Data from: Specific leaf area predicts dryland litter decomposition via two mechanisms

1. Litter decomposition plays important roles in carbon and nutrient
cycling. In dryland both microbial decomposition and abiotic degradation
(by UV light or other forces) drive variation in decomposition rates, but
whether and how litter traits and position determine the balance between
these processes is poorly understood. 2. We investigated relationships
between litter quality and their decomposition rates among diverse plant
species in a desert ecosystem in vertically contrasting positions
representing distinct decomposition environments driven by different
relative contributions of abiotic and microbial degradation. Thereto, leaf
litter samples from 17 desert species were sealed into litterbags and
placed on the soil surface under strong solar exposure versus shade
conditions, or buried in the soil at 10 cm depth, for a whole year. 3.
Litter decomposition rates were 21 and 17 % higher in burial and
light-exposed treatments, respectively, than those in shade. Leaf traits,
i.e. specific leaf area (SLA), litter C:N ratio and lignin concentration
could predict litter decomposition to some degree, but their predictive
power was dependent on litter position. However, multiple linear
regression showed that SLA, litter C and P significantly affected k values
for leaf litter decomposition besides litter position, with SLA standing
out as a strong determinant of litter decomposition rate as related either
to solar radiation or the environment below the soil surface. Furthermore,
the interspecific differences in litter decomposition rate decreased over
time, implying that afterlife effects of leaf traits on decomposition were
attenuated. 4. Synthesis. These findings suggest that abiotic
photodegradation and soil burial mediated microbial decomposition could be
responsible for higher than expected litter turnover in dryland. They
point to a dual role of specific leaf area as a promotor of decomposition
rates: via relative exposure of the leaf surface to abiotic factors such
as UV light versus to soil moisture and microbes under soil burial.