1. Прочитайте текст и ответьте на вопросы

1. What wood harvesting operations do you know?

2. What instruments are used in hand felling?

3. How is limbing called in British English?

4. How may bucking be done?

5. What process is called log hewing?

2. Переведите следующий фрагмент текста с помощью словаря

The person bucking is generally called a Bucksawyer or Bucklogger, or just a Bucker and runs as many saws as he can, switching out saws as soon as one is dull. This method of logging is perhaps more dangerous than the actual felling of the trees for the bucklogger is usually cutting from the edge of a treepile which can be twenty feet high and as long as there is room to dump them from the truck. Each tree has to be picked out of the pile and cut so that a controlled fall of more trees can be worked as the former fall has been cut and skidded to its respective pile.

3. TIMBER HARVESTING SYSTEMS

IN THE USA

Over the years, the forests of southern New England have seen several different timber and wood/pulp harvesting systems.  Until the advent of the internal combustion engine, all felling and bucking was done with axes and hand saws; all skidding was done with horses or oxen.  In the 1930's, chainsaws and crawler tractors (bulldozers) began to replace axes, handsaws, and draft animals.  In the 1960's, 4-wheel-drive, rubber-tired skidders began to replace crawlers.  Now fully mechanized harvesting systems are beginning to replace chainsaws and skidders.  The following will describe and discuss these harvesting systems, all of which (except axes and handsaws) are still in use in this area.

 

Horses or Oxen

Logs are loaded onto a low-to-the ground sled or attached at one end with choker chains to a 2-wheel forecart which are pulled by the horses/oxen.  The animals are specially bred and have been trained for their work.  Some are capable of skidding from stump to log landing and back unassisted.

The main advantage of horse/oxen skidding is the very low level of damage to the residual trees and the forest soils.  The main disadvantage is the low limit on skidding distance for which draft animals are economical.  Uphill skidding on grades steeper than 10% is generally not feasible. 

Crawler Tractors

Crawlers run on metal tracks which give them excellent traction and maneuverability.  They most often have a cable winch attached to the rear end with several log choker chains attached to the cable.  The chains may be attached to logs (or whole stems) lying close to each other.  When the cable is winched in, the logs come together to form a hitch which is then skidded out to the log landing.

The main advantage of crawlers is that they compact the soil less than rubber-wheeled skidders because their weight is spread out over a much larger tractive surface area.  They are also able to do road construction work with their blades, and their manueverability can help avoid damage to residual stands.  The main disadvantage for crawlers, as for draft animals, is the cost factor.  Tracks require more maintenance than wheels and they limit the speed of the machine.  Some land is too rocky to operate with crawlers because rocks can damage tracks and the low-slung undercarriages of crawlers. 

Rubber-Wheeled Skidders

Skidders use winches in the same way as crawlers to haul out logs or tree stems.  Their axles move independently in the vertical plane.  They are articulated (jointed) in the middle to allow full independent movement of front and rear sections.  They have high ground clearances so they can operate on all kinds of terrain.  They can haul much faster than draft animals or crawlers.

The main advantages of skidders are their speed and ability to operate under all but the most adverse conditions.  Therefore, they are the lowest-cost harvesting systems.  The principal disadvantages are the relatively higher levels of damage to residual stands and skid roads, plus increased soil compaction.  However, these disadvantages may be minimized or even eliminated when the equipment is run by a careful operator who carefully plans his hitches and skid roads, and avoids skidding when soils are wet (to reduce soil compaction). 

Other Systems

In regions of the country with relatively flat, rock-free soils, other harvesting systems have become popular.  They are now also being used in southern New England.  Large, hydraulically-operated sawheads and stem gathering systems mounted on tracked or rubber-wheeled tractors are very fast and safe for operators.  These equipment systems, called feller-bunchers, leave bunches of tree stems along skid roads which are run by forwarders or grapple skidders.  Forwarders pick up and carry cut logs; grapple skidders drag whole trees.

A forwarder has a front section like a skidder, but instead of a cable winch, has a hydraulic knuckle-boom log loader behind the cab and a small log deck above the rear axle.  Forwarders are used with conventional chainsaw felling and feller-bunchers.  When loaded, the forwarder has a high center of gravity which makes it unsuited to steep or rough terrain.  Grapple skidders have a large grapple mounted on the rear; they may also have a cable winch.

In planning a harvesting operation, all the equipment systems described above should be considered along with their associated costs and benefits.  Independent of the harvesting system chosen, additional consideration should be given to the disposal of slash and the clean-up and seeding of landings and skid roads.  Since the effects of a harvesting operation are visually and ecologically long-lasting, these considerations deserve careful attention.