The role of floral traits in community assembly process at high elevations in Lesser Himalaya

Abstract

Ecological theory postulates that plant trait research should consider multiple traits related to different organs and/or ontogenetic stages as such traits represent different ecological niche axes. Particularly, floral traits have been suggested to play an important role in assembling plant communities along environmental gradients as they determine the reproductive success, one of the key functions in plants. Yet, the predictive power of floral traits in community assembly research remains largely unverified empirically. We analyzed the predictive power of six floral traits of 139 herbaceous species for inferring community assembly process in 21 sites located along an elevation gradient in Lesser Himalaya ranging from 2,000 to 4,000 meters above sea level. The floral trait variability along the gradient was analyzed using community-weighted trait mean (CWM) values and functional diversities (FD) calculated for each of the study communities. The CWM values for onset of flowering and flower display area increased significantly with increasing elevation, whereas specific flower area showed an opposite pattern. In combination with convergence in onset of flowering and specific area (i.e., lower FD values in high elevation sites), these patterns suggest that abiotic filtering and plant-pollinator interactions affected the floral trait composition of the communities studied. Increasing low-temperature stress towards high-elevation sites selected for late-flowering species that produce resource-intensive flowers with larger display areas. Low pollinator abundancy and activity in high elevation, could also explain why these traits were selected in the study communities. Delayed flowering with increasing elevations might facilitate the phenological overlap of plants and their pollinators, as pollinator activity at higher elevation peaks in the second half of the vegetation period. The dominance of species with low specific flower area and larger display area in high elevation communities were attributed to the increased flower longevity and attraction of pollinators, respectively, to maximize pollination success under pollinator scarcity. Synthesis. Our study provides empirical support of the recent argument that floral traits contribute considerably to the assembly of plant communities along environmental gradients. Thus, such traits should be included into community assembly research agenda as they represent key growth and survival ecological functions.

The role of floral traits in community assembly processes at high elevations in the Himalayas

“…Data used for the statistical analyses are archived at Zenodo https:// doi.org/10.5281/zenodo.7580640 (Ahmad et al, 2023).…”

Intraspecific variation in pollination ecology due to altitudinal environmental heterogeneity

“…Floral traits have received less attention, even though they have critical relevance for the pollination and reproductive success of plants (E‐Vojtkó et al., 2020 , 2022 ). Floral traits within a plant species might vary across altitudinal gradients in a way that reflects local acclimatisation to abiotic conditions or change in the abundance and composition of pollinator communities (Ahmad et al., 2022 ; Heinrich & Raven, 1972 ; Petanidou et al., 1996 ). For example, the bee to fly transition that occurs with increases in altitude will lead to shifts towards different flower colours that are preferred by the local pollinator taxa (Bergamo et al., 2018 ; Renoult et al., 2015 ).…”