COASTAL WETLANDS OF THE BIOBÍO REGION (CHILE): A VEGETATION GRADIENT AND A NEW SALT MARSH PRAIRIE ASSOCIATION

Abstract

Wetlands of the river mouths along the Chilean Pacific coast are brackish that present similarities to salt marshes in terms of ecological conditions, with azonal flora and vegetation as these depend on ground water and not on macroclimate. The floristic structure along an altitudinal gradient was studied in two of such localities: Vegas del Itata and Tubul-Raqui wetlands, Region of Biobío, Chile. A new plant association at the highest level of the marsh was described. The ordination of the gradient resembles the distribution of the vegetation samples along the studied gradient. Low gradient levels were similar to those described for the southernmost regions of Araucanía, Los Ríos and Los Lagos, confirming the status of azonality of them. The soil and dominant plants nutrients in the lower levels of the marsh were analyzed, showing that the carbon:nutrient ratio is high, indicating low biological activity. However, higher levels are biologically more active and have higher grazing anthropogenic activity. Hordeo-Stenotaphretum secundatae is described as a new secondary anthropogenic plant association for Chile, located in the high and intervened gradient levels.