This chapter addresses resilience and its relationship to ecosystem services. Plant biodiversity and biomass decrease with increasing salinity moving from. Mar 19, Carbon sequestration and storage, and the resilience of carbon stocks. .. and the ecosystem services of interest have been made, based on the UK to differentiate between the effects of plant diversity and biomass. Relationships between species richness, evolutionary diversity, and aboveground live tree biomass across US forests Biodiversity conveys numerous functional benefits to forested ecosystems, including community stability and resilience. Assessing ecosystem services across broad regions using forest inventory and.
Greater biodiversity should therefore increase the probability that a system will provide a consistent level of performance over a given time Naeem and Li, The relationship between biodiversity and ecosystem resilience may take different forms, depending on the underlying mechanism Figure 3.
There are three possible models for the relationship between biodiversity and ecosystem resilience: The available evidence favors the redundancy hypothesis Cardinale et al.
Declining resilience of ecosystem functions under biodiversity loss
However, species redundancy decreases over time as species sort into niches Reich et al. Modified from Naeem Although greater diversity tends to lead to greater system resilience, some ecosystems are highly resilient even though they are not particularly diverse, such as coastal wetlands.
Plant biodiversity and biomass decrease with increasing salinity moving from tidal freshwater wetlands to salt marshes Wieski et al. Salt marshes on the GoM coast are dominated by the smooth cordgrass Spartina alterniflora. Despite low plant biodiversity, salt marshes are extremely resilient, even in the face of the DWH oil spill Silliman et al.
Salt marshes exemplify extreme environments characterized by hypoxic soils, high salinity, and high sulfide concentrations soluble sulfide concentrations of 1—5 millimolar in soil are lethal to most plant life.
Economic Diversification Enhancing economic diversity is another route to increasing resilience of social-ecological systems. Communities whose economies are heavily dependent on specific natural resources are vulnerable to shocks to those resources. Highly diversified economies, such as biodiversity-rich ecosystems, can weather shocks to particular resources or particular industries, much as ecosystems can lose some species and still maintain overall system performance Briguglio et al. Sectoral diversification is expected to have a positive influence on economic resilience Simmie and Martin, The reliance of its economy on specific natural resources makes the GoM region vulnerable to shocks such as the DWH oil spill.
Fishing grounds were closed, and recreational and tourism activities suffered large losses in after the spill.
Some communities along the Gulf Coast are almost totally reliant on the oil and gas industry, fishing, recreation, and tourism. When these industries experience downturns, the economies of these communities suffer.
In the case of the DWH oil spill, however, much of the economic harm—though serious—was temporary. The immediate aftermath of the spill in was very difficult for many GoM communities see Box 2.
However, oil and gas production, fishing, and tourism largely rebounded in Drilling was allowed to resume, fisheries were reopened, and tourists returned. Managing Feedbacks and Slowly Changing Variables Strong negative feedbacks increase system resilience by offsetting the effect of a disturbance that pushes a system away from equilibrium.
Negative feedbacks exist in ecological systems in which biological organisms perpetuate conditions favorable to their continued existence. In social-ecological systems, actions aimed at maintaining existing conditions can provide negative feedbacks.
For example, fisheries management that adjusts harvest quotas based on current population size can help to stabilize fish populations by reducing harvests when stocks are low and increasing harvests when stocks are high Reed, However, maintaining stable stocks can mean highly variable harvests from year to year. But maintaining constant harvests, especially if set to maximize yields in an average year, can lead to fishery collapse Roughgarden and Smith, Managing systems to maintain stability for certain outcomes, such as harvests, can reduce stability in other dimensions and can affect overall system resilience Gunderson and Holling, ; Gunderson and Pritchard, Much as an individual whose general health is declining is more susceptible to disease, ecosystems compromised by ongoing stress may be more vulnerable to rapid change from disturbances Gunderson and Holling, ; Walker and Salt, For example, levees and channels to reduce flooding along the Mississippi River have changed the supply of sediment to coastal systems and have made parts of Louisiana more susceptible to damage from coastal storm surges Costanza et al.
Modularity and Connectivity Connections among components within a system can allow shocks to propagate through the system so that tightly coupled systems may be more vulnerable to systemwide risks May et al.
Building in a degree of modularity may be important for preserving overall resilience Levin, Placing booms to limit the spread of oil into coastal marshes is one example of modularity in practice. However, marine systems are inherently highly interconnected, and sometimes interconnections provide resilience, such as when local populations are reestablished through recolonization after local extinction events.
Adaptive Management and Learning If we knew exactly what the future had in store, then it would be easier to plan for it. Adaptive management has proven difficult to implement in practice, in part because it involves risk taking that can put managers in a difficult position of justifying failures even when it provides valuable information, as well as because it requires resources for ongoing monitoring and evaluation Lee, Of particular importance to managing complex systems is having some ability to predict regime shifts prior to their occurrence.
There are some signals of the imminent onset of a regime shift Scheffer et al. Whether these signals can be received in time, and management revised to forestall a regime shift, is doubtful Biggs et al. The potential for a harmful regime shift in the future should influence current management.
In most cases, this potential shift should cause management to take precautionary actions to reduce the probability of its occurrence Polasky et al. However, in some cases the impact on management of a potential shift could work in the opposite direction. Improving Governance and Increasing Social Capital The ability of a social-ecological system to recover from shocks such as a hurricane or an oil spill is improved by having highly functional institutions and a high degree of social cohesion.
Disasters that inflict large-scale and widespread damage put ecosystems and human communities under great stress. Help from outside the stricken area, such as from the federal government, is often essential to provision of relief in the immediate aftermath of a disaster. But long-term recovery depends in large part on the resources and resourcefulness of the local community Picou and Martin, Good governance also aids in assessing potential threats and long-term stresses and in bringing about changes in management or behavior to address them Folke et al.
Trust in institutions is a key variable in attaining cooperation to make changes, especially if the change requires at least some short-term sacrifice. Lack of good governance or social capital can lead to social, economic, or ecological decline and a downward spiral in environmental conditions and human well-being Folke et al.
Although systems are complex, it may be possible to manage them in ways that increase system resilience. Management itself can enhance system resilience if it creates responses to current conditions in ways that lessen the impacts of disturbances. The effectiveness of management can be enhanced by improving understanding of system dynamics, reducing uncertainty, and developing better early warning signals of approaches to thresholds.
Management for specific resilience uses knowledge of specific types of disturbances to design plans to minimize damages and promote recovery. Management for general resilience is needed when the type of disturbance is unknown or when many types of disturbances are possible. Conserving biodiversity or increasing economic diversity can make social-ecological systems more resilient to a range of different of disturbances, as can the other management approaches summarized in Table 3.
The emphasis on properties to promote general resilience is important given the inability to predict the type, timing, scale, and interaction of future disturbances. Because resilience management represents a significant change from current management priorities or decision-making processes, congressional authorization in the form of new or amended laws Ruhl, may be necessary to make it part of the process. A fundamental principle of federal administrative law, rooted in Article I of the U.
Constitution, is that agencies cannot act in ways that exceed the statutory authority Congress has given to them Doremus, Whether resilience management is consistent with current resource management laws depends upon current statutory authority and the details of resilience management.
For example, an agency committed to incorporating resilience management would need to craft a firm definition of resilience for the system in question; identify a means of measuring the current state of resilience; build a model capable of predicting to some degree of certainty the resilience effects of specific decisions or to design management experiments that could lead to the development of predictive capacity ; and explain both the process and the results to the public and to the judges likely to review the agency's decisions Allen et al.
In many ways, the challenges that agencies face in resilience management are similar to those in adaptive management. Some federal agencies, notably the U. Forest Service, the U. Fish and Wildlife Service, the Bureau of Reclamation, and the National Oceanic and Atmospheric Administration, have begun to recognize the importance of resilience management and to incorporate it into their broader policy objectives Benson and Garmestani, Implementing resilience management could, in theory, be easier in the marine environment than in terrestrial environments.
Unlike terrestrial systems, the oceans are entirely public and are not interspersed with private holdings. The federal government thus has more freedom both to set and adjust regulations. In federal waters outside of state jurisdiction, federal agencies could manage all resource use holistically to attain broad systemic goals. Finally, the laws pertaining to resource use in the oceans have traditionally been designed to function under changing environmental conditions and substantial uncertainty.
Declining resilience of ecosystem functions under biodiversity loss
The Magnuson-Stevens Fishery Conservation and Management Act MSA requires regular input of scientific information and annual consideration of management measures, which enable decision makers to respond to environmentally driven stock fluctuations Carlarne and Eagle, Still, resilience management in the GoM ecosystem faces challenges. The United States lacks a legal tradition of managing complex systems as multiple, interacting systems.
Congress has traditionally written laws that address resources individually; thus, the MSA governs the use of fisheries, the Outer Continental Shelf Lands Act regulates oil and gas and mineral use, and so on Eagle, The resource-by-resource approach is less amenable to resilience management than is a place-based approach. That approach, in which a single agency has jurisdiction over most resource use within a single place e.
In addition, the GoM ecosystem is affected by actions taken on land that influence nutrient and sediment inputs and are controlled by agricultural and other policies Rabalais et al. Finally, although there are no private property interests in federal Gulf waters, there are private interest groups that would likely oppose significant changes to the current system of resource management.
Because these groups have the incentives and resources to oppose change at all levels, a management shift would need to be accompanied by an explanation of why its benefits would outweigh the real or perceived costs Ruhl, Although the maintenance of resilient ecosystems has many benefits, including provision of a steady flow of ecosystem services, political, legislative, and institutional barriers may impede implementation of resilience management. Implement a Portfolio Approach to Management How might governments manage publicly owned resources in a way that minimizes disruption to the flow of ecosystem services during and after a disaster?
One approach is to move away from the current legal approach to managing marine ecosystems and toward a set of laws that aim to manage distinct, defined areas of the sea for narrower, specific objectives. The direct management of marine life populations in federal waters of the GoM currently occurs pursuant to two laws: Although the efficacy of these laws in achieving their stated objectives is debatable, it is clear that each law uses a single, science-based concept aimed at achieving a single goal with respect to the GoM marine species under its auspices.
So, Congress could, for example, modify the MSA and the MMPA so that managers would be required to apply a range of strategies over a set of geographically defined management areas or over a set of distinct fish or mammal populations. Some areas or species could be managed using more conservative versions of the traditional optimum yield or potential biological removal tools, and some areas or species could be managed using entirely different approaches and with different ends in mind.
As Gordon Munro observed, fishery or ecosystem management is similar to other forms of capital management: Economists view capture fishery resources, as they do all natural resources, as a form of natural capital, assets that are capable of yielding a stream of economic returns broadly defined through time.
Since fishery resources are capable of growth like forests, but unlike mineralsthese resources—natural capital—can be managed on a sustained basis, essentially by skimming off the growth through harvesting.
This also means that the resources can provide economic benefits to society indefinitely. It means further that one can, within limits, engage in positive investment in the natural capital by harvesting less than the growth.
Munro,p. Conceptually, such laws offer one of the most promising approaches to enhancing system resilience and thereby reducing the impacts of future human-engineered or natural disasters on the people who rely on those systems.
One option for facilitating resilience management is employment of a portfolio approach to designing the system of laws regulating use of the Gulf of Mexico.
Under a portfolio approach, different management goals and strategies would be applied to discrete geographic ocean and coastal areas. Such an approach, as compared with an aspatial management strategy that tries to ensure that all similar systems provide equal amounts of all services, provides a buffer against uncertainties, including future large-scale disturbances. Implementation of this portfolio approach would require congressional action because a set of new statutes would be needed.
Ecosystem Restoration and Resilience Following an oil spill or other disturbance to an ecosystem, a key management objective is ecosystem restoration. Ecosystem restoration after a disturbance and ecosystem resilience are closely linked. Systems with low resilience may recover slowly or switch to a different regime and fail to return to original conditions. In the case of the DWH oil spill, of particular interest is how well restoration efforts will work to recover ecosystems to pre-spill conditions, both in terms of restoring the provision of ecosystem services and increasing resilience to further disturbances and ongoing stresses.
Much has been written about the restoration of the Mississippi River Delta Boesch et al. We used binomial mixed effects models 8 to estimate trends in frequency of occurrence across 1 km grid cells for each species in Great Britain between and This approach has been shown to be robust to spatiotemporal variation in recorder effort in a simulation study comparing different methods 8.
It produces trends in species' occurrence that reflect national and local abundance trends, where data are available for comparison.
For each species' model, we tested the null hypothesis of no trend in occurrence over time, at three different thresholds of type 1 error: Next, we grouped all species by the primary ecosystem functions that they underpin, namely: Our assumption is that changes in the national frequency of species in each functional group can provide an indication of trends in resilience of those functions.
Rather than compare absolute numbers of declining species across functional groups, we assessed the balance of increasing versus decreasing species using proportion tests and presented results as log ratios, so that our tests were not biased by differences in total species numbers or statistical power between functional groups arising from differences in the mean numbers of records per species. We repeated the tests at each threshold of type 1 error to assess sensitivity to the level of statistical significance for trends.
To put species into functional groups, we consulted taxon experts and reviewed published literature to classify which higher taxa are primary or secondary providers of pollination, pest control, decomposition, carbon sequestration and experiential cultural values.
First, functional contribution measurements are often context specific as the roles of species can change over space and time 410 In different environments, species' relative frequencies vary, affecting their functional contributions 101415while there are also changes in the per capita contributions of individual species to function provision 7. For example, the per capita roles of natural enemies vary depending on which crop pest is dominant and which other natural enemies are present 13 A second reason for our species grouping is that environmental resource managers are tasked with ensuring the continued provision of ecosystem functions under changing environments, that is, their resilience 5.
This includes maintaining ecosystem functions in the face of the challenges posed by climate change, habitat degradation, invasive species and pollution. Publication Notes Check the Northern Research Station web site to request a printed copy of this publication. Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact Sharon Hobrla, shobrla fs. We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
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