Spatial distribution and interspecific association patterns between Mansonia altissima A. Chev., Ceiba pentandra (L.) Gaertn and Triplochiton scleroxylon K. Schum. in a moist semi-deciduous forest

Abstract

Key message: Mansonia altissima A. Chev. has an aggregated distribution at the juvenile life stage that becomes random at the mature life stage. Ceiba pentandra (L.) Gaertn could play the role of nurse plant in the management of M. altissima populations providing them a moderate forest shade in large gaps for early growth. M. altissima and Triplochiton scleroxylon K. Schum. displayed independent distribution patterns. Context: M. altissima is a species with economic value found in moist semi-deciduous forests of tropical Africa. The analysis of spatial distribution patterns can help to understand the ecology of this species in forest stands dominated by emergent pioneer tree species like C. pentandra and T. scleroxylon. Aims: To assess the spatial distribution patterns of M. altissima and spatial relationships with C. pentandra and T. scleroxylon in their natural habitat. Methods: We investigated the spatial patterns of the three species during three life stages; juvenile (immature trees), premature (trees with minimum flowering diameter) and mature (trees with minimum fruiting diameter). Diameter at breast height (DBH) was measured and geographical coordinates of trees were recorded within ten one-ha plots, divided into sixteen subplots (625 m2). We computed the L(r) function, normalized from Ripley’s K(r) function to detect aggregated, random or regular distribution patterns. Results: Aggregations were detected in juvenile and premature M. altissima. Size and scales of spatial aggregation were inversely proportional to the DBH size. M. altissima and C. pentandra displayed interspecific association patterns at the similar life stages. Both species were positively associated within a radius ≥ 3 m. No positive association was detected between M. altissima and T. scleroxylon. Conclusion: Interspecific association patterns between M. altissima and C. pentandra suggest that C. pentandra could be used as a nurse tree in reforestation and management practices of M. altissima populations.