EDAPHIC MESOFAUNA COMMUNITY STRUCTURE IN ORGANIC AND CONVENTIONAL MANAGEMENT OF CRANBERRY (Vaccinium sp.) PLANTATIONS: AN AGROECOLOGICAL APPROACH

The aim of the present study was to determine and compare taxa richness, abundance and diversity of the edaphic mesofauna community between plantations of cranberries (Vaccinium sp.) subjected to organic and conventional management in farms in central-south Chile (37°28'S), as also to evaluate changes produced in their diversity and abundance diversity and abundance, as result of the change from conventional to organic management. In July 2006 two farms were chosen, one with one year under organic management (OM1) and a second one under six years of certified organic management (OM6). Each farm was divided in four quadrants, each one with a surface of 2,500 m . In each quadrant was extracted one sample with six replicas of 188.5 cm3 each. Samples were processed in the laboratory using the Berlesse-Tullgren system for the extraction of mesofauna and the subsequent counting and identification of specimens. To compare the organic managed plantation, it was selected a farm under conventional management (CM) with similar climatic and edaphic conditions. On each parcel, taxa richness, abundance, alpha (a) diversity, dominance and beta (P) diversity were determined. Significant differences between diversity values were determined with Student's t test (a = 0.05). It is concluded that taxa richness is similar in all plantations, independent of agricultural management, whereas abundance of each taxon individually is different between both types of management. There are significant differences in diversity between the organic plantations (OM1 versus OM6) and between the conventional (CM) versus organic plantations (P<0.05). Qualitative (taxocenotic) and quantitative (biocenotic) similarity recorded in the edaphic communities from both types of plantation management may be explained by soil type and climate similarity, as well as by the homogeneity of the edaphic ecosystem.