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Abstract:
Background and aims Fine root decomposition contributes
significantly to element cycling in terrestrial
ecosystems. However, studies on root decomposition
rates and on the factors that potentially influence
them are fewer than those on leaf litter decomposition.
To study the effects of region and land use
intensity on fine root decomposition, we established
a large scale study in three German regions with
different climate regimes and soil properties.
Methods In 150 forest and 150 grassland sites we
deployed litterbags (100 μm mesh size) with standardized
litter consisting of fine roots from European
beech in forests and from a lowland mesophilous
hay meadow in grasslands. In the central study region,
we compared decomposition rates of this standardized
litter with root litter collected on-site to
separate the effect of litter quality from environmental
factors.
Results Standardized herbaceous roots in grassland
soils decomposed on average significantly faster (24±
6 % mass loss after 12 months, mean ± SD) than beech
roots in forest soils (12±4 %; p<0.001). Fine root
decomposition varied among the three study regions.
Land use intensity, in particular N addition, decreased
fine root decomposition in grasslands. The initial
lignin:N ratio explained 15 % of the variance in grasslands
and 11 % in forests. Soil moisture, soil temperature,
and C:N ratios of soils together explained 34 % of
the variance of the fine root mass loss in grasslands, and
24 % in forests.
Conclusions Grasslands, which have higher fine root
biomass and root turnover compared to forests, also
have higher rates of root decomposition. Our results
further show that at the regional scale fine root decomposition
is influenced by environmental variables such
as soil moisture, soil temperature and soil nutrient content. Additional variation is explained by root litter
quality.
