Characterization of soil organisms communities in native and invaded grasslands from the Inland Pampa, Argentina

YAHDJIAN, LAURA; GIMENA VILARDO; ADELIA GONZÁLEZ ARZAC

Mar del Plata

Congreso; 2nd World Conference on Biological Invasions and Ecosystem Functioning BIOLIEF 2011; 2011

Feedbacks  between  soil biota and  plant  communities  can explain  plant species replacement along succession and  the  invasion by  exotic  species, which in turn have impacts  at  the ecosystem level. The objective of this study was to describe soil biota communities, including abundance and diversity of the main soil functional groups in both natural remnants and exotic-invaded grasslands. Soil macro and  mesofauna  were sampled  along spring  and  summer from native  grasslands and  old field communities in the Inland Pampa region, Argentina. We established pitfalls during a week in plots of each community, and extracted mesofauna from soil with Tullgren  funnels. Total abundance of soil biota  was higher in  invaded  communities  than in natural grasslands,  although differences were marginally significant  (p=0.068). The  same trend was found for the  abundance of  Homoptera (p=0.063),  Isopoda  (p=0.095)  and  Collembola:  Symphypleona  (p=0.052).  The  high abundance of Isopoda  organisms, particulary  from de genus  Armadillidium  which feed most on detritus,  and Collembola would be related  to  the enhancement of  litter decomposition. We also found significantly higher  (p<0.05)  soil respiration rates in  invaded  old field than in  native  remnants.  These  results showed that exotic plant species invasions produced important changes in soil community structure and soil processes, which in turn might  have  consecuences on aboveground-belowground interactions and the persistence of exotic plants species.