INVESTIGADORES
PIÑEIRO Gervasio
congresos y reuniones científicas
Título:
Power laws are better than exponential decay models for representing litter and soil organic matter decomposition
Autor/es:
GERVASIO PIÑEIRO; MANZONI, STEFANO; JOHN, KIM; ESTEBAN G. JOBBÁGY; MARGARETS. TORN; WILLIAM J. RILEY; AMILCARE, PORPORATO; JACKSON, R.B.
Reunión:
Encuentro; 96th ESA Annual Meeting; 2011
Resumen:
Background/Question/Methods Litter and soil organic matter (SOM) decomposition models are often based on first-order exponential decay functions of the type (Ct= Co.e-kt). The decomposition or decay factor k is assumed constant over time, implying that the same proportion of the litter or SOM pool is decomposed per unit time throughout the decomposition processes. These models can be parameterized for one or multiple pools, and are usually adjusted to observations from litterbag experiments, SOM incubations and SOM labeling experiments. We evaluated the assumptions behind exponential decay models (EDM) and compared them with four different power law models (PLM). We used the LIDET experiment (>200 litter decomposition series over 10 years) and compiled published datasets and our own experiments (>100 SOM incubations and labeling series). Results/Conclusions Our results show that for 71% of the litter studies and almost all SOM studies adjusted k values decreased with increasing time span and number of data points. Furthermore, k also decreased with time for different litter and SOM fractions, suggesting that even for fractions assumed to be relatively homogeneous decomposition rates declined over time. Our analysis showed that the turnover time (1-k) of SOM estimated in contrasting climatic regions and soils was strongly related with the length of the experiment (r2=0.57, p