A felling unit for processing small-dimensioned wood, the felling unit comprising: a frame, provided with a coupling device for attaching the frame to a boom of a movable forestry machine; at least one cutting device for the cutting of standing small-dimensioned trunks; and means for temporarily storing several cut small-dimensioned trunks for the time of cutting new small-dimensioned trunks; and wherein the cutting device comprises two opposite disc blades (19a, 19b), their rims facing each other and forming between each other a cutting gap, and the disc blades are arranged to rotate in opposite directions relative to each other as driven by at least one rotating motor (21a, 21b, 36a, 36b); the felling unit comprises a temporary storage space arranged to receive several cut small-dimensioned trunks; the felling unit comprises a transfer device for transferring the cut small-dimensioned trunks in a feed direction from the cutting gap to the temporary storage space; and wherein the transfer device comprises a first transfer shaft and second transfer shaft that are parallel to each other, the transfer shafts being rotatable in opposite directions relative to each other by means of at least one first rotating device (20a, 20b) and being located at said cutting gap at a transverse distance from each other and forming between each other a feeding gap; and both of the transfer shafts (18a, 18b) comprise several transfer projections arranged to push the cut small-dimensioned trunks in the feed direction from the cutting gap towards the temporary storage space when the transfer shafts (18a, 18b) are rotating; characterized in that the transfer shafts of the transfer device are rotatable in an opposite direction relative to the feed direction when small-dimensioned trunks are unloaded from the temporary storage space, such that the transfer projections are arranged to push small-dimensioned trunks via the feeding gap out from the felling unit. a frame, provided with a coupling device for attaching the frame to a boom of a movable forestry machine; at least one cutting device for the cutting of standing small-dimensioned trunks; and means for temporarily storing several cut small-dimensioned trunks for the time of cutting new small-dimensioned trunks; and wherein the cutting device comprises two opposite disc blades (19a, 19b), their rims facing each other and forming between each other a cutting gap, and the disc blades are arranged to rotate in opposite directions relative to each other as driven by at least one rotating motor (21a, 21b, 36a, 36b); the felling unit comprises a temporary storage space arranged to receive several cut small-dimensioned trunks; the felling unit comprises a transfer device for transferring the cut small-dimensioned trunks in a feed direction from the cutting gap to the temporary storage space; and wherein the transfer device comprises a first transfer shaft and second transfer shaft that are parallel to each other, the transfer shafts being rotatable in opposite directions relative to each other by means of at least one first rotating device (20a, 20b) and being located at said cutting gap at a transverse distance from each other and forming between each other a feeding gap; and both of the transfer shafts (18a, 18b) comprise several transfer projections arranged to push the cut small-dimensioned trunks in the feed direction from the cutting gap towards the temporary storage space when the transfer shafts (18a, 18b) are rotating; characterized in that the transfer shafts of the transfer device are rotatable in an opposite direction relative to the feed direction when small-dimensioned trunks are unloaded from the temporary storage space, such that the transfer projections are arranged to push small-dimensioned trunks via the feeding gap out from the felling unit.