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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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Index listové plochy solitérů a liniových výsadeb dřevin
Binková, Tereza
Abstract Bachelor thesis Leaf area index of solitaires and line plantation deals with the findings of LAI in selected line plantations and solitaires with direct and indirect methods. For indirect method of leaf area index measurement two instruments were used these are: 1) LAI-2000 PCA (LiCor, USA) as a world use standard and 2) LaiPen LP_100 (PSI, ČR) as a new parallel instrument, which is similar to the one mentioned above, however, more easy to be used in practice. As direct method of comparison method of litter traps was used. The aim of the work was to evaluate if above mentioned instrument based on indirect method are usable to determining LAI of line plantation and solitaires in landscape. The results showed that used indirect methods are probably not suitable for LAI estimation of solitaires and line plantations mainly because of great influence of synoptic situation. In addition, the selected direct method also does not reach required accuracy, because of influence of wind, which affects the amount of litter in traps. Due to these serious reasons it is recommended to use different direct, semi-direct or indirect methods.
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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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