NON-CONSPICUOUS BUT WIDESPREAD NESTS OF THREE ANT SPECIES FAVOUR PLANT GROWTH IN NW PATAGONIA

LESCANO, M.N.; WERENKRAUT V; PIRK, G.I.; ELIZALDE LUCIANA

Congreso; International Congress of IUSSI; 2018

Ants provide a variety of ecosystem services, particularly through processes such as nutrient cycling and formation of soil structure. As a result of ant activity, soils around nests differ in physical properties and are usually enriched compared to adjacent soils, often favouring plant growth. In desert areas, vegetation recovery after disturbance is usually slow, so ant nests could enhance this process. In the Patagonian steppe (Argentina) large nests and refuse dumps of the leafcutter Acromyrmex lobicornis favour vegetation growth but other species with less conspicuous nests but a broader distribution, including degraded areas, have not been studied. We evaluated the effects of nests of Pheidole spininodis, Pogonomyrmex carbonarius and Dorymyrmex tener on soil properties and plant growth in the Patagonian steppe. We took samples of 10 nest and adjacent soils per species and performed physical and chemical analyses. We then tested the growth of two native plants, Pappostipa speciosa (Gramineae) and Oenothera odorata (Onagraceae), in nests vs. adjacent soils in a greenhouse. Analyses of similarity showed similar soil properties between nest soils and non-nest soils, while univariate analyses showed only a higher soil conductivity and K concentration in nests but no differences in the other variables. Final dry biomass of P. speciosa was not higher in nest soils, but O. odorata achieved a higher final biomass in P. carbonarius and D. tener nest soils. Thus, despite similar soil properties between substrates, differences in a couple of variables, and likely in unmeasured ones (e.g., soil porosity, texture, and other nutrients), affected plant growth. Nests of P. carbonarius and D. tener enhance plant growth but this effect depends on the plant species involved. These species could be important in vegetation recovery of degraded areas evidencing the key role that, overlooked species with non-conspicuous nests, play in shaping ecosystem structure and function.