Evaluation of abundance and diversity of arbuscular mycorrhizal spores in Austrocedrus chilensis forests affected by wildfire in Patagonia, Argentina

TALARICO, S.; SALGADO SALOMÓN, M.E. ; BARROETAVEÑA C.; URRETAVIZCAYA M. F.; GIANOLINI, S.

Valdivia

Workshop; Mycorrhizal Simbiosis in the Southern Cone of South America; 2017

Universidad Austral de Chile, Universidad de La Frontera, Universidad de Concepción, Centro de Estudios Avanzados en Fruticultura, EarthShape Project (DFG)

During February of 2015, near to Cholila (Chubut,Argentina) an extreme behaviour wildfire occurred, leaving 27,101 ha burned. Approximately5700 ha of this area corresponded to pure and mixed Austrocedrus chilensis forests. The symbiosis between arbuscularmycorrhizal (AM) fungi and A. chilensishas been established and has great ecological importance for the species regeneration.Therefore, is important to determine AM spore bank state in post-fire undergroundin order to understand the evolution of these stands and to properly managetheir restoration. This study was carried out in three sites with A. chilensis forest near to LasHorquetas (Cholila, Chubut) where three treatments were selected: unburnedforests, forests moderately affected, and forests severely affected by fire,with the aim of determine and compare the abundance and diversity of AM sporesin soil affected by different fire severities. Five composite soil samples weretaken in each treatment and site, at the first 15 cm of soil profile; AM sporeswere extracted with the wet sieving-sucrose gradient method, quantified and classifiedaccording to morphological characteristics in binocular stereomicroscope. Arbuscularmycorrhizal spores were significantly more abundant in moderate fire treatment(258 spores/100 g dry soils). It was possible to identify 6 differentmorpho-species present in all treatments, two of them (Glomus-like) being the most abundant. Evenness declinedsignificantly in moderate severity treatment (EI=0.68; EA-V=0.74,p<0.0001, respectively). The spore bank in unburned soil (85 spores/100 gdry soils) did not significantly differ with the high severely treatment (121spores/100 g dry soils). Thinking in restoration strategies, it has to beconsidered that wildfire would also cause the extramatrical mycelium loss,although some stimulus occurs in moderately affected soil that increased sporesabundance. Moderately burned areas have better chances of natural restorationconsidering the abundant AM spores bank, while artificial inoculation has to beconsidered for severely affected areas.