In the face of shifting weather patterns influenced by a changing climate, the garden can be a confusing place these days. What stressors are coming next, and which plants will have the resilience required to stand up to whatever those prove to be? With no group of plants is that more essential environmentally to think about, or trickier to figure out, than with the trees. Because of their long lifespans, a tree planted today will be reaching maturity in what may be a whole different world.

Safeguarding the Future of Our Urban Forests

Outline:- Mt. Cuba Center's Resilient Tree Canopy Project- Evaluating Native Tree Species for Climate Resilience- Leveraging Data and Tools to Inform Tree Selection- Considering Microclimates and Horticultural Practices- Assessing Tree Species for Varying Levels of Climate Resilience- Embracing Native Trees with Proven Adaptability- Monitoring and Adapting Strategies as Climate Projections Evolve- Mt. Cuba Center's Educational Offerings on Climate-Resilient Gardening

Mt. Cuba Center's Resilient Tree Canopy Project

At Mt. Cuba Center in Delaware, the esteemed native plant research site, a new effort called the Resilient Tree Canopy Project is underway to begin thinking about tree choices for the future. George Coombs, the Director of Horticulture at Mt. Cuba, explains that the center's predominantly tulip poplar canopy, which is around 100 years old, is rapidly aging. With a lack of natural regeneration beneath this canopy, the team recognized the urgent need to plan for the next generation of trees.However, the challenge lies in the fact that the trees planted today will be reaching maturity in a vastly different climate. Coombs emphasizes the importance of ensuring that the future canopy remains healthy and intact, rather than setting the garden up for potential failures. This realization prompted the launch of the Resilient Tree Canopy Project, a comprehensive effort to assess native tree species and their suitability for the changing environmental conditions.

Evaluating Native Tree Species for Climate Resilience

The Mt. Cuba team has undertaken a thorough analysis of native tree species, drawing on various data sources and tools to inform their decision-making process. One of the primary resources they've utilized is the U.S. Forest Service's Tree Atlas, which models how different species might react to climate change. However, Coombs notes that the Forest Service's recommendations were not always directly applicable to the horticultural setting of Mt. Cuba's gardens.To address this, the team turned to the Botanic Gardens Conservation International (BGCI) Climate Assessment Tool, which provides a more horticulture-focused perspective. This tool leverages data from public gardens to offer insights into the temperature ranges and climate suitability of various plant species, both in natural and cultivated settings.

Leveraging Data and Tools to Inform Tree Selection

In addition to these resources, the Mt. Cuba team has also explored the Future Urban Climate Web application, which paints a sobering picture of the potential climate shifts that certain regions may experience. Coombs shares that the projections for Philadelphia, for example, suggest the city could transition from a climate akin to southern Maryland to one more similar to Memphis, Tennessee, under a high-warming scenario.This data has been instrumental in shaping the Resilient Tree Canopy Project, as the Mt. Cuba team seeks to identify the tree species that are most likely to thrive in the face of these dramatic climate changes. Coombs emphasizes that the team is not just relying on yearly average temperature data, but also considering the potential impacts of extreme weather events and temperature fluctuations, which can be equally, if not more, detrimental to tree health.

Considering Microclimates and Horticultural Practices

As the project progresses, the Mt. Cuba team is also exploring the role of microclimates and horticultural practices in enhancing the resilience of their tree plantings. Coombs explains that in natural forest settings, the distribution of tree species is often dictated by the unique microclimatic conditions of different aspects and slopes. Applying this level of nuance to the placement of trees in the garden setting is a crucial consideration.Additionally, the team is investigating how specific horticultural techniques, such as soil preparation, irrigation, and mulching, can be leveraged to support the establishment and long-term health of the trees. By taking a holistic approach that considers both the environmental factors and the cultural practices, the Mt. Cuba team aims to create the best possible conditions for their future tree canopy.

Assessing Tree Species for Varying Levels of Climate Resilience

The Resilient Tree Canopy Project has resulted in the development of a comprehensive assessment of native tree species, categorized by their projected levels of climate resilience. Coombs shares that the team has identified several tiers of trees, ranging from those with "no concern" to those that should be "avoided" due to their heightened vulnerability to the anticipated climate changes.The "no concern" category includes familiar native species such as red maple, sweetgum, tulip poplar, white oak, and sycamore, which the team expects to continue thriving even in the face of a high-warming scenario. The "likely to be fine" tier includes trees like sugar maple, cucumber magnolia, and chestnut oak, which may experience some stress but are still expected to perform well overall.However, the team has also identified a group of trees that they believe will be more significantly impacted by the projected climate shifts. These include species like swamp white oak, yellow buckeye, and butternut, which the Mt. Cuba team plans to use more sparingly and monitor closely for any signs of distress.

Embracing Native Trees with Proven Adaptability

While the Resilient Tree Canopy Project has highlighted some concerning trends for certain native tree species, Coombs emphasizes that the overall outlook is not entirely bleak. Many of the trees that are deeply rooted in the local ecosystem, such as red cedar, sweetgum, and various oak species, are expected to continue thriving in the face of climate change.This realization has been a source of relief for the Mt. Cuba team, as it underscores the inherent resilience of many native tree species. Coombs notes that the team is excited to continue monitoring the performance of these trees, particularly in the newly planted garden that features a dominant presence of moosewood (striped maple), a species that may face challenges in the changing climate.

Monitoring and Adapting Strategies as Climate Projections Evolve

As the Resilient Tree Canopy Project progresses, the Mt. Cuba team remains cognizant of the fact that climate projections and their associated impacts are constantly evolving. Coombs acknowledges that the data and tools they've relied on have already undergone revisions, with the future climate scenarios becoming increasingly dire.This dynamic landscape requires the Mt. Cuba team to maintain a flexible and adaptive approach to their tree selection and planting strategies. They understand that their initial assessments may need to be refined and adjusted as new information emerges, and they are committed to closely monitoring the performance of their tree plantings to validate or refine their assumptions.By embracing this iterative process, the Mt. Cuba team aims to stay at the forefront of climate-resilient horticulture, ensuring that their gardens continue to thrive and serve as a model for other institutions and gardeners grappling with the challenges of a changing climate.