Fire Regime Has a Greater Impact Than Selective Timber Harvesting on Vegetation in a Sub-Tropical Australian Eucalypt Forest

Tom Lewis,Tracey Menzies,Anibal Nahuel Pachas

doi:10.3390/f12111478

Abstract

We compared selectively harvested and unharvested areas located among treatments of annual burning since 1952, triennial burning since 1973 and an area that had received no prescribed burning, but with a single wildfire in 2006 (one fire in 72 years), in a dry sclerophyll eucalypt forest, south-eastern Queensland, Australia. Historic fire regime, rather than low-intensity, selective timber harvesting (17% to 37% live tree basal area removed) had a greater impact on a range of vegetation and soil attributes. Plant taxa composition was influenced more by historic fire regime than recent harvesting; of the 25.5% of the variation in taxa composition explained, fire treatments alone accounted for 96.4% of the explained variation and harvesting alone accounted for just 4.8%. Selective harvesting of timber had a predictable influence associated with removal of tree cover and physical impacts associated with extraction of logs. In harvested areas there were increases (p < 0.05) in bare-ground cover and in coarse woody debris volumes and decreases in understorey vegetation height, particularly where woody understorey was present. However, overall, the combined effects of timber harvesting and fire regime were relatively minor. These sub-tropical dry eucalypt forests appear to be resilient to the impacts of combined, but low-intensity disturbances.

Highlights

Published: 28 October 2021Tropical and sub-tropical forests worldwide are threatened by anthropogenic impacts such as clearing, over-harvesting, a changing climate and inappropriate fire regimes [1,2,3,4].As such, remnant forests need to be carefully managed to preserve their ecological integrity and the impacts of management options such as the use of prescribed fire and timber harvesting need to be understood.Selective timber harvesting has been a feature of many dry eucalypt forests, including those of sub-tropical Queensland over the last century [5]
Despite the fact that this form of disturbance is widespread across sub-tropical forests, few published studies have reported the impacts of selective harvesting on vegetation assemblages in Australia
This study was located at Bauple State Forest (25◦ 480 S 152◦ 370 E) in southeast Queensland, Australia (Figure 1) in an open forest ecosystem dominated by Corymbia citriodora subsp. variegata (F.Muell.) A.R.Bean & M.W.McDonald, Eucalyptus siderophloia Benth., E. acmenoides Schauer, with E. fibrosa F.Muell. subsp. fibrosa, E. tereticornis Sm., E. moluccana

Summary

Introduction

Remnant forests need to be carefully managed to preserve their ecological integrity and the impacts of management options such as the use of prescribed fire and timber harvesting need to be understood. Selective timber harvesting (i.e., partial harvesting) has been a feature of many dry eucalypt forests, including those of sub-tropical Queensland over the last century [5]. Despite the fact that this form of disturbance is widespread across sub-tropical forests, few published studies have reported the impacts of selective harvesting on vegetation assemblages (i.e., structure and composition) in Australia. Eyre et al [13] report impacts of selective timber harvesting on habitat features in dry eucalypt forest in Queensland; they reported a lower density of live trees with hollows and large

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