Predicting the distribution of the invasive species Hyptis suaveolens in Nigeria

Hyptis suaveolens is an exotic plant that has become established in Nigeria because it is grows vigorously and produces allelochemicals that adversely affect the growth of adjacent plants. In this study, we predict the distribution of Hyptis suaveolens in Nigeria using a Maximum Entropy modelling approach. Pearson correlations were used to select five bioclimatic variables to which type of soil and altitude were added to give a total of seven environmental variables that were then included in the MaxEnt model. This model predicts that Hyptis suaveolens can colonize 25%, 45% and 25% of the total land area in FCT, Nasarawa and the River States in Nigeria. In addition, Hyptis suaveolens in Nigeria grows mainly in sandy clay and sandy loam soils. Bioclimatic conditions most suitable for this species include temperatures between 26– 30 °C, 9–10 hour photoperiod, low altitudes of around 200–800 m and rainfall within the range of 200–800mm. The MaxEnt model indicates that Hyptis suaveolens is currently a threat to the survival of native species of plants in the North Central part of Nigeria. The MaxEnt model further reveals that because of its high adaptability and tolerance of changes in abiotic factors, Hyptis suaveolens is likely to invade a new environment, the humid forest zone in Nigeria. As this species can become very abundant, we recommend that its spread is monitored and controlled, particularly in areas of high suitability.