Heterospecific Tree Density and Environmental Factors Affect Afzelia africana Sm. Population Structure in the Pendjari Biosphere Reserve, West Africa: Implications for Management and Restoration

Abstract

Information on how abiotic and biotic factors affect species population structures and regeneration are critical for understanding plant growth in natural habitats. Here, we used the data from three spatially distinct populations of Afzelia africana Sm. in the Pendjari Biosphere Reserve in Benin, to determine how the species population structures respond to abiotic and biotic factors. Afzelia africana population structures were studied using several parameters including basal area, tree height, density of successive diameter classes, and size class slope. We tested for individual effects of abiotic (mound density, soil type, and terrain slope) and biotic (heterospecific tree density) factors on the species population structure. We also tested for similarity of species composition among studied A. africana population stands. Results revealed a tree density structure with mature individuals, and size class distribution indicating a recruitment bottleneck at the juvenile stage (10-20 cm diameter), possibly due to mammal browsing, natural and artificial fires. Heterospecific tree density was positively associated with A. africana adult density but negatively related to the species growth parameters (mean diameter, basal area, and tree height). These results indicate some degrees of niche overlap between A. africana and coexisting species but also partly reflect A. africana tolerance and adaptation to limited resources environment. Soil type significantly influenced both basal area and regeneration density, greater values being observed on silt-sand-rocky soils. Basal area was higher on steeper slope, probably a result of species conservative strategies. These findings were discussed in line with management and restoration action needs in the Pendjari Biosphere Reserve.

Spatial distribution patterns of Afzelia africana (Fabaceae – Detarioideae) in a tropical savanna of Benin: implications for management

“…Three stands of A. africana populations in mixture with other species were identified and characterized along a core zone -hunting zone gradient in a preliminary study by Atanasso et al (2019). These include Batia in the hunting zone of Pendjari, Bali in the core zone, and Bondjagou at the edge of the core zone.…”

“…Previous studies described the species population structure and associated drivers (Mensah et al 2014;Assogbadjo et al 2017;Nacoulma et al 2017;Amahowe et al 2018;Atanasso et al 2019). There are consitent reports of poor natural regeneration and a recruitment bottleneck of the species even in protected areas (Sinsin et al 2004;Bonou et al 2009;Amahowe et al 2018).…”

Variabilité démographique de Saba senegalensis (A. DC.) Pichon suivant le gradient climatique au Burkina Faso

“…La forte densité des sujets adultes de S. senegalensis dans certaines populations pourrait conduire à une intense compétition intra-spécifique pour les éléments nutritifs et être également source d'une faible régénération naturelle. Cela a été rapporté par Atanasso et al (2019) qui montrent que la densité de la strate juvénile est négativement influencée par celle des adultes.…”

Species diversity, composition, and heterospecific associations of trees in three altitudinal gradients in Bird's Head Peninsula, Papua, Indonesia

“…The conspecific association occurs between individuals in the same species of trees such as juveniles and mature individuals (Luo et al 2009;Murdjoko et al 2016a). The heterospecific association is the interaction of individuals among different species of trees (Zhu et al 2015b;Johnson et al 2017;Atanasso et al 2019).…”