Also, carbon stocks of forest soil and dead organic matter (especially coarse woody debris] appear to increase with stand age. Forest soil carbon stocks are driven by site productivity and soil type (primarily driving litter production but also influencing decomposition), litter quality, and local topography and disturbance history. The relationships between external drivers and soil carbon stocks are complex, and it is therefore difficult to describe clear patterns in the response of soil carbon stocks to such drivers. Generally, variation in soil carbon stocks with environmental drivers is most pronounced for the organic layer, less so for the mineral soil and total soil carbon stocks.