season. Needle method is inexpensive and easy to use but it significantly underestimates LAI. Its use for comparison of multiple species will always require calibration.
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LAI- kvantifikátor pěstebního zásahu =: LAI- quantifier of silvicultural treatment /
Černý, Jakub
The thesis divided into four research topics dealt with an issue of the relation between silvicultural treatments and an amount of the bearing photosynthetically active assimilation apparatus quantified by leaf area index (LAI) in forest stands of an economically important tree species in the Czech Republic. In pure Norway spruce pole stands at the middle altitudinal zone, an effect of silvicultural treatments on the LAI and an efficiency of the photosynthetically active radiation (PAR; 380-720 nm) by foliage within the photosynthetic uptake was evaluated through both canopy production index (CPI) and leaf area effectivity (LAE), and the highest value of the LAI was achieved in a plot with the highest stand density. However, the highest efficiency of the PAR utilisation (CPI, LAE) was noted in the stand, which was tended by thinning from above. Thus, it was proved that not only the total LAI value but especially an efficacy of the leaf area reflecting sun and shade foliage ratio is the more relevant parameter for an evaluation of the effectivity of the thinning treatment. In a forest regeneration, the LAI can also be used for quantification of the regeneration process stage related to a growth dynamic of the natural regeneration. Besides that the newly developed device LaiPen LP 100 (PSI, ČR) for indirect optical LAI estimation was tested within this study. LAI values measured by LaiPen LP 100 showed almost same accuracy of the measurement and identical trends as world standard (LAI-2200 PCA; LI-COR, NE, USA); both at the stand level and the particular measurement point level. Within the study of the efficacy of the PAR utilisation by foliage in photosynthetic uptake expressed by radiation use efficiency (RUE) in pure, fully-stocked and not defoliated Norway spruce mature stands, it was found that mean air temperature most significantly affect annual and monthly values of the RUE with the significant linear relationship (R2 = 0.19; p < 0.05). In the spruce stands, the significant linear relationship (R2 = 0.85; p < 0.001) between an amount of the sequestrated carbon in the form of atmospheric CO2 molecules and the RUE was also proved. The research topic dealt with a seasonal dynamic of the LAI in selected pure and even-aged European beech and sycamore maple stands revealed findings that a culmination of the LAI is achieved within summer months (DOY 120-140) in the investigated stands. The period is the most suitable for estimation and mutual comparison of the LAI due to the stability of its values in investigated (but also in another deciduous) stands. In studied beech and maple stands, maximum LAI values were noted in the second half of June (DOY 170). General findings of underestimation of LAI values estimated by indirect optical methods compared to direct methods were also confirmed. In the last research topic, an effect of the stand age on the leaf area development was studied in pure, even-aged, and fully-leaved (not defoliated) forest stands of an economically important tree species (Norway spruce, Scots pine, silver fir, Douglas fir, European beech, pedunculate oak, and black walnut). Except for black walnut stands, significant linear relationships proving a decrease of the leaf area with increasing age of the stand were found. The relation between the leaf area expressed by effective plant area index (PAIe) and the age of stands was studied for monitoring of the leaf area dynamic within forest stands with a different age.
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Assessing short rotation coppice poplar biomass and its determinants on former arable land in Czech Republic
Tripathi, Abhishek Mani
Forest coppice biomass, fast growing short rotation coppice (SRC) trees such as willows (Salix) and poplar (Populus) have a substantial potential of storing carbon (C), and has been considered as a sustainable source of woody dry mass. Woody dry mass production, energy efficiency and economic profitability of poplar are important and essential to be studied in Czech Republic. The aim of this PhD thesis was to predict standing woody dry mass, maximize the productivity and quantify the determinants of poplar clone J-105 (Populus nigra × P. maximowiczii) under short rotation coppice (SRC) management on former arable in Czech Republic. This PhD study was carried out in Domanínek, Czech Republic (49°31´N, 16°14´E and 530 m a.s.l.). Plantations were established in high density (9,216 trees ha-1) with single stem hardwood cuttings for verification purposes and to test the performance of poplar clone J-105 on former arable land. The plantations were harvested above 15-20 cm from base in winter 2008/2009 (established in April 2001) and 2009/2010 (established in April 2002). In this thesis, short rotation woody coppice (SRWC) plantations are mentioned as SRWC1 (coppice established in 2009) and SRWC2 (coppice established in 2010), respectively. In spring 2009, SRWC1 was divided into four randomized blocks and treated with three different fertilizers such as minerals [Nitrogen (N), Phosphorus (P), and Potassium (K)], sewage sludge and ash, lime and control (without any treatment of fertilizer). In the plantation SRWC2, no further (at beginning of second rotation-coppice) fertilizer treatment was applied. For the prediction of standing aboveground woody dry mass (AGWDM) in fertilizer treatments and control, allometric equations were developed. The allometric equations thus developed may be considered robust and site specific for poplar clone J-105. After the successful development of allometric equations standing annual AGWDM was estimated followed by annual inventory at the end of each growing season. There were no significant differences observed in allometric equations for AGWDM among the fertilizer treatments (including control) within the year over four years of study from 2011-2014. This experiment was repeated in plantation SRWC2, for which the allometric equation was developed separately, for the purpose of allocation of the aboveground and belowground woody dry mass (BGWDM) at the same site. In this plantation for estimation of AGWDM, allometric equation was developed in 2011 (after two years of plant growth in coppice) and for BGWDM, the equation was developed in 2014 (after more than four years of plant growth in coppice). In SRWC2 plantation, dynamics of annual and cumulative above and belowground woody dry mass were estimated over four years from 2011-2014, where average AGWDM were observed from 8.29 to 11.02 t ha-1 year-1 and average annual BGWDM varied between 2.50 to 3.02 t ha-1 year-1. Growth and wood production mainly depend on photosynthetic area and light efficiency. Therefore, leaf area development including leaf area index (LAI) and leaf area duration (LAD) and radiation use efficiency (RUE) was studied to find a suitable determinant for aboveground woody dry mass production. In the results, maximum leaf area index LAImax was observed to be 9.5 after four years of plant growth in coppice, maximum number of LAD was 185 days after two years of plant growth in coppice and maximum RUE was observed to be 1.3 gMJ-1 in GS4 (growing season four) after four years of plant growth in coppice. LAI and LAD showed a strong positive correlation for AGWDM (R2 values ~1) while RUE showed a moderate positive correlation with AGWDM, where R2=0.50 (p=0.52). This implies that AGWDM is strongly dependent on LAI and LAD. To conclude a robust and site specific allometric equation was developed for poplar clone J-105 and also, this study confirmed that, there was no significant impact of fertilizers for maximizing the AGWDM production on former arable land. For determinants of AGWDM, it confirmed that LAI, LAD and RUE could be a good and reliable predictor of standing AGWDM in SRC poplar clone J-105 on former arable land.
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Optimalizace technologického procesu zpracování dat leteckého laserového skenování pro výpočet zásob lesních porostů
Patočka, Zdeněk
Airborne laser scanning has already become an essential part of forest inventories in the Nordic countries and in Canada. However, its wider practical forestry application in the Central European countries is awaiting. In the first part of this thesis, a procedure for modelling of the basic stand variables, especially forest stand volume, was designed using an area-based approach. Not only linear regression was used for modelling but also machine learning (k-nearest neighbor algorithm, Random Forest, Support Vector Machine and neural networks). In the second part, the thesis deals with biomass estimation using the area-based approach and with comparison of the empirical and semi-empirical approaches to modelling. The third part deals with leaf area index (LAI) estimation using penetration indices and LiDAR metrics. The eLAI estimated by optical method is commonly used for model fitting in overwhelming majority of scientific papers. The benefit of this study is usage of LAI derived by destruction method (directly). The thesis as a whole has shown that the airborne laser scanning is also usable in a variety of forestry applications in Central European countries.
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Evaluation of water use efficiency of short rotation poplar coppice at Bohemian-moravian highlands
Hlaváčová, Marcela
The diploma thesis provides basic characteristics of short rotation coppice plantations, then the most significant short rotation coppice species cultivated in the Czech Republic are described. The detailed description of particular Populus L. clone J-105 grown at the plantation of the Test Station Domanínek Ltd. follows. Afterwards, key determinants of short rotation coppice yield are presented in the text. The last theoretical part of the thesis deals with water use efficiency (WUE) with emphasis on the method used at the experimental plantation in Domanínek. The methods of sap flow measurements and biomass determinations are described for this purpose. The main aim of the practical part of the thesis is to determine WUE of 16 measured trees where sap flow measuring systems were installed. These trees are divided into 3 cohorts according to diameters at breast height (DBH) at the beginning of the growing season 2013. The additional measurements were carried out: phenological imaging, soil moisture measurements, LAI measurements and sapwood area determination. The statistical analysis of WUE did not show any statistically significant differences between values of WUE for individual cohorts. Only in May, the statistically significant difference between cohort 1 (trees with the thickest stems) and cohort 3 (trees with the lowest values of DBH) appeared.
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