Jiří Kalčík

The effect of Lasius niger (Hymenoptera, Formicidae) ant nest on selected soil chemical properties

Summary The set of chemical properties: total, available and watersoluble P, total C, available K, Na, Ca and pH in H2O and KCl were studied in 64 nests of Lasius niger and in surrounding soils (control). Ant nests were located in wide range of soil conditions. Additionally, spatial distribution of those parameters was studied in three nests. The pooled average values for all investigated soil parameters, except that of Ca and C were significantly higher in the nests than in surrounding soil. At the same time, chemical properties of the nest were effected by chemical properties of surrounding soil; pH value in the nests increased in comparison to control in acidic soils but the opposite was true in alkaline soil. Content of available P in the nest was higher than in surrounding soil. As the content of available P in surrounding soil increased the enrichment of the nest (increase of available P in nest in comparison with control) was higher. Adjacent soils with low available Ca and total C supported nests that were higher in these elements while surrounding soil with higher Ca ans C supported nests that were lower in these elements. The changes in chemical properties were more pronounced in the aboveground than in the belowground part of the nest. The results indicates that the main processes taking part in chemical changes of soil in the ant nests are soil mixing due to excavation of deeper soil layers, enrichment of substrate by ants (by rest of food, excreta etc.) and interactions of nest chemistry with other physical, chemical and microbial parameters in the nest.

Growth strategy of heterotrophic bacterial population along successional sequence on spoil of brown coal colliery substrate

The bacterial population of brown coal colliery spoil (Sokolov coal mining district, Czechia) was characterized by measuring viable bacterial biomass, the culturable to total cell ratio (C:T), colony-forming curve (CFC) analysis and species and/or biotype diversity. Bacterial representatives that differed in colony-forming growth (fast and/or slow growers) were used for growth-strategy investigation of heterotrophic bacteria. Spoil substrates from the surface (0–50 mm) and the mineral (100–150 mm) layers were sampled on 4 sites undergoing spontaneous succession corresponding to 1, 11, 21 and 43 years after deposition (initial, early, mid and late stages). The bacterial biomass of the surface layer increased during the initial and early stages with a maximum at mid stage and stabilized in the late stage while mineral layer biomass increased throughout the succession. The maxima of C:T ratios were at the early stage, minima at the late stage. Depending on the succession stage the C:T ratio was 1.5–2 times higher in the mineral than the surface layer of soil. An increase in the fraction of nonculturable bacteria was associated with the late succession stage. CFC analysis of the surface layer during a 3-d incubation revealed that the early-succession substrate contained more (75 %) rapidly colonizing bacteria (opportunists, r-strategists) than successively older substrates. The culturable bacterial community of the mineral layer maintained a high genera and species richness of fast growers along the succession line in contrast to the surface layer community, where there was a maximum in the abundance of fast growers in the early stage. There was a balanced distribution of Grampositive and Gram-negative representatives of fast growers in both layers. A markedly lower abundance of slow growers was observed in the mineral in contrast to the surface layer. Gram-positive species dominated the slow growers at the surface as well as in the mineral layers. The growth strategy of the heterotrophic bacterial population along four successional stages on spoil of brown coal colliery substrate in the surface layer displayed a trend indicative of a r-K continuum in contrast to the mineral layer, where an r-strategy persisted.

Carbon and nitrate utilization in soils : the effect of long-term fertilization on potential denitrification

Abstract Soil samples were taken from plots at 3 different experimental sites that had received different fertilizer applications for more than 20 years. Denitrification capacity (DC) and denitrification potential (DP), defined as the amount of N 2 O released from the soils amended with KNO 3 and KNO 3 + glucose, respectively, and incubated anaerobically in the presence of 10 kPa acetylene were measured at 25°C for up to 48 h. Also, CO 2 evolution and microbial biomass were determined. Both DC and DP were significantly influenced by the treatments. Application of manure (40 t ha −1 every 4 yr) and lime (5 t CaCO 3 ha −1 every 4 or 5 yr) alone as well as in combination with moderate amounts of inorganic fertilizers (80 kg N + PK ha −1 yr −1 ) increased DC and DP. In highly fertilized soils (manuring, liming and 160 kg N + PK ha −1 yr −1 ), however, DC was further enhanced in one soil only, while DP was significantly decreased in all soils. When no lime was applied but large amounts of fertilizers were (manure and 160 kg N + PK ha −1 yr −1 ), DC and DP were further significantly decreased, in some cases even below the rates in unfertilized soils. Overall carbon dioxide production from soils followed similar pattern as DC and DP. Fertilization did not significantly affect microbial biomass in limed soils, but decreased it in unlimed soils. Possible indirect influences of long-term fertilization, related to changes in soil chemistry in general and in soil pH in particular, are discussed.

Chemical properties of forest soils as affected by nests of Myrmica ruginodis (Formicidae)

Chemical properties (total and available P concentration; oxidizable C concentration; available K, Na, and Ca concentration; and pH) were quantified for 33 nests of the ant Myrmica ruginodis and in surrounding soil in young spruce forest stands. All properties, except total P, were significantly higher in the nests than in the surrounding soil. Total P was not higher in nests than in surrounding soil across all nests because nests had higher total P than surrounding soil if the soil contained low concentrations of total P but nests had lower total P than surrounding soil if the soil contained high concentrations of total P. The effect of nests on total P in the surrounding soil corresponded with effects of nests on oxidizable carbon (an indicator of organic matter) in the surrounding soil (concentrations of oxidizable carbon and total P were closely correlated). Available P concentrations were much higher in nests than in surrounding soil. Overall, the results indicated that two main processes explain the chemical changes of soil in the ant nests: (i) mixing due to excavation of deeper soil layers and (ii) deposition of excreta and food residues. The effect of soil mixing (whereby ants transport mineral soil from deeper layers to layers near the surface) is more pronounced in soils with high organic content near the surface because mixing increases the proportion of mineral soil in the nest while decreasing the proportion of organic matter and the concentration of total P.