Wood harvesting method and a harvester head needed for its implementation

A wood harvesting method used to harvest trees from a forest site without having to bring a harvester to the site more than once, to bunch trees in the harvester's grapple by using grapples fastened to the harvester and to cut them with a cutting device fastened to the harvester, two of said grapples being rigid and another grapple being articulated, said method comprising using at least the following work phases in the harvesting in bunches, essentially in the following order:

• place the harvester head against a first tree with all grapples open,
• close all the grapples around the first tree,
• cut the first tree with the cutting device,
• lift the cut first tree, holding the cut first tree with the grapples fastened to a telescopic boom and using a stroke cylinder to move the telescopic boom in relation to a main body,
• move to the next tree to be cut, holding the cut first tree in an upright position,
• take the harvester head close to the second tree, open the rigid grapples and keep the cut first tree in an upright position with the articulated grapples,
• close the rigid grapples around the second tree, which leaves the articulated grapples between the cut first tree and the second tree,
• open the articulated grapples, so that turning tips of the articulated grapples can slide away from between trees,
• close the articulated grapples around all trees,
• cut the second tree with the cutting device,
• lift the cut first and second trees, holding them with the grapples fastened to the telescopic boom and using the stroke cylinder to move the telescopic boom in relation to the main body,
• continue working in the above described order, cutting and collecting more trees, until the grapples are full,
• after which all grappled cut trees are at least one of processed further and loaded to an intermediary depot, on a transporting vehicle or to a device for further processing.