Utah State University Extension specialists are encouraging residents to move away from treating urban trees as isolated landscape elements and instead adopt "mini-forest" techniques to promote healthier growth. By recreating natural forest conditions, such as shade and organic ground cover, growers can better support trees that are genetically adapted to living in close proximity to other vegetation.
Recreating Natural Ecosystems
According to Michael Kuhns, an Extension Forestry Specialist, most urban trees are genetically adapted to living near other trees within a forest ecosystem. Despite this biological predisposition, many landscape managers treat trees as individual elements, often ignoring how their surroundings or neighboring plants affect them.
To address this, Kuhns suggests the creation of mini-forests. These are defined as groups of trees and other plants that provide shade and are covered by organic matter rather than grass. To establish these areas, residents should determine specific locations in their landscapes where trees and related plants can be given priority. These areas must be large enough to contain several trees so that the plants can provide mutual protection and shade to one another.
Soil and Mulch Management
Successful mini-forest management requires specific soil and ground cover practices. The Utah State University Extension recommends mulching the ground around these tree groups using organic matter such as wood chips, bark, compost, leaves, or grass clippings. These mulch areas should surround the tree groups and extend at least several feet beyond the perimeter of all trees in the group.
When applying mulch, Kuhns advises using different depths based on the material; coarse mulches can be up to four inches deep, while finer mulches should be kept shallower. Additionally, the Extension warns against using plastic sheeting or weed barrier fabrics under mulch, noting that these materials interfere with the movement of oxygen, water, and organic matter into the soil—conditions that do not exist in natural forests.
Forestry Resources and Guidelines
The Utah State University Extension provides a wide range of specialized resources for managing various forestry and landscape needs. These include technical guides for urban and community forestry, such as instructions for selecting and planting landscape trees, managing irrigation restrictions, and understanding soil quality guidelines for landscaping.
Other available resources include the Utah's Forest Water Quality Guidelines, which includes both a practical user's guide and a technical manual published by the Utah Division of Forestry, Fire and State Lands. For those managing specific plant types, the Extension offers guides on managing pests for ornamental aspens, managing home orchards, and identifying the trees of Logan Canyon and the northern Wasatch mountains.
Prioritizing Tree Health
Effective mini-forest maintenance involves prioritizing the needs of the trees over traditional landscaping features like turf or sun-loving annual plants. While small, shade-tolerant trees, shrubs, or herbaceous perennials can be planted under larger trees, growers must be careful to minimize damage to tree roots during this process.
Management of these areas should also include minimal herbicide use to prevent tree damage and cautious fertilization. The Extension notes that while forests are often nutrient-poor, trees typically thrive without much assistance; therefore, fertilization should only occur if there are clear signs of nutrient deficiency, such as poor vigor or inadequate growth.
Species-Specific Management
Irrigation management is a critical component of maintaining a healthy urban forest. Growers must provide enough water to meet specific tree needs while avoiding over-watering, which can kill roots, waste water, and add carbonates to the soil that raise the pH level.
Because different species have different requirements, mini-forest designs must be adjusted accordingly. For instance, junipers may thrive with wide spacing and minimal water, whereas sugar maples may require closer grouping and more frequent irrigation. All plants within a single group must be compatible in terms of their water needs, size, and shade tolerance based on their vertical position in the canopy.
Comprehensive Forestry Support
The Utah State University Extension continues to provide extensive documentation for various forestry and environmental needs. This includes checklists for woody plants in Logan Canyon and Tony Grove, as well as information on managing noxious weeds and wildfire risks. These resources aim to assist both urban and rural residents in maintaining healthy landscapes and understanding the complex ecosystems of Utah's forests.
Long-Term Landscape Success
By following these forest-mimicry principles, residents can create more resilient urban landscapes. The transition from individual landscape elements to integrated mini-forests allows for a more natural management style that recognizes the biological needs of trees while creating attractive, diverse landscapes.
