Seedling establishment and regeneration in a harvested Eucalyptus plantation at Maragamuwa, Naula, Sri Lanka

K B Ranawana,W G S Yasarathne,T M Reed

doi:10.4038/cjs.v46i1.7422

Abstract

The first year of secondary succession in a harvested Eucalyptus camaldulensis plantation near Maragamuwa village, Naula, was examined to see the possible effect of distance from the adjacent relatively undisturbed mature forest on the form and composition of natural regeneration after removal of eucalypts. Composition, relative densities and absolute abundance were examined in cleared 40, 20 × 20 m 2 quadrats placed in eight 1 ha blocks in two types of locations: harvested eucalypt plantation away from the natural forest (MP) and harvested blocks next to the natural forest (MT), and compared with 20 similar sized quadrats sampled in the adjacent mature forest (NF). Relative density values for MT and MP were compared with the adjacent NF using Kruskal-Wallis and Mann-Whitney U tests. A total of 11,207 individuals from 77 species were recorded per hectare in MP, while 11,658 individuals/ha from 61 species were recorded from MT and 5,925 individuals/ha from 39 species in NF. Relative densities of seedlings in MP and MT were significantly different from NF ( p p>0.05 ). Most individuals in MP and MT were 1-100 cm tall. Species composition suggests the basis for seral succession, with the cleared and distant MP plots having most non-forest species, and a high abundance per species compared with the MT plots adjacent to the mature forest. Natural forest plots had fewer individuals in each family or species, and a far lower density of the lianas typical of the first stages of colonization. In the first year of succession, there were indications of a distance effect in blocks adjacent to forest sites.

Highlights

Eucalyptus spp. have been widely planted in tropical and subtropical regions as fast-growing timber trees (Munasinghe, 2003)
Eucalyptus camaldulensis Dehnh is the most commonly planted eucalypt in the semi dry areas of Sri Lanka (Vivekanandan, 1979), though not all plantations have been successful (Perera, 1998) with many suffering from limited growth due to thin soils, the relatively dry climate, and due to their vulnerability to periodic flash fires common in the agricultural areas
The current study reports on the first year of monitoring of plots cleared of eucalypts, and provides a baseline for changes in biodiversity and the possible effect of distance from the adjacent native forest on the colonization of cleared plots

Summary

Introduction

Eucalyptus spp. have been widely planted in tropical and subtropical regions as fast-growing timber trees (Munasinghe, 2003). With the right species in the right soil, under suitable climatic conditions, Eucalyptus can rapidly grow stands of good quality timber (Timothy et al, 2004) and trees could be harvested during early years (within 7-8 years) for getting more income per annum (Tanvir et al, 2002). Widely planted for timber, their success has been mixed at best (Reed et al, 2009). Because of their impacts on biodiversity, water resources and ecosystem services, the management and recovery of thousands of hectares under failing eucalypts back to native forest is of especial interest to foresters and researchers, as well as to the Sri Lankan Government (Bandaratillake, 1996)

Methods

Results

Conclusion