Pedestrian Areas in Moscow as Rapidly Expanding Urban Sites for Biocrust-to-Mineral Interactions

The area of stone pavements on the streets of contemporary cities is increasing especially in pedestrian areas. Following this trend, we expect the new habitats for biocrusts and associated organo-mineral interactions to appear. Pedestrian zones of Moscow represent a vast area of exposed natural hard rock mainly of the granitic origin or concrete paving slabs both ready for the establishment of biocrust. The pavements contain a regular network of inter-block pore spaces filled with autochthonous but mainly allochthonous fine earth conductive to pedogenic processes. The change from the asphalt to discontinuous stone pavement leads to 1–15% increase in the spatial share of small scale soils (5–10 cm deep) located in the inter-slab seams. The other important components of artificial covers in pedestrian areas are the micro profiles (1–2 cm deep) that establish in the stone slabs, they resemble pedogenic horizonation although developed in hard rock. The data on these bodies (soloids) dominated by microbial biocrusts are very scarce in the urban environment. Various combinations of cryptogamic and microbial photoautotrophs contribute noticeably to the carbon and nitrogen budget of the newly established stone pavements in pedestrian areas of Moscow. Top 5 cm of the two-component pavement system could contain 1.20 kg C m –2 and 0.07 kg N m –2 on average, while inter-slab spaces colonized by the moss-dominated biocrust store as much as 7.90 kg C m –2 and 0.42 kg N m –2 . These data suggest pavement systems should be placed among other urban hot spots of C and N accumulation.