Background and aims – Temporal phenological segregation among species within a plant community can be viewed as a niche differentiation that promotes species co-existence. Following this hypothesis the functional assessment of the flowering pattern was analysed in sub-Mediterranean mountain grassland. Methods – The study was carried out in two sites at different elevations. Four fenced plots of 50 m ² each were established in both sites. Phenological relevés were carried out in each plot every fifteen days and soil samples were collected in each plot. The functional traits sets of the flowering species were analysed at each considered time interval. Key results – Each phenological phase tends to be linked to a group of functional traits (e.g. bulbs or tuber/rhizome, low height and spring green leaves for the early spring period; rhizome or tuber, hemicryptophyte caespitose, mid height, presence of stolons and persistent green leaves for the late spring period). dominant species reach their maximum phenological forwardness in the middle of the vegetative season, while non- dominant species 'exploit' the beginning and end of the vegetative season. Two main sets of strategies allowing non-dominant species to co-exist with the dominant ones were highlighted. The first characterizes the tall graminoids-dominated patches, where a pattern of traits allows subordinate species to differentiate the flowering temporal niche compared to the dominant ones. The second set of strategies is related to some small-sized species, which can co-exist with dominant species by exploiting gaps due to livestock disturbance, or by forming patches given their clonal ability. This strategy allows them to share the optimal temporal niche with dominant species. Conclusions – Flowering pattern promotes species co-existence and is driven by functional differentiation of species that in turn is filtered by environmental stress/disturbance type and intensity.

CO-EXISTENCE; FLOWERING PATTERNS; FUNCTIONAL TRAITS; MOUNTAIN GRASSLANDS; PHENOLOGY; SPECIES COMPETITION; TEMPORAL NICHE