Cost-effectiveness of ecological restoration
Restoration ecology is a large business and a growing field, with numerous studies comparing techniques and linking restoration to ecological theory. Yet restoration practitioners face critical decision-making challenges, including unclear metrics for success, lack of information on costs, and a need to understand how environmental variation influences effectiveness. Here, we provide the first comprehensive analysis of the success of different methods of ecological restoration according to money spent on different phases, taking environmental variation into account, and providing tools to facilitate decision-making. We identify exact costs of multiple restoration methods for each of three phases of restoration of highly degraded habitat: (1) site preparation, (2) seeding & planting, and (3) maintenance. We focus on a large-scale (25 ha) demonstration effort in Orange County, California, to address the following questions: (1) What are the financial implications of different options available to restoration practitioners within the three phases of restoration? (2) During what phase of restoration should practitioners allocate their funds? (3) What is the role of environmental variation in determining the cost-effectiveness of restoration? Understanding the answers to these questions would be a step forward in optimizing the ecological and economic realities surrounding the practical implications of ecological restoration.
There was a significant positive relationship between money spent on restoration and resulting cover of native plants. Some techniques, such as imprint or drill seeding followed by frequent maintenance, were identified as the most cost-effective. Money spent at the seeding & planting phase of restoration had the strongest influence on native plant cover, followed by money spent on maintenance. Additional funds spent on site preparation had a negative effect on native plant cover, presumably because rainfall decreased during the study such that additional years of site preparation resulted in natives that were seeded & planted during drier years. Moderate, N-facing slopes had higher native plant cover for the amount of money spent, while steep, S-facing slopes were especially difficult to restore. Areas restored to Coastal Sage Scrub resulted in higher native plant cover than areas restored to California Grassland/Prairie, but they also cost more to maintain. Our results demonstrate how knowledge of the costs of multiple restoration techniques, combined with an understanding of how environmental variation influences effectiveness, can aid in decision-making. Additional metrics for success and valuation studies would allow for a more complete, cost-benefit analysis, potentially transforming the practice of restoration.