Spatiotemporal effects of logging and fire on tall, wet temperate eucalypt forest birds

Abstract

Forests globally are subject to 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-yr period, we investigated the response of bird species to spatiotemporal changes in forest cover associated with logging and wildfire in the mountain ash (Eucalyptus regnans) forests of southeastern Australia. Specifically, we examined how bird occurrence changed with shifts in the proportion of area burned or logged in a 4.5 km radius surrounding our 88 long-term field survey sites, each measuring 1 ha in size. Overall species richness was greatest in older forest patches, but declined as the amount of fire around each site increased. At the individual species level, 31 of the 37 bird species we modeled exhibited a negative response to the amount of fire in the surrounding landscape, while one species responded positively to fire. Only nine species exhibited signs of recovery in the 6 yr of surveys following the fire. Five 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. We also identified relationships between the coefficients of life history attributes and spatiotemporal changes in forest cover and stand age. Large-bodied birds and migratory species were associated with landscapes subject to large amounts of fire in 2009. There were associations between old growth stands and small-bodied bird species and species that were not insectivores. Our study shows that birds in mountain ash forests are strongly associated with old growth stands and exhibit complex, timedependent, and species-specific responses to landscape disturbance. Despite logging and fire both being high-severity perturbations, no bird species exhibited similar responses to fire and logging in the landscape surrounding our sites. Thus, species responses to one kind of landscapescale disturbance are not readily predictable based on an understanding of the responses to another kind of (albeit superficially similar) disturbance.

New spatial analyses of Australian wildfires highlight the need for new fire, resource, and conservation policies

“…In addition, species richness of birds can be reduced by ∼10% with each additional fire in a given ecosystem (15). Similarly, expanding the proportion of a landscape that is burnt will drive down mammal and bird species richness (16). Conversely, some management activities in burnt areas are critical, particularly the control of invasive herbivores (such as introduced deer) and carnivores (e.g., feral cat) that are attracted to fire-damaged locations.…”

Temporal fragmentation of a critically endangered forest ecosystem

“…First, additional logging and additional fire in Mountain Ash and Alpine Ash forest increases the landscape‐level dominance of young regenerating forest which is, in turn, prone to additional high‐severity disturbance such as crown‐scorching (Taylor et al ; Zylstra ). Fires can have significant negative impacts on a range of elements of the biota including arboreal marsupials (Lindenmayer et al ) and birds (Lindenmayer et al ) as well as on populations of large old trees (Lindenmayer et al ) and soil microbiomes (Bowd et al ). Second, further disturbances such as additional logging in Mountain Ash and Alpine Ash forests will drive a decline in ecosystem integrity; for example, additional logging coupes in wood production landscapes accelerate rates of decay and collapse of large old trees in remaining uncut areas (Lindenmayer et al ).…”

“…Third, both the Mountain Ash and Alpine Ash forests have been targeted for intensive and extensive logging for many years by the native forest timber industry (DCFL ; Flint & Fagg ) and there are proposals to further expand the amount of forest that is clear‐cut over the next 5–10 years (VicForests ). These same forests also have been subject to large scales in the past 35 years (Cruz et al ; Lindenmayer et al ). Finally, the extent of disturbance in Mountain Ash and Alpine Ash forests has significant impacts on levels of carbon storage (Keith et al ; Keith et al ) as well as the production of water (Langford ; Langford et al ; Taylor et al ).…”

Managing interacting disturbances: Lessons from a case study in Australian forests

“…logging) in biologically important locations such as refugia, or areas supporting keystone structures. Intact old growth stands are refugia in many forest types (Watson et al., 2018) including in Mountain Ash forests where they are critical for birds (Lindenmayer, Blanchard, Blair, Westgate, & Scheele, 2019). Large old trees are keystone structures that should be protected from the impacts of interacting disturbances in many forest ecosystems (Lindenmayer & Laurance, 2017), including Mountain Ash forests.…”