Chainsaws, harvesters, and feller bunchers are now used to cut or fell trees. The tree is turned into logs by removing the limbs (delimbing) and cutting it into logs of optimal length (bucking). The felled tree or logs are moved from the stump to the landing. Ground vehicles such as a skidder or forwarder can pull, carry, or shovel the logs. Cable systems "cars" can pull logs to the landing. Logs can also be flown to the landing by helicopter. Logs are commonly transported to the sawmill using trucks. Harvesting methods may include clear cutting or selective cutting. Concerns over the environmental impact have led to controversy about modern logging practices. In certain areas of forest loggers re-plant their crop for future generations.