Non-conspicuous but widespread nests of three ant species favour plant growth in NW Patagonia

PIRK, GABRIELA INÉS; ELIZALDE, LUCIANA; LESCANO, MARÍA NATALIA; WERENKRAUT, VICTORIA

Guarujá

Congreso; International Union for the Study of Social Insects (IUSSI2018); 2018

Ants provide a variety of ecosystem services, particularlythrough processes such as nutrient cycling and formation of soil structure. Asa result of ant activity, soils around nests differ in physical properties andare usually enriched compared to adjacent soils, often favouring plant growth.In desert areas, vegetation recovery after disturbance is usually slow, so antnests could enhance this process. In the Patagonian steppe (Argentina) largenests and refuse dumps of the leafcutter Acromyrmex lobicornis favourvegetation growth but other species with less conspicuous nests but a broaderdistribution, including degraded areas, have not been studied. We evaluated theeffects of nests of Pheidole spininodis, Pogonomyrmex carbonarius andDorymyrmex tener on soil properties and plant growth in the Patagonian steppe.We took samples of 10 nest and adjacent soils per species and performedphysical and chemical analyses. We then tested the growth of two native plants,Pappostipa speciosa (Gramineae) and Oenothera odorata (Onagraceae), in nestsvs. adjacent soils in a greenhouse. Analyses of similarity showed similar soilproperties between nest soils and non-nest soils, while univariate analysesshowed only a higher soil conductivity and K concentration in nests but nodifferences in the other variables. Final dry biomass of P. speciosa was nothigher in nest soils, but O. odorata achieved a higher final biomass in P.carbonarius and D. tener nest soils. Thus, despite similar soil propertiesbetween substrates, differences in a couple of variables, and likely inunmeasured ones (e.g., soil porosity, texture, and other nutrients), affectedplant growth. Nests of P. carbonarius and D. tener enhance plant growth butthis effect depends on the plant species involved. These species could beimportant in vegetation recovery of degraded areas evidencing the key rolethat, overlooked species with non-conspicuous nests, play in shaping ecosystemstructure and function.