Forest plantations in Tanzania play a critical role in supporting sustainable wood supply hence reducing pressure on natural forests. However, expansion of forest plantations in the coastal lowland areas remains constrained by the limited availability of appropriate tree species that combine varieties of traits such as acceptable wood quality, stem form, and resistance to biotic stresses in order to cope with the challenging site conditions. This study evaluated wood basic density (WBD), stem quality, and disease resistance of eight-year-old iCorymbia/i and iEucalyptus/i pure species/provenances grown at North Ruvu Forest Plantation, Kibaha District, Tanzania. The trials were established using a randomized complete block design (RCBD), with five replications for iCorymbia/i and six for iEucalyptus/i. WBD was determined from increment core samples, while stem quality and disease resistance were assessed in the field using standardized visual scoring systems. The results (presented as mean ± standard error (SE)) shows that (iCorymbia/i species/provenances differed significantly in WBD, ranging from 385 ± 18 kg msup-3/sup (iC. henryi/i, CSIRO) to 475 ± 27 kg msup-3/sup (iC. citriodora/i, TTSA). In contrast, iEucalyptus/i species showed lower and more uniform WBD values (mean = 394 ± 0.9 kg msup-3/sup), with no significant differences detected among entries. iC. variegata/i (CSIRO) and iC. citriodora/i (TTSA) showed the highest stem quality, with 100% and 92% high-quality stems, respectively. Disease resistance was strongest in iC. citriodora/i (TTSA and ZFC) and iE. camaldulensis/i (TTSA), where no visible disease symptoms were observed. Overall performance ranking identified iC. citriodora/i (TTSA), iC. variegata/i (CSIRO), and iE. camaldulensis/i (TTSA) as the most promising species/provenances for coastal lowland conditions. These findings demonstrate the strong potential of selected iCorymbia/i species as viable alternatives or complements to iEucalyptus/i in Tanzanian plantation forestry and provide empirical guidance for site–species matching and diversification strategies in similar environments.
Rashid et al. (Fri,) studied this question.