volume: issue, issue:
Mechanical site preparation (MSP) is widely performed around the globe to enhance the success of forest plantations. However, MSP can cause severe soil disturbance whose magnitude depends on various factors such as soil characteristics, soil moisture conditions and the type of machinery. In an experiment conducted in Northeastern France, we analyzed the combined effects of machine size and soil water content on the soil structural quality following MSP performed with subsoilers mounted on excavators. MSP was carried out at two dates with different soil moisture contents (average soil moisture content at 10 cm depth: 40–54% during the wet period, 32–34% during the dry period), using two excavators that differed in weight (2.7 T and 9 T) and engine power, in two forest stands that differed in their soil characteristics (a sandy loam and a clay loam) and that both showed compacted soils. We used a profile wall method (i.e. a visual soil estimation method) to describe the soil structural quality, 2 to 6 months after MSP was performed. All instances of MSP resulted in an increase in the volume of soil favorable to root growth, i.e., soil with a friable structure, compared to the unprepared control (+60%). No evidence of soil degradation due to MSP (compaction, smearing, puddling, voids) was found in comparison to the unprepared control. The larger excavator prepared the soil to a greater depth due to its larger MSP tool and its higher engine capacity (depth of 40 and 53 cm, for the small and large excavator, respectively). MSP performed during the dry period resulted in a greater volume of soil favorable to root growth than MSP performed during the wet period (+60%). Our results indicate that MSP provides better results when conducted during the dry period. Therefore, it is strongly recommended that forest operators carefully consider the timing of MSP operations and prioritize dry soil conditions to execute them.
volume: 47, issue: 2
Mechanical site preparation (MSP) is widely performed around the globe to enhance the success of forest plantations. However, MSP can cause severe soil disturbance whose magnitude depends on various factors such as soil characteristics, soil moisture conditions and the type of machinery. In an experiment conducted in Northeastern France, we analyzed the combined effects of machine size and soil water content on the soil structural quality following MSP performed with subsoilers mounted on excavators. MSP was carried out at two dates with different soil moisture contents (average soil moisture content at 10 cm depth: 40–54% during the wet period, 32–34% during the dry period), using two excavators that differed in weight (2.7 T and 9 T) and engine power, in two forest stands that differed in their soil characteristics (a sandy loam and a clay loam) and that both showed compacted soils. We used a profile wall method (i.e. a visual soil estimation method) to describe the soil structural quality, 2 to 6 months after MSP was performed. All instances of MSP resulted in an increase in the volume of soil favorable to root growth, i.e., soil with a friable structure, compared to the unprepared control (+60%). No evidence of soil degradation due to MSP (compaction, smearing, puddling, voids) was found in comparison to the unprepared control. The larger excavator prepared the soil to a greater depth due to its larger MSP tool and its higher engine capacity (depth of 40 and 53 cm, for the small and large excavator, respectively). MSP performed during the dry period resulted in a greater volume of soil favorable to root growth than MSP performed during the wet period (+60%). Our results indicate that MSP provides better results when conducted during the dry period. Therefore, it is strongly recommended that forest operators carefully consider the timing of MSP operations and prioritize dry soil conditions to execute them.
