Natural Supports in Logging: The Role of Rigged Trees in Cable Systems

In modern logging - especially on steep or sensitive terrain - cable logging systems are essential for transporting logs safely and efficiently. These systems rely on a combination of cables, blocks (pulleys), anchors and support structures. Interestingly, one of the most important components isn't manufactured at all - it’s a living tree, used as part of the rigging setup.

These trees go by different names depending on how they’re used: spur trees, lift trees, intermediate supports and spar trees. Together, they form a smart and sustainable solution to the challenges of working in rugged forests.

Types of Rigged Trees in Cable Logging

Spur Trees

A spur tree is a standing live tree used to anchor cables or support rigging components. Rather than being cut down, it's incorporated into the logging system to:

• Anchor yarding cables or guy lines

• Hold blocks (pulleys) that redirect or tension the cable system

• Provide natural height and structure in the absence of man-made towers

Spur trees are typically located off to the side or behind the logging corridor and are chosen for their strength, stability and proximity to the rigging layout.

Lift Trees

Lift trees are positioned at or near the end of the cable line and are used to provide elevation (lift) to the mainline or skyline. Their main role is to raise the cable off the ground to:

• Keep logs suspended above sensitive soils

• Reduce friction and drag

• Protect both the terrain and the logs from damage

Lift trees help maintain cable tension and elevation over long distances, especially in uneven terrain.

Intermediate Support Trees

Also known as intermediate supports, these trees are used mid-span between the yarder and the felling site. Their purpose is to:

• Support sagging cable lines across low points, canyons, or draws

• Provide lift in the middle of a corridor

• Ensure smoother and safer yarding operations

Intermediate supports are crucial in large or steep units where one tree or tower alone can’t maintain adequate cable height across the full distance.

Spar Trees

Though not commonly used today, spar trees were once the centerpiece of traditional skyline logging. These trees were:

• Rigged and topped near the landing area

• Used as the main support tower for logging cables

• Carefully selected for height, strength, and access

In modern systems, spar trees have largely been replaced by portable steel towers or yarders with built-in spars. However, the term still holds historical significance in logging culture.

Why Use Rigged Trees?

Using live trees for rigging provides several environmental and practical advantages:

• Reduces the need for metal towers or artificial anchors

• Minimizes ground disturbance - ideal for steep slopes or fragile ecosystems

• Lowers operational costs by leveraging what the forest already provides

• Improves lift to keep logs suspended, reducing soil impact and log wear

These benefits make rigged trees an important part of sustainable forestry practices.

How Are These Trees Selected and Used?

Not just any tree will do. Rigged trees must meet strict criteria for:

• Size and strength

• Healthy root systems

• Absence of rot, disease, or structural damage

• Proper location relative to the logging corridor and terrain

Loggers climb and rig these trees using spurs, harnesses and blocks. After the operation, the rigging is removed and the tree is often left standing, illustrating how working forests can balance efficiency with environmental care.

Nature + Engineering = Smarter Logging

Whether it's a spur tree, lift tree, intermediate support or the old-school spar tree, each plays a unique role in cable logging. These rigged trees demonstrate how foresters can use natural resources intelligently, respectfully, and sustainably.

By combining traditional knowledge with modern practices, cable logging continues to evolve - and trees remain at the heart of the system, not just as a resource to harvest, but as a partner in the process.