Comparable early-stage decomposition but contrasting underlying drivers between surface and cave habitats along an elevational gradient

•Decomposition was studied at surface and in caves along an elevational gradient.•Overall decomposition levels were comparable in above and below ground habitats.•At the surface abiotic and biotic factors correlate only with decomposition rate.•In caves abiotic and biotic parameters are associated with stabilizing factor.•Current predictions underestimate the net carbon budget in areas with caves.