Trees outside forests (TOF) encompass all trees and shrubs not classified as dense, natural forests or other wooded lands. They are found in various human-modified environments, including agricultural and urban areas. These trees offer diverse environmental, social, and economic benefits.
Where Trees Thrive Beyond Forests
Trees outside forests are found in numerous settings shaped by human activity.
In urban and suburban areas, trees populate parks, line streets, and grow in residential yards and commercial zones. They are integral to the “urban forest,” encompassing every tree across a community. Cities often feature hardy species like silver birch, sycamore, and London plane.
Agricultural landscapes also feature trees, appearing as scattered individuals in fields, along hedgerows, and as part of agroforestry systems. These trees are integrated into farmlands, interacting with crops, livestock, and wildlife. They are found in homegardens, along roads and streams, and in small woodlots or fallow lands.
Beyond urban and agricultural settings, trees thrive in rural areas, such as along roadsides, scattered across pastures, and around farmsteads. Roadside trees provide shade and help stabilize soil, while trees in pastures offer shade and act as windbreaks for livestock. They also contribute to the aesthetic appeal of rural areas and can help reduce airborne dust.
The Essential Roles of Non-Forest Trees
These trees offer numerous benefits. Their presence in diverse landscapes provides ecological, social, and economic advantages.
Trees improve air quality. They absorb gaseous pollutants like carbon monoxide, nitrogen oxides, and sulfur dioxide. Trees also filter particulate matter, such as dust and soot, by trapping these particles on their leaf and bark surfaces. This process helps reduce respiratory issues and improves public health.
Trees contribute to water management. Their canopies intercept rainfall, reducing the amount of water that reaches the ground directly, which helps decrease stormwater runoff. Tree roots hold soil in place, preventing erosion and allowing water to infiltrate the ground slowly, recharging groundwater reserves. This also helps filter pollutants from runoff before they enter waterways, improving water quality.
Scattered trees support biodiversity. Areas with scattered trees have greater species richness and abundance of wildlife. These trees provide food, shelter, and nesting sites for a variety of wildlife. They can also serve as stepping stones, enabling wildlife movement through fragmented environments.
Trees help regulate local climates, particularly by mitigating the urban heat island effect. Their canopies provide shade, which lowers surface temperatures. Evapotranspiration, the process where trees release water vapor, further cools the surrounding air. Strategic placement of trees can reduce ambient air temperatures.
Beyond environmental impacts, these trees offer social benefits. They enhance the aesthetic appeal of landscapes, providing shade and creating more comfortable outdoor spaces. Access to green spaces and tree-lined streets can improve mental and physical well-being, reducing stress and encouraging physical activity. The presence of street trees has also been linked to fostering community interaction and potentially reducing crime rates.
Economically, trees can increase property values. They also reduce energy costs by providing shade in summer, which decreases air conditioning needs. In winter, trees can act as windbreaks, reducing heating costs. Trees can support local economies through products like fruits or timber, and by encouraging longer shopping times in tree-lined commercial areas.
Nurturing Trees in Our Shared Spaces
Proper care and management are important for the health and longevity of trees. Thoughtful practices from planting to ongoing maintenance contribute to their well-being.
When planting a new tree, selecting the right species for the specific location is important, considering factors like sunlight, soil type, and mature size. The planting hole should be two to three times wider than the root ball, but only as deep as the root ball to ensure the trunk flare remains at or slightly above ground level. After placing the tree, backfill the hole gently, packing the soil to remove air pockets, and water thoroughly to settle the soil around the roots.
Ongoing maintenance involves consistent watering, especially for newly planted trees. Daily watering may be necessary initially, gradually decreasing as roots establish. Deep and infrequent watering encourages deeper root growth, making trees more drought-tolerant.
Mulching is another beneficial practice, as it helps retain soil moisture. A 2-3 inch layer of organic mulch, such as wood chips or shredded leaves, around the tree’s base helps regulate soil temperature, suppress weed growth, and improve soil fertility as it decomposes. Mulch also protects the trunk from mechanical damage caused by mowers and trimmers.
Proper pruning techniques are important for tree health and structure. The “three D’s”—dead, diseased, and damaged branches—should be removed first. When cutting, make clean cuts just outside the branch collar, the swollen area where the branch connects to the trunk, to allow for proper wound closure. Avoid removing too much of the tree’s canopy in a single pruning cycle to prevent undue stress.
Trees face various threats, including limited root space, soil compaction, and damage from construction or vehicles. Pests and diseases, such as the emerald ash borer or oak wilt, also pose risks. Environmental factors like extreme heat waves, de-icing salts, and air pollutants from traffic can further stress trees. Recognizing these threats allows for proactive measures, such as avoiding root compaction during landscaping and advocating for tree protection in development plans.
Community involvement is important for nurturing trees in shared spaces. Local organizations and municipalities often implement community forestry programs that provide technical support, education, and resources for tree care. These programs may include tree giveaways, workshops on planting and maintenance, and volunteer opportunities for tree planting and stewardship. Such collective efforts help ensure the long-term health and expansion of urban and rural tree canopies.