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The Two Cats Timber is a privately owned 200-acre woodland located near Elma, WA. Nearly the entire forest was clearcut in 1998 by the previous owner and replanted with Douglas-fir. Since then, multiple native species of hardwoods and conifers have colonized the property, resulting in a highly diverse, and very dense third-growth forest. One management challenge facing the forest owners is overstocking and competition within, in particular, red alder dominated stands. Red alder naturally colonized many areas of the forest at high densities, and is now competing directly both with itself and the planted fir.

This forest owner has received funding through the USDA’s Environmental Quality Incentives Program (EQIP) to offset the cost of the pre-commercial thinning of this stand.



Project completed March 2021


Grays Harbor County

Project Description

This project treated a dense stand dominated by 22 year old red alder with the following two prescriptions:

  1. Pre-commercially thin to 180 – 220 TPA (13’ – 15’) – 1 acre
  2. Pre-commercially thin to 240 – 260 TPA (14’ – 16’) – 1 acre

Stand Description

This stand encompasses areas of the forest where hardwoods have, or are, effectively outcompeting the original Douglas-fir plantation. Red alder is the dominant species, followed closely by bitter cherry and big leaf maple. As is common with naturally regenerating alder, stocking densities vary considerably, ranging from as low as 300 TPA to as high as 1,300 TPA. Live crowns across most of the dominant and co-dominant trees still exceed 40%, but are quickly diminishing. Timber quality across this unit varies considerably, with a high level of storm damage in dominant and codominant alder and an increasing rate of suppression mortality amongst the least dominant trees. Despite this high defect, there is ample stocking of high quality timber trees that can be encouraged through thinning. Although it’s been nearly entirely outcompeted, Douglas-fir continues to persist as lone individuals or in small groups. There are also a fair number of fir that are struggling beneath the hardwood canopy that likely could be released through thinning. Red cedar, western hemlock, and big leaf maple are naturally regenerating throughout the stand.

Treatment Goals

Despite the seemingly unruly nature of this unit, presented a higher short-term revenue opportunity than the Douglas-fir dominant stands due to the growth rates and market value of the alder. Therefore, this unit was managed to optimize alder production and maintain the Douglas-fir where it exists. Over time, the unit will be transitioned to a higher conifer stocking. Pre-commercial thinning was necessary throughout nearly the entirety of this unit in order to release the most dominant and highest quality alder and fir. Following PCT, the alder in this unit will be commercially thinned in 10 years, underplanted with conifers, then commercially thinned again in 20 years. Natural regeneration of both alder and conifers should maintain an optimal stocking density for long-term timber production.

The objective of this PCT treatment was to retain the most dominant and highest quality trees. Storm damaged trees that were not expected to yield merchantable timber were also removed. This thinning treatment will allow long-term comparisons of the relationship between stocking density, diameter and height growth, and timber quality.

About the Treatment

USDA stand density guidelines for red alder within this diameter range recommend a residual thinning density of 200 – 260 TPA (average 13’ – 15’). The two treatment sites were thinned to densities at both the upper and lower end of this range (180 – 220 and 240 – 260 respectively). 


Additional thinning prescriptions included:

  1. Thinning red alder “from below” removing the least dominant trees and retaining the most dominant trees.
    1. Cut trees were lopped and scattered to the extent necessary to reduce the slash mat to below waist height. 
    2. No trees were left leaning on other trees.
    3. All stumps were cut to within 6” of the ground.
    4. Where Douglas-fir and alder were directly competing, favor the Douglas-fir.
  2. Retaining all other hardwood species: bitter cherry, cottonwood, willow, Oregon ash.
  3. Retaining all snags, regardless of diameter or height.

Study Design

The Two Cats Timber project included two 1.0-acre treatment sites. Within each treatment site four 1/20th-acre (0.05 acres) permanent monitoring plots/acre were installed prior to implementation of prescribed treatment. Each plot was permanently monumented with a rebar stake and 4’ white PVC pipe with bright orange ribbon tied to the top. For each plot, the following macro-data was recorded: GPS plot location, Average stand age, Soil type, Site index & class, Elevation, Rainfall, Aspect, Slope. Pre-activity data was collected from the treatment sites, the respective treatments were implemented, then post-activity data was collected immediately following treatment. Plots were remeasured 24 months after treatment.

Plot design and data collection for each treatment was as follows:

Young Red Alder Stand PCT

  1. TPA
  2. Tree species
  3. SPA (saplings per acre): all hardwoods & conifers <6’ tall
  4. DBH
  5. Height
  6. LCR
  7. Defect: broken top, wane, trunk forked below 26’, etc.
  8. Snags
  9. Understory shrubs: species, % cover, avg. height of entire shrub layer
  10. Photo points from plot center: E, W, N, S, canopy, shrub layer
  11. Qualitative
    1. Forest health
    2. Wildlife use
    3. Observations

Treatment Plot Data

View the pre-treatment stand plotcard data for this project here: PDF | Excel worksheet
View the post-treatment stand plotcard data for this project here: PDF | Excel worksheet

Labor/Cost Statistics

  1. Treatment site 1 (1.0 acres): PCT from 306 to 221 TPA
    1. Labor: 2 workers 3 hours total (6.0 person hours)
    2. Cost: $588/acre (EQIP funding provided $312/acre)
    3. Fuel: 2 gallons (assumption: .25 gallons of gas/45 minutes/worker)
      1. Carbon emissions: 39lb CO2 (assumption: 19.64 lbs CO2/gallon. source)
  2. Treatment site 2 (1.0 acres):: PCT from 311 TPA – 266 TPA 
    1. Labor: 2 workers 2 hours total (4 person hours).
    2. Cost: $588/acre (EQIP funding provided $312/acre)
    3. Fuel: 1.3 gallons (assumption: .25 gallons of gas/45 minutes/worker)

Carbon emissions: 25.5lb CO2 (assumption: 19.64 lbs CO2/gallon. source)