By combining regional data from terrestrial, freshwater and marine environments, it is possible to systematically evaluate spatial or economic efficiency when choosing priority sites for conservation. This also represents a viable approach to test assumptions of ecological accuracy.
The greater gains in efficiency in the Cook Inlet Basin ecoregion were likely attributable to integration across three environments because efficiency may be easier to attain in less fragmented regions. The WPG ecoregion is heavily fragmented by urbanization and land use practices (i.e. logging, agriculture). In less fragmented regions, there are more opportunities to choose alternative scenarios to meet goals for the conservation targets. However, the costs of conservation are often greater in more fragmented landscapes and thus even small gains in spatial efficiency may represent significant savings in total conservation costs.
Our results in the Pacific Northwest Coast ecoregion showed that ignoring threats that travel between terrestrial and marine systems in conservation planning exercises leads to the identification of areas that likely are at substantial risk. Sites that were identified as the best sites in the single-system scenario have high potential for adding to biodiversity representation, although these sites could also be considered at high risk where they coincide with cross-system threats. However, if terrestrial management was aimed at abating cross-system threats then selected high biodiversity areas within these areas might become priority. Alternatively, the best sites identified under both single- and cross-system threat scenarios could contribute most to biodiversity representation under current conditions. By comparing the best and sum solutions of the single- and cross-system scenarios, we identified areas ideal for preservation or restoration through integrated management. Our findings lend quantitative support to the call for explicitly integrated decision-making and management action in terrestrial and marine ecosystems.
True ecological accuracy is impossible to measure in a regional planning effort and as a proxy, precision in meeting goals was used. In both the Cook Inlet and WPG ecoregions, goals were met less precisely in the integrated analyses as compared to the un-integrated analyses. It is not surprising that it may be more difficult to meet goals precisely in integrated analyses because of the added constraints of having to meet goals across more environments jointly with more targets. Size and shape of assessment units have a significant role here in determining the precision of meeting goals, and more work clearly needs to be done in sensitivity analyses that address this issue. Other proxies or indicators for ecological accuracy are needed to better understand, plan and manage for the many connections in species, systems, and processes that span environments.
These three ecoregions provide examples of integration across the land/sea margin. While there are many methods that can be designed to address both spatial efficiency and ecological accuracy, we believe the work presented here are viable test cases in building a decision support system toward integrated conservation and management.
Given the historical divisions in science, conservation and management across the coastal zone, why should we worry about integrating efforts across terrestrial, freshwater, and marine environments? The answer is to improve accuracy and efficiency. The first set of reasons for better integration is that efforts that recognize these connections across environments can be more ecologically accurate. There are real connections between environments and incorporating these connections can improve resource management.
Many ecosystems and species straddle environments. All estuarine ecosystems must be understood, by definition, to be partly in freshwater and partly in marine environments and require an understanding of processes, fluxes and connections across environments. All intertidal environments are part marine and part terrestrial in nature. Many species have life histories that require physical connectivity and passage between the different environments. Their populations cannot be managed appropriately if these connections are not conserved and maintained. These species primarily fall in to two categories:
- those with joint marine and freshwater requirements (e.g., anadromous and catadromous species including salmonids, sturgeon, and eels)
- those with joint marine and terrestrial requirements (marine feeders/terrestrial breeders including seabirds, seals, sea lions, and turtles)
We make ecological mistakes that may result in inefficient or even wasteful management when we do not account for the full life history of these species. For example, a popular strategy for sea turtle conservation is to protect turtle nesting grounds (e.g., night patrols and removals of eggs for artificial rearing). Studies have shown for loggerhead turtles in the Gulf of Mexico that the critical life history stage for mortality is the transition from the juvenile to adult stage in males. Efforts to protect nesting loggerhead mothers and their eggs may be inspiring, but to ensure the viability of these populations management needs to focus on the protection of juvenile males to ensure that they reach adulthood.
It is less commonly recognized that these connections go both ways and that many coastal species from bears to wine grapes receive sustenance from the seas. Terrestrial planning efforts that do not consider factors such as effects of overfishing on seabirds or estuarine concentrations of pollutants that rise through coastal food webs will not accurately identify appropriate conservation actions for terrestrial species and ecosystems. For example, Helfield and Naiman (2001) found that 22-24% of the nitrogen in trees and shrubs near salmon spawning streams was marine derived. This marine subsidy significantly influenced growth rates in Sitka spruce trees (Picea sitchensis), which may in turn make these streams better for salmon spawning, because of increases in shading, sediment and nutrient filtration, and the production of large woody debris. If the source of these nutrients and the connections among environments is not recognized and managed, we could lose the forest ecosystem for not seeing the fish.
The second set of reasons for integrated conservation and management is that it makes good economic sense to be efficient in planning and management (e.g., the development of preserves, parks, and programs). For example, it is cost efficient to do one integrated plan instead of three separate efforts across terrestrial, freshwater and marine environments. Integrated planning can result in improved communication and fewer redundancies in effort. Many of the threats considered by planners are similar across environments and this information could be compiled just once instead of three separate times.
Integrated conservation and management can lead to more efficient investments in programs. Many areas with high estuarine and near shore marine diversity and productivity occur in areas where uplands are intact and diverse. This correlation occurs in part because many stresses to coastal waters arise upstream. In many places, even if there are not strong direct connections, there appear to be correlations among terrestrial and marine hotspots in biodiversity. There is a clear efficiency to co-locating investments in programs and offices across environments for working with partners and in staffing for monitoring and enforcement.
Finally, conservation impact is enhanced when actions can be clearly demonstrated to affect species and ecosystems across environments. When actions have benefits across multiple environments and jurisdictions, there can be dramatic increases in the congruence, cooperation and support among groups and agencies. For example, organizations focused on improving practices on agricultural lands find new support for these actions when they can be shown to benefit swimming and fishing downstream.