Nampa, ID-Kohlerlawn Cemetery Case Study

From Monoculture to Deciduous Diversity

Nampa Parks and Recreation maintains Kohlerlawn Cemetery, a 43-acre site with over 550 trees.
More than half are between 10 and 90 years old, including several stands of Arborvitae planted
70–75 years ago. These trees were originally chosen to create a uniform canopy that emphasized
beauty and tranquility, but the reliance on a single species has introduced ecological vulnerabilities.

Uniformity is often a goal within urban forests, and cedars seemed like an excellent choice. Their shape is ideal, and they’re also drought-tolerant and resilient. Like sentinels watching over the cemetery, these trees stood for decades, growing tall.

Unfortunately, they are also highly susceptible to cedar borer outbreaks when planted in dense stands.  Sadly, the Arborvitae monoculture was infested over the years, resulting in dying branches, dead leaders, and entire trees succumbing to insect damage.

While Insecticide treatments were implemented and applied regularly, the damage was too severe, and the treatments failed to curb the problem. 

Because of this, the conifer-heavy landscape was endangered: once the beetles attacked, the lack of species diversity created an ideal environment for rapid spread and high mortality.

This resulted in defoliation and tree loss, negatively affecting the site's visual appearance and prompting customer complaints. Furthermore, dead branches and additional infestations can also pose safety risks and, ultimately, prove quite costly.

As a cemetery, it was also crucial to the city that the space and landscape reflect local history and honor the veterans, city leaders, and beloved family members buried there. To do so would require some big moves.

Nampa decided to remove any trees identified as diseased, declining, pest-infested, or posing a safety hazard to the public. However, the removal of 286 trees was devastating to the landscape. Both the city forester and city leaders were also looking to plant and restore the site's beauty, while improving canopy diversity for the future.

Check out local news coverage of this story here!

The SuperTrees Response: Deciduous, Diverse Replanting & Funding Support

The city of Nampa turned to SuperTrees, a trusted nursery and tree partner, for their expertise and locally grown, regionally adapted trees. It was clear that the city and Kohlerlawn Cemetery would need to undertake a large-scale tree project, including the removal and replanting of trees, ultimately replacing the Arborvitae and cedars with a mix of deciduous trees. Key features of the project:

  • Funding: An urban forestry grant dedicated to urban forestry and replacement provided $1 million to the city, helping to not only conduct a tree canopy inventory for future strategic growth but also  underwrite the cost of trees, planting, labor, and supplemental watering.

  • Tree supplier/implementation: SuperTrees carried out the replanting in February, selecting suitable deciduous species. The planted stock included: 

  • Prairifire Crabapple- 27 (trees)
  • Prospector Elm- 23
  • Exclamation Planetree- 19
  • Green Spire Linden- 16
  • Skyline Locust- 13
  • Hackberry- 11
  • Krauter Vesuvious Plum - 9
  • Golden RainTree- 9
  • Hornbeam ‘franz fontane’ - 7
  • Tulip Tree- 7
  • Negundo Sensation Maple- 6
  • Cupressina Columnar Spruce- 4
  • English Oak- 4

These were chosen for their suitability, diversity, visual appeal, and variety. Furthermore, these selections are recognized for their robust root systems and rapid establishment.

  • Establishment care: Trees were planted in February, allowing them to establish before spring rains and summer heat. During that early growth period, supplemental watering was crucial, enabling the newly planted trees to develop their root systems and survive beyond the critical first months.
  • Canopy Diversity: While aesthetic goals were significant, the key lesson learned was the vital importance of canopy diversity in maintaining healthy urban forests. In addition to a variety of species, the diversity also offers year-round beauty, shade, and wildlife appeal.

Outcomes: Impressive Survivability & Benefits

Early results from the Nampa project have been incredibly positive, showing that the diversified approach succeeded where the monoculture failed:

  • 100% survival rate observed at the 6-month check-in vs. the prior expectation of devastation in the juniper monocultures (often known for a high mortality rate).
  • Dramatic improvement over the estimated 10% loss rate typically seen in projects of this size and nature.
  • Better canopy cover, improved shade, more aesthetic appeal, and likely better microclimate and habitat benefits.

Why This Matters for Other Urban & City Foresters

This example is valuable for urban forest managers for a few key reasons:

  • Monoculture danger: High risk of catastrophic loss when a single species dominates. Bark beetles, drought, or disease can quickly wipe out large sections in those cases.
    Benchmarks from studies show that tree mortality rates in monotypic stands are significantly higher during pest/disease outbreaks. For example, in lodgepole pine forests during a pine beetle outbreak, a mortality rate of nearly 30-40% in some plots.
  • Canopy diversity & species mix reduce that risk, by breaking pest/disease cycles, increasing ecological resilience, and ensuring that some trees survive even if others fail.
  • Deciduous trees also often provide more varied benefits: seasonal shading, habitat (flowers/fruit), fall color, improved microclimates, leaf litter that benefits soil health, etc.

Lessons Learned From Nampa, ID and Kohlerlawn Cemetery

Kohlerlawn Cemetery’s experience illustrates a few key takeaways for urban forestry and city forest programs:

  • Planting a variety of deciduous species, rather than relying on a single species, is crucial for enhancing pest and disease resilience, providing shade, maintaining aesthetic appeal, and promoting ecological diversity. It is possible to keep the desired uniformity for unique city spaces across a variety of species.
  • Early and proper care (especially supplemental watering during dry periods immediately after planting) is critical to ensuring high survival.
  • Using funding instruments (e.g., the IRA grant) can make large-scale replanting feasible and help offset upfront costs for more resilient plantings.

For city foresters and urban planners, this case highlights that investing in canopy diversity and healthy propagation and planting practices can yield exceptionally high survivability rates, protect public investment, and lead to healthier, longer-lasting urban forests.

Sources:
1. Jack-Scott, E. J. (2012). Survival and growth factors affecting community-planted urban street trees. Cities and the Environment (CATE), 4(1), Article 10. https://doi.org/10.15365/1932-7048.1050

2. Hilbert, D. R., Roman, L. A., Koeser, A. K., Vogt, J., & van Doorn, N. S. (2019). Urban tree mortality: A literature review. Arboriculture & Urban Forestry, 45(5), 167–200. https://doi.org/10.48044/jauf.2019.015

3. Google. (2025). Google Earth [Satellite imagery]. https://earth.google.com/