Abstract:
The spatial and dynamic pattern of landscape changes has a profound effect on the
supply of environmental services, including the provision of habitat for fish and wildlife. Spatial
heterogeneity is a common feature of landscapes in the Pacific Northwest, most notably in areas
important to the production of salmonid fish species. This heterogeneity complicates attempts to
design and implement policies to conserve the stocks of such species. To date, millions of
dollars have been spent to improve habitat for salmonids, with mixed success.
This research examines the spatial implications of habitat restoration activities for the
benefit of endangered salmonid fish species. A theoretical model defining an economically
efficient allocation of restoration practices is developed for a hypothetical stream with a range
of hydrological and spatial characteristics. An integrated hydrological, biological and economic
modeling approach is then developed, and an empirical analysis is applied to the upper Grande
Ronde River basin in northeastern Oregon.
Results of these analyses indicate that the heterogeneous nature of riparian conditions
and stream morphology has a substantial effect on the efficacy of restoration activities. The minimum cost allocation of restoration activities for small temperature reductions is to apply
restoration efforts to nearby upstream reaches, while cumulative effects become important as
the magnitude of desired temperature reduction increases. However, as the magnitude of desired
temperature reductions increases, temperature reduction per dollar of restoration efforts
decreases rapidly. In terms of specific riparian restoration efforts, passive restoration is
preferred to active restoration as the magnitude of desired temperature reductions decreases and
/ or as the time frame considered is increased. It is also less costly in general to implement
restoration activities in tributaries if the objective is to maximize stream length where water
temperatures decrease by a specific amount. When two targeting options are compared (a fish
abundance goal vs. a temperature reduction goal), this study found that temperature targeting is
inefficient in the sense that it is possible to produce a larger salmonid population with the same
budget, and that the levels of temperature targets have significant impacts on fishery benefits.
