High mountain environments in Patagonia Argentina: analysis of relations between plants, intraradical fungi and soil characteristics.

BRUZONE MA. CLARA, FERNÁNDEZ NATALIA, FONTENLA SONIA

Montpellier

Simposio; International Symposium of Interactions of Soil Minerals with Organic Components and Microorganisms; 2011

Commission 2.5 International Union of Soil Sciences - INRA

High Mountain environments constitute variable terrestrial ecosystems with rigorous climatic characteristics. They comprise a floristic diversity adapted to harsh conditions, associated to a variety of habitats. Mycorrhizal fungi are considered to be a strategy of nutrient uptake and improvement in plants fitness. Mycorrhizas and Dark Septate Endophytes (DSE) of High Mountain environments in Patagonia Argentina have been scarcely analyzed. The functional interface between roots, fungi and edaphic characteristics could be one of the keys to understand these environments. The aim of this work is to study the relation between intraradical fungal colonization, plant species and soil characteristics, along a precipitation gradient (3500 to 500 annual mm) and different environments in high mountain sites and steppe environments in Patagonia Argentina. Three High Mountain sites (above timberline, 1600 m a.s.l.) and one Patagonian Steppe site (800 m a.s.l) were sampled. Also different environments were distinguished and analyzed: screes, meadows, forest and patagonic steppe. Nine plant species were sampled, all of them present in at least 3 sampling sites. Occurrence and quantification of mycorrhizal and DSE fungi were studied in all individuals. Analysis of soil and plant nutrients (P, C and N); soil pH and moisture content were determined. Pearson Correlation and Principal Component Analysis (PCA) were used. Eight species presented Arbuscular Mycorrhizal (AM) infection. DSE occurred in all species. Both types of infection showed a wide distribution and co-appeared in the different sites and environments. Soil nutrients availability showed no correlation with nutrients in aerial plant parts, positive correlations were found between AM and DSE infections and between this last two and plant C. Scree environments were grouped and characterized by low levels of soil nutrients. Steppe and meadow environments show intermediate values and the forest has the highest contents of soil nutrients. Previous studies concluded that root infection levels are regulated by amount of soil N and P. Is not the case of these particular environments, were benefit and cost balance of sustaining root symbionts is delicate. The wide occurrence of intradical symbionts highlights them as an important strategy in plant nutrient assimilation in Patagonic High Mountain, and the relation between intraradical fungi and their host might be the prevalent regulation process in root infection.