Tree diameter performance in relation to site quality in smallholder timber production systems in Gunungkidul, Indonesia

• Published in: Agroforestry systems 2018-02, Vol.92 (1), p.103-115
• Main Authors: Sabastian, G. E., Kanowski, P., Williams, E., Roshetko, J. M.
• Format: Article
• Language: English
• Subjects: Agricultural production; Agriculture; Agroforestry; Biomedical and Life Sciences; Farmers; Farms; Forestry; Growth rate; Herbivores; Information management; Life Sciences; Mathematical models; Plant species; Small farms; Soil types; Soils; Species; Trees
• ISSN: 0167-4366; 1572-9680
• DOI: 10.1007/s10457-016-0018-9

Smallholder farmers’ choices of tree species in the Gunungkidul region have been limited by lack of management information. This paper describes activities to help inform farmers’ choices of three common timber species— Tectona grandis , Swietenia macrophylla and Acacia auriculiformis —in agroforestry systems in the region through (1) developing models predicting tree diameter growth based on reference growth function and the growth retardation performance and (2) estimating the contributions of site quality variables to the diameter growth retardation of ≤5 and >5-year-old stands. A total of 48 farms were selected, representing three slope ranges and two soil types, with a circular sample plot of 10 m radius established at each farm. A Quadratic model for each timber species indicated that the age of the tree explains a high percentage of the variance in diameter growth. Diameter growth varies with tree age and responds differently in each soil type and slope position. A set of site quality variables were able to predict retarded diameter performances of each tree species in two group ages and two soil types. These results suggest that the models can inform farmers’ choices of tree species and management.