Resumo

GARAY, MM; AMIOTTI, NM  e  ZALBA, P. Potential risk of biologic pollution associated to the introduction of Pinus radiata in grassland areas. Phyton (B. Aires) [online]. 2015, vol.84, n.2, pp.280-287. ISSN 1851-5657.

Aforestation is a recommended practice to mitigate global warming. However, their implementation may generate undesirable impacts, mostly if exotic species are used. Plantations of Pinus radiata D Don in Ventania (Bs. As., Argentina) soils showed notorious increments of extractable P (Pe), which could afect the dynamic of this element as well as the degree of phosphorus saturation (GSP_Bray). The objectives of this study were: i) to quantify the GSP_Bray in Mollisols aforested with P. radiata comparing the results with those coming from adjacent, natural grassland areas (base line); ii) to evaluate the potential environmental risk induced by aforestation through the identification of a change point (PC) in the GSP_Bray indicative of a phosphate leaching increment. Treatments included mature stands of P. radiata (TB) and adjacent areas with natural grassland vegetation (TP). Samples were taken at 0-15; 15-30 and 30-45 cm soil depth, and texture, pH, total organic carbon (COT), Pe, soluble reactive phosphorus (PSR), phosphorus sorption index (ISP) and GSP_Bray were determined. The results showed a significant acidification in TB and an increase in the COT stock, indicating an additional atmospheric CO² sequestration by the trees. The Pe and PSR values were notoriously higher in TB, and they were reflected in a signifcant increment in the GSP_Bray with respect to TP. The detection of a significant PC in the GSP_Bray -PSR regression indicates higher chances of phosphate leaching in the forest stands, which could reach water courses, lakes and artificial reservoirs promoting their eutrophication. Because of the potential environmental pollution risk of biologic origin derived from the aforestation with P. radiata in Mollisols areas, their inclusion in clean development practices must be reconsidered.

Palavras-chave : Land use change; Grassland soils; P. radiata; Soluble phosphorous; Biological pollution.

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