The phenology of the endangered Nogal (Juglans neotropica Diels) in Bogota and its conservation implications in the urban forest

Abstract

Nogal, Juglans neotropica Diels is an endangered woody angiosperm of tropical origin. Several trees of this species have been planted in Bogota City, Colombia. The field of study is urban tree phenology. The research question of the current work is when do phenological changes occur throughout the year in urban nogal trees in the northern portion of Bogota, Colombia? The main research objective was to characterize the phenological changes of nogal according to the German (Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie) scale. The study area was located between 137 to 152 streets and along a major avenue on the northern portion of Bogota. Selected sites and tree sampling criteria were based on tree density (number of trees per site), tree height (three to seven meters in height), healthy individuals, and phenological stage. We selected a total of 19 trees. Vegetative flushes, flowering, fruiting, and leaf abscission occur once yearly. Nogal is a deciduous tree species that abscises its leaves on portions of the canopy and initiates new vegetative flushes at the same time. Nogal is protandrous, bearing both catkins and pistillate flowers. The scale can be used for in situ conservation of the species as a non-destructive, and consistent tool to manage nogal populations. BBCH also can be used to monitor the phenological stages of nogal and for future research studies within the city and elsewhere. We observed birds such as Thurdus fuscater, Zonotrichia capensis and Zenaida spp perching on the branches of this tree. The city is an important sanctuary for nogal conservation. The BBCH scale is an effective and non-destructive tool to monitor the precise timing of phenological events.