Establishment techniques of some dipterocarps on ex-mining land in Peninsular Malaysia

July 9, 2010 by

RENFODA – JICA project

L.H. Ang

Forest Research Institute Malaysia

Fax No: 603-62804614, E-mail: anglh@frim.gov.my

Abstract

Ex-mining lands on Peninsular Malaysia are mainly alienated from natural lowland dipterocarps forests before the 1900s. About 113 750 ha of such degraded land resulted from the mining industries of 1930s. Large tracts of idle ex-mining land formed the landscape of many major west-coast towns of the peninsula. To-date, despite various uses for idle ex-mining lands were encouraged including golf-range, housing and recreational parks, about 80 000 ha remain unutilized. Poor site quality of tin tailings renders the site difficult for growing trees, especially dipterocarps. Some dipetrocarps, such as Shorea leprosula, Shorea platyclados, Shorea parvifolia, Dryobalanops oblongifolia, Shorea ovata and Hopea odorata had been trial planted on ex-mining land. Only Hopea odorata has successfully grown on bare sand and a well-drained slime tailing, and Dryobalanops oblongifolia has been growing well on well-drained slime tailings. Hopea odorata had mean annual height increment (hMAI) of 0.5 to 1.5 m y-1. These two diperocraps have great potential for greening of the idle denuded sites.

Keywords: dipetroacarp plantation, ex-mining land, Hopea odorata and Dryobalanops oblongifolia.

Introduction

Deforestation activities are parts of a process for developing a nation. Properly organized deforestation activities for different land uses are deemed suitable in many developing nations. One of the land uses is tin mining. Tin mining often requires a total removal of trees and other vegetation, and alters the original soil composition. Malaysia was heavily dependent on tin in the 1960s. The results of tin ore extraction had resulted in large tracts of ex-mining land totalling approximately 113 700 ha (Chan 1990) comprising tin tailings (85.6%) and water bodies (14.4%) across three main states: Perak, Selangor and Negeri Sembilan on Peninsular Malaysia. Chan (1990) reported that only 4 730 ha (4.2%) of the ex-mining lands had been utilized for agriculture and 5.5% for other uses. Furthermore the agricultural uses remain limited due to heavy metal contamination in the soil. Some fruits and vegetables from these areas had concentrations of heavy metals, such as mercury, cadmium, arsenic and lead, beyond the permissible limits of Food Acts 1986.

The other potential use of tin tailings is planting of timber tree species, as some studies had shown that tree species may take up heavy metals and improved the soil quality of tin tailings. The Forest Research Institute Malaysia (FRIM) was given a mandate to develop technique for growing tree species on tin tailings. A demonstration plot of about 124 ha of tin tailing was leased from the State Government of Perak to be eventually developed into a plantation with a number of timber species. Among these successfully trialed timber species, two dipterocarps have shown great potential to be used for greening such land. The technique of planting these two commercially important dipterocarps on tin tailings is discussed in this paper.

Study site

The study site is located at Bidor (4°06’N latitude, 101°16’E longitude), a mining town about 128 km north of Kuala Lumpur. The site was mined in the 1950s using dredging and gravel pump methods. The study site was formerly used as grazing ground and dominated by grasses, and small pioneer species such as the Macaranga spp. and Vitex spp. grown on depressions located at the fringes of ex-mining ponds. Other plant species such as the rambutan, coconut, Melia azadiractha and Pterocarpus indicus were planted for fruits, medicinal products and shade respectively, by the illegal settlers.

The mean total annual rainfall for the period was 4390±1083 mm indicated that the project site was rather wet. No distinct prolonged dry period has been recorded. However, the periods from January to March and June to July are noted to be drier than the other months during some of the years (Ang & Ho 2004).

Site improvement

Site amelioration efforts depend completely on species selected for growing on tin tailings (Ang 1994). Hopea odorata and Dryobalanops oblongifolia require no additional modification of microclimate, amelioration of soil and proper water management would be sufficient. Three main types of tin tailings at the project site have been documented namely: slime, sand and sandy slime. Timber tree species can be easily cultivated on sandy slime. However, sand tailings would normally require higher input of fertilizers and a better irrigation system as in agricultural production. Techniques of amelioration needed for growing suitable timber species on sand and slime are different; however, amelioration efforts normally focus on improving physical properties of tailing and improving chemical properties of tailings.

 

Improving physical properties of tailings

Main physical properties of tin tailings that need improvement to enhance growth and survival of timber tree species include mechanical impedance and water status. Both sand and slime tailings require loosening as part of site preparation but for different reasons.

Sources: 8th Round-Table Conference on Dipterocarps

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