Guyana – Reduced Impact Logging – is this a workable concept for biodiversity protection?

Written by Dr Tim Coles

Protecting forests from any form of exploitation as National Parks, Wildlife Preserves or any of a number of conservation categories, is a key component of forest and wildlife protection in most countries.  However, this strategy is never going to affect more than around 10% of the forests in a country (note there are exceptions to this such as Dominica where around 20% of the island is protected) so do we just abandon wildlife protection in these other areas which are going to need to produce income for local communities?  Clearly converting forests to other land uses (eg agriculture) has a major impact on the wildlife of those forests but what types of income generation can be used to leave the majority of the forests still standing and the wildlife communities mainly intact?

In 1989 the Guyana government offered 1 million acres of primary lowland forest to the Commonwealth as a site to demonstrate how biodiversity and income generation could be combined successfully.  This eventually led in 1996 to the formation of the Iwokrama Rainforest Preserve and since 2011 research teams from Opwall have been completing annual surveys of a range of taxa (large mammals, bats, birds, reptiles and amphibians and dung beetles) at a series of sites across the forest.  Iwokrama was split into approximately 50% of the forest that is Wilderness Preserve with no exploitation allowed and 50% that is a Sustainable Use area and the survey sites have been structured so that forest in both categories have been monitored annually.

Most of the Sustainable Use areas though have only been used for low level ecotourism activity with virtually no structural change to the forest.  However, in 2004 Iwokrama started on a concept of Reduced Impact Logging within the Sustainable Use Areas.  The basis behind this plan was to develop income from the 20 – 25 species of tree that could be sold commercially (eg Greenheart a hardwood species endemic to the Guiana Shield, Purpleheart, Wamaradan etc) but to leave the rest of the forest standing.  This approach dubbed Reduced Impact Logging (RIL) was designed to log only the target species on a 60 year rotation.  The whole sustainable use forest was mapped into just over 1000 X 1km square felling blocks with the target being to harvest around 18 of these felling blocks each year.  RIL requires a LOT more investment in planning than traditional harvesting techniques but this investment is made back at the cutting stage because it is so much more efficient.

RIL starts with detailed inventories of each felling block.  A 1km square has cross trails marked every 50m and the GPS location of each of the target tree species to be harvested within each 50m square is marked.  The trees have to be mature, cannot be closer than 10m to another tree that is due for felling and there are strict limits on how close to a water course any tree for felling can be harvested.  The net result is that only 1% of the trees (5% by volume) within each felling block on average are identified for felling.  In South America where there are just a few species that have commercial value, the normal technique is to take an order for say Purpleheart and the chainsaw team just wanders through the forest looking for that species and felling it.  Large machinery then follows in to pull out the trees but in around 50% of the cases can’t find the trees that have been felled!  So the total amount of forest damaged is enormous, as the machinery used to drag out the timber makes unnecessary trails searching for the felled trees.  Note in places like Indonesia where many more of the tree species are commercially valuable, entire areas are clear felled rather than concentrating on just the commercially valuable species.

With the RIL technique, directional felling is used for each of the trees to be harvested.  The forest inventory surveyors mark the direction of fall for each tree to minimise impact on surrounding trees and to maintain the canopy as intact as possible.  Removing the trees is done using skid trails where a wheeled crane called a skidder pulls the felled trees out along a skid trail to a central location (see example felling block map which shows the position of the skid trails which have been set up to minimise damage to the forest).

On the face of it, if this technique can yield as much value as more damaging forest techniques, then it would have enormous applications for forestry elsewhere around the world.  It sounds as though the impact on biodiversity should be minimal – but is this really the case?  That is what the Opwall surveys are attempting to answer but so far all the indications are that this is a technique with minimal impact on the biodiversity.  If this can be demonstrated then the implications for how the 90%+ of forests not within protected areas around the world can be exploited whilst still protecting their biodiversity, are enormous!