Flowering patterns in sub-Mediterranean grasslands: a functional approach

Abstract

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.\ud Methods – The study was carried out in two sites at different elevations. Four fenced plots of 50 m2 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\ud at each considered time interval.\ud 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 nondominant\ud 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\ud 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.\ud 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

Effect of tall-grass invasion on the flowering-related functional pattern of submediterranean hay-meadows

“…As indicated by Ansquer et al (2009) andCatorci et al (2012b), and in accordance with the phenological "middomain hypothesis" (Morales et al 2005), species with life forms different from those of the dominant species tend to avoid the flowering co-occurrence with dominant plants, which reach their maximum phenological forwardness in the middle of the vegetative season. Catorci et al (2012a) indicated that higher the presence (cover value) of dominant species, higher the "edge" effect in the flowering patterns of the subordinate and accidental ones. In the present study, we demonstrate that when the dominant species is a tall grass with competitive behaviour (sensu Grime 2001), the magnitude of this phenomenon is amplified, enhancing a set of traits devoted to stress tolerance or underlying a long reproductive cycle.…”

“…In each plot, we counted the number of flowering shoots per species at each time (we considered shoots with more than 70% of flowers in full blooming). On the basis of previous studies (Catorci et al 2012a(Catorci et al , 2012b, we assumed that the time interval between two consecutive observations was wide enough to record the flowering time for all the species and to avoid to count flowering shoots twice during the subsequent times of sampling.…”

“…These species do not need functional strategies allowing fast pre-emption of the canopy or tolerance to stresses (Catorci et al 2012b). Instead, subordinate and accidental species (sensu Grime 2001) have functional strategies that allow them to flower before or after the dominant ones or to share the same period through a different type of space occupation (Catorci et al 2012a). Catorci et al (2012b) stated that the functional set underlying the flowering pattern of subordinate and accidental species has a dual ecological meaning.…”

Do subordinate species punch above their weight? Evidence from above‐ and below‐ground

“…ecological filters selecting species with suitable traits for a given habitat), while subordinate species are stabilized by niche differentiation. These findings suggest that co‐dominant species should be functionally similar and occupy the same ecological niches while subordinate species should be functionally dissimilar and occupy multiple niches dependent on specific abilities for soil nutrient preemption (Werger et al ., ; Dassler et al ., ) or different phenology (Catorci et al ., ). This implies also that systems with multiple niches would promote communities composed essentially of subordinate species, while systems with low niche availability would promote dominance of few dominant species.…”

Fire effects on invasive and native warm‐season grass species in a North American grassland at a time of extreme drought

“…in flowering time between C 3 herbs vs C 4 grasses; Howe 2011; Boughton et al 2013). Even within communities of functionally equivalent species there is sufficient difference in phenological timing to suggest that members of the same functional type could also be differentially sensitive to a burn or cut if it was scheduled during periods of phenological offset (Wilsey et al 2011;Catorci et al 2012).…”