Abstract
Whilst soil respiration is often increased in response to litter inputs,
the magnitude of the effect and the underlying drivers remains poorly
understood. We synthesized 66 recently published papers on forest
ecosystems with 2436 observations using a meta-analysis approach to
investigate the effect of litter inputs on soil respiration. The results
showed that litter inputs had strong positive impacts on soil
respiration, labile C availability, and the abundance of soil
microorganisms, with less of an effect on soil moisture and temperature.
The increase in soil respiration in response to litter inputs showed the
following patterns: with coniferous forests (50.7%) >
broad-leaved forests (41.3%) > mixed forests (31.9%). The
effect also depended on stand age with middle-aged forests (53.3%)
> mature forests (50.2%) > young forests
(34.5%). Correspondingly, microbial biomass carbon (MBC) and dissolved
organic carbon (DOC) were increased by 21.0%-33.6% and 60.3%-87.7%,
respectively, in response to normal and doubled litter inputs, whilst
soil respiration increased linearly with increases in DOC and MBC.
Normal and doubled litter inputs increased total PLFA (Phospholipid
Fatty Acid) by 6.6% and 19.7%, respectively, but decreased the
fungal/bacterial PLFA ratio by 26.9% and 18.7%, respectively.
Increases in soil respiration in response to litter inputs were closely
related with total PLFA, fungal PLFA, bacterial PLFA, and
fungal/bacterial PLFA ratio. Therefore, in addition to forest type and
stand age, labile C availability, and soil microorganisms are also
important factors that influence soil respiration in response to litter
inputs.