TreeLines

Considerations for Lower Density Planting: How Genetics Influence Value 

Planting density has become a hot topic as timber markets continue to evolve across the Southeast. 

As a Reforestation Advisor, I frequently have conversations with landowners about the right number of trees per acre for their property and objectives. Many are looking for ways to reduce reforestation costs while also limiting the amount of pulpwood produced in a market with fewer outlets. 

Planting fewer trees per acre can lower establishment costs and provide more room for individual trees to grow. With less competition, trees have the opportunity to put on more radial growth. However, when planting density is reduced, tree quality becomes an even more important driver of return on investment. 

Looking at Real-World Data 

Let’s look at data from a genetics-by-density demonstration plot. 

This block-plot demonstration area was established in 2015 and contains multiple ArborGen product categories planted at 622 and 435 trees per acre. For the purposes of this discussion, we’ll compare OP Pro and MCP®Pro+ families. 

Figure 1. Age 9 Genetic Comparison by Average DBH, Percent Rust, and Percent Sawtimber Potential 

At age 9, there is already a measurable difference in diameter at breast height (DBH) between the two planting densities for both OP Pro and MCP® Pro+ families. 

As these stands continue to mature, those diameter differences could translate into movement between product classes – for example, from pulpwood (PW) to chip-n-saw (CNS), or from chip-n-saw to sawtimber (ST). Given today’s pulpwood market challenges, this is an important consideration. 

One metric we pay close attention to is sawtimber potential, which measures the percentage of trees within a stand that are free from rust, straightness, and forking defects. In other words, it helps estimate how many trees have the potential to become higher-value products such as chip-n-saw, sawtimber, or poles rather than lower-value pulpwood. 

Even the best OP families typically have lower sawtimber potential than MCP® families. As shown in Figure 1, sawtimber potential in OP families generally tops out around 50–60%, while MCP® families consistently perform in the 75–80% range. 

In this comparison, average sawtimber potential is approximately 20 percentage points higher in the MCP® Pro+ family. That difference carries significant economic value because solid wood products, including CNS, sawtimber, and poles, often command stumpage prices three to five times greater than pulpwood. 

The increase in sawtimber potential is largely the result of controlled pollination between carefully selected mother and father trees. Open-pollinated families are subject to pollen contamination from wild pollen sources, which can travel long distances and contribute to greater variability in performance. 

Yield and Product Mix 

Next, let’s look at how planting density and genetics influence yield and product distribution over a rotation. 

This analysis was performed using the SiMS growth-and-yield simulator for the Upper Coastal Plain and Piedmont regions of Georgia and South Carolina. 

The 605 trees-per-acre (TPA) regime, referred to here as the high-density regime, included: 

• Chemical site preparation 
• Machine planting of bareroot seedlings 
• Herbaceous weed control 

Thinnings occurred at ages 14 and 21, with final harvest at age 31. 

The 454 TPA regime, referred to as the low-density regime, used the same establishment practices but received one thinning at age 16 and a final harvest at age 29. 

Figure 2. SiMS Growth and Yield Harvest Volume by Product Class and Category 

Several observations emerge when reviewing the volume data. 

First, the high-density regime, regardless of genetic category, produced more total volume and a higher percentage of solid wood products than the low-density regime. This is primarily due to higher initial stocking levels and the stand improvement benefits provided by two thinning entries. 

The lower-density, one-thin regime is included because it represents a potentially attractive option in today’s changing markets. Executing a single, well-timed thinning may be easier to achieve in a weaker market environment while also providing greater flexibility in thinning timing. 

The data also shows that planting fewer trees per acre does produce larger trees, as reflected in Figure 1. However, larger trees alone do not necessarily result in more solid wood and less pulpwood. 

According to this analysis, that outcome is achieved when higher-performing genetics are included in the equation. 

When comparing the two lower-density regimes, the MCP® Pro+ stand produced 21% less pulpwood, with that volume instead shifting into higher-value products such as chip-n-saw, sawtimber, and poles. 

Perhaps most notably, when comparing the high-density OP Pro regime to the low-density MCP® Pro+ regime, the low-density MCP® Pro+ regime produced more total tons along with a significantly stronger product mix. 

Translating Volume Into Value 

Ultimately, volume matters because volume drives value. 

Bare Land Value (BLV) is a useful tool for evaluating the financial impact of silvicultural decisions. BLV calculates the present value of all expected future revenues minus all costs, assuming the property is managed in perpetuity. 

Because it incorporates both costs and returns, BLV can be helpful when comparing planting densities, genetic selections, rotation lengths, and even alternative land uses. 

Figure 3. Bare Land Value (BLV) by Product Category and Planting Density 

The results are straightforward. 

Lowering planting density without increasing the level of genetics reduces BLV. 

The more compelling question for landowners may be this: 

Would you rather plant 25% fewer trees and decrease BLV by 17%? 

Or plant 25% fewer trees and increase BLV by 25%? 

There are many factors to consider when determining the best planting density for a reforestation project. Site conditions, management objectives, market outlook, and operational considerations all play important roles. 

But as this analysis demonstrates, the conversation should begin with genetics. 

When planting density decreases, the quality and performance potential of every tree becomes even more important. 

Drew Fasano is a Reforestation Advisor at ArborGen, where he works with landowners, forestry consultants, and forest industry professionals across the Southeast to develop reforestation strategies that support long-term forest productivity and value. With more than 15 years of experience in forest management, silviculture, and forest operations, Drew is passionate about helping customers make informed decisions that maximize the potential of their land.