Abstract

PEREDO-P., Santiago F.; BARRERA-S., Claudia P.; PARADA-Z., Esperanza  and  VEGA-C., Marcela. Taxocenotic and biocenotic analysis over time of edaphic mesofauna in organic Vaccinium sp. plantations southern central Chile. Agrociencia [online]. 2012, vol.46, n.2, pp.163-173. ISSN 2521-9766.

Soil functioning is determined by the diversity of organisms inhabiting the soil and their role in the edaphic ecosystem, and the variety of forms and functions of the roots of the plants where they live. Invertebrates are an integral part of soil and are important in determining the suitability of the soil for the sustainable production of healthy crops or trees. In Chile there are no studies on edaphic mesofauna in plantations subjected for a longer period to certified organic management. The aim of the present study was to analyze the taxocenotic and biocenotic similarities over time of taxa of edaphic mesofauna in a cranberry plantation (Vaccinium sp.) subjected to organic management practices in farms in Southern Central Chile (37° 28' S). In July 2006 two farms were chosen: 1) with one year under certified organic management as a transition organic plantation (OM1) and 2) under six years of certified organic management (OM6); both with similar climate and edaphic features. Each farm was divided in four quadrants, each one with 2500 m². In each quadrant, was extracted at random one sample with six replicas (188.5 cm³ each), 24 replicas on each plantation. 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 analyze changes over time in the structure of the edaphic mesofauna community, in July 2007 sampling was repeated in OM1 and OM6 plantations under organic management (OM2 and OM7). The richness, abundance of taxa and density (nm^-2) per plot were evaluated, as well as the diversity (H') and evenness (J') of the mesofauna taxa in each plantation (OM1, OM2, OM6 and OM7). The α diversity and dominance were calculated using the Shannon (H') Index and the Evenness (Equity) Index (J'). In addition, β diversity was determined to establish the taxocenotic and biocenotic similarities using the Bray Curtis Index estimated with the Biodiversity Pro software. Significant differences between diversity (H') values were determined with Student's t test (p≤0.05). There was a high taxocenotic similarity on time in the edaphic community structure of Vaccinium sp. organic plantations. Fourteen taxa form edaphic mesofauna taxocenosis, being Acaridida, Oribatida and Entomobryomorpha the most abundant. There were differences (p≤0.05) between the diversity (H') of mesofauna taxa in organic plantations with one year of transition to organic management (OM1) respect to OM2, OM6 and OM7. The communities of edaphic mesofauna in the organic plantations of Vaccinium sp. were stabilized two years after conversion from conventional to organic management.

Keywords : edaphic mesofauna; organic farming; cranberries; mediterranean climate; Chile.