Ecosystem services mediaed by ants (Hymenoptera: Formicidae) in the Arid Chaco, Argentina

CUEZZO, F.; CASTELLARINI, F.

Fortaleza, Brasil

Simposio; XXI Simpósio de Mirmecologia; 2013

Universidade Estadual de Ceará, Brasil

ECOSYSTEM SERVICES MEDIATED BY ANTS (HYMENOPTERA: FORMICIDAE) IN THE ARID CHACO, ARGENTINA F. CUEZZO1 & F. CASTELLARINI2 1INSUE ? CONICET, Facultad de Ciencias Naturales e IML, UNT. Miguel Lillo 205, CP: T4000JFE - San Miguel de Tucumán, Tucumán, Argentina. e-mail: cuezzof@yahoo.com.ar 2IMBIV, (CONICET- UNC), 5000, Córdoba, Argentina. Despite the well-known key role of ants in almost any terrestrial environment, few studies have focused their importance as providers of ecosystem services, especially in arid or semiarid landscapes. The main objective of this work was to identify ecosystems services provided by ants, derived from its local biodiversity and its vulnerability against changes in land uses and cover changes. Our study was conducted close to Cruz del Eje, NW of Córdoba province, central Argentina. This area belongs to the Arid Chaco, with an average annual rainfall of 400 mm. Natural vegetation is represented by low, open woodland, reduced to isolated patches embedded in a predominantly agricultural matrix. We consider fourtypes of land use: 1) native forest; 2) pasture; 3) perennial crop and 4) annual crop in the studied environment. Grown dwelling ants were collected using five pit-fall traps (8 cm diameter x 10 cm deep) filled with a solution of propylene glycol diluted to 30%. Pit-falls were located at the vertices and center of a rectangle (90 mx 30 m) and were active during three consecutive days. Each replica was taken in six plotsseparate by a minimum distance of 500 m by area. The specimens in the five traps by plot were grouped into a pool. As measure of biodiversity we use Shannon-Weaver index. A cluster analysis was performed using a complement of Chao-Sorensen index as a distance measurement. We found a total of 60 ant species, with Forelius nigriventris as dominant, with a similar frequency between sites. Ant richness in forest, pasture and permanent crops was comparable and significantly higher than that found in seasonal(annual)crops. Cluster analysis shows a close affinity between ant communities in pasture and permanent crops. Following the nomenclature provided by the ?Millennium Ecosystem Assessment?, and considering all 60 ant species, 20 potential ecosystem services represented by a 33% of the ant community was clearly determined, corresponding to cultural, regulation and provision services. Ants found in pastures, perennial and annual crops provided eight services more than those in forests. The difference was probably based on the greatest number of seed dispersers species present in the three environments mentioned above. It is important to consider that the results here provided are only preliminary.Note that services provided by 67% of the species remains unknown,demonstrating the lack of knowledge still exists about this topic. (FonCyT ? ANPCyT, Argentina, BID PICT-PRH 108)