The effects of elevated UV-B (280-315 nm) radiation on the long-term decomp
osition of Quercus robur leaf litter were assessed at an outdoor facility i
n the UK by exposing saplings to elevated UV-B radiation (corresponding to
a 30% increase above the ambient level of erythemally weighted UV-B, equiva
lent to that resulting from a c. 18% reduction in ozone column) under array
s of cellulose diacetate-filtered fluorescent UVB lamps that also produced
UV-A radiation (315-400 nm). Saplings were also exposed to elevated UV-A ra
diation alone under arrays of polyester-filtered fluorescent lamps and to a
mbient solar radiation under arrays of nonenergized lamps. After 8 months o
f irradiation, abscised leaves were placed into litter bags and allowed to
decompose in the litter layer of a mixed deciduous woodland for 4.08 years.
The dry weight loss of leaf litter from saplings irradiated with elevated
UV-B and UV-A radiation during growth was 17% greater than that of leaf lit
ter irradiated with elevated UV-A radiation alone. Annual fractional weight
loss of litter (k), and the estimated time taken for 95% of material to de
cay (3/k) were respectively increased and decreased by 27% for leaf litter
exposed during growth to elevated UV-B and UV-A radiation, relative to that
exposed to UV-A alone. The present data corroborate those from a previous
study indicating that UV-B radiation applied during growth accelerates the
subsequent decomposition of Q. robur leaf litter in soil, but indicate that
this effect persists for over four years after abscission.