Managing Resilience for Ecosystem Restoration in a Changing Climate

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Grand Canyon National Park / CC BY 2.0
The development of management systems along the Colorado River have radically transformed the river’s ecosystem, decreasing sediment flow and dropping water temperatures

Across the US, billions of dollars are devoted towards large scale ecosystem restoration programs. The Everglades in Florida is the recipient of a $15 billion program over 30 years; Chesapeake Bay $7 billion over a decade. The list goes on: the San-Francisco Bay Delta, the Grand Canyon, the Gulf of Mexico, and the Missouri River. These projects add up to one of the biggest shifts in how we view natural resources and manage major ecosystems in the United States. For decades, governments have sought to contain rivers and waterways, whether to control flooding or meet the demands for agriculture, energy production, or urban development. These large scale infrastructure projects—like dams and levees—have largely met objectives of flood control or water supply, but at the same time, have eroded ecological resilience that threatens the very development they have enabled. After decades of dam and levee building, there is now a gradual shift back towards a more holistic approach to ecosystems—one which aims to restore natural processes in order to mitigate against climate change.

Whether ecosystem restoration can become one of the guiding principles of this century will depend on how quickly we can dispense with traditional ways of thinking about the environment. During the 20th century, development of management systems accelerated, as dams and levees were constructed to constrain flood effects and provide water and energy for human activity.1 Dams were built along the Colorado River to store water in reservoirs and allow for the control of water flow to supply water for economic development. Similarly, levees and canals in southern Florida facilitated the supply of water and flood protection for urban, agricultural, and environmental needs. One of the challenges facing ecologists is that these man-made alterations have led to radical transformation of ecosystem structures and functions, often signaling a loss of resilience, and making it harder to restore their original states.2

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Master Sgt. Mark Olsen, US Air Force / CC BY 2.0
The costs of weather related disasters in the US are steadily increasing, with hurricane Sandy in 2012 running up a bill near $60 billion.

Such transformations have been documented in all types of ecosystems: aquatic (clear or turbid lakes), terrestrial (grassland or shrub land), wetlands (open water or vegetated marshes), and marine (coral or algal reefs).3 More specific examples facing ecosystem restoration managers include the transition of the Colorado River from one where sediment, flow, and temperature pulsed on an annual basis to a river that is sediment starved, clear, and cold. Indeed, the name ‘Colorado’ refers to a blushing river—one that changed from green to red. Such broad scale ecosystem regime shifts are also responsible for the extirpation and endangerment of a few species, such as the humpback chub in the Colorado. In the Everglades, landscape level vegetation shifts and decline of key bird populations are due to declines in long term flows associated with upstream water diversions, increases in nutrients from agricultural runoff, and changes caused by disturbances such as fire, drought, freezes, and cyclones. Thus, many of these large-scale restoration programs are attempting to shift or flip ecosystem states. Perhaps one of the largest concerns is the inherent uncertainty in facilitating regime shifts. Due to the number of the variables involved, and the complexity of interactions among variables, scientists and managers have great difficulty in predicting outcomes. Another issue is that there is little experience of solving such complex problems; many managers will admit that they are attempting to achieve results that have never been done before. In response to this inherent uncertainty, most of these large-scale restoration programs have taken an adaptive management approach.4

Adaptive management programs in the Grand Canyon and the Everglades have been ongoing for well over a decade. In these programs, management actions have been proposed as tests or trials to see if these actions will help facilitate regime transitions. In the Canyon, short flow releases have been largely successful at helping the managers learn how to restore extant sediment to portions of the river ecosystem, as have predator control experiments to benefit endangered fish taxa. In the Everglades, an active adaptive planning program is underway—while a few system wide experiments have been planned, no experimental manipulations have yet to be realized.

In both the Everglades and Grand Canyon, managers are trying to manage for a variety of social objectives. Ecosystem restoration is but one of many, including water supply, flood control, endangered species, water quality, and recreational benefits to name a few. Due to recent executive orders, federal agencies now must also add adapting to climate change to this growing list of objectives.

Adapting to Climate Change

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Master Sgt. Mark Olsen, US Air Force / CC BY 2.0
The costs of weather related disasters in the US are steadily increasing, with hurricane Sandy in 2012 running up a bill near $60 billion.

While linkages between a changing climate and cumulative weather events are debated, the costs of such weather related natural disasters in the United States are increasing substantially. In 2011, over 55 billion dollars were spent recovering from weather events.1 Estimates of damage from the storm Sandy in 2012—a marginal hurricane—are in the range of 60 billion. Some of this rise in fiscal impact may be due to more frequent and more intense storms, but other factors such as development in disaster-prone areas, including flood plains or coastal areas, contribute to the increasing social costs. While discrete weather events are causing impacts, other longer-term climatic changes such as increasing recurrence and intensity of flood and drought cycles are creating economic hardships across scales—from farms to regions to the nation. Perhaps one of the reasons for a renewed focus on adaptation to climate change in the US is because of the recent, dramatic rise in economic impacts from weather events. Such events have helped to bring discussions about resilience and adaptation to the forefront of public discourse, and especially to the minds of those charged with managing public lands, public waters, and other natural resources.

Instead of viewing these as disturbances to be managed against, they could be viewed as ways for managers to test ideas (i.e., passively experiment) as to how to achieve management objectives. Two illustrative examples of such learning opportunities have occurred in the past, as described in the following paragraphs.

Florida makes use of waste water

In the early 1980s, high rainfall over south Florida saturated the Everglades. The general management strategy was to discharge this water as quickly as possible to the ocean and Gulf of Mexico. Indeed a similar issue is occurring as I write this, as the Governor of Florida is blaming the federal government for ruining estuaries and degrading tourism by discharging excess freshwater. But rather than play politics with the environment, thirty years ago managers requested that the excess water be delivered to Everglades National Park. Such a change in policy required an act of Congress. As a result, Congress passed the Experimental Water Delivery Act, which—as a test—redirected the flow to the park.

The result of this experiment was resolution of three chronic problems with water management that had persisted for decades. The first problem involved the fact that the park was receiving less than its fair share of the water, and moreover the pattern of delivery was harming resources. In other words, water managers had been delivering a set amount of water to the park, regardless of rainfall or ambient conditions. From the findings of the flow test, managers developed a rainfall-based formulation to deliver water in sync with the weather. As a result, the park has gotten more water in wet years and less water in dry years—much more like the way the ecosystem functioned prior to intensive development.

The second lesson revealed by this experiment was that water quality and water quantity were intimately linked, as scientists and managers realized that any sources of upstream water would carry nutrients that could cause unwanted flips in vegetation communities. The third lesson was that passive experiments such as this one could be used to determine solutions to long-term problems such as how much water should be delivered to the park.

Colorado stays cool

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Al_HikesAZ / CC BY-NC 2.0
The Glen Canyon Dam shifted the Colorado River ecosystem to one with constantly cold water, until water managers harnessed a natural fluctuation in the dam to serve as temperature control rather than implementing further artificial systems.

Another example of a learning opportunity is occurring in the Grand Canyon portion of the Colorado River. Managers in the Grand Canyon Adaptive Management Program are using an ongoing drought to resolve questions around mitigating impacts from the Glen Canyon dam. Built in the early 1960s, the dam was constructed in such a way that cold, clear water is taken from Lake Powell reservoir and discharged downstream. As a result of the dam, the river ecosystem has undergone an ecological regime shift from one that fluctuated between hot and cold on an annual basis to one that is consistently cold water. For many years, managers have proposed a costly solution: to retrofit the dam with a temperature control device to be able to deliver water of varying temperatures. Managers feared detrimental impacts from warmer water discharges in the river system that had adapted to the cold water.

The ongoing drought has lowered the reservoir to the point where warmer surface waters have and are being released downstream. Managers have thus been able to simulate the effects of warm water, without building a multi-million dollar temperature control structure.

Using climate change to help ecosystem restoration

Both the examples of Florida and Colorado suggest that variability from a changing climate will produce opportunities for experimentation, but will also require frameworks that allow for institutional learning and policy reorientation that respond positively to the changing climate and other global drivers.7 Recurring knowledge assessments of resources, plus visioning and scenario processes, should help managers to prepare for and manage such changes. They will also require the continuation of research and monitoring programs that focus as much on learning about the complex dynamics of these systems as they do on collecting more data. Managers will need to be flexible and opportunistic as these events emerge, often with little or no forewarning. Whether these pieces can be put in place is a challenge, but at least these discussions have the potential to increase awareness of the value of ecosystem restoration and the opportunities afforded by climate change to change our mindsets and learn our way into a more desirable future.