Alien plant species are precursors for invasion: a case study of Alternanthera brasiliana (L.) Kuntze in Ile-Ife (Nigeria)

The impact of Alternanthera brasiliana on vegetation and soil seed bank was assessed in Ile-Ife, Nigeria. Ten sample plots, 10 m x 10 m each, were established in invaded plant communities with high density of Alternanthera brasiliana and adjacent uninvaded plant communities where the weed species has low density. In each sample plot, twenty 1 m x 1 m quadrats were randomly laid and all rooted plant species were identified and counted. Post-dispersal soil seed bank was collected by randomly taking five core samples of top soil per sample plot to estimate the soil seed bank density and floristics of the sites. The species composition of soil seed bank was compared with that of the above-ground vegetation so as to assess the invader’s impact on the vegetation using Sorensen’s index of similarity. The results showed that Alternanthera brasiliana invasion significantly impacted on the species diversity (t = 5.27; df = 18; p = 0.0003) and evenness of species distribution (t = 4.50; df = 18; p..., Study area
The study was carried out in some abandoned sites interspersed within the Obafemi Awolowo University estate in the City of Ile-Ife, in the southwestern Nigeria (Fig. 1). The university estate covers approximately 56.09 square kilometers (Makinde et al. 2021). Ile-Ife is found in the lowland rainforest type (Keay 1959) (latitudes 7° 30′ to 7° 35′ N and longitude 4° 30′ to 4° 35′ E, 213–457 msl) (Hall 1969). Ile-Ife has a short dry season that persists for approximately four months (November to March) with the rainy season occupying the remaining months with an average annual temperature of 25.5 °C, average annual rainfall of 1302 mm, average relative humidity of 82%, annual solar radiation of 164.30 Wm-2, and average annual wind speed of 2.06 kmhr-1 (Atmospheric Physics Research Group 2013). The land use system of the university estate is apportioned as follow: 18% of the area constitutes built infrastructure, 22% serves as agricultural and research farmland, with 60% remainin..., The files are in text and excel formats., # Alien plant species are precursors for invasion: a case study of Alternanthera brasiliana (L.) Kuntze in Ile-Ife (Nigeria)

[https://doi.org/10.5061/dryad.3bk3j9kpx](https://doi.org/10.5061/dryad.3bk3j9kpx)

The excel file contains two different two site types (aboveground vegetation and soil seed bank) where *Alternanthera brasiliana* is present in high abundance (invaded) and present in low abundance or absent (uninvaded). The data contains the densities across all ten plots of the invaded and uninvaded sites, as well as the percentage contribution of each species to the total site density. Ten plots were examined for each of the sites and presented as mean and 95% CI. All rows in columns A and B are string variables comprising the taxa (species names and their families), with the last row of columns A and B merged to signify the total (sum) of all the corresponding columns from C to P.

The R code file contains the code used in the R software to perform the indicator species analys...