Weed community structure of mandarin orchards under conventional and integrated management in northern Spain

Mandarin orchards under conventional and integrated production (IP) practices were surveyed in the area around the delta of the Ebro River (Spain). The floristic and functional structures were evaluated to compare weed communities and to determine the relationship between community structure, mandarin orchard characteristics and type of management. The alpha diversity observed was 12.3 (S.D. 5.84) and 18.0 (S.D. 5.50) for conventional and IP orchards, respectively, and gamma diversity was 77 for conventional and 96 for IP agricultural practices. Differences were found in overall inter-row vegetation cover (11.3% conventional, 90.4% IP). Analyses of variance and mean comparison tests revealed no differences in any of the functional traits considered between the two types of management. All the multivariate methods of analysis employed revealed that the weed community composition was related to the inter-row management system. Mowing orchard inter-rows led to a successional trajectory from typically agrestal weed communities to ruderal vegetation, giving rise to high richness and also high cover.