Benchmarks of fallen timber and man's role in nature: Some evidence from eucalypt woodlands in southeastern Australia

Fallen timber is widely considered to be a key element of ecosystem structure and function that is critical to maintenance of biodiversity. This concept is closely linked to ideas of wilderness and old growth. ‘Conventional wisdom’ is that fallen timber has been drastically depleted from natural levels by human activity. However natural conditions reflect interactions of Aborigines with their environment, and fallen timber as well as broadcast fire was critically important to Aboriginal economies in the New World and Australia. Quantitative historical data are not available, so it is necessary to use qualitative historical information to describe natural loads and dynamics of fallen timber. A comparison against detailed historical descriptions of woodlands under Aboriginal management in Australia indicates that benchmarks from ‘undisturbed’ examples of the same types of vegetation are generally inflated. The ecological history of grassy woodlands since European settlement shows that proposed ‘restoration’ measures will favour common and widespread biota at the expense of rare and endangered species. No correlation of biodiversity with fallen timber has been demonstrated for grassy eucalypt ecosystems. Globally, conservation strategies that minimize human activity have generally failed because resilience of ecosystems and ancient trees has been reduced and rare species have been lost. The concept of wilderness has little application outside the unpeopled continent of Antarctica.

► Use of fallen timber and broadcast fire was critical to Aboriginal economies.
► Fallen timber accumulates in the absence of human economy.
► Associated changes can favour common species over rare species.
► Ecosystems that developed with humans need human economy to function properly.