A chronosequence of three species of logs (Pinus sylvestris L., Picea abies
(L.) Karst, and Betula pendula Roth.) from northwestern Russia was resampl
ed to develop a new method to estimate rates of biomass, volume, and densit
y loss. We call this resampling of a chronosequence the decomposition-vecto
r method, and it represents a hybrid between the chronosequence and time-se
ries approaches. The decomposition-vector method with a 3-year resampling i
nterval gave decomposition rates statistically similar to those of the one-
time chronosequence method. This indicated that, for most cases, a negative
exponential pattern of biomass, volume, and density loss occurred. In the
case of biomass loss of P. sylvestris, however, polynomial regression indic
ated decomposition rates were initially low, then increased, and then decre
ased as biomass was lost. This strongly suggests three distinct phases: the
first when decomposers colonized the woody detritus, a second period of ra
pid exponential mass loss, and a third period of slow decomposition. The co
nsequences for this complex pattern of decomposition were explored at the e
cosystem level using a simple model. We found that a single rate constant c
an be used if inputs vary within a factor of 10, but that this approach is
problematical if inputs are more variable.