In recent years the IMA has made a commitment to the Indianapolis community to become more conscientious stewards of the environment in its pursuit of fulfilling the museum’s mission. This has been a worthy challenge for an institution to take on within the confines of the museum itself, but we also have the unique position of having 152 acres of gardens and woodland that give us an advantage over many urban institutions when measuring our carbon footprint. In an effort to evaluate that advantage, we turned to a software analysis tool created by the USDA Forest Service called i-Tree.
The intention of i-Tree is to allow communities and other users to assess their current urban forest cover, create awareness and educational opportunities, and guide application for better management of those trees. It has frequently been applied on a city-wide scale, but can also analyze an entire state’s urban forest, or a small, local city park. The results are based on field data collected from random plots, accounting for tree species, height, trunk diameter, and canopy characteristics. The data is then entered into the Urban Forest Effects (UFORE) analysis model, which calculates the amount of air pollution removed, carbon sequestered and stored by the trees, and sustained economic benefits.
To elaborate on the terminology of carbon sequestration and storage, a brief review of plant photosynthesis may be helpful. Photosynthesis is the process of converting light energy to chemical energy in the form of sugar (glucose). Carbon dioxide (CO2) and water (H2O) molecules are broken down with energy from the sun into glucose (C6H12O6), a usable energy form, and oxygen (O2), which, lucky for us, is expelled into the environment as a waste product.
Eventually, that glucose can be reorganized into different forms: sucrose, starch and cellulose. Each of these sugars is made of a different 6-carbon compound, which are used as sources for plant energy, or stored as organic compounds to develop plant growth and the structural form of the plant (i.e. the inner wood of a tree). Think of these terms when discussing carbon sequestration and storage, where you can associate sequestration with removing carbon from the air for the process of photosynthesis, and associate storage with the amount of carbon that has been accumulated in the size development of the tree. This is important, because if the tree were to die, all that stored carbon would be released back into the air or soil as the tree decomposes.
The results of measuring carbon sequestration and storage have more meaning when you can understand, in part, how they fit into the plant’s life cycle. Now that you know some of the conditions and terminology, you’re ready to hear what we found about our own, IMA urban forest!