Effects of spacing on biomass distribution and nutrient content of Tectona grandis Linn. f. (teak) and Terminalia superba Engl. & Diels. (afara) in south-western Nigeria

Abstract

The effects of four different spacings (teak stand: 1.37 m× 1.37 m, 1.98 m× 1.98 m, 2.9 m× 2.9 m and 3.96 m× 3.96 m; afara stand: 1.8 m× 1.8 m, 2.8 m× 2.8 m, 4.2 m× 4.2 m and 6.1 m× 6.1 m) on biomass and nutrient distribution in Tectona grandis and Terminalia superba have been studied at the Gambari Forest Reserve, south-western Nigeria. Biomass estimates (10 3 kg ha −1) were 317.26, 293.14, 382.23 and 225.57 for square spacings of 1.37 m, 1.98 m, 2.9 m and 3.96 m respectively in Tectona grandis and 140.78, 127.33, 90.77 and 86.16 for square spacings of 1.8 m, 2.8 m, 4.2 m and 6.1 m, respectively, in Terminalia superba. In Tectona grandis the initial growing space did not significantly affect the total stand dry weight. However, there were significant differences between spacings in dry weights of small branches and big roots. Total biomass in Terminalia superba decreased with increasing spacing. With the exception of the stemwood dry weight, the other tree components showed no significant differences between spacings. Tectona grandis showed no consistent pattern of total nutrient with spacing. In Terminalia superba the total content of phosphorus, potassium and magnesium decreased with increasing spacing.