Abstract
BackgroundSenna didymobotrya is a native African flowering shrub. It is suspected that climate change encourages the introduction and spread of invasive alien species. The possible invasion of S. didymobotrya across the continent is expected to increase in the future due to ongoing climate change. Nonetheless, there is still paucity of empirical evidence on the extent to which the changing climate contributes to the surge of the flowering shrub. This study, therefore, investigated the present and potential invasion of S. didymobotrya using the species distribution model under changing climate conditions. The two representative concentration pathways (RCP4.5 and RCP8.5) and eight bioclimatic variables and one topographic variable were used to simulate the current and future (2050s and 2070s) invasion of S. didymobotrya in Africa. The model performance was assessed using the area under the receiver operating characteristic curve (AUC) and true skill statistics (TSS).ResultsThe results of the study showed that under the current climatic conditions, 18% of Africa is suitable for the establishment and invasion of S. didymobotrya. The most suitable hotspot for S. didymobotrya invasion is eastern Africa, followed by southern Africa. The predicted model showed that by 2050, 3.3% and 3.12% of the continent would be highly suitable areas for the invasion of the species under RCP4.5 and RCP8.5, respectively. In the 2070s, under RCP4.5 and RCP8.5, the highly suitable area would be 3.13% and 2.7%, respectively. In relation to the current suitability, the cumulative projected areas of the low and moderate suitability class under RCP4.5 and RCP8.5 will rise by the years 2050 and 2070. However, under both RCPs, the non-suitable area for S. didymobotrya invasion would gradually decrease.ConclusionsFrom the findings, it can be concluded that the ecosystem’s vulnerability to S. didymobotrya invasion under future climatic conditions will proliferate significantly. Hence, to prevent the projected harm to biodiversity and ecosystem services, governments need to focus their future biodiversity management and policy directions on the means and strategies of minimizing the invasion and the distribution rate of S. didymobotrya across habitat types.
Highlights
Invasive alien species are posing a great threat to global biological diversity (Mainka and Howard 2010; Shiferaw et al 2018) and agricultural productivity and economic growth (Simberloff et al 2013)
Over 164 invasive alien plant species were reported in Africa by Witt et al (2018); of these, Senna didymobotrya (Fresen.) Irwin & Barneby is among the most frequently reported invasive species
The results demonstrated that by the 2050s, an increased rate in the new invasion areas by 61.57% and 79.82% was projected under Representative Concentration Pathways (RCPs) 4.5 and RCP8.5 respectively (Table 5 and Fig. 3)
Summary
Invasive alien species are posing a great threat to global biological diversity (Mainka and Howard 2010; Shiferaw et al 2018) and agricultural productivity and economic growth (Simberloff et al 2013). S. didymobotrya, named as a bush encroacher, is known to suppress the regeneration and growth of native plant species by forming large dense impenetrable brushes and mono-cropping stands (Witt et al 2018) and obstructing the movement of wild animals It can establish itself in diverse habitat types, including grasslands, woodlands, forests, riparian zones, dumpsite, disturbed area, and coastal scrub (Tamiru 2017; Witt and Luke 2017). The model performance was assessed using the area under the receiver operating characteristic curve (AUC) and true skill statistics (TSS)
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