Resumo

TARABINI, Manuela; GOMEZ, Federico  e  LA MANNA, Ludmila. Recent volcanic ash as an indicator of particle retention in the soils from Andean Patagonia. Cienc. suelo [online]. 2019, vol.37, n.1, pp.101-112. ISSN 1850-2067.

Most Patagonian Andean soils were developed from volcanic ashes, showing high forest aptitude. In 2008, Chaitén volcano (Chile) eruption affected Chubut province in Argentina and left a recognizable ash layer on the soils. The objective of this study was to estimate the capacity of different vegetation systems for entrapping particles transported by the wind, using as indicators the recent volcanic ash and the overlying mineral material (i.e., ash and other sediments re-transported and deposited after the eruption). Near Esquel town, Chubut, entrapping capacity was evaluated in ponderosa pine plantations and in adjacent rangelands, located in flat sites. Variables associated with entrapping capacity (soil cover, dasometric characteristics) were also analysed. Plantations showed a continuous organic layer which favoured particle retention. Thus, entrapping capacity was higher in plantations than in rangelands (24,13 ± 8,16 vs. 1,70 ± 0,44 m³ha^-1 for recent ash and 2,29 ± 1,08 vs. 1,34 ± 1,08 m³ha^-1 for mineral material). Dasometric variables positively correlated with this capacity were: age, number of trees per hectare, basal area, height, and crown projection area. Just seven years after the eruption, most of the plantations showed a quantifiable deposit of mineral material over the recent ash, representing a soil growth rate of 0,98 ± 0,46 m³ha^-1year^-1. These results highlight plantations ability for entrapping and retaining particles transported by the wind, emphasizing not only their influence on erosion mitigation, but also on soil genesis.

Palavras-chave : Entrap; erosion; new mineral material; plantations.