Flowering Phenological Patterns of Entomophilous Plants in an Alpine Grassland of the Qilian Mountains

Flowering phenology is a critical life-history trait determining the reproductive success of entomophilous plants in alpine ecosystems. However, comprehensive characterizations and cross-level comparative studies of these phenological patterns remains limited. In this study, we conducted high-frequency phenological monitoring of 36 entomophilous species across 15 families in a typical alpine grassland in the Qilian Mountains, extracting parameters at the individual, population, functional group, and community levels. Our results demonstrate that the community flowering season lasted approximately 100 days, beginning in early June and terminating in early September. Community flower abundance exhibited a bimodal distribution, reaching distinct peaks in early July and early August. Overall flowering synchrony among plants was generally low, indicating clear temporal niche differentiation. The plant community comprised early-, mid-, and late-flowering groups. The temporal overlap of early- and mid-flowering species jointly contributed to the first floral peak in early July, whereas late-flowering species drove the second peak in early August. Among these functional groups, the early-flowering group accounted for the lowest proportion of species, whereas the late-flowering group accounted for the highest. Both early- and late-flowering groups tended toward mass-flowering strategies, while the mid-flowering group leaned toward steady-flowering. At the interspecific level, earlier-flowering species typically exhibited shorter flowering durations and more right-skewed floral distributions, meaning the interval from the first to the peak flowering date was shorter than that from the peak to the last flowering date. At the intraspecific level, individuals that initiated flowering early or late typically exhibited longer flowering durations but lower synchrony with conspecifics; conversely, individuals blooming during the middle of the population’s season exhibited the opposite pattern. These findings systematically delineate the hierarchical temporal structure of alpine entomophilous communities, objectively reflecting the differential utilization of a limited growing season through inter- and intraspecific phenological variation.