Abstract
AimsLitter decomposition patterns, non-additive effects, and spectral data of abundant alpine leaf litters were assessed in litterbag experiments containing single species and mixtures. We tested if low-quality shrub litter decomposes faster in mixtures with high-quality litter and if predictions on decomposed litter using spectral data are feasible.MethodsChemical and physical traits and near-infrared reflectance (NIR) spectra of six alpine freshly fallen litter types were measured. A litterbag experiment (0.1 mm mesh size) with single and 2- and 3-species mixtures was conducted with three species from three functional groups (shrub, grass, forb). Decomposition rates, litter mass loss, non-additive effects, and NIR spectra were recorded after 6, 12, and 24 months.ResultsThe six freshly fallen litter types differed significantly in leaf litter traits and NIR spectra. Decomposition rates steadily slowed during the 24 months, with shrub litter having the lowest on all sampling dates. In litter mixtures, shrub and grass litter showed higher decomposition rates after 12 and 24 months compared with the single-species treatments.DiscussionThe accelerated decomposition in litter mixtures indicates stimulating interactions between low- and high-quality litter types, most probably mediated by their associated microbiomes. By using NIR spectra, we successfully predicted all initial litter traits, but only total carbon content along the entire decomposition period.
Highlights
The decomposition of plant litter material on the soil surface is essential for terrestrial ecosystems by means of influencing vital ecosystem services such as nutrient cycling, carbon sequestration, and above- and belowground biodiversity (Berg and McClaugherty 2014)
About 500 g freshly fallen leaf litter of six common and abundant alpine plants as representatives of the functional groups grass, forb, and dwarf shrub were collected at the Alpine Long-Term Ecological
The six freshly fallen alpine litter types significantly differed in their litter traits (Fig. 2; Table 1 and A1) and near-infrared reflectance (NIR) spectra (Fig. A3 and A4)
Summary
The decomposition of plant litter material on the soil surface is essential for terrestrial ecosystems by means of influencing vital ecosystem services such as nutrient cycling, carbon sequestration, and above- and belowground biodiversity (Berg and McClaugherty 2014). Leaves and stems from an array of plant species belonging to different functional groups (e.g. shrubs, grasses, and forbs) contribute to building up the litter layer. During decomposition, these litter types – and their associated microbiomes – interact, and it has increasingly been recognized that patterns are often not predictable from single-species dynamics (Gartner and Cardon 2004; Hättenschwiler et al 2005). Litter types influence each other’s decomposition rates by changing the chemical environment and by physically altering the litter surface, resulting in non-additive patterns (Gartner and Cardon 2004). Cuchietti et al (2014), for example, found that the decomposition of slow-decomposing low-quality leaf litter can be accelerated by mixing with fastdecomposing high-quality litter
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