Disagreements about how to value the future among conservationists affects today's protection priorities

Amanda A. Hyman, Diane Le Bouille, Xingli Giam and Paul R. Armsworth, Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, Gengping Zhu, College of Life Sciences, Tianjin Normal University, Tianjin, TN, China, Charles Sims, Department of Economics & Howard H. Baker Jr. Center for Public Policy, University of Tennessee, Knoxville, Knoxville, TN

Background/Question/Methods
When seeking to protect the environment, should decision-makers favor actions that will make immediate differences or those promising long-term gains? The choice depends on how individuals weight benefits and costs experienced through time, something temporal discount rates can represent. Discount rates are parameters used to compare trade-offs that accrue through time by converting the value of future goods to present values. A small change in discount rates can alter the optimal timing and location of conservation actions, in addition to affecting estimated costs of conservation by millions of dollars. Hence, discount rate selection can have long-term consequences. Despite the wide use of discount rates in environmental management, no study has investigated discount rates used by practitioners.
Results/Conclusions
We show that practitioners, who work at environmental NGOs, heterogeneously think about decisions through time. Their median rate was 11.9% (ranging from -23% to 74%), significantly higher than values traditionally used in environmental policy. Domain and the interaction between domain and delay had significant effects on discount rates. Our survey results suggest that 1) time preferences are a potential axis in which NGOs could differentiate themselves and 2) practitioners have high discount rates, potentially implying financial insecurity among land trusts.
Our prioritization models show that variation about how to value the future among practitioners leads to conflicting recommendations about where to protect today. For example, biodiversity prioritization models with high discount rates favored counties with near-term threats for species that would otherwise be extirpated without any additional investment. Priorities shift as discount rates lower. Lower discount rates put more emphasis on future benefits and thus, places that will only become important in a few decades take on higher priority in today’s decisions. Such conflicting priorities are most distinct when spatio-temporal variables exist.