Soil and leaf nutrient status on growth of Macaranga gigantea in secondary forest after shifting cultivation in East Kalimantan, Indonesia

Abstract

Macaranga gigantea is an important pioneer plant species in the tropical secondary forest of Kalimantan and as far the attractive wood sp ecies was not commercially cultivated. This study aims to determine the soil and nutrient status on growth of M. gigantea in the secondary forest particularly after shifting cultivation activity. For this purposes, the observation plots with 50m x 50m size s were made and measured to collect the data of diameter, height, soil conditions and leaf nutrient concentrations (N, P and K) of M. gigantea in different ages of natural growth. A simple linear correlation analysis was used to determine the relationship of plant growth with the leaf and soil nutrient concentrations as well. The results showed that the soil condition on growth of M. gigantea has the average at pH 4.7, CEC 5.57 meq/100g, base saturation 30.22%, and the concentration of soil nutrients were 0 .062�0.015 % (N), 12.65�4.9 ppm (P), and 57.76�33 ppm (K). We also found that the leaf nutrient concentration was 1.94�0.13% (N), 0.22�0.08% (P) and 0.66�0.27% (K), respective ly. Moreover, the highest growth of diameter was found from the 6 years old of pla nt (27.88 m). The annual yield of diameter and high were 4.65 cm year - 1 and 2.96 year - 1 and it was gradually decreased until the 10 years old of plant. The negative correlations was observed from the soil nutrient K and growth of diameter and high of M. gi gantea (r=0.95, p< 0.05). The positive correlation was observed from the P and K content in the leaf of plant and growth of M. gigantea (diameter, height and volume increment, p<0.1). We suggested that phosphorus and kalium content was play an important ro les on the growth of M. gigantea and this nutrient factor should be considered well when this species will be cultivated for the commercial purposes in the future.