Initial litter properties and decay rate: a microcosm experiment on Mediterranean species

Abstract

Twelve leaf litters belonging to 10 Mediterranean species of coniferous and broad-leaved trees and shrubs and grass species were incubated in microcosms in the laboratory at 22 °C and constant humidity for 14 months. Samples were collected at 0.5, 1, 2, 4, 6, 10, and 14 months, the remaining dry weight being measured at each sampling time. At the end of 14 months, the litters had lost between 52 and 74% of their original mass. The comparison of regressions fitted to the various functions showed that for the species studied, the litter mass loss in relation to incubation time best fitted a double-exponential decay function. The mass loss therefore resulted from the simultaneous decomposition of two main compartments, a labile compartment that decreased rapidly (half-life of 20 – 60 days under the experimental conditions) and a resistant compartment that depending on the species, either did not decrease significantly or decreased 10 to 20 times slower than the labile compartment (half-life of 320–630 days). The litters studied could be categorized according to the relative importance of these two compartments. This was related to the initial content of water-soluble substances and of carbon in the litters. It was also strongly correlated with the spectral information of the initial litters obtained by near-infrared reflectance spectroscopy. In contrast, the rate at which the labile and resistant compartments decreased was related to the permeability of the leaves for the former and to their thickness and mass per surface area for the latter. Near-infrared reflectance spectroscopy provides new perspectives for characterizing the capacity of litters to decompose. Key words: litter, decomposition, near infrared reflectance spectroscopy.

Changes in organic compounds during leaf litter leaching: laboratory experiment on eight plant species of the Sudano-guinea Savannas of Ngaoundere, Cameroon

“…Similarly, Mangenot & Toutain (1980) demonstrated that the litter types that are richest in watersoluble substances are also those that are most quickly decomposed. We have also shown (Gillon et al 1994) that the dynamics of mass loss during the decomposition of 12 Mediterranean litters in microcosms was largely explained by their initial content of water-soluble substances. Prolonged leach ing could therefore transform fresh litter into iForest (2008) 1: 27-33…”

Predation, resource availability, and community structure in Neotropical water-filled tree holes

“…4A). This pattern suggests that the major effects of litter resources on community structure occur only during the early stages of leaf degradation, when most soluble compounds are leached into the water (e.g., Carpenter 1982b;Gillon et al 1994). Results of the litter manipulation experiment in natural holes ( Fig.…”

“…Individual leaf fragments were progressively smaller from the high quantity treatment to the low quantity treatment. Because the decomposition rate of a leaf is associated with its physical characteristics, such as permeability and thickness (e.g., Gillon et al 1994), the correlation of percent litter remaining with initial litter mass is partly attributed to the greater relative surface area of leaf fragments in the low and medium litter treatments. An alternative explanation is that water in cups containing high litter quantities became saturated with soluble compounds, thereby slowing the rate of leaching.…”

OMDY: a new model of organic matter decomposition based on biomolecular content as assessed by 13C-CPMAS-NMR

“…The mass partitioning of plant cellular material into different pools broadly corresponding to structural classes of biomolecules was attempted in further modelling descriptions (Gillon et al 1994;Liski et al 2005;Adair et al 2008;Incerti et al 2011). These models corresponded to an exponential decay following a first-order kinetics (Olson 1963) and were proved to largely fit experimental decomposition datasets.…”