Ecological factors aff ecting the fruiting success of a Tibouchina trichopoda (DC.) Baill. (Melastomataceae) fl ower
ABSTRACTTh e abundance and distribution of resources for pollinators modulate the reproduction of plants. Th is study attempted to determine whether and how the fruiting success of Tibouchina trichopoda fl owers varies due to plant size, number of fl owers produced, distance between individuals and cardinal orientation of the fl owers. From July 2009 to February 2010, we conducted monthly evaluations of 21 plants in an area of regenerating forest within the Atlantic Forest biome, located near the municipality of Antonina, in southern Brazil. Floral density was monitored weekly. During the study period, the species bloomed twice: once during the cool, dry season, showing an extended fl owering period with scattered fl owering individuals; and once during the hot, rainy season, showing a brief fl owering period with a high density of fl owering individuals. Plant size was not found to infl uence fruiting success. Th ere was greater production of fl owers and fruits during the brief fl owering period. Th e extent of the fl oral display positively aff ected the fruiting success of the fl owers, the eff ect being greater when the density of fl owers was low and tending to stabilize at higher densities. Th e northern-facing portions of tree crowns produced more fl owers and therefore had greater fruiting success than did the southern-facing portions. However, the proportion of fruits produced per fl ower was the same.