Weed flora dynamics during the first years of grassland establishment

摘要

A long term experiment was initiated in 2005 at the INRA research centre of Lusignan (western France) to evaluate environmental impacts of temporary grasslands. One of the objectives is to study the dynamics of plant community, seeded species as wellas weed flora, taking into account grassland duration in crop rotation and nitrogen supply. Weeds originate from the seed bank and seed dispersion. Seed bank was evaluated at the beginning of the experiment and aboveground weed flora was observed once ayear. Results show a modification of the weed community structure during the first years of grassland establishment. Quantitatively, with a decrease of specific richness and Shannon index, and qualitatively, with a reduction of cool-growing plants that were very important in the first years to the benefit of perennial species that are frequently observed in grasslands. Weed flora in low N treatment differed from high N treatment in the third year.