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The research covered the application of near−infrared spectroscopy (NIR) to evaluate selected properties of forest soils, necessary to calculate the Soil Trophic Index (SIG). We analyzed 50 samples from 15 study plots located in the Miechów Forest Districts (S Poland). Five plots were established per each variant of the site conditions: upland deciduous forests (Lwyż), upland mixed deciduous forests (LMwyż) and upland mixed coniferous forests (BMwyż). On each plot soil pit was dug out and samples were taken from organic and three mineral (0−10 cm, 10−40 cm and 40−150 cm) horizons. NIR measurements were performed using Antharis II FT spectrometer to assess the following properties of forest soil: the content of organic carbon (Corg), total nitrogen (Nt), C:N ratio, the share of fine ø<0.02 mm) fraction, the content of base cations (S) and total acidity (Hh). Based on the 30 spectrums and the identified properties of soils, the calibration model was developed. The validation of the model was performed on independent set of 20 samples. Next, the SIG values were calculated on the basis of laboratory measurements and compared with the values obtained with NIR. Very good calibration results were observed for almost all soil properties (fig. 1, tab.). The highest correlation coefficient was obtained for the C:N ratio. During the validation, the nitrogen content was well estimated, as evidenced by the highest R²W values (tab.). The content of Corg, soil particles ø<0.02 mm and S were also relatively well estimated. The results suggest that the NIR technique can be successfully applied to evaluate the soil properties necessary to calculate SIG. The calculations are made at a much lower cost and in a very rapid way compared to laboratory methods.
The correct assessment of the site conditions is the basis of the good management of forest areas. The aim of this study was to find a set of soil properties, which allow separating the diverse sites in terms of the soil productivity. We used 180 locations in the Carpathians and the Sudety Mountains for testing. The study plots were located in transects from the foothills to the top along the slopes, taking into account the variability of site conditions, geological substrate and exposition. The index was calculated on the basis of the content of <0.02 mm particles, the sum of exchangeable base cations, soil acidity and the ratio between total N content and organic C in the humus−mineral horizon. The soil trophic index for mountain areas (SIGg) that include the climatic factor was introduced. The factor is defined as the 650/altitude ratio for a given point above sea level. In the mountains, the content of <0.02 mm fraction, the sum of exchangeable base cations and soil acidity were determined in the column of 1 m² of the soil cross section and depth of 1 m (1 m³ of volume) due to the lower depth of the soil profile. The SIGg correctly separates soil of different productivity as the properties closely associated with the stable elements of the soil, expressing its production and properties, which reflect the current state of the soil environment, were used in the construction SIGg.
In recent years, we face a massive dieback of Norway spruce stands in Poland. The cause of this process may lay in the way of their monocultural silviculture. The correct assessment of the habitat conditions and soil properties in particular is the basis of the proper management of these forest areas. The aim of this study was to verify application of the trophic soil index for mountain areas (SIGg) in the assessment of site conditions for spruce stands with different health condition. Three types of spruce stands were distinguished: degenerated, weakened and stable. In total, 32 study plots were established in following forest districts in southern Poland: Ustroń, Wisła, Bielsko, Węgierska Górka, Jeleśnia, Ujsoły and Lądek Zdrój. The SIGg was calculated on the basis of <0.02 mm fraction content, the sum of exchangeable base cations, soil acidity and the total content of N and organic C in the humus−mineral horizon. These attributes are useful to determine the potential productivity of the soils did not differentiate visibly the analyzed stand variants. The soil in degenerated and weakened spruce stands showed higher degree of acidity and less the content of base cations compared to soils of stable spruce stands. Mountain trophic soil index can be applied in the assessment of the forest sites potential. Although it does not enable to monitor the disturbances in the nutrients circulation, the detailed analysis of its components allows for precise assessment of the forest sites status.
Deep dystric Cambisols developed on the homogenous regoliths of granite in the Stołowe Mountains National Park (SW Poland). In general, the soils have a texture of gravelly sandy loam, apparently silty, the strong acid reaction and the base saturation below 30% throughout the profile (oligotrophic variant). Only the soils developed in lower parts of slopes have a base saturation up to 40−50% or more (oligo−mesotrophic and mesotrophic variants respectively). These soils rich in humus and biologically active create in the low mountain zone the habitats suitable for the mixed mountain forests and, in a less acid variant, for the broadleaf mountain forests. Combined trophic soil index reached the values from 29 to 33 that confirmed mesotrophic type of the forest habitats. Most Cambisols developed from granite in the Stołowe Mountains are currently covered with spruce stands of artificial origin. However, a phytosociological analyses of vegetation carried out in preserved beech stands documented the presence of Luzulo luzuloidis−Fagetum community of poor beech forest that should be considered a potentially natural forest community on these soils and the strategic goal of the forest reconstruction in the national park.
Chemical properties and fertility of soils were compared under spruce, mixed and beech stands in four types of forest habitat (mountain broadleaf forest, mountain mixed broadleaf forest, mountain mixed coniferous forest and mountain coniferous forest) in 373 sites of forest monitoring in the Stołowe Mountains National Park, SW Poland. Soils under the spruce stands had higher organic carbon pools in their upper horizons, but lower pH, increased activity of exchangeable aluminum, lower contents of exchangeable base cations, available potassium and magnesium, resulting finally in lower values of the soil trophic index (SIG). The negative impact of spruce monocultures on the physicochemical soil properties was much stronger in the eutrophic habitats (dedicated to broadleaf forest) than in dystrophic ones. Weak positive effect of the beech introduction on soils in the dystrophic habitats indicated that the conversion of the coniferous into mixed or deciduous stands would not cause a rapid improvement in the physicochemical properties deformed previously under spruce monocultures.
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