Long term changes in soil structure of microbial crusts

Highly eroded environments can be stabilised using plant structures which often produce crusted soil layers. In the steppified desert region of Shapotou (China) a vegetated protection system was progressively established since the 1950s up to 2004. Initially, a sand barrier was built with woven willow branches or bamboos to reduce wind erosion. Behind the sand barrier, straw chequerboards (wheat or rice straw) were installed, usually with sections of 1 m2 area. The fixed sand surface led to the formation of very different microbial soil crusts although applied on the same soil according to the age of the straw structures. X-ray Micro-CT scanning have been used in order to physically characterise three very different aggregates representing such long term structure evolution