Logging studies plagued by sampling problems

Jeremy Hance
March 18, 2013

A logging road splits rainforest in the Malaysian state of Sabah in Borneo. Photo by: Rhett A. Butler.
A logging road splits rainforest in the Malaysian state of Sabah in Borneo. Photo by: Rhett A. Butler.

Although research into the impact of selective logging in tropical forests has been booming recently, much of it is undercut by basic research flaws, according to a new study in mongabay.com's open access journal Tropical Conservation Science. Selective logging means targeting certain species or only a particular number of trees per hectare, and as such is considered generally more environmentally-friendly than clearcutting, which strips entire forests.

"Selective logging has been proposed as a type of land use that is the least detrimental to animal and plant communities in tropical forests," the researchers from the Federal University of Amapá in Brazil and the University of East Anglia in the UK write. "Hence, a growing number of studies have sought to determine the effects of selective logging on tropical forests."

But analyzing 75 studies on selective logging, the scientists found that 88 percent did not include a pre-logging baseline, making it difficult to note what impacts in fact were due to logging. In addition the studies employed a wide-variety of different time and spatial scales while using different animal groups to measure impact. Such variations make it near impossible to compare studies side-by-side.

The researchers also found that many studies left out vital information.

"For example, basic but critically important information such as geographic coordinates of study areas are rarely reported," they write. "Many of the studies we reviewed failed to present a map showing the geographic location of the logged and unlogged forest areas, the availability of unlogged primary forest or other relevant information on surrounding habitat types (e.g., secondary forest, plantation, pasture)."

The scientists recommend that future studies on logging impacts should include as large as spatial areas as possible, information both on pre- and post-logging, and should be conducted over the longterm if possible. More rigorous studies are needed if we are to really understand the impacts of selective logging in the world's tropical forests.

"Logged areas will become of increasingly greater importance for tropical forest wildlife conservation, considering the growing global demand for timber products and the resulting increase in the intensity and extent of selective logging in vast areas of tropical forests," the authors write.

CITATION: Laufer, J., Michalski, F., and Peres, C. A. 2013. Assessing sampling biases in logging impact studies in tropical forests. Tropical Conservation Science Vol. 6(1):16-34.

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Jeremy Hance
mongabay.com (March 18, 2013).

Logging studies plagued by sampling problems.