From forest to shrubland: Structural responses to different fire histories in Prosopis flexuosa woodland from the Central Monte (Argentina)

• The woodlands structure Prosopis flexuosa is strongly controlled by fire history.
• The change in the growth habits of the tree is a consequence of fire activity.
• Fire generates a community dominated by trees with many small stems.
• All woodlands supported a high percentage of healthy trees.
• The most frequent tree growth forms were semi-erect and decumbent.

We estimated post-fire population trajectories, and analyzed the effect of fire recurrence on the post-fire recovery of seven different fire histories in the Central Monte. The structure of stems showed that unburned woodlands and woodlands with the longest post-fire recovery time, presented higher proportion of stems with basal diameter (BD) > 5 cm. On sites with higher recurrence of fires, the stems with BD > 5 cm almost disappeared. Tree height and crown diameter showed a significant decrease at sites recently burned, and this pattern was reinforced in areas with recurrent fires. Results suggest that the structure of woodland in the southeast of the Province of Mendoza in Argentina has been strongly controlled by fire history. Fire generates a population dominated by individuals with numerous smaller-sized stems, which becomes more evident in environments where fire recurrence is higher. Structural changes induced by fire indicate that logging may not be possible in the area. The development of forestry practices for post-fire management is needed for the burned areas. An increase in fire frequency is expected in the area, therefore this would cause the modification in the structure of the Prosopis flexuosa population. Furthermore, this will lead to the conversion from woodland to shrubland, and the loss of its capacity for natural recovery.