Effects of soil amendments on survival and early growth of three timber species grown on sand tailings in the peninsular Malaysia

Abstract

Existing large tracts of tin tailings are problematic soils that were created from natural lowland rainforests of high biodiversity in Peninsular Malaysia. These ex‐mining sites are low in biodiversity with poor natural succession. Especially, isolated patches of tin tailings trapped in agricultural and urban developments have virtually very little natural regeneration. Hence artificial regeneration needs to be carried out. Successful tree planting techniques developed for greening sand tailings have been recorded. Yet, there is a lack of scientific data to support the soil amendment treatments recommended. This study was embarked with the aims to determine the effects of soil enrichment on survival and growth of Acacia mangium × Acacia auriculiformis (Acacia hybrid), Swietenia macrophylla (mahogany) and Khaya ivorensis (khaya). The study plots were established as a 3x4 factorial combination of soil amendments, fertilizer treatments and tree species in a completely randomized design. Fertilizer treatments including control, 120 g chicken manure point-1 at six‐month interval and 120 kg empty fruit bunch (EFB) point-1. The soil amendments assessed were control and application of 60 kg of mineral soil point-1. The seedlings were planted at 3x3 m spacing. Weeding and fertilization were carried out at three months interval. Soils were systematically and properly sampled for chemical analysis. The data of survival, vegetative growth, biomass and physiological responds of the three species were collected for analysis. Net photosynthesis and transpiration with leaf temperature of timber species were measured using a portable H2O/CO2 analyzer and LICOR super porometer, respectively. All the data collected were statistically analysed. The results show that Acacia hybrid had the highest survival, vegetative growth and biomass among the three species. The significantly greater survival, growth and high biomass accumulation of Acacia hybrid is due to its high adaptability by producing abundant leaves that enlarges the photosynthetically‐active leaf area. In addition, this study shows that at optimum temperature, the net photosynthesis, stomatal conductance and transpiration of Acacia hybrid were significantly greater than khaya and mahogany. This study also shows that soil treatment increased the growth of the three timber species on sand tailings. Chicken manure is a better type of fertilizer than EFB for timber species grown on sand tailings. Acacia hybrid treated with soil plus EFB or chicken manure had significantly the highest growth rates resulted in greatest biomass. Khaya ivorensis requires site preparation using soil plus chicken manure or EFB. Swietenia macrophylla treated with chicken manure or soil plus chicken manure grew better than other treatments. This study shows that the right species choice with viable site preparation technique and treated with suitable organic fertilizer are crucial to ensure the success of growing the timber species on impoverished ex‐mining sites.