Thinning Pine Trees and Plantations: When, Why and How

Are your pine trees too densely packed?  Thinning pine stands at the right time is crucial for their health, growth rate and future value. In this post, we’ll cover the key things to know about pine thinning – the benefits, optimal timing, methods, and how to conduct the thinning harvest.

The Problem of Overstocked Pine Stands

The number one issue in managing young natural pine stands is having too many trees. After a clearcut harvest of a mature pine stand, the area often reforests naturally with native pine seedlings, sometimes at densities of 1,000 to 10,000+ seedlings per acre. Abandoned fields also frequently fill in densely with pines.

While this natural regeneration is cheap and effective, the optimal density for a young pine stand is only around 400-500 trees per acre. Overstocked stands lead to stunted growth, poor crown development, disease susceptibility and overall stand stagnation.

Benefits of Thinning Pine Plantations & Natural Stands

Strategic thinning of your pines, done at the right time, provides major benefits:

• Redistributes growth to your best, highest-value crop trees
• Improves health, vigor and resilience of the entire stand
• Reduces losses to disease, insects, wildfire and stagnation
• Provides early income from lower-quality trees
• Enhances wildlife habitat and hunting/recreation value

Pines grow very rapidly in their first few decades, often more than 10% volume/ year. But they need space and resources to reach their potential. Thinning lets you capture value early from the trees you’d lose anyway to competition while freeing up the high-quality trees to pack on valuable volume and log grade. Pruning the lower limbs can further improve wood quality.

When to Thin Your Pines

The timing of your first thinning depends on your management goals and the characteristics of your specific stand. But maintaining vigor by preventing overcrowding should always be a key objective. Perform the first thinning when trees are beginning to compete for resources but have reached a merchantable size, typically around:

• 13-18 years old
• 6″ diameter at breast height or larger
• Basal area over 100-120 sq ft per acre

How to Thin Pine Stands

Proper thinning technique varies between natural stands and plantations. But in general, thin heavier on poorer sites and lighter on better sites. Several common methods of thinning include:

Row/Selective Thinning

• Remove every 3rd, 4th or 5th row entirely
• Selective thin the remaining trees to your desired density
• Fast and simple, but doesn’t discriminate between tree quality

Pure Selective Thinning 

• Evaluate and mark individual trees for removal
• Allows you to favor the best trees to make up the residual stand
• Need to consider the expense of tree marking

Your first commercial thinning usually removes only pulpwood but occasionally a limited amount of small saw timber. Any diseased, damaged, poorly formed and slow-growing stems should be removed to achieve the optimal density, generally 60-90 of basal area/ acre . The stand can be thinned once or twice during this phase.