RESPIRATORY ACTIVITY OF SOIL ORGANIC HORIZON OF FOREST ECOSYSTEMS FROM CENTRE AND SOUTH OF CHILE
Keywords:
Decomposition, leaf litter, C-CO2 evolution, temperate forestsAbstract
The soil litter layer (Oi and Oe horizons) of forest ecosystems is used as both habitat and nutrient and energy source
for a great diversity of soil organisms. As a consequence, carbon (C) flows from plant detritus as CO2
by respiration of litter biota. Here we measured and compared the respiratory activity under laboratory conditions of litter samples collected from three forest types of Central and Southern Chile: Nordpatagonian forest (Nothofagus), Evergreen
Coniferous forest (Fitzroya) and Schlerophyllous forest (Cryptocarya). Samples of the later forest were separated in
three particle size fractions (>2.4; 2.4-1.2 and < 1.2 mm) in order to tests the hypothesis of constancy of respiration
rate per dry mass unit during decomposition of homogeneous substrates, derived from theoretical model of Ågren &
Bosatta, accounting for the effect of water content of samples. Incubations were done at 20 ºC, during up to 22 days
and the CO2 produced was collected in alkaline solution and measured by titration. Curves of cumulative C-CO2
production were built, estimating respiration rates per dry mass unit as the slope of linear portion of curves. Unbiased
estimates of rates were obtained by means of resampling without replacement (bootstrap). Respiration rates per dry
mass varied between 2.8 and 57.7 mg C-CO2 100 g-1 day-1, being higher in the litter samples of Nordpatagonian forest.
In Schlerophyllous forest litter, we did not find significant differences among particle size fractions. However, the
higher respiration rate observed in the fine fraction (11.8 mg C-CO2 100 g-1 d-1) was associated to its higher water
content. We did not find significant differences between respiration activity of litter of Coniferous and Nordpatagonian
rain forests, despite the huge difference of its C/N ratio. The results are discussed within the theoretical framework of
decomposition of organic matter and the carbon dynamics within soils of forest ecosystems.
