Different growth strategies in the tropical pioneer tree Trema micrantha during succession on a large landslide on Casita Volcano, Nicaragua

Abstract

Abstract:In this study we examined the size-structures and allometric relationships between height and diameter over 2 y in populations of the pioneer tree Trema micrantha on a large landslide (Casita Volcano, Nicaragua). The landslide comprised three different zones (erosional, depositional and transitional) based on fertility and geomorphological stability. We attempted to analyse the development of canopy hierarchies and intraspecific competition, and the existence of different growth strategies, within the T. micrantha populations of the different landslide zones. Vegetation was surveyed in 2810 × 10-m plots in which a total number of 307 T. micrantha individuals were recorded and tagged. In the depositional zones, size-hierarchies and one-sided competition for light were apparent and, among the short stems (0.0–2.5 m) of the understorey, plastic responses to shade consisting in a marked increase in height in relation to diameter were evident. In the erosional zones, size-hierarchies were not apparent. All stems were small and, among them, the shortest ones (0.0–1.0 m) were dead whereas the tallest (>1.5 m) grew slowly, increasing their diameter to a greater extent than their height. Our study shows that T. micrantha individuals developed different growth strategies in the different areas of the landslide and suggests that this species allocates resources to growth and survival differently depending on environmental conditions. Trema micrantha is a highly versatile species capable of dealing not only with extremely infertile substrates and conditions of high light availability, but also with partially shaded environments such as those in secondary forests.