Diversity of invasive alien plants in the Universitas Sumatera Utara Arboretum, Deli Serdang, Indonesia

Abstract. Nathaniel G, Basyuni M, Tarigan AA, Baba S. 2025. Diversity of invasive alien plants in the Universitas Sumatera Utara Arboretum, Deli Serdang, Indonesia. Asian J For 9: 332-345. Invasive alien plants are one or more plant species that are introduced into a different ecosystem and become dominant, disrupting the local ecosystem. In Indonesia, there are more than 300 species of invasive plants. The aim of this study is to analyze species diversity, examine morphological relationships, and analyze the distribution of invasive alien plants. This research was designed using a quantitative approach. Data collection was conducted through vegetation analysis using the "systematic sampling with random start" technique. The results of the study identified a total of 4,143 individual invasive alien plants belonging to 29 species from 16 families. The diversity index of invasive alien plants in the arboretum was calculated at 1.99, the evenness index was 0.5895, and the species richness index was 3.35. The highest importance value index at the shrub level was found in Clidemia hirta (Melastomaceae) with a value of 40.18%, while at the ground cover level it was Asystasia gangetica (Acanthaceae) with a value of 72.07%. Several species showed very close morphological relationships, indicated by a similarity index of 1. These included C. hirta with Melastoma malabathricum, Elephantopus scaber with Ageratum conyzoides, Eragrostis amabilis with Panicum maximum, Cyperus rotundus with Rhynchospora colorata, and Caladium bicolor with Alocasia macrorrhizos and Limnocharis flava. The distribution of invasive alien plants was found primarily on flat and gently sloping terrain, at distances ranging from 0 to 150 meters from the arboretum road, and from 0 to 375 meters from the river.