BIG GREEN INVESTMENT

ARCHITECTURE & ENGINEERING Big Green Investment

The value of planning and maintaining landscaping

Abuilding will never again look as good as it did at the ribbon cutting. In comparison, the ribbon cutting for a landscape marks the start of another five years or more to give it time to grow in and begin to mature. Then, depending on the maintenance it receives, a landscape will continue to evolve forever. As the adage goes, “The best time to plant a tree was twenty years ago. The secondbest time is now.”

Landscapes are a long-term investment, and as such they can have high installation costs. They also aren’t always optional. Many jurisdictions in Alaska have specific landscape requirements for undeveloped and previously developed properties, including the Municipality of Anchorage, Fairbanks North Star Borough, City of Palmer, and City of Wasilla. These codes mandate the type and extent of landscape that needs to be installed, although they often leave it open (to various degrees) to how those requirements are met. A stipulation within these codes is that the landscapes are maintained in compliance with their permitted conditions, and some of these jurisdictions require bonds to guarantee that plants establish successfully.

With significant recent increases in plant material costs and installation, this required landscape can represent a large investment. This also applies to the landscapes that an owner may choose to invest in without the code requirement.

Here are some tips to protect that investment. • Purchase and install quality planting material. Industry standards set a quantitative basis for quality, including the American Standard for Nursery Stock. Poor quality

plant material is a bad investment and may cause future problems. • Install as much high-quality planting soil as possible. Good soils provide moisture retention and nutrients for tree growth, and the larger the soil extends, the more likely that a tree will be healthy and remain structurally sound. For example, research supports that an 8-inch caliper tree benefits from 600 cubic feet of soil for vitality.

Many of our poorly performing landscapes can be attributed to poor or overly compacted soils. • Select the correct species.

Whether to align with the space available, desired design, or for lower maintenance, use the right tree or shrub species in the right place. The wrong plant or the wrong location can create future problems as plants get larger, create maintenance requirements, or affect adjacent structures. • Maintain the investment. Trees require ongoing maintenance, including pruning. Work with a certified arborist or spend the time to learn how to prune trees correctly.

With a good quality tree or shrub in good soils, with reasonable ongoing maintenance, vegetation will meet site goals and the community goals that are the intent behind landscape requirements.

No matter how basic it might be, every site should have a landscape maintenance plan and schedule, with someone to implement it.

By Peter Briggs

Investment Dividends

The value of trees and shrubs on sites is well-documented. Beyond their aesthetic and intrinsic ecological values—including air quality, stormwater control, and habitat—they can also be strategic for land valuation. A site with existing trees and shrubs that are preserved for development can offset landscape costs for you or a future buyer.

The code valuation of existing trees typically emphasizes larger trees, so a strategy could be installing and maintaining trees in advance of development to let them mature to achieve minimum code sizes or count for more credit as larger trees.

Let’s look at two examples.

Within the Municipality of Anchorage, an existing spruce tree 10 feet in height or taller is equivalent to three new trees. A commercially installed code minimum sized 6-foot height evergreen tree has a value of around $800, so maintaining an evergreen tree in place offsets approximately $2,400 in costs. The same ratio and approximate costs apply for protecting deciduous trees 6-inch or greater in caliper (the diameter for a 6-inch caliper tree is the trunk circumference as measured 54 inches above the root crown). Otherwise, code minimum is 2-inch caliper deciduous trees (the diameter for a 2-inch caliper tree is the trunk circumference as measured 6 inches above the root crown).

The City of Wasilla has a similar 3:1 ratio for these sizes of existing trees, but cost offsets are higher for the code minimum size for trees being 10-foot height or 2-inch caliper, whichever is larger.

While there is some risk related to future development needs, informed estimates for where landscape will be needed can take into account adjacent roads, zoning, and typical development patterns for where parking lots would be expected.

Provided that they are in good health,

maintaining even a few trees on a site can contribute to cost effectively meeting code requirements, in addition to some “instant landscape.”

Time is Money

Landscape plans are best when they look to the future twenty years or more. They provide the space and soil for trees to achieve their mature sizes. If a project requires a higher level of instant landscape appeal, this ideally occurs through planting larger shrub material or more dense perennial plantings. Providing denser shrub plantings is also an option, but this is ideally followed by removing shrubs as they grow into one another. Dense tree planting should not be a part of instant landscape appeal due to their initial expense and difficulty in transplanting over time.

Whether required or desired, landscape improvements provide aesthetic improvement and are a component of development investments. No different than financial investments, selecting the right landscape improvements and maintaining them for the long-term will maximize returns.

Changes Over Time

Whether an owner has an interest in an aesthetic landscape or a responsibility to reflect a corporate image, landscapes can be renovated when needed. This may exist at the landscape contractor level to clean a site up, make some replacements, and do some pruning. Or it may require more intensive assessment and development of a work plan where a landscape architect and arborist would be of benefit.

Regardless, whenever a site may be influenced by code, a landscape architect can provide guidance on code compliance. For trees, arborists should also be consulted about potential hazards or assistance with aesthetic or health/structural pruning of a tree.

Peter Briggs is a landscape architect who believes in the business case for design (and writes about it at highestexpertise.com). He's the founder of Corvus Design, a fullspectrum landscape architecture, planning, and design firm that has fifteen years of projects around Alaska and the Northwest.

URBAN TREES REALLY NEED SOIL

Street trees are an excellent example of how important it is for a tree to have access to a large volume of good quality soil, protected from compaction.

Trees have traditionally suffered in any location where they are planted in areas where they are surrounded by pavement. Anchorage is no exception, with a poor track record for trees downtown: Fourth, Fifth, and Sixth Avenues have a large number of locations where previous street tree locations have been filled in with concrete where the trees failed. These locations include some where great effort was expended on technical solutions intended to provide for good tree health. These areas likely failed due to the unintended consequences of maintenance around them (physical and chemical damage), lack of access to the volume of soils the trees needed, and insufficient long-term maintenance.

For recent renovations to Fourth Avenue between E and C Streets, street trees were included in the design. Building on some recent successes at the Dena’ina Convention Center and along E Street, these new trees will be protected from physical and chemical damage (with a raised concrete planter around them) have a large volume of soils available to each tree (provided within structural soil cells below the sidewalk), and data collected will guide maintenance, thanks to moisture sensors in key locations.