Functional variation of Brachypodium genuense (DC) Roem et Schult in sub-Mediterranean grassland

We hypothesized that B. genuense was able to spread and dominate the sub-Mediterranean grassland communities (Monti Sibillini, central Italy) subjected to a wide range of environmental conditions, thanks to its broad spectrum of performances. In fact, it showed large plasticity, mirrored by high variations of Specific Leaf Area (SLA), plant height and tussock cover values. We found that in more productive conditions (deeper soil, medium/high pH values, northfacing slopes, and “conservative” landforms) populations of B. genuense had higher SLA, plant height and cover values. This underlies a fast-growing strategy based on high resource rate of acquisition and use, as well as higher competitive ability for aboveground resources (e.g. light). In unproductive/dry conditions (south-facing slopes, shallow soils, lower pH values) B. genuense had lower SLA, plant height and cover values, underlying a slow-growing strategy with low rate of resource acquisition and high rate of resource conservation. In addition, we found that very high nitrogen amount might have a detrimental effect on B. genuense individuals decreasing the SLA values, thus requiring the plant to change the growth strategy. We also inferred that the invasive/dominant behavior of competitive-stress tolerant tall grasses is related not only to clonal integration strategy, plant height, litter deposition, etc., but also to the morphological plasticity of leaves, allowing plants to maintain the coordination of multiple resource capture and, hence, to sustain dominance.