Growth response of Heritiera simplicifolia (Mast.) Kosterm. and Scaphium macropodum (Miq.) Beumée ex Heyne due to abiotic factors in the nursery

In the earliest stage of development, non-dipterocarp wildlings require specific environmental conditions; they are only able to acclimate to harsher environmental conditions after this stage. As such, the environment acts as a limiting factor of early-stage development in non-dipterocarp shade-tolerant species. We examined the survival rates and growth rates of Heritiera simplicifolia and Scaphium macropodum from the family Malvaceae in the different sets of abiotic conditions. Three abiotic environmental factors medium type, greenhouse technique, and light intensity were varied. The experiment was conducted for six months in an area near Hulu Terengganu Hydroelectric Dam, at the edge of the Tembat Forest Reserve. Height, diameter, leaves numbers, and leaf area was recorded. Our results indicate that the wildlings preferred higher daytime relative humidity and natural air ventilation at night, and they grew more quickly under SN50 (358.74 Photosynthetically Active Radiation; PAR) than under SN70 (101.41 PAR). Subsoil supplemented with vermicompost improved wildling growth more consistently than subsoil supplemented with compost or burned mesocarp. The wildling’s height relative growth rate (HRGR) and survival were affected by all treatments. These results indicate that restoration efforts using young indigenous tree species at degraded sites, supply better growth environments and organic nutrients to the rhizosphere.