Ecological traits of the tropical treeline species Polylepis quadrijuga (Rosaceae) in the Andes of Colombia

Information is presented on the phenology, herbivory, phytochemistry and pr oduction of the tree species Polylepis quadrijuga. Leaf production was lowe r during the dry season than during the wet season, when minimum temperatur es also occurred. Flower and fruit phenology were also seasonal. Herbivory was significantly higher for leaves expanded during the wet season (20%) th an during the dry season (1%), and was also higher for younger leaves. Flav onoids, compounds known as UV-B protectors, were found in high concentratio n in leaves of P. quadrijuga. There was a significant positive relationship between monthly rainfall, monthly minimum temperatures and flavonoid conce ntration, but no relationship was found with leaf age. The annual fine litt erfall for the Polylepis forest was estimated to be 3.9 t ha(-1) y(-1), a h igh value when compared to other paramo and upper montane rain forests in t ropical mountains. High production was associated with high leaf nitrogen c oncentration (3.0-3.5%), high rates of nitrogen retranslocation (80% dry we ight), and relatively low leaf longevity (8.4 mo). High production in P. qu adrijuga is probably a key factor in explaining the existence of this large woody species in a paramo environment otherwise dominated by bunch grasses , cushion plants and giant rosettes of the genus Espeletia.