Litter decomposition in Mediterranean pine forests is enhanced by reduced canopy cover

This study investigated the impact of canopy cover and seasonality on litter decay in Mediterranean pine forests to enhance climate predictions. We conducted litterbag experiments in plots of different tree densities in two Mediterranean pine forests differing in precipitation amounts. In each plot, local litter was placed in forest gaps and under tree canopies for 613 days, starting in the dry season. Litter mass loss was greater in forest gaps than under tree canopies across forests and tree densities. Similarly, a reduction in tree density tended to increase mass loss. Additionally, while the decay rate slowed down from the first to the second wet season, the decay rate remained constant during the first and the second dry season, and the dry seasons contributed 30% to the overall mass loss. Reduction in canopy cover enhances litter decay, and the stability and magnitude of the dry season contribution to annual mass loss have the potential to control litter mass loss when accounting also for the dry periods in the wet season. Combined, the ongoing tree mortality and the predicted prolongation of dry periods due to climate change may enhance litter decay, possibly reducing ecosystem carbon stocks in drylands.

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