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Hyperspectral image segmentation for estimation of biomass at reclaimed heaps
Pikl, Miroslav ; Zemek, František
This paper presents the preliminary results from a study that aims at estimation of above ground biomass and soil carbon content at reclaimed mining heaps in the Sokolov region. Two image segmentation methods are presented. We applied maximal likelihood (ML) and neural network (NN) classifi ers on airborne hyperspectral data. Th e objective of this part of the study was to prepare a land cover classifi cation of the region. Th e main focus was paid to discrimination of six classes with prevailing forest species cover. Th e classifi cation accuracy of the training sites was 93.75 % for NN and 79.12 % for ML respectively. But ML outperformed NN in overall classifi cation accuracy with 61.54 % compared to 40.9 % of NN. Th e more accurate results of the ML classifi er are probably infl uenced by properties of the training samples. Th e larger size of the training samples derived for ML enabled better representation of class histograms. Th e lower overall NN accuracy could result from high spatial resolution of HS data.
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Forest floor respiration of tuczno scots pine stands
Urbaniak, M. ; Pavelka, Marian ; Heronim Chojnicky, B. ; Juszczak, R. ; Dařenová, Eva ; Baran, M. ; Danielewska, A. ; Ziemblinska, K. ; Olejnik, Janusz
Tuczno forest is a 60-year-old Scots pine stand that is located in the North-West part of Poland. During the period between 20th and 25th August 2012 an experiment consisting of the measurement of forest fl oor CO2 effl ux was carried out. For this purpose, manual chamber systems were used. Measurements were taken at 60 collars located on a rectangular plot 25m x 45m. Th is research area was located in the range of footprint of the Eddy-covariance (EC) tower. Th e preliminary results indicate that the average CO2 effl ux from the forest fl oor, as measured during the experiment (5.09 μmol m-2 s-1), is lower than the total ecosystem respiration, estimated from EC data (6.25 μmol m-2 s-1). Spatial variability of soil CO2 effl ux (Rs) can be explained by humus thickness (Ht) variability; however, the tree root respiration can be considered a valuable part of CO2 emission from the forest bottom.
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Treeline shift under global change - ectomycorrhizas as a limiting factor?
Vašutová, Martina ; Holub, Filip ; Čermák, Martin ; Cudlín, Pavel
It is assumed that global change will cause a treeline shift . Because competitive abilities and natural regeneration of trees are infl uenced by ectomycorrhizal (ECM) symbiosis and fi ne roots and ECM mycelia play a key role in belowground carbon turnover, we have studied the ECM associations of treeline ecosystems. We aim to fi nd out how resistant and resilient current ECM associations of these ecosystems are and whether the absence of appropriate ECM symbionts could be a limiting factor of an ecosystem shift . We have focused on natural mountain spruce forests and spruce forests on the treeline; dwarf pine stands with scattered spruce trees above the treeline will be studied in years to come. Ectomycorrhizas were described by morphological features and sequenced to identify fungal species. In the case of taxonomically complicated ECM fungal groups, sequences from microscopically identifi ed sporocarps were used for the identifi cation of ectomycorrhizas. A disproportion between ECM fungi diversity in spruce stands and dwarf pine stands revealed based on a literature review can indicate diff erent ectomycorrhiza patterns at the treeline. According to preliminary results from the Giant Mts. there is an adequate ECM fungal species diversity in mountain spruce forest and spruce forests on the treeline.
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Response of epidermal blue-green fluorescence emission from Barley leaves to uv radiation stress
Karlický, Václav ; Nezval, J. ; Štroch, Michal ; Špunda, Vladimír
Blue-green fl uorescence (BGF) is emitted by plant tissue when excited by UV radiation. Th e emission spectrum of BGF varies with plant species and is aff ected by the physiological status of the plant. BGF has been attributed mainly to cell wall-bound ferulic acid, although a contribution from fl avonoids and other simple phenols has also been suggested. Th e BGF signal is of interest due to its potential application in the remote sensing of plant stress: such techniques use ratios of blue and green to chlorophyll red and far-red fl uorescence emission intensities to estimate plant stress. In this work we investigated the response of BGF to UV-radiation stress and characterized changes in the shape of BGF emission spectra. We found these changes to be more signifi cant during the acclimation to UV-B radiation in comparison with UV-A or high irradiance of PAR. Furthermore, the spectral changes in BGF emission were due to a decline of fl uorescence at a wavelength of 435 nm compared with bands around 455 nm and 520 nm. In view of this, we have tried to distinguish individual fl uorescent components using more detailed fl uorescence analysis and to explain the causes of these spectral changes.
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Segmentation of tree crowns from airborne hyperspectral and lidar data: method comparison
Novotný, Jan ; Zemek, František
Structural and spectral information on single trees is needed for diff erent purposes in forest research and its applications. It can help, e.g., to explain the physiological performance of trees, to improve a parameterization of radiative transfer models, to estimate more precisely tree biomass or tree health status. Th is technical note aims at informing about the basic steps in the use of two categories of airborne digital data for tree crown segmentation: 1) passive multispectral (MS) and hyperspectral (HS) data; 2) active laser scanning (LiDAR) data. Basic assumptions of data quality and their pre-processing chains are mentioned for both data categories, followed by an analytical description of the basic steps in crown segmentation: a) detection of individual trees; b) delineation of a projected tree crown. Methods related to each data category and their common use are compared. As a result, synergic application of HS and laser scanning data resulted in the highest precision of tree crown delineation.
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Effects of UV radiation and drouhgt on the accumulation of UV-screening compounds and photosynthetic parameters in selected herbs and grasses of the mountain grassland ecosystem
Klem, Karel ; Holub, Petr ; Urban, Otmar ; Rajsnerová, Petra ; Kubásek, Jiří
The main objective of the experiment conducted on a mountain grassland ecosystem was to investigate the interactive eff ects of UV treatment and drought on the changes in accumulation of UV-screening compounds and photosynthetic parameters in selected herb (Hypericum maculatum) and grass (Agrostis tenuis) species. Th e experimental plots were manipulated using roof constructions enabling exclusion or transmission of incident precipitation and UV radiation, respectively. Generally, UV and drought treatments had a similar eff ect on the accumulation of fl avonols. UV exclusion resulted in a slight reduction of UV-screening compounds, particularly under the conditions of ambient precipitation. Likewise, drought treatment caused an increase in the accumulation of fl avonols per area unit. Under UV exclusion, drought slightly reduced the light-saturated CO2 assimilation rate (Amax) in both the species studied. Th e presence of UV radiation, however, led to less of a diff erence in Amax between [wet] and [dry] treatments. In addition to the increased induction of fl avonols, UV radiation increased water use effi ciency and alleviated thus the negative impact of drought on photosynthesis.
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Preconditioning under high par of exposure to UV-A radiation both allow acclimation of the photosynthetic apparatus of barley transferred to UV-B radiation
Štroch, Michal ; Materová, Z. ; Vrábl, D. ; Šigut, Ladislav ; Špunda, Vladimír
The acclimation response of the barley photosynthetic apparatus was examined aft er transfer of plants grown under low and high PAR to common conditions both with the same PAR and acute dose of UV-A and/or UV-B radiation. The aim was to evaluate how PAR received during growth aff ects the induction of regulatory and protective mechanisms during UV exposure. Contrary to UV-B radiation, UV-A exposure of barley plants acclimated to low PAR had no negative impact on the function of photosynthetic apparatus. Th e UV-A spectral region we used (350–400 nm) can be eff ectively utilised in photosynthetic reactions, thus compensating low PAR. Th e presence of UV-A radiation during acclimation to simultaneous UVA and UVB treatment not only mitigated but completely eliminated any negative eff ect of UV-B radiation on the photosynthetic function. Th e eff ect of UV-A and UV-B exposure was similar in plants grown under high PAR – causing moderately enhanced photosystem II (PSII) photoinhibition. We proposed that the ability to accumulate a considerable amount of UVscreening compounds under high PAR itself contributes to the resistance of PSII to UV-B radiation.
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Influence of cultivation conditions relating to climatic change on the selected polyphenol content in grapevine plants
Tříska, Jan ; Balík, J. ; Vrchotová, Naděžda ; Mikeš, O.
Winegrowing is highly climate sensitive. Even small changes in temperature could have big impacts on the whole industry. Because of the relatively high crop value, many growers can aff ord to invest in adaptation resources that might not be feasible for less valuable crops. Th ere are two basic types of response to climate change: working to adapt to or manage the impacts experienced, and trying to prevent or minimize further change (mitigation). Th ese are not mutually exclusive, and in fact, both are increasingly regarded as necessary. In our contribution we will discuss the eff ects of drought, irrigation and cultivation in greenhouses in comparison to cultivation in vineyards on the content of trans-piceid and trans-resveratrol in white and blue varieties of Vitis vinifera plants.
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Long term investigation of resveratrol content in moravian red wines in relation to climate conditions
Vrchotová, Naděžda ; Tříska, Jan ; Totušek, J. ; Balík, J.
The considerable commercial importance of wine together with the necessary quality control and investigation of the biological quality of constituent compounds leads to the development of adequate and reliable methods for the determination of macro- and micro-components in wine. Although wine contains a large amount of known compounds e.g. volatile (fl avour compounds), semi-volatile (phenolic) and non-volatile components (pigments), new compounds from all the above mentioned classes are still found in wine and are under heavy investigation, especially regarding their biological activity and their relation to the vinifi cation processes. Th e most signifi cant and famous due to the so-called French paradox is resveratrol-3,4´,5-trihydroxystilbene. Resveratrol is a stress metabolite formed in the grapevine in response to abiotic (UV irradiation) and biotic stresses (Botrytis cinerea). UV irradiation transforms trans isomer to cis form. But according the recent literature cis resveratrol could be also a result of organic farming – natural means of defence in organic viticulture against fungal infections. In our study we have investigated resveratrol content in diff erent vineyards in relation to annual mean temperature, precipitation and sun irradiation.
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Comparison of eddy covariance and bowen ratio energy balance method. Energy balance cloruse versus bowen ratio similarity assumption
Fischer, Milan ; Trnka, Miroslav ; Pozníková, Gabriela ; Sedlák, Pavel ; Orság, Matěj ; Kučera, J. ; Žalud, Z.
The Bowen ratio and the Monin-Obukhov similarity principles are based on the assumption that the eddy diff usivities for temperature and humidity are equal to each other under all atmospheric stratifi cations within turbulent surface boundary layer. However, several authors reported that this equality was violated under advective inversion or during the non-stationary conditions due to clouds passing by and sudden change of wind speed and direction. Th e inequality of the eddy diff usivity can lead to errors in the energy partitioning estimates by gradient techniques like the Bowen ratio energy balance (BREB) and the aerodynamical method, or methods based on residual energy balance such as the Penman-Monteith or Priestley-Taylor models. Th is study investigates two seasons of simultaneous measurement by eddy covariance (EC) and BREB above a high density poplar plantation at the Domanínek locality. Th e direct measurement of eddy diff usivities by EC is reinvestigating the validity of the long term measurement (since 2008) by BREB. Results showed unequal exchange coeffi cients with their mean 0.31 to 0.35 m2 s-1 for 2011 and 2012, respectively, favouring the transport of latent heat. Th is might be explained by the diff erent footprints of the BREB and EC methods, an undeveloped internal boundary layer or instrumental errors.
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