An Ecosystem Services Approach to the Evaluation of Soil Conservation Policy in New Zealand Hill Country.

Current approaches to evaluate soil conservation practices are often limited, as the assessment is usually restricted to the costs of erosion including clean up and reinstatement of built infrastructure. Assessment of the lost soil natural capital stocks, if included, is generally limited to quantifying the area of land affected by slips and debris tails. Until the evaluation of such conservation policies includes the assessment of the whole range of ecosystem services provided by landscapes, the information available to policy makers remains utterly incomplete.

This study presents an ecosystem services approach to the evaluation of soil conservation practices, implemented in the Hawke’s Bay region in New Zealand. In April 2011, a heavy rain storm provoked landslides on hill slopes along a 250km coastal strip in the Hawke’s Bay. Following this erosion event, this study undertook to characterise the loss of ecosystem services from a sheep and beef grazed pasture. It also examines the recovery of the provision of ecosystem services in the 20 years following the erosion event, and the influence the introduction of space planted conservation trees has on the provision of services from pasture soil. A cost-benefit analysis of an ecological infrastructure investment in soil conservation is also realised.

The total value of the ecosystem services provided by an uneroded pasture on steepland on a typical sheep and beef farm was $3,717/ha/yr. This value drops by 64% following a single erosion event. Fifty years on from the erosion event, the ecosystems services only recover to 61% (in dollar value) of uneroded levels. In sharp contrast, the same land planted with conservation trees to reduce the risk of erosion provides, after 20 years, additional ecosystem services (+23% in dollar value) from the similar unprotected landscape.

The cost benefit analysis of soil conservation showed that, from a strictly farm financial point of view, planting conservation trees isn’t profitable for farmers, unless the trees are harvested for timber after 20 years, and low discount rates (<5%) are used. However, when the value of the additional ecosystem services provided is included in the analysis, the Net Present Value of the investment is greatly positive regardless of the discount rate (0-10%).

This study addresses a real-world conservation issue and shows how an ecosystem services approach can be integrated and used on the ground to advance existing governance frameworks and to solve resource management challenges.