This issue's cover: Within the macroaggregate structure (center), microaggregates (top left) are formed around particulate organic matter (bottom left). Fungi (top right) and bacteria (bottom right) are some of the major actors in the formation of these microaggregates, which physically protect the organic matter incorporated in them. In less disturbed ecosystems, such as afforested and no-tillage system, the dynamics of macroaggregates are slower. The slow macroaggregate dynamics induces the incorporation of organic matter in newly formed microaggregates and consequently leads to C sequestration in these ecosystems. See the articles "Measuring and Understanding Carbon Storage in Afforested Soils by Physical Fractionation" by J. Six, P. Callewaert, S. Lenders, S. De Gryze, S.J. Morris, E.G. Gregorich, E.A. Paul, and K. Paustian, p. 1981-1987, and "Aggregate-protected Carbon in No-tillage and Conventional Tillage Agroecosystems Using ¹⁴C-labeled Plant Residue" by H. Bossuyt, J. Six, and P.F. Hendrix, p. 1965-1973. We thank V.S.S.R. for some of the images and R. Moreno for help with producing the image.