Soil biodiversity and function are highly responsive to natural and anthropogenically inflicted changes. Soil microorganisms are affected by climatic factors (temperature and soil moisture) as well as by the quality of above and belowground litter. Climatic variables affect soil microbial community structure and activity by direct and indirect interactive factors. Directly, via suppression of particular microbial groups by low/high mean annual temperatures or by drought/flooding, and indirectly, via regulation of plant community composition and productivity. Plant communities determine structure and activity of microorganisms by chemical composition of litter and root exudates (nutrients), as well as modifying soil chemical properties (pH, soil organic matter content and quality). In addition, anthropogenic practices strongly modify climatic conditions, impact nutrient cycling and cause an input of man-made substances and toxins, which may shift or even tilt the natural equilibrium of microbial communities and processes in soil.

In a series of oral and poster presentations this session will present advances in three important and interconnected topics: soil biological and functional diversity, soil nutrient cycling and turnover of organic matter, as well as soil gas emissions and anthropogenic impacts on all of these processes.

The first section of this session deals with the formation of soil microbial community structures and activities under the effects of i) temperature and soil moisture fluctuations (climatic factors), ii) plant community types (forests, grasslands, biological soil crusts, agricultural lands) iii) various agricultural practices (including flooding, application of mineral and organic fertilizers). Particular attention is given to the i) separation of the effects of climatic and biotic factors, and ii) simultaneous estimation of microbial community structure and activity to reveal the driving factors for both. Overall, this section will give a broad overview about the effect of environmental conditions on formation and functioning of microbial communities in soils and possible new research directions.

The second section of this session concentrates on a major function of soil communities: nutrient cycling and organic matter turnover. Nutrient cycling in soils includes a series of integrated processes carried out by a variety of organisms. It involves initial fixation of nutrients, rendering them available to other organisms in the biosphere, turnover of organic and inorganic matter and loss of available nutrients from the biosphere. Natural resource management strategies and agronomic practices affect soil biological nutrient cycling and thus soil fertility and soil organic matter. Research has been conducted to understand the links between environmental conditions, management and soil function, and methods are constantly developed to analyse soil processes. This section will cover various aspects of biological nutrient cycling, including natural and managed factors affecting the rate and pathways of cycling, and the communities involved in nutrient cycling and organic matter turnover. It will also present and discuss new and/or improved methods for measuring nutrient cycling and analyzing the biological communities involved.

The third section of this session will deal with soil microbial gas emission and anthropogenic impacts on soil structure and function. Gas emissions are influenced by microbial and nutrient composition as well as nutrient cycling within these communities. Gas emissions depending on nutrient input and disturbance events will be investigated in this session. In a second part we will focus on the effects of human activity, such as an accumulation of chemical and biological hazards, which may form a source of harmful nitrogenous and carbon gases. The development of new and innovative technologies, using microbial activities to clean up hazardous waste sites, represent a fascinating solution for decontamination of polluted soil. This section will deal with the use of soil microbial activity in bioremediation processes and the microbial processes involved in gas emission.