Assessing and classifying the health and risk status of avenue trees

Abstract

ABSTRACT This study assessed and classified avenue tree health and risk status using the University of Venda (UNIVEN) and Louis Trichardt town (LTT) in Limpopo Province of South Africa to determine trends and create baseline data against which future assessments can be evaluated. A 100% survey was conducted in seven selected streets. Crown and stem diameter, height, crown length, species, coordinates, health, stability, and hazard status were assessed for each tree. A total of 621 trees were assessed, comprising 92 species. Spathodea campanulata and Olea africana accounted for 29.2% and 11.5% of trees in LTT and UNIVEN, respectively. The average tree density was higher in UNIVEN (366.82/km) compared to LTT (115.03/km). Percentages of healthy trees were high in LTT (65.9%) and UNIVEN (75.7%). Caesalpinia ferrea ranked first in both locations in the critical stability class. Only LTT had 1% of trees in the severe hazard category. Common structural defects in the severe hazard class include basal decay, excessive lean, and weak branches. Management implications include large-scale inventory of street trees, replacement of large-sized with medium-sized tree species on narrow streets, and restriction of the planting of hazard-prone trees to parks and gardens.