The distribution and abundance of woody invasive alien plants in small towns in Eastern Cape Province, South Africa

Abstract

Invasive alien plants (IAPs) are rapidly increasing around the world, mainly due to land transformation, climate change, and urbanisation. Whilst urban areas are highly susceptible to invasion by IAPs, crucial information on the distribution and abundance of woody invaders in small towns is limited. Here, we determined the distribution and abundance of woody IAPs across different suburbs and land use types in 12 small towns in the Eastern Cape province of South Africa. We enumerated 38 427 individual woody IAPs, and their abundance and distribution varied across surveyed towns. Although species such as Melia azedarach, Pinus elliotti, Jacaranda mimosifolia, Eucalyptus camaldulensis, and Ligustrum lucidum were the most distributed, species density varied across towns. More than half of the woody IAPs were identified in affluent (56%) suburbs compared to the townships (23%), Central business district (CBD) (16%), and low-income housing neighbourhoods (5%). There were significant differences in woody IAPs distribution across different land use types, with more than half (54%) found in the residential areas compared to road verges (32%) and public urban green spaces (14%). Some socio-economic and environmental predictors such as town population, mean temperature, unemployment rate, and Gross domestic product (GDP) showed significant and positive correlations with woody IAPs species richness and density. Our findings suggest an uneven spatial distribution and diversity of woody IAPs across the different small towns, suburbs, and land use types in the region. It is recommended that small towns in South Africa need financial and human resources support to effectively manage IAPs.