Abstract
Background: Many alien plant species, such as Tithonia diversifolia, T. rotundifolia and T. tubaeformis, have been introduced to areas outside of their natural distribution range to provide benefits, but have subsequently become invasive, threatening biodiversity and agricultural productivity.Objectives: The aim of this study was to determine the current distribution and dates of introduction of invasive Tithonia species in eastern and southern Africa and to document the effects of T. diversifolia on rural livelihoods in Zambia.Method: Roadside surveys, and other sources of information, were used to determine the distribution of invasive Tithonia species in eastern and southern Africa. Household interviews were conducted to gauge perceptions and understand the impacts of T. diversifolia on local livelihoods in Zambia’s Copperbelt province.Results: Tithonia diversifolia is widespread in Uganda, Kenya, Tanzania, South Africa, Malawi and parts of Zambia but less so in Zimbabwe. Tithonia rotundifolia was comparatively uncommon in eastern Africa but common in some southern African countries, while T. tubaeformis was invasive in Swaziland, South Africa, Zambia and possibly also Zimbabwe. According to the majority of respondents in Zambia, T. diversifolia has negative impacts on native vegetation, mobility or access, water availability, crop yields and animal health.Conclusion: Invasive Tithonia species are widespread and spreading throughout much of Africa. Livelihood and biodiversity costs have not been considered by those actively promoting the use and further dissemination of T. diversifolia. We therefore recommend that detailed cost–benefit studies should be undertaken to support informed decisions on the future management of these species.
Highlights
Invasive alien species pose significant threats to biodiversity and human well-being, especially where rural communities are dependent on natural resources (Shackleton et al 2007; Vaz et al 2017; Vilá et al 2010)
In southern Africa T. diversifolia was first recorded in South Africa in 1927
Tithonia diversifolia and T. rotundifolia were already present in disturbed areas in Malawi, Mozambique, Zambia and Zimbabwe in the 1960s (Wild 1968)
Summary
Invasive alien species pose significant threats to biodiversity and human well-being, especially where rural communities are dependent on natural resources (Shackleton et al 2007; Vaz et al 2017; Vilá et al 2010). Many invasive species were introduced intentionally as ornamentals, for restoration in degraded landscapes, as agro-forestry species or as crops (Rejmánek & Richardson 2013) Many of these species are beneficial, contributing to rural livelihoods by providing a wide range of products (Kull et al 2011; Shackleton et al 2007). Assessing people’s perceptions of these invasive species can provide insights into their negative impacts, and into attitudes and perceptions regarding their management (Mwangi & Swallow 2008; Rai et al 2012) This information can inform decisions on whether or not to attempt control, especially where the target species has both benefits and costs (‘conflict species’) (see Novoa et al 2016; Shackleton, Le Maitre & Richardson 2015; Van Wilgen & Richardson 2014). Many alien plant species, such as Tithonia diversifolia, T. rotundifolia and T. tubaeformis, have been introduced to areas outside of their natural distribution range to provide benefits, but have subsequently become invasive, threatening biodiversity and agricultural productivity
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