Soil biochemical alterations and microbial community responses under Acacia dealbata Link invasion.

Abstract

A critical outcome of the invasive processes of exotic plants is the impact on soil microbial communities and chemical parameters. We studied the impact of Acacia dealbata on soils of mixed forests and shrublands. We hypothesized that A. dealbata can alter soil microbial community function and soil chemical profile in invaded ecosystems. Two sampling dates were selected depending on the phonological stage of A. dealbata (vegetative vs. reproductive). Soil chemical parameters were deeply modified in the invaded sites. Total C and N, P, K, Ca, Mg, NO3 and NH4þ content and available P, were significantly higher in invaded soils of both mixed forests and shrublands. Soil microbial community activities were affected by the sampling date, soil type and ecosystem. Enzymatic activities mainly varied in soils collected during the vegetative stage of A. dealbata in mixed forests and during both vegetative and reproductive stages in shrublands. Soils invaded by A. dealbata showed increased acid phosphatase, b-glucosidase and N-acetyl glucosaminidase activities and the geometrical mean of these activities. Soil basal respiration was significantly reduced in invaded patches of mixed forests. Our results showed an alteration of soil chemistry and microbial community function related to A. dealbata presence, probably leading to acceleration in the decomposition and mineralization rates.