Test for species richness saturation on arable plant communities of functionally different crop species

POGGIO, SANTIAGO L; CHANETON, ENRIQUE J; GHERSA, CLAUDIO M

Montreal

Congreso; IX INTECOL International Congress of Ecology, 90th Annual Meeting of the Ecological Society of America (ESA); 2005

INTECOL-ESA

In the Rolling Pampas of Argentina, pea crops harbour greater weed species diversity than wheat crops at both field and regional scales. Assuming that the same pool of weed species is available to invade both types of crop fields when occurring in the same landscape, we hypothesised that the local-regional diversity relationship would be a saturating one for wheat fields, but would be linear (unsaturated) in pea fields. Weed communities were surveyed in 9 fields of each crop species across landscapes of contrasting habitat heterogeneity. Test for community saturation was performed using regression models on local versus regional species richness plots. The pea model was significantly linear (P<0.05), which suggests lack of saturation for these weed communities. The wheat model was only marginally linear (P<0.10), and mean local richness did not significantly differ across landscape types (P>0.10). Local interference on weed establishment (biotic resistance) appears to be stronger in wheat fields, due to a more homogeneous and denser canopy of this crop. Pea fields were more susceptible to weed invasion. Meso-scale dispersal rates together with the size of landscape pools of weedy species may be controlling plant richness in pea fields.