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Martin Westgate

Research Fellow
Fenner School of Environment & Society
Australian National University


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Spatio-temporal effects of logging and fire on tall, wet temperate eucalypt forest birds

DB Lindenmayer, W Blanchard, D Blair, MJ Westgate & BC Scheele (In press) Ecological Applications 10.1002/eap.1999

First published 2019-09-13

Abstract

Forests globally are subject to multiple disturbances such as logging and fire that create complex temporal variation in spatial patterns of forest cover and stand age. However, investigations that quantify temporal changes in biodiversity in response to multiple forms of disturbance in space and time are relatively uncommon. Over a 10-year period, we investigated the response of bird species to spatio-temporal changes in forest cover associated with logging and wildfire in the Mountain Ash (Eucalyptus regnans) forests of south-eastern Australia. Specifically, we examined how bird occurrence changed with shifts in the proportion of area burnt or logged in a 4.5km radius surrounding our 88 long-term field survey sites, each measuring 1 ha in size. Overall species richness was greatest in older forest patches. The number of bird species detected declined as the amount of fire around each site increased. At the individual species level, most species were more likely to be detected in old growth than younger forest. Twenty-five of 36 bird species we modeled exhibited a negative response to the amount of fire in the surrounding landscape, while two species responded positively to fire. Only nine species exhibited signs of recovery in the six years of surveys following the fire. Ten species were more likely to be detected as the proportion of logged forest surrounding a site increased, suggesting a possible “concentration effect” with displaced birds moving into unlogged areas following harvesting of adjacent areas. In contrast to predictions from the disturbance-congruence hypothesis, no bird species exhibited similar responses to fire and logging in the landscape surrounding our sites. Large-bodied bird species recovered more quickly than smaller species in landscapes subject to a large amount of fire; small-bodied species were more likely to be found in old growth forests; and migratory bird species were less likely to be detected in landscapes subject to large amounts of logging in the preceding 1-5 years. Our study showed that birds in Mountain Ash forests are strongly associated with old growth stands and exhibit complex, time-dependent and species-specific responses to landscape disturbance. Despite logging and fire both being high-severity perturbations, species responses to one kind of landscape-scale disturbance are not readily predictable based on an understanding of the responses to another kind of (albeit superficially similar) disturbance.

tags: landscape_ecology