MODERN FOREST HARVESTING
PROCESSES AND TECHNIQUES
What is involved in a forest harvesting operation?
DGL performs forest harvesting services in Hawke's Bay. Utilising the latest technology to ensure safe and efficient extraction DGL is one of the largest privately owned operators in New Zealand employing close to 160 staff.
While the primary harvest is the fast-growing Radiata Pine, the company also has qualified operators for the felling and extraction of other species including Eucalyptus, Douglas Fir and natives. We pride ourselves on safe, efficient and modern techniques.
Once the extraction plan has been designed, felling of the forest can begin. At DGL we use the latest methods for safe and efficient tree felling. This is to ensure the least damage to the logs and the optimal direction for extraction.
Tree felling can be carried out in two ways, manually (using a chainsaw), or mechanically (using specialised felling equipment).
Which method is used depends heavily on the terrain and weather conditions that are encountered. Flat, easily accessed land is best for mechanical felling, where as steep or difficult to access blocks are usually felled manually or using steep slope harvesters.
Once trees have been felled, they are extracted this can be done using several different methods. Again, this is dependant on the terrain and is typically done according to the extraction plan completed prior to work commencing.
When establishing the extraction plan safety and the environment is paramount, accompanied by proficient workers to ensure minimal damage with maximum return to the forest owners.
Possible methods for extraction include:
Ground-Based - Operating a skidder, tractor of forwarder. This is done on gradients of 22º or less.
Cable Logging - Operating a hauler or swing yarder. This method is best for steeper, difficult to access terrains.
Shovel Logging - Operating a excavator with a grapple. This method is best for short distances where the landing for processing is nearby.
Aerial Logging - Operating a helicopter. This method is best for ensuring the least environmental impact but is not very cost efficient. It is generally used for high value logs such as native timber.
Once the trees have been extracted, they then need to have their limbs removed so that they can then be measured and graded for log making. This can be done manually with a chainsaw, or mechanically with a delimbing machine, or static delimber.
Once delimbed, trees are then measured and graded to extract the maximum value from each. They are then cut up in to logs either by a log maker using a chainsaw, or using a mechanical log maker.
Mechanical log makers use computers and sensors to measure, grade and cut logs, this is often the safest and most profitable way of log making.
Once the tree has been processed and turned in to logs, they are transported to either the mill for processing, or to the port for export.
The logs are loaded on to trucks using a boom or wheel loader. Each load will be for a specific grade of log, the oldest logs are typically loaded first. Loading operations can run over long hours and it is not uncommon on busy sites for loading to run 24 hours a day.
Throughout the extraction process, quality control checks are carried out to ensure that the logs being delivered are of the best possible grade and that grading is correct. Both internal and external quality control checks may be carried out, any issues that arise are rectified immediately by the Operations Manager.
The final stage of the harvesting process is to clean up the site leaving as little environmental impact as possible. This includes cleaning the site of slash and rubbish, reparation to site access roads and landings, also ensuring waterways are repaired and clean.
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