Current status of the invasive shrub Berberis julianae C.K. Schneid. (Berberidaceae) in Golden Gate Highlands National Park (Free State Province, South Africa)

Abstract

• Berberis julianae is an alien invasive evergreen shrub in South Africa. • Surveys were conducted to determine effectiveness of previous control interventions. • Cut-stump and chemical treatment were effective for controlling adult plants. • Seedling numbers increased significantly over 6 years after initial control. • Follow-up control should be implemented immediately to stop spread. Berberis julianae commonly known as Wintergreen barberry or Chinese barberry, is an evergreen shrub species native to China which has been introduced into South Africa and has become invasive in a few locations. In 2015, management measures were taken in an attempt a control a population in Golden Gate Highlands National Park (GGHNP) in the Free State Province. After assessing the plant demographics within the park, the following management options were implemented: cut stump treatments of larger shrubs, foliar spray herbicide applications and hand pulling of seedlings. It was recommended that follow-up research be conducted to check if control measures were successful or not. This study aimed to map and determine the current distribution of B. julianae in GGHNP and to investigate the change in B. julianae population demographics to that recorded previously. The study showed that the number of seedlings had multiplied from 6 seedlings in 2014 to 588 in 2020, whereas the number of mature shrubs had decreased in the same time period. In conclusion, the control measures conducted have been successful in reducing the adult population, however, additional follow-up control of seedlings is urgently required to stop further spread.