Species ethnobotanical values rather than regional species pool determine plant diversity in agroforestry systems

Orou G. Gaoue,Daniel K. N’Woueni

doi:10.1038/s41598-021-03408-3

Abstract

The conversion of natural systems into farms and agroecosystems is the main cause of biodiversity loss. In human-dominated landscapes, understanding the interactions between agroforestry systems and adjacent natural vegetation is fundamental to developing sustainable agricultural systems. Species can move between these two systems with natural systems providing the regional pool of species that shape the agricultural values and conservation value of the agroforestry systems. We investigated the influence of neighboring natural habitats on traditional agroforestry systems in the buffer zone of Pendjari Biosphere Reserve in Benin to understand the contribution of regional processes on the quality of agroforestry systems. We expected that agroforestry parklands adjacent to natural vegetation with high species diversity will also have higher plant species diversity. We found no similarity in plant species composition between agroforestry systems and adjacent natural habitats. A small proportion of species in adjacent natural habitats were found in agroforestry systems. The proportion of shared species was not significantly influenced by plant diversity in adjacent natural habitats or the distance from the agroforestry systems to the natural adjacent habitat. However, plant diversity in agroforestry systems was strongly associated with site ethnobotanical values indicating that farmers act as a supplemental but severe environmental filter of the regional species pool. Our study suggests that promoting the plantation of plants with high ethnobotanical use-value is a potentially viable strategy for sustainable agriculture and ecological restoration in Biosphere reserves.

Highlights

The conversion of natural systems into farms and agroecosystems is the main cause of biodiversity loss
Consistent with the island biogeography theory[28,29], the closer the agroforestry systems are to the regional species pools, the more likely are species going to disperse into agroforestry systems and the higher diversity and shared species richness are expected
Regular species found in the adjacent natural habitat included Combretum fragans, Terminalia avicennioides, Burkea africana whereas only Lannea acida was represented in agroforestry systems

Summary

Introduction

The conversion of natural systems into farms and agroecosystems is the main cause of biodiversity loss. Investigating the factors that shape diversity in the traditional agroforestry systems in the transition zone of Biosphere reserves is central to maintaining the double role of protected areas to safeguarding long-term ecological sustainability and satisfying basic human n eeds[36]. We used the theoretical framework of the environmental filtering and island biogeography theories to examine the effects of various socio-cultural and agricultural (ethnobotanical value, agricultural practices) and proximity to natural habitat (distance from adjacent natural vegetation) on species diversity in traditional agroforestry systems in the Pendjari biosphere reserve in Benin (west Africa, Fig. 1;37). Consistent with the island biogeography theory, we hypothesized that the distance from agroforestry systems to adjacent species pools of natural vegetation will predict the number of species in agroforestry systems and the proportion of shared species between the two plant communities. We hypothesized that species ethnobotanical values along with the proximity of agroforestry to natural vegetation will predict local species assemblages in agroforestry parklands

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