- Brazil accounts for 85 percent of all native neotropical forest roundlog production, but the sustainability of timber harvests beyond the initial, typically selective rounds of logging, remains poorly understood, according to a study published in the journal PLOS ONE today.
- A team of researchers with the University of East Anglia (UEA) in the UK studied 824 harvest areas in private and community-owned forests scattered throughout the 124-million-hectare (more than 306-million-acre) Brazilian state of Pará, which is the source of almost half of all timber production in the Brazilian Amazon.
- They say their results show that managing yields of selectively-logged forests is crucial for the long-term health of forest biodiversity as well as the financial viability of local industries.
Researchers in the Brazilian Amazon say they have found no evidence that the composition of timber species and total forest value recover even after highly selective logging, suggesting that the most commercially valuable species must inevitably become rare or even “economically extinct” in old logging frontiers.
Brazil accounts for 85 percent of all native neotropical forest roundlog production, but the sustainability of timber harvests beyond the initial, typically selective rounds of logging, remains poorly understood, according to a study published in the journal PLOS ONE today.
A team of researchers with the University of East Anglia (UEA) in the UK studied 824 harvest areas in private and community-owned forests scattered throughout the 124-million-hectare (more than 306-million-acre) Brazilian state of Pará, which is the source of almost half of all timber production in the Brazilian Amazon. The researchers analyzed data from legal logging operations that harvested some 17.3 million cubic meters of timber from 314 different tree species.
They say their results show that managing yields of selectively-logged forests is crucial for the long-term health of forest biodiversity as well as the financial viability of local industries. And these lessons don’t just apply to the Brazilian Amazon, they write in the study: “The logging history of eastern Amazonian old-growth forests likely mirrors unsustainable patterns of timber depletion over time in Brazil and other tropical countries.”
Dr. Vanessa Richardson of UEA’s School of Environmental Sciences, the lead author of the PLOS ONE study, says there are parallels between the impacts of supposedly sustainable logging and other slow-growing, commercially valuable species that have been overexploited throughout human history — “just look at the whaling industry or fisheries,” she said in a statement.
“Yet many tropical timber species are still thought of as a renewable resource,” Richardson added. “We are only beginning to see over-exploitation parallels in tree species. Our research shows that many high-value timber species are logged until their populations collapse altogether.”
However, over-exploitation is not inevitable, Richardson and her co-authors note in the study. Rather, over-exploitation is usually a consequence of inadequate regulation of industry combined with open-access systems such as forests, a dynamic that has been referred to as “the tragedy of the commons.”
Previous studies of Asian markets have found that current commercial agreements could lead to “peak timber” and widespread economic extinctions across tropical regions, Richardson said. “Our study adds a Neotropical body of evidence to support this. We can already see a market shift, in which loggers in old depleted Amazonian logging frontiers are forced to depend on fast growing, soft-wood timber species.”
Logging operations in tropical forests vary widely in the degree to which they can be deemed “sustainable,” but timber is generally considered a renewable resource, the study notes. But if forests never recover from the initial, selective cuts, that prevailing wisdom may now be seriously called into question.
The first rounds of logging tend to target valuable hardwood species, but when loggers can no longer depend on areas where these high-value species were formerly abundant, they are forced to extract timber trees from new areas of unlogged primary forests in order to see the same economic returns.
As a result, many valuable Amazonian timber tree species are facing moderate to high extinction risk, per the study, including a range of canopy and emergent species such as big-leaf mahogany, Brazil-nut tree, freijó cinza (Cordia goeldiana), ipê (Tabebuia serratifolia, T. impetiginosa), jatobá (Hymenaea courbaril), and pau amarelo (Euxylophora paraensis).
The authors of the PLOS ONE study write that they “urge national policy makers to curb the largely unchecked tide of widespread depletion of the most harvest-sensitive timber species.”
“Our analysis shows that even so-called ‘reduced-impact logging’ in tropical forests can rarely be defined as sustainable in terms of forest composition and dynamics in the aftermath of logging — never mind the greater susceptibility of logged forests to catastrophic fires,” Carlos Peres, a professor with UEA’s School of Environmental Sciences and a co-author of the study, said in a statement.
“Environmental licensing and market certification of logging concessions need to take this into account, and review minimum preconditions in terms of volumetric quotas of roundlogs harvested per species and regeneration standards over multi-decade logging cycles.”
CITATION
- Richardson, V. & Peres, C. (2016). Temporal Decay in Timber Species Composition and Value in Amazonian Logging Concessions. PLOS ONE. doi:10.1371/journal.pone.0159035