A research project was conducted in a native forest of Nothofagus pumilio in one of the southernmost Chilean Nation Parks, Torres del Paine, to check the amount and timing of leaf fall, their decomposition rate and the respiration rate of the soil on an annual cycle.This paper also provides the results of the decay of fallen leaves in time, the loss curve of leaf weights, the evolution of water content and records of the larger taxonomic groups of microarthropods associated with the decomposition of the material.