Plant species richness assessment in Pampean agro-ecosystems

POGGIO, SANTIAGO L.; DE LA FUENTE, ELBA B.; GHERSA, CLAUDIO M.

Bari, Italia

Congreso; 13th European Weed Research Society Symposium; 2005

European Weed Research Society

The importance of biodiversity in agro-ecosystem has promoted a lot of controversy. Nonetheless, it is accepted that the richer a plant community, the more the available refuges for different life forms, and that low diversity increases susceptibility to invasion and the spread of biotic breakdowns. Land use intensification may threaten the plant diversity of arable fields and their surrounding area and may consequently reduce biodiversity services in agro-ecosystems. However, differences among methods to assess species diversity at different spatial scales have received some criticism, because of the difficulties in data comparison and interpretation. The objectives of this work were to study agro-ecosystem plant diversity in different cropping systems, and, based on this, to discuss the methodology for studies on plant biodiversity of agro-ecosystems. Floristic surveys were done in soybean, maize, wheat and pea crops in the Argentine Pampas during the last decade. Braun-Blanquet relévés of cultivated fields and surveys of management information of each surveyed field were obtained. Diversity measures were estimated. Cropping history and agronomic management were important factors defining the diversity and structure of plant communities, and in some cases, were unaffected by the crop species. The methodology proved to be successful for comparing plant community diversity, since sampling size was sufficiently large to comprise most of the species able to occur in arable fields, and to integrate the different spatial scales in which ecological processes that determine the species richness of local assemblages take place.