Species richness and evenness as a function of biomass in arable plant communities

POGGIO, S; GHERSA CM

WEED RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2011 vol. 51 p. 241 - 249

0043-1737

We evaluated the hypothesis that competitive dominantschange the species richness and evenness of arable plantcommunities. Three field experiments including coolseasoncrops and unsown short fallows were carried outin Buenos Aires, Argentina. Ground cover, biomass andspecies richness of crops and weeds were assessed.Evenness was calculated by using species biomass data.Richness and evenness were correlated with total communitybiomass, and with the biomass of either weeds orthe dominant species in the community. Crops, throughgrowth and shading effects, affected the species richnessand evenness of arable plant communities. Conversely,the dominant weed in fallows was not as suppressive ascrops. Species richness and evenness were constrained bycommunity biomass. Species richness of understoryweeds decreased as crops suppressed weed growth.Evenness also decreased as the dominant species becameincreasingly productive, regardless of their identity(weeds or crops). Our findings provide valuable modelsto characterise the trajectories that species richness andevenness may follow in different farming scenarios.Community biomass is a major constraint on themaximum diversity of local communities and, consequently,of substantial ecological importance for bothbiodiversity conservation and weed managementpurposes