Removal of Woody Debris from Logging Gaps Influences Soil Physical and Chemical Properties in the Short Term: A Study Case in Central Amazonia

Generally, woody residues generated from logging remain on site, although recently, forest managers have been harvesting this material for energy generation. We evaluated the impact on an Oxisol's physical and chemical properties after removal of residues (coarse woody debris, CWD) from logging-created gaps. The logging operations occurred on private timberland in the Central Amazon. Eighteen months after creation of the gaps, soil samples were taken up to 150 cm depth in each treatment: mature undisturbed forest (FOR), gaps with residues retained on site (RET), and gaps with removal of large branches greater than 10 cm in diameter that were from logging (REM). Clay content, up to 20 cm depth, was higher in RET and REM soils than in FOR soils. Soil bulk density values increased progressively from areas of FOR to RET and REM at 0-5 cm. The highest carbon and nutrient contents were observed in the 0-5 and 5-10 cm soil layers of RET. In the 10-30 cm depth, the contents of all nutrients, except phosphorus, were higher in REM soils. According to these short-term results, it is not possible to affirm categorically that the removal of CWD has a negative impact on the nutrient status of soils in gaps created by logging operations. Study Implications: This study aimed to investigate the influence of coarse woody debris removal for energy generation on soil nutrients in a logging area in the Amazonas state, Brazil. We compared three areas, one in which the residues were removed from the gaps, another where residues in gaps were retained, and one undisturbed natural forest as control. We found that coarse wood debris removal does not significantly change soil physical properties. On the other hand, removal accelerates leaching of nutrients to greater soil depths and leads to higher calcium contents in depths to 150 cm, although the soil phosphorus decreases after debris removal.

Automated summary

The study investigated the influence of coarse woody debris removal for energy generation on soil nutrients in a logging area in the Amazonas state, Brazil. It was found that debris removal does not significantly change soil physical properties but accelerates the leaching of nutrients to deeper soil depths, resulting in higher calcium contents but lower soil phosphorus levels.