The main reason for the transformation of spruce monocultures at sites of mixed broadleaved forests is to create more natural relationships between the species structure of a stand and soil processes. The presented study compares humus conditions and basic growth characteristics of two mixed stands (spruce with beech and larch with beech) aged 25 years with a beech stand (aged 40 years) and spruce stand (aged 30 years). The purpose of the study is to evaluate (<I>i</I>) forms of forest floor, (<I>ii</I>) soil reaction, (<I>iii</I>) the content and total reserves of carbon, nitrogen and C/N ratio, (<I>iv</I>) dissolved organic carbon (DOC) in relation to stand characteristics. The highest reserve of forest floor is detected in the mixed stand of larch with beech (52.6 t/ha), the lowest reserve in a beech stand (21.0 t/ha). The soil reaction of the spruce stand and the beech stand is 4.0 (± 0.3) and 5.1 (± 0.3), respectively. The C/N ratio of the spruce stand is 23.5 (± 1.8) and that of the beech stand 18.8 ± 2.9. The DOC content decreases with layers of surface humus towards depth. Mixed stands represent by their values of soil conditions a mean between spruce and beech stands.

A pedological survey was carried out in a spruce monoculture, beech stand, and in a mixed stand at a field research station in Rájec-Němčice of the Institute of Forest Ecology (IFE), Mendel University of Agriculture and Forestry (MUAF) in Brno in the region of the Drahanská Upland in [2004][2005][2006]. The aim of the paper was to evaluate (i) humus reserves and forms, (ii) soil reaction, (iii) reserves of total carbon and nitrogen for the forest floor layers and (iv) carbon/nitrogen ratio. Soil analyses were carried out on samples taken at the end of the growing season in a spruce, beech and mixed stand. The highest reserves of forest floor were found in the spruce stand (71.8 t/ha), which also corresponded to the exchangeable soil reaction 3.3 ± 0.4, the C/N ratio being 27.3 ± 3.0. The lowest reserves were found in the beech stand (46.7 t/ha), the soil reaction was 3.6 ± 0.5 and the C/N ratio was 26.0 ± 5. problem of allochthonous spruce (Picea abies [L.] Karst.) stands grown at sites outside the region of natural range has been discussed. The majority of the authors reported their effect on the soil environment as negative (Němec 1928;Pelíšek 1964;Kulhavý 1997). The humus of even-aged spruce monocultures conditions the process of acidification of the soil profile. This phenomenon was first described and termed in the 80s as "new forest decline" when Ulrich (1983) outlined possible damage to forest stands due to acidification of soils. Nevertheless, this theory has also its opponents, e.g. Šály (1978), who described acidification only as a natural process which cannot be "taken out" of the whole context of soil-forming processes and who stated that it was not possible to attribute an absolute effect to the process. Under conditions of the Krkonoše Mts., Emmer (1998) and Emmer et al. (2000) assessed borealization as a process of natural acidification of soils and impoverishment of basic cations. They found that in spruce stands pH values decreased by 0.2-0.3 and the base-exchange complex was reduced even by 10% as compared to beech stands. The problem of acidification has acquired a new dimension particularly due to the heavy air pollution load which has become evident in the Krušné hory Mts. (Erzgebirge) since the 1950s (Materna 1963;Hruška, Cienciala 2001). At that time, mass forest decline occurred in mountain regions as ecosystems with lower resistance to air pollution changed the chemistry of precipitation and atmospheric deposition (Hruška, Cienciala 2001).Health problems of spruce monocultures occur not only due to the effects of pedological processes mentioned above but also by means of a complex of factors affecting spruce stands (fungal pathogens, insect pests, abiotic effects such as wind, dry spell, frost or the increasing general mean annual temperature in connection with the potential global change of climate). Problems of spruce monocultures affect seriously more European countries particularly with respect to the new orientation of management and use of forest ecosystems. In the Cent...

ABSTRACT:Ecosystems, their services, structures and functions are affected by complex environmental processes, which are both natural and human-induced and globally changing. In order to understand how ecosystems behave in globally changing environment, it is important to monitor the current status of ecosystems and their structural and functional changes in time and space. An essential tool allowing monitoring of ecosystems is remote sensing (RS). Many ecosystems variables are being translated into a spectral response recorded by RS instruments. It is however important to understand the complexity and synergies of the key ecosystem variables influencing the reflected signal. This can be achieved by analysing high resolution RS data from multiple sources acquired simultaneously from the same platform. Such a system has been recently built at CzechGlobe -Global Change Research Institute (The Czech Academy of Sciences).CzechGlobe has been significantly extending its research infrastructure in the last years, which allows advanced monitoring of ecosystem changes at hierarchical levels spanning from molecules to entire ecosystems. One of the CzechGlobe components is a laboratory of imaging spectroscopy. The laboratory is now operating a new platform for advanced remote sensing observations called FLIS (Flying Laboratory of Imaging Spectroscopy). FLIS consists of an airborne carrier equipped with passive RS systems. The core instrument of FLIS is a hyperspectral imaging system provided by Itres Ltd. The hyperspectral system consists of three spectroradiometers (CASI 1500, SASI 600 and TASI 600) that cover the reflective spectral range from 380 to 2450 nm, as well as the thermal range from 8 to 11.5 μm. The airborne platform is prepared for mounting of full-waveform laser scanner Riegl-Q780 as well, however a laser scanner is not a permanent part of FLIS. In 2014 the installation of the hyperspectral scanners was completed and the first flights were carried out with all sensors.The new hyperspectral imaging system required adaptations in the data pre-processing chain. The established preprocessing chain (radiometric, atmospheric and geometric corrections), which was tailored mainly to the AISA Eagle instrument operated at CzechGlobe since 2004, has been now modified to fit the new system and users needs. Continuous development of the processing chain is now focused mainly on establishing pre-processing of thermal data including emissivity estimation and also on joint processing of hyperspectral and laser scanning data.

The study is aimed to explore the potential of time-series airborne hyperspectral and satellite multispectral data to track the changes in spruce forest decline expressed by a composite spruce decline indicator. Vegetation indices and exergy of solar radiation extracted from remote sensing data are used to predict the development of the composite spruce health indicator. The canopy-level spectral reflectance properties of spruce stands are investigated to identify categories of spruce stand decline: healthy, initial decline, and initial to moderate decline. The sensitivity peaks for initial decline and initial to moderate decline of spruce are shown. The highest potential for the estimation of the composite spruce health indicator is demonstrated by vegetation indices WBI and NDVI red_edge from airborne hyperspectral data, and by PSRI, NDII and exergy of solar radiation from Landsat and Sentinel-2 satellite multispectral data. MODIS data show only a poor correlation between the composite spruce stand health indicator and NDII index. The proposed methodology to obtain the distribution of the composite spruce decline indicator using remote sensing (RS) data promisingly suggests its applicability over a large forest area with potential time and economic benefits, since foliar spectral measurements, canopy chemistry, and laboratory analysis are not required.

ROSÍK JIŘÍ, FABIÁNEK TOMÁŠ, MARKOVÁ IRENA: Soil CO 2 effl ux in young Norway spruce stands with diff erent silviculture practices.