David Hillier (0719575)
Blog Assignment 2
October 14, 2010
It has become common knowledge that environmental degradation is made worse by excessive logging. Any individual with an understanding of the environment realizes this fact; trees perform photosynthesis which removes carbon dioxide from the atmosphere and we all breathe a little easier. When the trees are cut down, we all suffer. However, many do not think of the legacy of damage left behind by logging. The harvesting of forests requires great stretches of roads and the machinery that travel these roads have a negative impact on underlying soil say Flemish researchers.
“A good soil pore system is vital to soil biota, tree roots and ground vegetation,” say the researchers from Ghent University. In the paper, attention is drawn to soil compaction and contamination due to the repetitive back and forth movement of harvesting machinery; “…smaller pore sizes reduce hydraulic conductivity leading to a slower water infiltration and increased runoff… as root tips have to overcome soil strength to be able to elongate, root growth may be hampered.” Without productive soil leftover, a detrimental future is the result for our forests.
The research was conducted over the course of a year in both winter and summer conditions. Eight strands of forest in Belgium were used for the study. Measurements of dry-bulk density, penetration resistance, and soil carbon dioxide concentration were taken with initial soil texture, machine mass, and traffic frequency taken into consideration and controlled.
It was found that the relationship between soil compaction and traffic intensity grew in a logarithmic pattern. At first compaction was positive but soon became close to zero. Interestingly, the researchers therefore came to the realization that the frequency of traffic has a small impact on soil quality, “Significant effects on BD (bulk density) were nearly absent and occurred occasionally for PR (penetration resistance)... The negligible compaction degrees… are attributed to high initial compaction levels that prevented further compaction.” This means although the rate of soil compaction is high at first, once the soil becomes compact it is difficult to stress it any further.
Instead, carbon dioxide concentration proved to be the most significant indicator of soil compaction. The researchers observed that even after one back and forth movement of equipment a substantial jump in soil carbon dioxide concentration occurred both inside and outside of the tracks. It was found that any increase in soil compaction greatly reduces the ability for gas exchange. The sealing of pores and reduced oxygen concentration in the soil can mean doom for forest recovery, “…the altered gas exchange after soil compaction resulted in higher mean carbon dioxide concentrations and lower oxygen concentrations in the soil. This may cause problems… as root growth of seedlings is reduced when the oxygen concentration drops.” This makes reclamation far more difficult. The repetitive movement of heavy machinery seems to “choke out” the soil, limiting its ability to breathe.
A natural remedy exists but is very slow to act, providing ample time for forest damage. Time is something global warming does not seem to have a problem with, “Recovery of a compacted soil is a long-term process that is largely based on freezing and melting of soil water, swelling and shrinking of clay particles and biological activity of roots and soil animals that break up the soil. Literature shows that it can take at least 20–30 years before recovery is complete.” This time period is definitely a minimum. The authors go on to say that in some cases 30-40 years is insufficient for complete recovery. Gas diffusion and root density is still impacted after this time period. The authors say it best: “High compaction degrees should thus be prevented.”
The paper has several suggestions that would help with this issue. An understandable solution is reducing contact pressure by using lighter machinery. Another suggestion evolves from the data found earlier in the paper. The fact that compaction becomes less over time speaks to having permanent trail ways and use of already compacted areas. This would limit the area of soil that is affected. The authors also consider that some mechanical loosening could help to augment the natural recovery process.
This fresh research opens up an entirely new aspect to forest reclamation. This novel aspect could put added pressure on the industry to place more emphasis on the rehabilitation effort of our natural forest environments; all the better for saving the trees.
Blog Assignment 2
October 14, 2010
It has become common knowledge that environmental degradation is made worse by excessive logging. Any individual with an understanding of the environment realizes this fact; trees perform photosynthesis which removes carbon dioxide from the atmosphere and we all breathe a little easier. When the trees are cut down, we all suffer. However, many do not think of the legacy of damage left behind by logging. The harvesting of forests requires great stretches of roads and the machinery that travel these roads have a negative impact on underlying soil say Flemish researchers.
“A good soil pore system is vital to soil biota, tree roots and ground vegetation,” say the researchers from Ghent University. In the paper, attention is drawn to soil compaction and contamination due to the repetitive back and forth movement of harvesting machinery; “…smaller pore sizes reduce hydraulic conductivity leading to a slower water infiltration and increased runoff… as root tips have to overcome soil strength to be able to elongate, root growth may be hampered.” Without productive soil leftover, a detrimental future is the result for our forests.
The research was conducted over the course of a year in both winter and summer conditions. Eight strands of forest in Belgium were used for the study. Measurements of dry-bulk density, penetration resistance, and soil carbon dioxide concentration were taken with initial soil texture, machine mass, and traffic frequency taken into consideration and controlled.
It was found that the relationship between soil compaction and traffic intensity grew in a logarithmic pattern. At first compaction was positive but soon became close to zero. Interestingly, the researchers therefore came to the realization that the frequency of traffic has a small impact on soil quality, “Significant effects on BD (bulk density) were nearly absent and occurred occasionally for PR (penetration resistance)... The negligible compaction degrees… are attributed to high initial compaction levels that prevented further compaction.” This means although the rate of soil compaction is high at first, once the soil becomes compact it is difficult to stress it any further.
Instead, carbon dioxide concentration proved to be the most significant indicator of soil compaction. The researchers observed that even after one back and forth movement of equipment a substantial jump in soil carbon dioxide concentration occurred both inside and outside of the tracks. It was found that any increase in soil compaction greatly reduces the ability for gas exchange. The sealing of pores and reduced oxygen concentration in the soil can mean doom for forest recovery, “…the altered gas exchange after soil compaction resulted in higher mean carbon dioxide concentrations and lower oxygen concentrations in the soil. This may cause problems… as root growth of seedlings is reduced when the oxygen concentration drops.” This makes reclamation far more difficult. The repetitive movement of heavy machinery seems to “choke out” the soil, limiting its ability to breathe.
A natural remedy exists but is very slow to act, providing ample time for forest damage. Time is something global warming does not seem to have a problem with, “Recovery of a compacted soil is a long-term process that is largely based on freezing and melting of soil water, swelling and shrinking of clay particles and biological activity of roots and soil animals that break up the soil. Literature shows that it can take at least 20–30 years before recovery is complete.” This time period is definitely a minimum. The authors go on to say that in some cases 30-40 years is insufficient for complete recovery. Gas diffusion and root density is still impacted after this time period. The authors say it best: “High compaction degrees should thus be prevented.”
The paper has several suggestions that would help with this issue. An understandable solution is reducing contact pressure by using lighter machinery. Another suggestion evolves from the data found earlier in the paper. The fact that compaction becomes less over time speaks to having permanent trail ways and use of already compacted areas. This would limit the area of soil that is affected. The authors also consider that some mechanical loosening could help to augment the natural recovery process.
This fresh research opens up an entirely new aspect to forest reclamation. This novel aspect could put added pressure on the industry to place more emphasis on the rehabilitation effort of our natural forest environments; all the better for saving the trees.
Ampoorter, E., Hermy, M., Van Nevel, L. and Verheyen, K. (15 September 2010). Assessing
the effects of initial soil characteristics, machine mass and traffic intensity on forest soil
compaction, Forest Ecology Management, 260 (10), 1664-1676.
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