Empirical relationships between tree fall and landscape-level amounts of logging and fire

Proc. Natl. Acad. Sci. U.S.A.

Sato

2018

Self Cite

Increasing numbers of ecosystems globally are at risk of collapse. However, most descriptions of terrestrial ecosystem collapse are post hoc with few empirically based examples of ecosystems in the process of collapse. This limits learning about collapse and impedes development of effective early-warning indicators. Based on multidecadal and multifaceted monitoring, we present evidence that the Australian mainland Mountain Ash ecosystem is collapsing. Collapse is indicated by marked changes in ecosystem condition, particularly the rapid decline in populations of keystone ecosystem structures. There also has been significant decline in biodiversity strongly associated with these structures and disruptions of key ecosystem processes. In documenting the decline of the Mountain Ash ecosystem, we uncovered evidence of hidden collapse. This is where an ecosystem superficially appears to be relatively intact, but a prolonged period of decline coupled with long lag times for recovery of dominant ecosystem components mean that collapse is almost inevitable. In ecosystems susceptible to hidden collapse, management interventions will be required decades earlier than currently perceived by policy makers. Responding to hidden collapse is further complicated by our finding that different drivers produce different pathways to collapse, but these drivers can interact in ways that exacerbate and perpetuate collapse. Management must focus not only on reducing the number of critical stressors influencing an ecosystem but also on breaking feedbacks between stressors. We demonstrate the importance of multidecadal monitoring programs in measuring state variables that can inform quantitative predictions of collapse as well as help identify management responses that can avert system-wide collapse.

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Hidden collapse is driven by fire and logging in a socioecological forest ecosystem

Proc. Natl. Acad. Sci. U.S.A.

Sato

2018

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“…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 ). This will, in turn, have negative effects on species that are dependent on such trees such as hollow‐using vertebrates, many of which are already exhibiting marked patterns of population decline (Lindenmayer & Sato ).…”

Section: Discussionmentioning

confidence: 99%

Temporal fragmentation of a critically endangered forest ecosystem

Taylor

2020

Austral Ecology

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Landscape change and habitat fragmentation is increasingly affecting forests worldwide. Assessments of patterns of spatial cover in forests over time can be critical as they reveal important information about landscape condition. In this study, we assessed landscape patterns across the Mountain Ash (Eucalyptus regnans) and Alpine Ash (Eucalyptus delegatensis) forests in the Central Highlands of Victoria between 1999 and 2019. These forests have experienced major disturbance over the past 20 years through a major fire (in 2009) and extensive industrial logging. We found that around 70% and 65% of the Mountain Ash and Alpine Ash forest areas, respectively, were either disturbed or within 200 m of a disturbed area. Inclusion of planned logging increased these disturbance categories to 72% and 70%, respectively. We also found that the isolation of Mountain Ash core areas (patches of undisturbed forest >1000 ha) increased significantly (P < 0.05) over our study period, with the proximity between disturbed areas conversely increasing significantly (P < 0.05). This means that continued and planned disturbance through industrial logging will have an amplified adverse effect on remaining undisturbed ash forest patches, which will become smaller and more dispersed across the landscape.

“…(Lindenmayer et al, unpublished data). These sites have typically been subject to rapid rates of loss of large old trees, (Lindenmayer et al 2016;2018a;2018b). Ongoing declines in populations of hollow-bearing trees, coupled with the very limited recruitment of these trees (see below), will likely drive further marked declines in site occupancy by arboreal marsupials in the coming decades (Blair et al 2018).…”

Section: Responses Of Arboreal Marsupialsmentioning

confidence: 99%

“…The 98.8% of the Mountain Ash forest estate which is 120 years or younger is where rates of decline in condition and rate of tree collapse are fastest (Lindenmayer et al 2016). Rates of decline are also elevated on sites with increasing amounts of logging and fire in the surrounding landscape (Lindenmayer et al 2018b). During the past two decades of monitoring, there has been extremely limited recruitment of new hollow-bearing trees on our long-term sites (Lindenmayer et al 2012b;Lindenmayer et al unpublished data).…”

mentioning

confidence: 91%

Ten years on – a decade of intensive biodiversity research after the 2009 Black Saturday wildfires in Victoria’s Mountain Ash forest

Blair

McBurney

et al. 2020

Australian Zoologist

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The catastrophic 2009 wildfires in the Mountain Ash (Eucalyptus regnans) forests of the Central Highl&s of Victoria provided an opportunity to gain new insights into the responses to fire by various elements of the biota. Ongoing long-term monitoring at a large number of permanent field sites for up to 25 years prior to the fire, together with 10 years of post-fire monitoring, has provided an unparalleled series of datasets on mammal, bird, & plant responses on burned & unburned sites. The empirical studies briefly summarized in this paper show patterns of steep declines in large old trees & declines in site occupancy by arboreal marsupials & birds. These changes contrast markedly with the responses of the two most common species of small mammals (the Agile Antechinus [Antechinus agilis] & Bush Rat [Rattus fuscipes]), which recovered within two generations after the fire. Declines in arboreal marsupials, birds & large old trees have also occurred on unburned sites, indicating an ecosystem-wide trend. In general, logging had a greater impact than fire on the majority of groups of birds & plants, particularly post-fire salvage logging that occurred in some areas following the 2009 wildfires. Beyond interactions between fire & post-fire (salvage) logging & their effects on forest biota, we have uncovered evidence of other kinds of interactions in Mountain Ash forests. These include interactions between: (1) the severity of fires & logging history, (2) post-fire bird population recovery & long-term climate & short-term weather conditions, & (3) impacts on forest soils. The structure & l&scape composition of the Mountain Ash ecosystem has been radically altered over the last century. This has resulted from the combined impact of several large fires, including the 2009 fires as well as widespread clearfell logging that has been conducted within state forests over the last 50 years. The ecosystem now supports old growth cover that is 1/30th to 1/60th of what it was estimated to have been prior to European settlement. The ongoing decline of key components of the Mountain Ash ecosystem has led to it being classified as Critically Endangered & at high risk of ecosystem collapse. We argue that current forest policy & practices need to better mitigate the effects of fire on this already highly disturbed forest & enhance the possible persistence of species in this ecosystem. Several key strategies are required to do this. First, there is a need to significantly exp& the extent of old growth within the Mountain Ash forest estate. This is because fire severity is diminished in such areas. Spatial contagion across old-growth dominated l&scapes also may be suppressed relative to l&scapes composed primarily of young forest. Allied management strategies include the protection of more mesic parts of Mountain Ash l&scapes as these are less likely to burn or at least burn at high severity. Such enhanced protection should include an exp&ed network of buffers around drainage lines & waterways as these are where fire severity is likely to be lowest & also where old growth elements like large old hollow-bearing trees are more abundant. In addition, all existing living & dead hollow-bearing trees need to be protected by buffers of unlogged forest within wood production forests to promote their st&ing life & better conserve cavity-dependent fauna such as the Critically Endangered Leadbeater’s Possum (Gymnobelideus leadbeateri) & other declining taxa like the Greater Glider (Petauroides volans).