Volatile substances and gases resulting e.g. from degradation processes of chemicals in soils emit into the atmosphere and no chemical mass balance is complete without considering this path. Closed soil chambers allow the evaluation of this transfer to the atmosphere. This study deals with the influence of soil chambers with a glass plate cover on physical soil conditions in the chambers and the possibility to simulate the exterior conditions within the chambers. The water content immediately at the soil surface is an important factor for the microbial activity and the transfer of gaseous compounds to the atmosphere as well. It is monitored by specially designed water content sensors in 1 cm depth in the chamber and as control outside. Funnels with a cross section equal to the soil surface area of the chamber collect the rain water and channel it into the soil chamber. This results in soil water content in the chambers very similar to that outside. For the purpose of analysing ¹⁴CO₂ and volatile ¹⁴C-compounds, air is permanently pumped through the chamber. In order to simulate natural conditions, the wind speed is measured 1 cm above the soil surface outside the chambers. A control circuit adjusts the air flow through the chamber to a value corresponding to the wind speed outside. Temperature measurements in 1 cm depth verify that there is no significant difference between the soil chamber and the control outside.

Planting vegetation to restore the soil environment is one of the most important methods for combating desertification. Reasonable vegetation type and vegetation coverage has an important role in sand control and the regional ecological security. The objective of this study is to clarify the appropriate type and coverage of sand-fixing vegetation in the Mu Us Desert. We identified changes in the topsoil properties as affected by different types and coverage of sand-fixing vegetation, and assessed the relationship between the soil fractal dimension (D) and major soil properties. Our results showed that: (1) with increasing cover of sand-fixing vegetation, fine soil material and soil nutrient content increased, indicating that the soil environment could accelerate restoration after planting or recovery of sand-fixing vegetation | (2) there were significant positive relationships between D and soil properties, which indicated that D was a sensitive and useful index for evaluating the influence of sand-fixing vegetation on soil physicochemical properties | and (3) recovery of natural vegetation using fencing should be given priority in areas where the soil matrix is not completely destroyed, and plant cover should be maintained at approximately 40% to 60%. We suggest that native shrubs, rather than trees, should be considered when choosing a sand-fixing vegetation.