Marcin Chodak

Hot water extractable C and N in relation to microbiological properties of soils under beech forests

Hot water extraction is sometimes recommended as an easy method to estimate the readily mineralizable fractions of total C (Ct) and total N (Nt) in arable soils. However, the usefulness of this method for forest soils has not been adequately studied. The objectives of this study were to relate the hot water extractable C (Chw) and N (Nhw) to microbiological and chemical properties of the forest soils under beech (Fagus sylvatica L.) stands and to test the ability of near infrared spectroscopy (NIRS) to predict chemical and microbial properties of these soils. Soils differing in humus type, soil type and soil texture were collected from five locations and five depths. In all soils the amount of Chw was higher than the microbial biomass C (Cmic) indicating that a considerable part of Chw was of non-microbial origin. The amount of Chw in mineral soil correlated significantly (r =−0.30–0.53) with Cmic, basal respiration (BAS) and Ct/Nt ratio but was not related to Cmic/Ct ratio. The amount of Nhw was correlated with Cmic, BAS, Cmic/Ct ratio, and Ct/Nt ratio (r =−0.59–0.78). However, Ct and Nt values showed better relationships (r =−0.42–0.88) with all the parameters, indicating no advantage in using Chw and Nhw in forest soils. NIRS predicted satisfactorily Ct, Nt, Chw, Nhw, Cmic, Cmic/Ct ratio and BAS in the mineral soils [the regression coefficients (a) of linear regression (measured against predicted values) ranged from 0.84 to 1.17 and the correlation coefficients (r) ranged from 0.86 to 0.94] indicating the applicability of NIRS to estimate these properties.

The effect of different tree species on the chemical and microbial properties of reclaimed mine soils

The chemical and microbial properties of afforested mine soils are likely to depend on the species composition of the introduced vegetation. This study compared the chemical and microbial properties of organic horizons and the uppermost mineral layers in mine soils under pure pine (Pinus sylvestris), birch (Betula pendula), larch (Larix decidua), alder (Alnus glutinosa), and mixed pine–alder and birch–alder forest stands. The studied properties included soil pH, content of organic C (Corg) and total N (Nt), microbial biomass (Cmic), basal respiration, nitrogen mineralization rate (Min-N), and the activities of dehydrogenase, acid phosphomonoesterase, and urease. Near-infrared spectroscopy (NIR) was used to detect differences in the chemical composition of soil organic matter under the studied forest stands. There were significant differences in Corg and Nt contents between stands in both O and mineral soil horizons and also in the chemical composition of the accumulated organic matter, as indicated by NIR spectra differences. Alder was associated with the largest Corg and Nt accumulation but also with a significant decrease of pH in the mineral soil. Microbial biomass, respiration, the percentage of Corg present as Cmic, Min-N, and dehydrogenase activity were the highest under the birch stand, indicating a positive effect of birch on soil microflora. Admixture of alder to coniferous stand increased basal respiration, Min-N, and activities of dehydrogenase and acid phosphomonoesterase as compared with the pure pine stand. In the O horizon, soil pH and Nt content had the most important effects on all microbial properties. In this horizon, the activities of urease and acid phosphomonoesterase did not depend on microbial biomass. In the mineral layer, however, the amount of accumulated C and microbial biomass were of primary importance for the enzyme activities.

Near infrared spectroscopy for determination of total and exchangeable cations in geologically heterogeneous forest soils

Sustainable forest management requires information on a number of soil properties. Therefore fast methods of soil analysis are needed. The objective of this study was to test the ability of near infrared (NIR) spectroscopy to predict the total and exchangeable Na, K, Ca, Mg, Mn, Fe and Al, the cation exchange capacity (CEC), the base saturation (BS) and the total contents of Zn, Cu, Cd and Pb in geologically heterogeneous forest soils. The samples (n = 100) were collected from five sites covered by beech (Fagus sylvatica L.) forest stands and from four depths. The soils were analysed for total contents of Na, K, Ca, Mg, Mn, Fe, Al, Zn, Cu, Cd and Pb after pressure digestion in HNO3 and for contents of exchangeable Na, K, Ca, Mg, Mn, Fe and Al in NH4Cl. The spectra were recorded between 400 and 2500 nm at 2 nm intervals. Principal components analysis revealed significant spectral differences among the samples from different sites. The global NIR models predicted well the mean values of the total contents of all cations, Zn, Pb, the exchangeable K, Mg, Fe and BS in upper (0–10 cm) and lower (10–20 cm) layers of the studied soils: the correlation coefficients (r2) of the linear regression (measured against predicted values) varied between 0.90 and 1.00 and the regression coefficients (a) ranged from 0.94 to 1.07. The contents of Cu, CEC and the exchangeable Na, Ca and Al were predicted satisfactorily (r2 = 0.87–0.98, a = 0.86–1.14). The global models overestimated the values of total Ca and exchangeable Ca, Mn and Fe in the lower parts of their ranges resulting in biased estimations of the means at some of the considered sites. Splitting the sample population into spectrally similar groups enabled the development of local calibrations, which improved the prediction accuracy (lower standard errors of prediction) for most of the analysed constituents and removed the bias in the estimations of exchangeable of total Ca and Ca, Mn and Fe. The obtained results indicated the usefulness of NIR spectroscopy for determination of a number of soil constituents in geologically heterogeneous forest soils.

Composition and activity of soil microbial communities in different types of temperate forests

The composition and diversity of forest soil microbial communities may be affected by the composition of plant communities and characteristics of soils. The objective of our study was to compare microbial properties of soils under various types of temperate forests. The samples were taken from soil A horizons under dry and mesic pine forests, acidophilus and fertile beech forests, hornbeam and oak dominated deciduous forests and ash dominated riparian forest. The samples were analysed for pH and the contents of organic C and total N, P, K, Ca, Mg and Mn. Microbial analyses included determination of microbial biomass, basal respiration, community level physiological profiles (CLPPs) measured by MicroResp™ method and phospholipid fatty acid (PLFA) profiles. The soil microbial communities under the pine forests were lower, less active and exhibited different CLPPs and PLFA profiles than those under deciduous forests. The PLFA profiles and CLPPs were correlated to each other revealing that the observed different metabolic abilities under the pine and deciduous forest types resulted from differences in taxonomic composition of soil microbial communities. The CLPPs and PLFA profiles depended on soil texture and the contents of Corg, Nt, and Pt indicating that in the temperate forests the taxonomic and functional composition of soil microbial communities are shaped by both the soil properties and the vegetation. The functional diversity of soil microbial communities was not related to plant diversity indicating that in temperate forests the number of plant species has little effect on the ability of soil microorganisms to degrade different organic compounds.

The Use of near Infrared Spectroscopy to Quantify Lignite-Derived Carbon in Humus-Lignite Mixtures

Assessment of the percentage of lignite-derived C (lign-C%) in mine soils may be achieved only by using time-consuming and expensive methods. The objectives of this study were (1) to compare near infrared (NIR) spectra of forest humus and lignite and (2) to test whether NIR spectroscopy may assess lign-C% in artificial mixtures of humus and lignite. The experiment consisted of three trials (T1, T2 and T3). In T1 the mixed samples (n = 75) were produced from one humus sample and one lignite sample, in T2 (n = 74) from 74 different humus samples and one lignite sample and in T3 (n = 74) from 74 different humus samples and 15 lignite samples. In each trial, 35 samples were used to develop calibration equations and the remaining samples were used for validation. The humus and the lignite samples used to produce the mixed samples were analysed for C, H, N and S and their NIR spectra were recorded. The lignite samples contained more C, H and S and less N than the humus samples. Principal component analysis revealed significant differences between NIR spectra of the humus and the lignite samples. The prediction of lign-C% in T1 [regression coefficient (b) of linear regression (measured against predicted values) = 0.99, correlation coefficient (r2) = 1.00, standard error of prediction (SEP) = 1.2%] and T2 (b = 0.99, r2 = 0.99, SEP = 1.9%) was very good and in T3 satisfactory (b = 0.83, r2 = 0.92, SEP = 4.0%). The calibration equations of T2 predicted lign-C% satisfactorily and also in the validation samples of T3 (b = 0.88, r2 = 0.93, SEP = 4.0%). The results indicate the ability of NIR spectroscopy to predict lign-C% in the mixed humus and lignite samples and suggest usefulness of NIR spectroscopy for the assessment of the percentage of lignite-derived C in the organic horizons of mine soils.

The relationship between soil bacteria substrate utilisation patterns and the vegetation structure in temperate forests

The aim of the study was to explore the relationship between the functional diversity pattern of soil bacteria and the vegetation diversity and structure in temperate forests (Poland). Pine-dominated forests occur on soils with lower pH, fewer nutrient contents (P, Na, Mg, Mn and K) and higher C/N and C/P ratios than beech-dominated forests and mixed broadleaved forest with hornbeam and ash. Both forest type and soil horizon (O and A) strongly influenced bacterial catabolic activity and the number of substrates decayed on Biolog® ECO plates. Pine forest soil bacteria were less active and less functionally diverse than those in deciduous forest soils. The community-level physiological profiles (CLPPs) were dissimilar (one-way analysis of similarities) between pine and mixed deciduous forests, but only in the O soil horizon. Carboxylic acids primarily contributed to the average dissimilarity in CLPP between forests (the similarity percentage procedure); these substrates are preferentially used by pine forest soil bacteria. The canonical correspondence analysis indicated that soil pH, nitrogen and organic matter contents and plant diversity index

Community level physiological profiles of microbial communities from forest humus polluted with different amounts of Zn, Pb, and Cd—Preliminary study with BIOLOG ecoplates

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Soil Physicochemical and Microbial Drivers of Boreal Forest Soils Temperature Sensitivity

Hplant′ were related to bacterial CLPP in the O soil horizon. Only for the soil O horizon, the Mantel test showed a clear relationship between vegetation structure and bacterial CLPP.