Sago Root Studies in Peat Soil of Sarawak

Abstract

 The sago palms (Metroxylon sagu) grow more slowly and take longer period to mature on peat soils than on mineral soils. Based on the two field experiments at Sungai Talau Peat Research Station, Sarawak, Malaysia, this article aimed to compare the root biomass distributions in tropical peat soils in relation to peat thickness and shoot growth, and to provide ecological information on sago growth. In experiment 1, sago root biomass was measured by taking soil blocks to a depth of 40 cm from the deep peat soil and from the alluvial mineral soil. Total fine root biomass of sago (d ≦ 5 mm) was larger in the alluvial soil (11.4 t/ha) than in the deep peat soil (4.7 t/ha), which contradicts the previous data on sago. The patterns of vertical distribution of roots in each diameter (= d) class were similar between the two soil types; the large roots (d > 5 mm) were distributed below 10 cm in depth and more than half of them concentrated in 20-30 cm layer, whereas fine roots (d ≦ 2 mm) and intermediate roots (2 < d ≦ 5 mm) allocated more than 60% and 55%, respectively, in 0-20 cm layer. The sago root distribution was not affected by the existence of other tree roots or large woody debris. In experiment 2, roots and shoots of one year sago palms were investigated. Both in deep and shallow peat soils, the shoot growths of the sample palms did not much differ and the roots extended below 1 m in depth only after about one year. Total numbers of first-order roots from the stump were larger in the shallow peat. But the difference became small when roots growing upward were excluded. The diameters of first-order roots were not significantly different. Collectively, total fine root biomass was smaller in the deep peat soil where sago palms grow slowly than in the alluvial mineral soil, and the pattern of vertical distribution of sago roots of three diameter classes (mentioned above) were similar between the two soil types.