Temporal and spatial distribution of Araucaria angustifolia (Araucariaceae) pollen in Misiones, Argentina. Araucaria angustifolia (Bertol.) Kuntze is a native species of high commercial value that has indiscriminately been exploited and is currently in critical danger. This work represents the beginning of a research program in Aerobiology related to its reproductive phenology, being conducted in Misiones (Argentina). Two types of continuous volumetric samplers were used: one fixed and the other one portable, distributed in 6 sampling points located in the direction of the prevailing winds. The main pollination period in 2010 (90% of total pollen) lasted 30 days, accumulating 23,548 grains. The daily concentration showed a maximum of 10 to 14 hours following the circadian pattern of atmospheric conditions, with minimum values at 22 hours and 6 hours. An occasional small increase of pollen was observed in the evening, which could be ascribed to the local pollen entrainment. The days with higher concentrations coincided with warmer weather conditions, stronger winds and lower relative humidity with respect to the averages for the period. Lower concentrations were noticed in the endpoints bounds of population distribution, indicating limitations in transport. This study represents an advance in the proper management and conservation of the genetic resources of this species

Aims of the study: To describe the radial patterns of wood density, and to identify their main sources of variation, and the potential tradeoffs with mean tree growth, in two Eucalyptus species. Area of study: Mesopotamian (Corrientes and Entre Ríos provinces) and Pampean region (Buenos Aires province) of Argentina. Materials and methods: Eucalyptus grandis and Eucalyptus viminalis, growing in genetic trials installed in two sites per species were studied. X-ray wood microdensity profiles were developed from core samples. Each profile was proportionally divided in 10 sections. Mean, maximum, minimum and the standard deviation of wood density, for each section were computed. Mean annual growth was used to study the relationships with wood microdensity variables. A linear mixed-effects model computed the significance of different sources of phenotypic variation. Pearson´s correlation computed the relationships between variables. Main results: The pattern of radial variation in E. grandis showed a decrease in wood density from pith to bark, mainly due to the decrease in minimum wood density, while in E. viminalis, wood density increased towards the outer wood. In both species, the standard deviation of the wood density increased along the radial profile from pith to bark. Significant variation in wood density was explained by site, provenance and clone/family effects. In E. grandis mean, maximum and minimum wood density were negatively correlated with mean growth, whereas in E. viminalis correlations were positive but close to zero. Research highlights: Both the pattern of radial variation of wood density and the relationship between wood density and mean growth were different in the studied Eucalyptus species, and they varied within species depending on the site they were growing and genetic provenance.