Rehabilitation of Degraded Tropical Rainforest Using Dipterocarp Trees in Sarawak, Malaysia

Hattori Daisuke,Kenzo Tanaka,Sakurai Katsutoshi,Kendawang Joseph Jawa,Ninomiya Ikuo

doi:10.1155/2013/683017

Abstract

To develop rehabilitation planting techniques in tropical degraded forests, we investigated (1) basic soil characteristics and light conditions; (2) growth and survival of seven dipterocarp seedlings over 81 months; and (3) the effect of environmental factors on the survival of seedlings grown in three degraded vegetations (grassland, secondary forest, and logged forest) in Sarawak, Malaysia. The soil was weakly acidic, and kaolin minerals dominated. The amount of exchangeable bases in surface soils, soil temperature (>35°C), and relative light intensity were all highest in the grassland. Seedling growth was also highest in the grassland, whereas many seedlings died there over 81 months. Growth and survivability were very similar in secondary and logged forests. The death of the seedlings in the grassland was attributable to an extremely high light intensity for all species. In contrast, the seedling growth rate in all species was also enhanced by light intensity. In conclusion, dipterocarp seedlings can be planted on highly degraded land such as grassland, although high light intensity limits their survival. Planting under nurse trees such as regenerated pioneer trees may be an effective method to enhance seedling survival under open conditions such as grassland.

Highlights

Anthropogenic activities such as timber extraction, shifting cultivation, and the establishment of commercial plantations have led to the conversion, fragmentation, and degradation of tropical rain forests [1,2,3]
Various types of degraded forests remain after such degradation because of differences in the type of disturbance, environmental conditions, time elapsed since the disturbance, and the original vegetation type. These degraded forests can be broadly divided into three types of degraded vegetation, namely, grassland after burning, early successional secondary forest, and logged over forest after commercial logging [4]
The survival of planted dipterocarp seedlings was significantly limited by the high light intensity, especially for D. beccarii, S. macrophylla, and S

Summary

Introduction

Anthropogenic activities such as timber extraction, shifting cultivation, and the establishment of commercial plantations have led to the conversion, fragmentation, and degradation of tropical rain forests [1,2,3]. Various types of degraded forests remain after such degradation because of differences in the type of disturbance, environmental conditions, time elapsed since the disturbance, and the original vegetation type. These degraded forests can be broadly divided into three types of degraded vegetation, namely, grassland after burning, early successional secondary forest, and logged over forest after commercial logging [4]. Planting of indigenous trees is considered to be an effective rehabilitation method for such degraded tropical rain forests, because these trees provide benefits such as timber, food, and medical products [8,9,10,11,12,13]

Methods

Results

Conclusion