CONICET | Buscador de Institutos y Recursos Humanos

Aims: Land cover change due to the introduction of non-native pine plantations and subsequent pine invasion is increasingly affecting forest areas in the Southern Hemisphere, which is having negative impacts on diverse ecosystem components. We studied the abundance, biophysical attributes, and flammability of litter in temperate forests modified by the introduction of the non-native Pinus radiata, and later by its post-fire invasion from adjacent sites. We also evaluated the short-term effects on litter of mechanical removal of P. radiata from post-fire invasion sites.Location: Northwestern Patagonia, Argentina.Methods: We measured abundance, depth, moisture content, and determined species composition of litter samples collected at native forest, plantation, post-fire invasion, and removal sites. We also performed flammability tests on leaf litter samples of the dominant species from each habitat type. In all cases, litter traits from the modified habitats were compared with those obtained from native forest (reference system).Results: Moisture content and litter species composition were notably affected by habitat alteration. A decrease in species richness and changes in the identity and abundance of the dominant species were the most remarkable shifts registered in the modified habitats. While pine needles were mainly associated with parameters indicative of high leaf litter flammability, the opposite was found for leaves of the dominant native tree. Removal of invasive pines from early post-fire invasion did not reveal biophysical changes in litter to indicate a tendency towards the conditions found in native forest litter.Conclusions: Pine needles as a novel element to litter in the pine-dominated habitats represented a prominent impact on litter traits associated with alterations in key ecosystem properties in comparison with the reference system. For a short-term recovery of burned, invaded areas, additional ecological practices other than removal of invasive trees should be conducted for successfully driving successional changes towards conditions similar to those found in native vegetation.

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