A management proposition to preserve functional identity of grasses in mixed swards

The diversity of traits plays a key role in the maximization of ecosystems' multi-functionality, but interspecific competition in defoliated swards can lead to unpredictable changes in the functional traits over the plant community. However, we hypothesize that interrupting canopy regrowth at a height corresponding to critical leaf area index (LAI), associated with moderate intensity of defoliation, can be an effective management to preserve the functional traits of contrasting growth strategy grasses cultivated as a mixture. A 2-year experiment was conceived to assess continuously several traits of three cool-season perennial grasses (Arrhenatherum elatius exploitative], Dactylis glomerata moderately exploitative] and Festuca arundinacea conservative]) cultivated as single species stand or as a mixture. Dactylis glomerata was the less productive stand but no difference was observed between the mixture and the most productive monocultures. No change was observed in functional traits, whether the species were cultivated as monoculture or as a mixture. The dissimilarities over traits and, therefore, the functional identity of contrasting growth strategy grasses growing in multi-specific swards was preserved when canopy regrowth was interrupted at a height corresponding to the critical LAI associated with moderate intensity of defoliation. Since the diversity of traits maximizes ecosystem multi-functionality, our findings provide a step forward towards designing management practices that enhance ecosystems services delivered by cultivated multi-specific grasslands.