Influence of Microtus gregalis Pall. on the properties of the Kansk basin replantozems

Our research aimed at studying the effect of Microtus gregalis Pall. activity on replantozem features formed on open-pit coal mine dumps. There is a significant part of studying the dynamics, ecology and evolution of anthropogenic soils. Our study was carried out on 25-yr dumps of the Borodinskiy open pit coal mine in the Kansk-Achinsk Coal Basin (the Russian Federation) (55º52` N, 94º54` E). The dumps were recultivated; a fertile soil layer (FSL) was placed on the surface of the leveled dump surface. The material of the dump is a chaotic compacted mixture of overburden and enclosing rocks of the coal open-pit mine and fragments of mineral coal. The results of six years of our observations (2007-2012) showed that 44 to 100% of the reclaimed areas are dominated by the Microtus gregalis Pall., 1779. The animals build family settlements ranging from 0.3 to 120 m2, after the peak period covering up to 10% of the surface of such dumps. To study the effect of the Microtus gregalis settlements on replantozem features, we used a method of paired sites (''settlement'' and ''control''). Our results showed that replantozem aeration in the areas occupied by narrowskulled voles increases by 27%. It is assumed that it conditioned an increase in urease activity: 0.4 (the coefficient of variation - V = 40%) for the ''control'' and 0.8 mg N-NH3 g-1 (V=53%). Moisture pool reduced from 3.1 to 2.4 g cm-2. Spatial variation of pH in the ''settlement'' and ''control'' does not allow a definite conclusion about a significant influence of voles burrowing activity on soil. Ammonium composes a major part of mineral nitrogen replantozem on ''control'', and comparative part of nitrate nitrogen does not exceed 15%. Nitrate part varies widely (from 20 to 77%) on family settlements replantozem. Replantozems burrowed by voles have a higher total nitrogen content - 0.54 (V=15%), versus 0,45% (V=12%) for the ''control''. The average concentrations of microbial biomass in the Microtus gregalis burrows are 2 times higher than in ''control''. Significant microbial biomass fluctuations (from 73 to 316 and from 29 to 150 mg C g-1 for the ''settlement'' and ''control'', respectively) are, probably, due to uneven distribution of excreta in burrows of narrow-skulled voles, which, in its turn, is associated with specific behavior of animals. Root biomass stock in replantozem areas, rummaged by Microtus burrows, are usually higher than in ''control'': 0.8 versus 0.4 g cm-3, respectively. Acknowledgments: The authors are grateful to Ph.D. D.Yu. Efimov (V.N. Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russian Federation) for the description of the dump vegetation cover. The article contains 2 figures, 2 tables, 32 ref.

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