Polk Place Tree Report

(PDF version of this document)

Objective

To identify catalog and evaluate the health of the trees and foundation plantings at Polk Place. Develop thoughtful recommendations for future tree and building plantings.

Methods

Identified the trees and shrubs and assigned “low”, “moderate”, and “high” ratings based on how a healthy specimen of each taxon should appear. “Moderate”- to “high”-rated plants are in good to excellent condition and require “normal” maintenance. The “low”-rated would ideally be removed and new plantings constituted. Table 1 is the composite; Table 2 presents plants by location.

Results

Table 1. Total Tree and Shrub Composition of Polk Place

Over 100 woody taxa were cataloged. No genus/species/cultivar dominated the Polk Place landscape. The diversity is important to avoid monoculture and pedestrian aesthetics. The Landscape Department should be lauded for incorporating new/unusual plants. For example, Camellia sasanqua, Caryopteris ×clandonensis, Fothergilla ‘Mt. Airy’, Hydrangea quercifolia, Ilex verticillata, Illicium floridanum, Loropetalum chinense var. rubrum, Osmanthus species, Sarococca confusa, Styrax obassia and Viburnum tinus reflect a spirited, vibrant commitment to color, fragrance and texture. Stumbling upon this cornucopia of woodies provided identification challenges. Ilex taxa, hollies, comprised 21% (145/680) of the plants surveyed plus several hedges and masses. Hollies are aesthetic, functional, durable, and long-lived; all desirable traits for campus landscapes.

Surprisingly only one Buxus sempervirens was cataloged, 0.14%. Many new, disease-resistant boxwoods are now available. The question was raised about moving some of the boxwood from Bell Tower to the Polk Place buildings. Certainly, this is doable.

Several plantings are totally higgledy-piggledy with one each of many taxa. Shade and root competition are factors affecting proper plant selection. Grouping and massing shade-tolerant plants would result in more robust compositions. Loropetalum chinense var. rubrum, Sarcococca confusa and S. hookeriana var. humilis, Camellia japonica and C. sasanqua, Abelia ×grandiflora, Aucuba japonica, Gardenia augusta, Ilex taxa, Osmanthus taxa, Mahonia taxa, Rhododendron taxa, Viburnum tinus and others are shade tolerant and currently performing quite valiantly in the Polk Place matrix. The use of plants to cover the ground instead of mulch results in a more aesthetically-pleasing  composition.

Opportunities abound for positive enhancement, and with the commercial introduction of numerous new (and reasonably tested) plants like the red hollies, Encore Azaleas, red loropetalums, cold hardy gardenias, cold hardy camellias (Camellia Forest Nursery, Chapel Hill), new remontant (reblooming) hydrangeas and fragrant viburnums, effective change is easily facilitated.

If a particular building was revamped in toto, the resultant landscape would speak to the future. Many nursery growers in North Carolina and the Southeast would possibly donate newer/unique plants. Design, installation and maintenance responsibilities reside with the University.

The majority of trees and shrubs are in “moderate” to “high” condition, with over 80% placed in these categories. Forty-three percent are rated “high”. These numbers reflect the excellent plant selection and maintenance by the Landscape
Department. The “low”-rated plants have been in situ too long and/or pruned to the degree of no salvation. With the advent of new compact (dwarf) selections of the shrubs listed above, future maintenance costs can be reduced.

The majestic Quercus alba on the Quad are generally in excellent condition. Eighty-five percent rated “moderate” to “high”. With the pedestrian traffic, construction, and events in this area, the white oaks are quite robust. I understand that Bartlett Tree, inc. consults on an as-needed basis. I recommend continued monitoring of white oak health. Consider seedling populations from the five healthiest trees to be utilized as eventual replacements. Contract with North Carolina grower(s) for number of trees and delivery dates. Need to develop (ASAP) replacements for those designated as “low”.

The Quercus phellos, willow oaks, range from “low” (6), “moderate” (8) to “high” (4). They form the outer boundary between the buildings and the white oaks. Several in the “low” category are liabilities and should be removed or at the least correctively pruned. These trees are suffering from compaction and reduced root zone spaces.

New design strategies are being proposed to provide more root zone area. If the Quercus alba were planted where the Quercus phellos currently reside, they would rate “low” or have long since died. The significant root zone area provided the white oaks has contributed to their good health and longevity.

Now is an opportunity to strategize about alternatives to the failing willow oaks. New own-root willow oaks such as Hightower® and an upright selection Upperton™ (‘RT3’, PP 16,444) are choice alternatives. Quercus falcata var. pagodifolia, cherrybark oak; Q. lyrata, overcup oak; Q. nuttallii, Nuttall oak; and Q. michauxii, swamp chestnut oak; tolerate low O2 tensions and, in nature, grow in wet soils. Choice specimens already grow on the University campus.

We live in the future so we might as well plan for it…the same applies to the continued care of Polk and the thoughtful regreening.

• Addendum: Running Observations
• Table 1
• Table 2