Abstract
This study aimed to determine levels of pressure and compaction induced by forest harvesting operations in a Red Latosol (LV) under planted eucalyptus. Undisturbed soil samples were collected from layers 0-3 and 15-18 cm and then used in a uniaxial compression test. Sampling was done before and after harvesting operations. Equipment being evaluated included: harvester, feller buncher, forwarder, self-loading adapted tractor, standard truck, wide-tire truck and grapple saw. Average pressures induced by the grapple saw were 320 kPa and 272 kPa, causing compaction in 80% and 20% of samples respectively from layers 0-3 cm and 15-18 cm, which indicates substantial degradation of soil structure in areas where timber is processed. In layer 0-3 cm, average pressures induced by the harvester and by the feller buncher were 240 kPa and 263 kPa respectively, while in layer 15-18 cm pressures were 234 kPa and 239 kPa respectively. The feller buncher caused higher soil compaction than the harvester in layer 0-3 cm, yet in layer 15-18 cm they had similar behavior. All timber forwarding equipment led to soil compaction. The wide-tire truck was the forwarding implement promoting the highest rate of compaction, in both residue conditions. Traffic intensity 7 promoted the highest rate of soil compaction.
Highlights
It was not until the 60s that the forestry sector started to become prominent in Brazilian economy, before it was characterized by predatory exploitation of forest resources
With the mechanization of harvesting operations came soil degradation due to heavy traffic of machinery (FERNANDES; SOUZA, 2003; LOPES et al, 2006), an activity often conducted under unsuitable moisture conditions or in a low load-bearing capacity soil (DIAS JÚNIOR et al, 2005), which lead to degradation of the soil structure and to soil compaction, to a point of jeopardizing productivity over time (DIAS JUNIOR et al, 2007)
In layers 0-3 cm and 15-18 cm, the grapple saw caused compaction in 80% and 20% of the samples respectively (Table 3), indicating substantial degradation of the soil structure in areas where timber is processed. These results agree with values found by Dias Junior et al (2005) and can be explained by the fact that timber processing occurred under moister than usual soil conditions, namely 0.4020 m3 m-3 and 0.4018 m3 m-3 for layers 0-3 cm and 15-18 cm respectively, and by average pressures as measured after harvesting operation being 320kPa and 272 kPa for layers 0-3 cm and 15-18 cm respectively (Table 3)
Summary
It was not until the 60s that the forestry sector started to become prominent in Brazilian economy, before it was characterized by predatory exploitation of forest resources. Among new technologies used in the sector were chainsaws and agricultural winch tractors (MALINOVSKI et al, 2002) It was only from the 90s (FERNANDES; SOUZA, 2003) that mechanized harvesting operations really intensified, with importation of machinery from Europe and United States such as feller bunchers, harvesters, skidders etc. A major challenge of studies on sustainability is to develop methodologies with which to evaluate quality of soils and environments subjected to human impact (MENDES et al, 2006) This technological development of mechanized forest harvesting and its resulting potential to promote soil compaction have prompted researchers to use several physical and mechanical properties to quantify the effect of compaction on soil structure
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