Effect of provenances on growth and stem form of 16-year Juniperus procera plantation in Injibara, Northwestern Ethiopia

Juniperus procera Hochst. ex Endl. is an evergreen highland tree species reaching 30-40 m high and restricted to some mountainous areas. This tree is a species of great ecological and economic significance in supporting biodiversity, preventing soil erosion, and providing valuable resources. The study aimed at comparing the provenances effect on growth and yield performance of a 16-years-old J. procera plantation. This long-term experiment included eleven provenances from different regions of Ethiopia. It was laid out in a randomized complete block design with four replicates. The plot size was 100 m² with 2.5 m by 2.5 m spacing. Growth parameters such as height and diameter over a 1-m interval of standing trees were measured for sample trees. The results showed that the overall mean of basal area for 11 provenances was ranging from 4.4 ± 0.29 to 5.2 ± 0.33 m² ha⁻¹. The biggest (11.3 ± 0.14 m) and smallest (9.8 ± 0.16 m) mean height was obtained in the provenances of Kolobo and Dikisis, respectively. The mean volume of the stem ranges from 12.3 ± 0.93 to 17.9 ± 1.1 m³ ha⁻¹. The highest and lowest form factor was obtained in the provenances of Gaynt (0.43 ± 0.02) and Hirna (0.32 ± 0.02), respectively. The generic form factor is 0.4 ± 0.01. Provenance Kolobo had the best growth rate in all growth stages with 1.4 m height greater than the poorest provenance Dikisis and 23% greater than the overall average volume (14.5 m³ ha⁻¹) at age of 16 years. The variations in growth and yield performance among the provenances could be attributed to genetic differences and adaptation to the local environment. Provenances originating from similar altitude such as Kolobo's provenances showed better growth and yield performance, possibly due to their adaptation to the cooler and wetter conditions prevailing in the study area. Choosing provenances that are well-adapted to the local site conditions can lead to improved productivity and economic returns.