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Logged rainforests are a cheap conservation option

Selectively logged lowland forest in Indonesian Borneo
Selectively logged lowland forest in Indonesian Borneo. Photo by Rhett Butler

With old-growth forests fast diminishing and land prices surging across Southeast Asia due to high returns from timber and agricultural commodities, opportunities to save some of the region’s rarest species seem to be dwindling. But a new paper, published in the journal Conservation Letters, highlights an often overlooked opportunity for conservation: selectively logged forests.

A number of studies have shown forests logged for only a few valuable tree species retain the majority of their biodiversity. The new paper, authored by Princeton University’s Brendan Fisher and others, confirmed this by analyzing the number of birds and dung beetles — considered good indicators of overall species richness — in logged and unlogged forests in Malaysian Borneo. The researchers then looked at financial returns of logging in the same forests.

Changes in standing timber value and species richness for all birds, understory birds, and dung beetles across unlogged (primary), once-logged, and twice-logged lowland forests. The left-hand y-axis corresponds to mean number of species per sampling unit and the right-hand y-axis corresponds to mean standing timber value per hectare in dollars (in 2009 U.S. dollars). Image and caption courtesy of Fisher et. al 2011. Click to enlarge

Fisher and colleagues found that while the value of standing timber fell dramatically after one (60 percent drop) or two (80 percent drop) harvest cycles, the level of biodiversity fell by less than a quarter. The results suggest that selectively logged forests represent a cost-effective means for wildlife conservation: logged-over forests may be less expensive to acquire for protected areas and corridors to connect existing parks and reserves.

“Enlarging existing protected areas by acquiring logged
forests can ensure larger, more viable populations of
forest-dwelling species and reduce deleterious edge effects,” write the authors.
“Moreover, well-protected logged forests are likely
to recover over time and therefore represent not only important
current habitat for species, but also future habitat
for species that require mature forests and cannot tolerate
logged forests. For such species, maintaining connectivity
between logged forests and unlogged forests is likely to be
important in order to permit eventual dispersal into the
recovering logged forest.”

The findings are especially relevant in Asia because roughly 50 percent of forests in Malaysia and Indonesia are zoned for logging. While these “production forests” may be degraded, they do retain substantial amounts of biodiversity and provide ecosystem services like carbon sequestration, erosion control, and watershed maintenance.

The authors conclude with a careful warning not to misinterpret their results, lest loggers see the study as an opportunity to push for first-time logging of existing protected areas. They also caution that the study doesn’t justify abandonment of primary forests as a priority for conservation efforts.

Selectively logged forests house more biodiversity and store more carbon than conventionally logged forests, industrial agriculture, and plantations—including oil palm and pulp and paper estates. Photo by Rhett Butler.

“The bird and dung beetle losses that occur during
logging are not trivial, and our results should not be
used to suggest that, by logging primary forests, governments
could gain huge financial profits at little cost to
biodiversity,” they write. “The logging of primary forests precipitates
a significant loss of biodiversity.”

“Beyond biodiversity, Southeast Asia’s lowland
dipterocarp forests provide numerous ecosystem services,
including carbon storage, regulation of river flows
and sedimentation, and a variety of aesthetic and cultural
benefits. In some cases, these ecosystem services
have quantifiable economic values, such that the logging
of primary forests will predicate (sometimes large) social

CITATION: Brendan Fisher, David P. Edwards, Trond H. Larsen, Felicity A. Ansell, Wayne W. Hsu, Carter S. Roberts, & David S. Wilcove. Cost-effective conservation: calculating biodiversity and logging
trade-offs in Southeast Asia. Conservation Letters 0 (2011) 1–8

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