Frequent fires do not affect sexual expression and reproduction in Vachellia caven

MARQUEZ, V.; CARBONE, L.; AGUILAR, R.; ASHWORTH, L.

AUSTRAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2019

1442-9985

In environments with high fi re frequency the impoverishment of abiotic resources may favour male sexual expression in plants as it is less costly than female expression. Also, fi re can modify pollinator communities and thus affect plant reproduction. Here we evaluate the effect of frequent fi res on sexual expression, pollination and reproductive success of Vachellia caven (Leguminosae), an andromonoecious tree that is highly dependent on animal pollination and is abundant in burned sites. We expect that increased fi re frequency willfavour maleness but it will decrease reproductive success due to abiotic resource depletion in repeated burned sites. To test this, we selected focal plants in three unburned sites and three frequently burned sites and measured their sexual expression, basal diameter, pollination and fruit set. The proportion of male in fl orescences per plant was not affected by fi re and it was negatively related with the diameter of the plant. The proportion of pollinated fl owers was not affected by fi re, and fruit set increased with maleness only in frequently burned sites. These results indicate that V. caven is adapted to regimes of high fi re frequency: not only was there similar fruit set in both burned and unburned sites, but more male plants had higher fruit set in burned sites. Despite the soil impoverishment triggered by repeated fi res, V. caven is able to maintain its sexual and reproductive functions, allowing it to persist and maintain viable populations in fi re-prone environments.