Leaf litter mixtures and neighbour effects: Low-nitrogen and high-lignin species increase decomposition rate of high-nitrogen an low-lignin neighbours

CUCHIETTI, A.; MARCOTTI, E.; GURVICH, D.E; CINGOLANI, A.M; PÉREZ HARGUINDEGUY, N.

APPLIED SOIL ECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 82 p. 44 - 51

0929-1393

tIn natural ecosystems plant litter is typically a mixture of more than one species and the rate of decom-position can be faster (synergistic) or slower (antagonistic) than the average of its component species(non-additive effects). We analysed the decomposition rates of two-species mixtures to determine ifthere were consistent non-additive effects of litter mixing on decomposition and how do they comparewith the effects of species identity on mixture decomposition. Then we tested if non-additive effects wereconsistently associated with the presence of particular species in the mixture, to the combination of Fast-or Slow-decomposing species, or to initial litter quality of mixtures. We found: (a) that species identitywas the primary determinant of the decomposition rate of mixtures, and (b) we detected significant, butweak, non-additive effects which were consistently synergistic in the most chemically heterogeneousmixtures. However, slower decomposing species appeared to increase the decomposition rate of fasterdecomposing species (30 times out of 41 after 2 months of incubation, and 17 times out of 24 after 9months of incubation). During the initial stages of decomposition, low-lignin mixtures showed mostlysynergistic effects, whereas high-lignin mixtures showed antagonistic effects. At more advanced stagesof decomposition, mixtures containing species with highest difference in initial N content had more syn-ergistic effects, whereas those with similar initial N content showed both synergistic and antagonisticeffects. Our results confirm previous findings about the importance of chemical heterogeneity of mix-tures as a driver of decomposition rates of litter mixtures. We propose that mechanisms related to carbonpriming may be related to synergistic effects in most heterogeneous mixtures, while nitrogen interac-tion with carbon may be resulting in antagonistic effects in homogeneous and Slow-decomposing speciesmixtures.