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Wood ants build large, long-lasting nests and maintain stable high temperatures in nest centers from April to September to support brood development. Similar nest temperatures have been recorded regardless of latitude and altitude, suggesting that nests from colder environments produce more heat than nests from warmer environments. We measured changes in temperature and in situ respiration in nests from 700 and 1000 m a.s.l. We also sampled ants and nest materials from the same nests and measured their respiration at 10 and 20 °C in the laboratory. Both ant and microbial respiration increased greatly as temperature increased in spring, especially at 1000 m, resulting in the increase in nest temperature in spring. Metabolic activity greatly increased for ants in March and for nest microorganisms in April when nutrient contents also increased because of input of plant material and food. Nests from 1000 m maintained similar temperatures as nests from 700 m in summer but were colder in winter. Ants were responsible for the maintenance of high temperatures during summer but metabolic activity did not differ between the two altitudes, suggesting that the increased respiration and heat production in summer by ants at the higher altitude resulted from an increase in numbers of ants per colony. [ABSTRACT FROM AUTHOR]

Abstract: Several previous studies reported on how the chemistry of the wood ant nest differs from the chemistry of the surrounding soil. There is enhanced amount of nutrients and cations in the ant nest and pH also differs from the nest surroundings. In this contribution, we focused on changes in soil chemistry with distance from the nest. Samples of mineral soil 0–5cm deep were taken in grid pattern at 1–19m from six Formica polyctena nests in a spruce forest in the Czech Republic. Soil pH decreased with distance; pH decreased rapidly between 1 to about 8m and then decreased more slowly. The decrease in pH corresponded with the increase in organic matter content with distance from the nest. Organic matter content was significantly and positively correlated with available Ca and K, i.e., available Ca and K increased with distance from the nest. The changes in organic matter content, pH, and available Ca were caused by ants collecting and using needles as building material. Wood ants can affect soil properties by rearranging organic matter, in nest surroundings. [ABSTRACT FROM AUTHOR]

How litter at various stages of decomposition reacts to C and N additions is unclear. Here we used five substrates (litter, fermentation [Oe] layer, bulk soil, and the light fraction [LF] and heavy fraction [HF] of SOM) obtained from sites supporting five plant monocultures (Alnus glutinosa , Quercus robur , Salix caprea , Calamagrostis epigejos , or Picea omorica) with foliage C:N ratios ranging from 17 to 48. These plant-specific communities were experimentally planted on a post-mining heap and had affected the substrates used in this study for 40 years. Soils and other environmental factors were similar among the sites. Substrates were incubated for 3 weeks without nutrient addition or with C (glucose) or N (ammonium nitrate) addition, and microbial respiration was determined weekly. Substrate C:N ratios were determined at the start of the incubation and were highest for litter followed by Oe layer > LF > bulk soil and HF. Foliage C:N ratio was a better indicator of microbial respiration than the substrate C:N ratio, suggesting that the foliage C:N ratio reflected unmeasured leaf properties that determined microbial respiration. Respiration was highest in the litter followed by Oe layer > bulk soil > LF > HF. C addition increased respiration of the bulk soil (+39%), LF (+48%), and HF (+72%). Priming of SOM respiration was therefore higher in substrates with less available C. N significantly increased respiration of litter (+19%) but decreased respiration of bulk soil (−18%). The difference in respiration of HF vs. bulk soil following N addition suggested that, in addition to the stage of decomposition, environmental properties present in bulk soil but absent in HF may cause the reduction in respiration after N addition to bulk soil. Overall, the results indicate that differences in the contents of SOM fractions among soils will affect the responses of those soils to C and N additions. • Initial foliage C:N was a better indicator of microbial respiration than substrate C:N. • C addition increased respiration of the more-decomposed organic matter. • N addition increased respiration of litter but decreased respiration of bulk soil. • Different responses to N addition may be caused by interactions with the soil matrix. [ABSTRACT FROM AUTHOR]