Logging of primary rainforests not ecologically sustainable, argue scientists
January 25, 2012
Rhett Butler, mongabay.com
Tropical countries may face a risk of 'peak
timber' as continued logging of rainforests exceeds the capacity of forests to
regenerate timber stocks and substantially increases the risk of outright
clearing for agricultural and industrial plantations, argues a trio of
scientists writing in the journal Biological Conservation. The
implications for climate, biodiversity, and local economies are substantial.
Reviewing an extensive body of recent scientific literature, Philip Shearman of
the University of Papua New Guinea and Australian National University, Jane
Bryan of the University of Papua New Guinea and the University of Tasmania, and
William F. Laurance of James Cook University conclude that dominant harvesting
practices in tropical forests do not allow enough time for forestry recovery,
leading to significant degradation of biodiversity and carbon stocks. The
researchers extend their argument to conventional logging approaches as well as
"sustainable forest management" techniques like reduced-impact logging
(RIL), which aim to cut collateral damage to the forest from selective logging.
recovery time taken for logged forest to resemble primary rainforest in
biomass, timber volume and species diversity has been variously estimated at
45–100 years, 120 years, and 150–500 years," they write. "Larger
rainforest trees can range in age from many decades to a millennium or more,
illustrating that recovery of large trees in logged forests requires far more
than the nominal 30–35 year logging cycles commonly applied in the
Shearman and colleagues says this inherent lack of sustainability motivates
loggers to continually move into virgin forest areas to maintain timber
production. Eventually loggers will find it harder and harder to find high
value tropical forests to log, say the authors, pointing to several Asian
countries — including Malaysia, Thailand, Laos, the Philippines, and the
Solomon Islands — which have already seen their timber production peak.
Shearman and colleagues use the Solomon Islands as a case study for the fate
that can befall tropical countries that rely heavily on old-growth forest
logging to produce raw-logs, which are "generally absent" from
"For nearly a decade, the nation had been warned that the volume of timber
annually harvested from native forests was too high and, if unchecked, that
timber stocks would be seriously depleted by 2012," they write. "In
2009, the Central Bank of the Solomon Islands asserted that exhaustion of
timber stocks had arrived even earlier than predicted and its economic
consequences were likely to be severe."
The scientists note that even rich countries have struggled to successfully
implement "sustainable" forestry in the tropics, where valuable trees
occur at a lower density than in temperate regions due to the high levels of
"Even in north Queensland, Australia, where advanced stand-yield models
were eventually used to set annual timber quotas and the Queensland Forestry
Department was heavily subsidized by government revenues, timber yields
declined sharply from the 1960s to 1980s, as virgin or near-virgin forests were
exhausted," they write. "If sustainable logging largely failed in
north Queensland, what chance does it have in most developing nations, where
economic pressures are paramount and a range of other complications, such as
poor enforcement of environmental regulations, weak or non-existent land
tenure, and often-high discount rates, further militate against sustainable
The experience in Australia seems to suggest that certification schemes based
on first-time logging of primary tropical forests would require extended
recovery times — upwards of 50 years — to be considered remotely sustainable.
Like other resource-extracting industries, the logging sector tends to
overcapitalize and overexploit.
"Having lower harvest intensities and longer rotation times becomes very
difficult under these circumstances," Laurance told mongabay.com via
email. "It's usually about 'cut and run', which is the pattern one really
sees now with the Malaysian and other logging multinationals. This is fine for
the multinationals but bad for timber-producing countries."
Logging today, gone tomorrow
Selective logging can be damaging in and of itself to forest ecology, but even
more worrying for the authors is that logging in any form substantially
increases the risk of complete forest clearing.
"[Rigorously implemented RIL] fails to address the insidious problem that,
in most parts of the world, logging catalyses much deforestation," they
write. "Across tropical Africa, Asia, and the Americas, labyrinths of
logging roads have opened up vast swaths of formerly remote forest for
colonization, hunting, illegal mining and other destructive activities."
Clearing of previously logged forest is particularly acute in Indonesia, where
palm oil producers and pulp and paper companies have converted vast swathes of
land for plantations. The authors note that Indonesia's recent decision to
exclude some 35 million hectares of logged-over secondary forest from their
moratorium on new concessions for plantations was in part driven by
accessibility granted by logging roads.
Could carbon payments stop unsustainable
is expected to figure prominently in a climate change mitigation measure known
as reducing emissions from deforestation and degradation (REDD), which is
currently under discussion in international climate talks. The concept
originally aimed to fund relatively conventional forest conservation, but has
since been expanded to REDD+ to include activities that degrade forests and
therefore produce carbon dioxide. REDD+ may involve logging in two ways:
providing funds to prevent it outright in a project area or acting as a form of
subsidy to shift conventional logging practices toward less damaging ones
(REDD+ compensation is based on reductions in emissions relative to a
predetermined baseline). The authors make the case that because any form of
logging degrades tropical forest, "REDD+ funds should be directed at
initiatives designed to keep loggers and their associated road networks out of
forests, rather than merely modifying logging operations."
"Compensating governments not to log is arguably the easiest and most
practical means to reduce greenhouse-gas emissions from the forestry sector,
whereas paying to restore logged forests in regions, where their degradation
continues apace is difficult to justify."
The authors also highlight opportunities to directly tackle tropical forest
logging, including bans on raw-log exports that have been adopted by many
countries, reducing annual allowable cuts and extending rotation times,
eliminating barriers to community ownership of forests through land tenure
reform, cutting subsidies that favor industrial forestry, and establishing
protected areas where logging is prohibited. Shearman, Bryan, and Laurance
conclude that unless the logging industry undergoes fundamental changes,
"logged tropical forests will continue to be overharvested and, far too
frequently, cleared afterward, leading to an inevitable global decline in
native timber supplies."
The impacts could be dire for global ecology as well as forest-dependent economies.
The authors compared it to concerns in other sectors.
"It has become common these days to speak of 'peak oil' and 'peak
phosphorus'. In the tropics, we assert, we should also begin seriously to
consider the implications of 'peak timber'."