Sustainable Trees and Land Management

The natural and societal benefits of trees, including urban trees, are numerous. Trees provide vital ecosystem services that result in cleaner air, storm water retention, transpiration, erosion prevention, carbon storage, and wildlife habitat. Trees form a natural shield from ultra-violet rays of the sun. The shade and natural cooling from urban trees have the secondary benefit of reducing heat island effects and saving energy. Trees also improve community aesthetics and raise property values. And of course, trees can provide food and the valuable raw material of wood.

Healthy green open spaces are critical to the overall health of the urban landscape. This includes the use of native plant species that thrive in our local soils, supporting native wildlife and insect species. Healthy soils are the most overlooked resource and are the most critical element to support healthy ecosystem services. Healthy soils, especially in urban environments, provide support for plant life, store a vast amount of carbon, and clean storm water, allowing it to recharge our critical aquifer. Healthy soil is a complex living system that requires hundreds (and sometimes thousands) of years to form. Living soils include not only a mix of silt, sand, and clay, but also organic matter, along with a complex mix of fungal mycorrhiza, beneficial bacteria, and millions of other organisms. Living soil provides the food we eat, sustains plants that provide the oxygen we breathe, and ensures clean water that we drink. Unfortunately, urban development destroys this system by paving over soil with buildings, roads, and parking lots. This living system can be destroyed with just a single pass of a piece of earth moving equipment, through compaction of the soil. Healthy open spaces, including sustainable urban farms, are a critical part of our urban ecosystem and are rarely considered in zoning codes or development practices. In many cases, the introduction of healthy native landscapes is prohibited in many codes, such as weed ordinances.

Interconnected systems of green spaces are critical for a healthy urban environment. These green spaces and interconnecting natural corridors contain living soils and complex landscapes that provide cooling shade trees, refuge from the built environment, and a natural habitat for wildlife and insects to move around and through. A fragmented and non-planned network of open space does not provide the same benefit to a community or its wildlife. Without natural corridors connecting green spaces, wildlife is at risk of wandering onto roads and into residential areas, seeking food and refuge. That is dangerous to both humans and wildlife. Planned, interconnected green space networks and corridors provide important benefits not just to the ecosystem but also to the economy. They entice economic development with places for recreation and garner higher land values along their boundaries.

The use of native vegetation in urban landscapes, including native tree and shrub species, helps to expand planned open space networks and the benefits they provide. Native vegetation is critical to wildlife and insect species, which help to keep our ecosystem in balance. Native insects, for example, require specific plant species to lay eggs and to use as food sources in order to develop into adults. These same insects are critical to pollinating the plants that provide us with fruits and vegetables. Landscapes containing a great diversity of species, including plants, animals, and insects, retain a balance where no individual species becomes dominant or out of control. The introduction of non-native plant species results in problems affecting our local ecosystems. Many introduced, or non-native, species provide no benefit to local wildlife or insect populations. In most cases, they are introduced species that our native insects cannot use for food, so they are not damaged or consumed by beneficial insects. This allows the non-native species to become invasive and take over landscapes, choking out or out-competing native species. The result is a less diverse ecosystem or, in a worst-case scenario, mono-culture landscapes. Our urban landscapes need to reflect - or at least contain - elements of our native landscapes to ensure overall environmental health.

Trees face a lot of threats these days, especially urban trees. Recall the Emerald Ash Borer – an invasive beetle species whose lifecycle was destructive to ash trees. A newer threat comes from the Asian Longhorned Beetle (ALB) – an invasive insect that threatens a wider variety of hardwood trees. The Asian Longhorned Beetle is already found in Ohio. Invasive tree species, particularly the Bradford pear are at best a nuisance, but are also seen to be crowding out native trees in eastern forests. Additional stresses for urban trees include ongoing development and the resulting alterations in hydrologic patterns, soil compaction, and road salt. Many of the benefits that trees provide, as listed above, do not occur until a tree reaches approximately 20 years of age. Unfortunately, the average lifespan of an urban tree is only 8 years.

Over the last few years, many communities in the Miami Valley have faced a significant loss of tree cover due to insect infestations, natural disasters, and trees reaching the end of their lifecycle. This has resulted in a decrease of tree cover in our Region. Conditions vary from community to community, but in a forested state like Ohio, achieving a tree canopy cover of between 40 to 60 percent is attainable. Few, if any, Miami Valley communities meet such a target. Additionally, research has found that lower income neighborhoods are likely to have less tree canopy cover than wealthier neighborhoods. Developing a tree plan to achieve greater, equitable canopy cover from healthy and diverse tree populations (i.e. tree species of varying ages) can provide a benefit to your community for generations.