Logging in the Amazon forests has serious impacts on forest health and biodiversity: it changes forest composition by removing valuable trees like mahogany, it damages surrounding trees during felling and road building, and it fragments the forest, elevating risks for fire. In the 1990s, the IMAZON institute documented that for every commercial tree removed, 16-27 other trees more than 10 cm in diameter are damaged, 40 m of road are created and 600 m2 of canopy is opened. Reduced impact logging (RIL) can help to reduce some of this damage. Techniques in the Amazon basin include directional felling, liana cutting and effective road planning; liberation cuttings are also used to improve tree growth. Testing trees for wood quality can also reduce waste, as hollow trees are often cut accidentally but left behind. Studies of RIL in Para, Brazil, have shown that reduced impact techniques minimize total forest damage compared to conventional logging.
While RIL techniques are often disregarded for their initial cost, studies often find them beneficial in the long term due to reduced wood waste and less damage to future growing stock. RIL techniques can also save labor and machinery operating time. Reduced impact logging is usually more practical in remote, selective logging areas of the Amazon basin, as opposed to more intensely logged regions, due to the lower efficiency. Finally, new research suggests that reduced impact logging techniques may be able to substantially reduce carbon emissions from forestry activities.
An important consideration in reduced impact logging is the effect that it will have on the regeneration potential of the site. Many Amazon species such as mahogany, Spanish cedar, and Brazil nut are light demanding and may need larger disturbance gaps than those provided by the small gaps from RIL and selection systems. Moreover, gaps are likely to be colonized by lianas and non-commercial pioneer species like Cecropia, and studies find that over time, both RIL and conventional logging can lead to deterioration of commercial value. Enrichment planting and tending techniques such as liberation cuttings and girdling of competitor trees can facilitate the maintenance of high value stands.
In the western Amazon, selective logging can be practiced alongside Brazil nut harvest (Bertholletia excels), a commercially profitable non-timber nut. Both activities can be compatible, as logging is usually practiced in the dry season (July-November) and nut harvest in the wet season (January-March) or year round. Studies find that in FSC certified operations, RIL techniques cause little damage on Brazil nut trees. See more about Brazil nut harvest and selective logging in this CIFOR blog. See an overview of reduced impact logging techniques.
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