Assessment of the impact of invasive Urtica dioica L. On herbaceous plant diversity in Nyeri county, Kenya

Globally, stinging nettle (Urtica dioica L.) is known to be invasive and this jeopardizes food security. Unfortunately, there is inadequate information available regarding the species' invasiveness and the ensuing effects on the diversity of herbaceous flora in Kenya's highlands. Therefore, the study aimed to evaluate the impacts of U. dioica on biodiversity in the Kieni West Sub County of Nyeri County, specifically in the Endarasha, Charity, and Watuka areas. Ten 1 m2 quadrats and 100 m long transects were used for stratified random sampling to collect data from roadside, riverside, pastureland, residential, and farmland regions. The diversity of other herbaceous plants and the mean density of U. dioica were analyzed using a one-way ANOVA. According to the results, U. dioica had the lowest mean densities (31±0.84) in the Endarasha farmland area and the highest mean densities (207±6.78 and 206±6.90, respectively) along the roadsides and riverbanks in Charity and Watuka. The diversity of other herbaceous species and U. dioica density were significantly correlated negatively (r=-0.8). The herbaceous species richness was lower at the other four research sites with high U. dioica density, excluding croplands. In spite of U. dioica's dominance, Spillanthes mauritiana and U. dioica have synergistic occurrences. In summary, the density, diversity, and species richness of other herbaceous plant species were lower in regions with high U. dioica densities. In pasturelands, the effects of U. dioica invasion are particularly severe, and to maintain high-quality fodder over the long term, U. dioica invasiveness needs to be controlled.