Araucaria araucana is one of the main Chilean conifer species, which along Nothofagus spp. dominates the Andean temperate forests of Chile. Despite not being at imminent risk of extinction, the combined factors of a past timber exploitation history, intense seed harvesting and slow regeneration dynamics, make this species susceptible to some disturbances, such as livestock, fires, pathogens and recently conifer invasions.
Pine invasions impacts have been broadly documented all around the globe, especially in natural areas where they can be multiple at different scales in the landscape. Pine invasions have been reported in the steppe and in forest ecosystems in Chile. Mostly originated due to the large scale growth of pine forest plantations observed in Chile since the 1970s.
The aim of this research was to evaluate if A. araucana regeneration has been affected by the P. contorta invasion in three conditions: Araucaria forest (AR), Araucaria-Nothofagus (AN) and Araucaria-Pine (AP). The objectives of this research were to 1) determine if changes in forest stand structure affects A. araucana regeneration and 2) examine the relationship between light conditions and regeneration density.
Results/Conclusions
Our results indicate that the stand structure characteristics vary significantly between conditions, where both Araucaria-Pinus and Araucaria-Nothofagus have a high density of trees (AN: 1686 ind/ha AP: 2014 ind/ha) than Araucaria forest which has a significantly smaller one (143 ind/ha). The regeneration density showed a marginal difference between Araucaria forest (5500 ind/ha) and the invaded area (4107 ind/ha), while both presented significantly different canopy covers (AR: 18% AP: 48%). Interestingly, the highest regeneration density, with 10250 ind/ha, was found under the Araucaria-Nothofagus assemblage which has not significant difference with Araucaria-Pine in terms of canopy cover. Unlike initial predictions, our results suggest that canopy cover it is not the main limiting factor for Araucaria regeneration. Further analyses may reveal whether specific understory composition or human-driven pressures (e.g. seed harvesting) help describe the current patterns of regeneration.