Reproductive strategies, sexual selection, and their relationship with the phenotype of individuals are topics widely studied in animals, but this information is less abundant for plants. Variability in flowering phenology among individuals has direct impact on their fitness, but how reproductive phenology is affected by the size of the individuals needs further study. We quantified the flowering intensity, length, and reproductive synchronization of two sympatric dioecious Wild Nutmeg tree species (Virola, Myristicaceae) in the Brazilian Atlantic forest, and analyzed its relationships with tree size. Two distinct strategies in flowering timing and intensity were found between species (annual versus biennial flowering), and among individuals in the annual flowering species (extended versus peak flowering). Only for the annual flowering species the reproductive output is related to tree size and large trees present proportionally higher flower coverage, and lower synchronization than smaller ones. Flowering is massive and highly synchronized in the biennial species. Sex ratios are not different from 1:1 in the two species, and in the two segregated reproductive subgroups in the biennial flowering species. The biennial flowering at individual level is a novelty among reproductive patterns in plants, separating the population in two reproductive subgroups. A proportional increase in the reproductive output with size exists only for the annual flowering species. A biennial flowering can allow resource storage favouring massive flowering for all the individuals diluting their relationship with size.

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The lack of secondary meristems shapes allometric relationships of the palms, influencing species segregation according to their capacity to adjust form and function to spatial and temporal changes in environmental conditions. We examined the stem height vs. diameter allometry of Euterpe precatoria across environmental gradients and measured how terrain inclination and palm size affected stilt root structure at two sites in Costa Rica. We dissected the root cone into eight variables and used principal component analysis to summarize their correlation structure. The fit of the stem diameter-height relationship to the stress, elastic, and geometric similarity models was examined using data from 438 palms. Terrain inclination did not affect stilt roots, whose structure was determined by palm size. Palms under 1 m showed geometric similarity, whereas palms above 1 m had slope values that were one and a half times higher, independent of successional stage, and did not adjust to any mechanical model. Taller palms departed from these models when they were large because they had stilt root support. We conclude that height in E. precatoria is constrained by structural support at the base and that diameter at the base of the stem and stilt roots balances height increments over all the size ranges examined.

Cloud forests have been found to lose more nitrogen in stream discharge than they gain from atmospheric deposition. They also support a large diversity and biomass of tree epiphytes, predominately composed of cryptogams. Since cryptogam epiphytes harbor nitrogen fixing cyanobacteria, they may help make up for the nitrogen loss from ecosystems. We assessed cryptogam biomass on the ground, boles and branches in Quercus costaricensis dominated stands near the tree line in the Cordillera de Talamanca, Costa Rica. Nitrogen fixation was assayed using 15 N 2 uptake. Total cryptogam biomass was 2 977 kg ha −1 , with 67% being found on the lower branches. Bryophytes and chlorolichens made up 53% and 44%, respectively, of the biomass. Half of the bryophyte mass was composed of the liverwort Plagiochila heterophylla, and 66% of the chlorolichen of Lobariella pallida. There were no significant differences in nitrogen fixation rates between the cryptogam species, with a mean rate of 5.04 µg N g −1 day −1 during the predominantly wet condition in the forest. The overall nitrogen input from fixation was 6.1 kg N ha −1 year −1 , of which 78% came from bryophytes, 18% from chlorolichens, and 4% from cyanolichens. Only 2.0% of the fixation occurred in cryptogams on the ground, whereas 67%, 24%, and 7% occurred on the lower branches, boles, and upper branches, respectively. These results show that tree epiphytes constitute a significant source of nitrogen for these forests, due to the trees' large surface area, and can make up for the nitrogen lost from these ecosystems.

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Among orchid bees that have been observed, nest initiation by multiple females is rare, and has never been reported from an aerial-nesting species. Here, we document nest initiation by multiple females in the aerialnesting Euglossa cybelia . Observations were carried out on five nests, which were found on the undersides of understory palm leaves in Costa Rica. Female bees collaborated in constructing the envelope, but when this was finished each bee built and provisioned its own cells. This species therefore shows communal behavior. In one of the nests, individual foraging trips and interactions between female bees were quantified. Although, there were no overall differences between individuals with respect to initiating or receiving aggression, this changed over time.

In a cloud forest dominated by Quercus costaricensis, the gap size between the crowns was consistent and crowns were asymmetrical, being elongated perpendicular to the prevailing wind direction. A wind storm of 20 m/s removed 1.5% of the leaves, consistent with the idea that wind abrasion shapes tree crowns.