Spatial Analysis of the Distribution and Abundance Patterns of Chromolaena odorata in Ghana: An Invasion Risk Assessment

Chromolaena odorata is a dominant invasive weed with capacity for extensive spread in Ghana. An invasion risk assessment focusing on the distribution and spatial abundance of seedlings and mature plants was conducted across 26 sites covering the major ecological zones of Ghana. High plant coverage within 10 mx10 m plots occurred in the tropical rainforest (65%) and tropical deciduous forest (60%). These percentages were significantly (p<0.001) higher than those of the coastal savanna (18%) and Interior Guinea Savanna (IGS) (5%). There were no plants (0%) recorded for the Sudan savanna and mangrove swamp zones. A comparison was made between the density of the species (per hectare) within fragmented forest patches (49.4%), continuous forest patches (34.5%) and abandoned wastelands described as marginal lands (41.9%). The results show that C. odorata was abundant and widely distributed within the forest zone. The densely populated colonies in the forest zone could be the source of rapid spread to non-colonized habitats within the savanna and adjacent arid zones.