May 2012 – Amelia Schmidt
Calculating the Value of Nature on Publicly Managed Open Space in Wake County, North Carolina: An Ecosystem Service Valuation
The public’s investment in open space property has provided Wake County with measurable value (Figure 1). While the environmental and recreational benefits of open space preservation may be apparent, economic benefits such as water purification, flood control, and climate regulation are sometimes less evident. In this study, ecosystem service benefits were estimated for nitrogen and phosphorus retention, carbon sequestration and storage, habitat protection and its direct influence on wildlife-associated recreation. As indicated in Figure 1, substantial value can be realized through the conservation of terrestrial and aquatic ecosystems, especially for carbon storage, wildlife habitat protection, and its associated recreational opportunities.
Carbon dioxide is sequestered (captured) by trees and shrubs and is stored as carbon in landcover where it remains until released through fire, harvest, or soil disturbance. The storage of carbon regulates the effects of climate change, reduces health problems caused by heart and lung disease, and reduces catastrophic damage caused by erratic weather conditions. These benefits would not exist if trees and shrubs were removed. Landcover sequestered an estimated 145 tons of carbon dioxide annually and two million tons of carbon was stored in the trees, shrubs, and soil in the study area. Annual sequestration was valued at $8.6 million and the benefit of accumulated carbon over a 50-year period was valued at $130 million in terms of the damage avoided.
Protecting wildlife habitat in Wake County’s publicly managed open space increases biodiversity, provides residents with a variety of activities including wildlife viewing and educational opportunities, as well as the occasion to engage in scientific discovery, with an estimated daily value of $55. An increase in biodiversity realized through habitat protection was valued at $45.4 million and the recreational opportunities afforded by this protection were valued at $39.3 million annually. The loss of biodiverse habitat would result in the loss of the aforementioned values as well as the waste management, flood protection services, and ecosystem health, which deliver tangible benefits to the citizens of Wake County.
Nutrient retention reduces water pollution when trees, shrubs, and soil remove nitrogen and phosphorus from stormwater runoff, thus reducing the cost of removing these nutrients artificially from water supply reservoirs —a benefit that would not exist if this open space had not been designated. Landcover retained an estimated 30 tons of nitrogen and phosphorus annually, which was valued at $2.5 million.
We often think of conservation in terms of its cost rather than its value.1 Conversely, we often measure residential and commercial land development in terms of its value rather than its cost. When we incorporate the services of ecosystems into the equation we may realize that the benefits of maintaining the integrity of ecosystems are high when compared with the costs of not having them. Calculating the economic cost of artificial water treatment or the social cost of carbon emissions may seem like an artificial way to value our connection to nature; yet appreciating nature from an economic perspective helps put environmental concerns on the table in a way that governments and institutions can understand.