Diversity of phenological patterns of Handroanthus ochraceus (Bignoniaceae) in Costa Rica

Abstract

The study of phenological patterns in plant communities is of vital importance for understanding the temporal cycles of ecosystems, but there is little information on the diversity of phenological patterns that can occur at the intraspecific level, as well as the genetic or environmental factors causing this variation. In Handroanthus ochraceus, a deciduous tree species of neotropical dry forests, ecophysiological studies have proposed the release of water stress as the mechanism that triggers flowering and the sprouting of new leaves. During four years, I observed the cycles of leaf fall, flowering, fruiting, and new leaf production in seven Costa Rican sites that differed in their proximity to water courses and in soil moisture. Six were located in dry forest areas, and one in premontane forest. There were two general phenological patterns: the explosive, where trees depend on the first rains for floral anthesis and the expansion of leaf meristems, and the staggered pattern, with unsynchronized flowering at the beginning and middle of the dry season, independently of rainfall. Although this phenological variation has been previously recognized, the occurrence of these two patterns is not determined by the proximity of water courses, contradicting phenological models proposed for this tree species.