Effects of Thinning Regimes on Growth and Yield of Tectona grandis at Longuza Forest Plantation, Muheza District, Tanzania

Abstract

Thinning regime implies stands thinned at successive intervals, type, and intensity influencing growth and yield. Teak Forests in Tanzania are the main source of hardwood raw materials however thinning operations are not properly implemented. The purpose of this study was to determine whether thinned stands could impair the eventual projected growth and yield. Growth and yield data were collected from 168 purposively selected circular plots of radius 9.78 m distributed systematically in 9 thinned compartments in three thinning regimes. Thinning history, tree diameter, and total height of three fattest trees were recorded. Simple t-test was used to compare whether thinned stands were significantly different from Teak yield table values in Dbh, volume, and stocking. Results show that 88.9% and 11.1% of thinned compartments were understocked and well stocked respectively based on the Teak yield table. Also, 100% and 75% of first and second thinnings respectively were well timed whereas 25% of second thinning was delayed. Among surveyed compartments, 66.7% and 33.3% belong to site classes I and II respectively. Effects of adequate and timely thinning on Dbh and volume were 2-42% and 9-53% respectively. Thinning and timing promoted positively Dbh and Volume growth. Adequate and timely thinning treatments are recommended