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Contents:
  1. Numéros en texte intégral
  2. Duke University Press - In Search of the Rain Forest
  3. Alchemy in the Rain Forest : Politics, Ecology, and Resilience in a New Guinea Mining Area
  4. PUBLICATION TITLE:

Humanity is already intervening in ecosystem function on a planetary scale Ehrlich and Ehrlich The central question is whether our interventions can be planned and guided in a way that is beneficial both to humanity and to other organisms. The arguments for moving on from—or at least expanding the scope of—restoration are both theoretical and practical and are directed at past and future ecosystem change and the moral hazards underlying the presumption that complete restoration is possible.

Because ecosystems are not static, the term restoration entails the open question of when to restore to—that is, to what historical state do we wish to restore the system? The world has changed a lot in the past through human- and non-human-controlled processes and will probably change even more in the future; therefore, we need to move on from the notion that we can restore to a previous static state.

An idea underlying much conservation and restoration activity, and indeed society's overall relationship with nature, is that some past ecosystem states had characteristics more desirable than those of the present ones e. However, we may not know the character of the historic ecosystem in any detail. History is always contingent on current knowledge and understanding and is interpreted through current cultural and scientific norms Carr Although methodology is improving Jackson and Hobbs , in many instances we are left with incomplete descriptions of the ecosystem at a particular time, without detailed information on the underlying dynamics.

Even for relatively recent disturbances, there may be little information on the predisturbance state, and nearby undisturbed systems are often assumed to approximate this state. Although this issue has been debated in the past e. Recent debate has been focused on how far we could or should consider turning the clock back e. With the requisite knowledge and capability, to what state might one restore a particular ecosystem, such as Yellowstone: to the condition it was in at the beginning of the ice ages, at the end of the Pleistocene, when human beings first saw it, when Europeans arrived, when it became the world's first national park?

And how would ecologists determine what those earlier states were like? Any restored system would probably be one that was modified and supported to some extent by human action. Debate continues over both the extent and the intensity of human activity in different regions, and it is likely that effects varied spatially and temporally Vale Although the pervasiveness of indigenous human management is still debated, evidence is accumulating from many parts of the world that the effects of such management were extensive, as was discussed by Mann [] and as has been illustrated, for instance, in Australia [ Head ] and California [ Anderson ].

In addition, the rate of change in many systems has escalated in recent times. The world is changing at an ever-increasing and unprecedented rate and in multiple ways Steffen et al.


  1. Being Forest Peoples: Globalizing Local Sustainability?.
  2. An International Journal.
  3. Introduction;

Climate change, loss of biodiversity, nitrogen deposition, land-use change, invasive species, release of toxic chemicals, resource exploitation, and many other parameters act synergistically to push the planet in directions never before experienced in human history. The results are no-analogue environments and novel ecosystems and species combinations Williams and Jackson , Hobbs et al.

Therefore, returning a system to even a semblance of a historic state is and will continue to be difficult. Even if the disturbance after which we wish to restore the community had not happened, the community is still likely to have moved on because of these external factors. Consequently, we should intervene with an eye to the future and toward managing for future change.

Given the current state of the science, the term restoration , taken literally, offers false promise. Although one view is that humanity has a moral responsibility to try to restore damaged areas, there is also a moral hazard in promising to do the impossible e. There are numerous myths in restoration ecology that give rise to false expectations of what is possible.

Numéros en texte intégral

These myths have been discussed in detail by Hilderbrand and colleagues , who characterized them as simplified and potentially misguided models for understanding and application. These models include ideas such as community assembly always being predictable, the existence of a single end point, and that fixing physicochemical conditions will allow biotic reassembly. False expectations arise partially because of an overselling of what restoration can do by some and partially because of a misunderstanding of the complexity and dynamics of the ecosystems being managed or restored.

As was discussed above, it is obviously not possible to fully replicate a complex and diverse ecosystem—to paraphrase an old saying, you can't step in the same ecosystem twice. Although many restoration ecologists recognize this problem either explicitly or implicitly, the message has not been promulgated effectively.

Duke University Press - In Search of the Rain Forest

Many people, and importantly, many policymakers, believe that it is possible and desirable to bring a system back to its predisturbance state. The belief that complex ecosystems are fully restorable opens the door to trade-off schemes between development and restoration and may lead to loss of high-value conservation areas.

In particular, the expectation that systems can be restored underlies much policy on offsets and mitigation Brooks et al. Concern has been expressed for some time about the effectiveness of mitigation and offsets in maintaining biodiversity values Roberts , Race and Fonseca These concerns remained largely unchanged in more recent evaluations Burgin , BenDor et al. A societal expectation that degradation can happen and can be either reversed in situ afterwards or offset by restoration somewhere else inevitably results in high-value areas being traded for restored areas elsewhere, with an overall net loss of biodiversity or ecosystem service value.

A recent example is the loss of 30 hectares ha of good-condition Banksia woodland within the Perth urban area of western Australia, resulting from the construction of a new hospital. This decision will result in the replacement of one of the largest remaining remnant patches within the central urban area with a number of smaller, partially restored areas and the protection of an area not under any immediate threat.

A further hazard relates to the false dichotomy that persists between restoration and conservation, which are often seen as separate enterprises conducted with different foci, by different people, and for different reasons Young , Noss et al. There has been a false perception that restoration requires action, whereas traditional preservation-focused conservation is mainly a passive attempt to retain an existing ecosystem or assemblage Hall However, the links between the two endeavors are already recognized Dobson et al.

Conservation faces the same set of challenges as restoration, and old ways of working have become less appropriate Heller and Zavaleta Because the world is changing, conservation more and more commonly requires active management, blurring the lines between it and restoration. A need to focus both on an uncertain past and on a more uncertain future has created an apparent paradox for restoration ecology. Recent attempts to deal with these problems include reframing restoration with a future rather than a historical focus Aronson and van Andel , Choi , Choi et al.

Most practitioners and researchers, however, acknowledge the need for intervention to achieve whatever goals are set. In a similar way, in conservation biology the challenge is to move the focus from preserving existing species and assemblages within particular designated places, such as reserves and parks, to considering how to conserve systems that are temporally and spatially dynamic. This challenge increasingly requires that answers be sought to questions of whether, how, when, and why intervention is necessary. As Matthews and Turner pointed out, humans have long undertaken ecological interventions, usually in response to particular environmental problems.

Interventions can take the form of manipulating the biotic or abiotic characteristics of the ecosystem and can vary in intensity from deliberate nonintervention through directed one-off interventions to ongoing, large-scale interventions Hobbs and Cramer Examples of these interventions include local activities, such as fencing an area of vegetation to exclude livestock, removing problem weed species from a local preserve, or reducing pollutant inflow to a wetland.

At larger scales, reinstatement of historic fire regimes, extensive revegetation to increase landscape permeability, and reinstatement of flow regimes in river systems are all interventions aimed at maintaining or repairing ecosystem services, including the conservation of biodiversity.

Interventions are intended either to maintain a system in a current desirable state or to move a system away from a current undesirable state. The former type of intervention would normally be couched in the rubric of conservation or ecosystem management—and maintaining desirable states and assemblages is often the highest priority for conservation—whereas the latter type would fall under the restoration terminology discussed above.

Interventions can also be categorized as reactive, active, or proactive and can occur primarily at a local, regional, or global scale table 1. Reactive interventions are attempts to maintain a current ecosystem state or to halt a process thought to degrade ecosystem values.

From rainforest to charcoal - DW Documentary

Active interventions are positive steps taken to change ecosystem properties in a particular direction. Proactive interventions are designed to limit the human drivers of processes that assault ecosystems. These intervention types cover the restoration-management-conservation spectrum while avoiding the past-focused aspects of restoration and conservation. As with all categorizations, there is overlap among the terms. Because of the complex nature of the material being covered, it is perhaps to be expected that the categories blur together. Most active and proactive interventions are still carried out in reaction to perceived problems or threats, whether those threats exist or are predicted.

For instance, an active intervention at the local scale is likely to form part of a reactive response to a broader degradation process. However, the intent of the intervention is important.

Revegetating a burned slope is the same action whether it is done with the intent to increase native plant populations or with the intent to halt erosion, but with the former intent it is active intervention, and with the latter it is reactive. A categorization based on intention forces a clear consideration of goals up front, rather than actions based on preconceptions or a failure to clarify and agree on goals at all Hobbs A useful question to consider in the context of intervention in ecosystems is whether leverage points can be identified—places to intervene in the system where a small change could lead to a large shift in behavior Meadows Useful leverage points include key elements and flows within the ecosystem, balancing-feedback loops that act to stabilize the system, and reinforcing-feedback loops that lead to rapid ecosystem change figure 1a.

Reactive management tends to be focused on the system components per se, rather than on processes or feedbacks, whereas active management tends to be focused more on processes, flows, and feedbacks. Importantly, however, interventions may also include altering policy and broader socioeconomic settings Chapin et al. As well as internal system properties, Meadows suggested that the most effective leverage points may lie in the information transfers, rules, and paradigms constructed around the system. This area is where there is the greatest opportunity for proactive interventions.

Changing rules and governance approaches may have a much more profound effect than tinkering with ecosystem properties per se. Restoration ecology is traditionally focused on the local system being restored, rather than on the broader socioeconomic and political settings, although there have been recent attempts to fuse the two Aronson et al. Both system properties and governance also need to be considered at multiple scales, broadening the traditional focus from the local system to include regional and global scales figure 2. This broadening of focus suggests both that ecological aspects need to be considered in a wider socioeconomic context and that an interdisciplinary or even transdisciplinary approach is needed.

There may be potential leverage points, where intervention can produce a large change in system behavior, associated with each system characteristic. Examples of particular issues are given in b and c. Here, the system characteristics are identified in normal text, and possible interventions are indicated in italics and categorized as reactive R , active A , or proactive P. Using the framework developed by Carpenter and colleagues , interventions are needed in both ecosystems and governance systems.

The traditional focus of management intervention is the local ecosystem, and this remains the most common scale at which interventions occur. However, it is increasingly recognized that local interventions have to be conducted within a broader landscape and regional context, and that regional interventions may be required to address many issues such as hydrologic imbalance, connectivity, and maintenance of key ecosystem services. Furthermore, the interconnectedness of local and regional systems within a global context is also increasingly relevant in the context of climate change, invasive species movement, and so on.

In the context of governance, there is now clearer recognition of the need to consider the socioeconomic settings within which interventions have to take place, at local, regional, and global scales. These settings often determine what interventions are possible or socially desirable at the local scale. Regional governance similarly sets the broader policy and legislative context, and interventions aimed at changing this context can significantly change the feasibility or priority accorded to ecosystem-level interventions.

Finally, global governance is perhaps the hardest arena in which to intervene effectively, but the one in which we could most effectively confront the ultimate drivers of many threats and environmental problems such as climate change and geopolitical stability. On one hand, clever use of leverage points could greatly enhance humanity's ability to manage ecosystems effectively in a rapidly changing world, but on the other hand, inappropriate application could make a difficult situation much worse. Careful identification of the most effective interventions requires that we achieve enhanced understanding of which system components and flows are key and where feedback loops might be in play figure 1b, 1c.

Possible interventions are indicated in these figures and categorized as proactive, active, or reactive. Interventions are focused on actions that alter the components of the system biotic, physical, or social that in turn change the status of the system in one way or another. Feedback loops can either balance a system in its current state or hasten its transition to an alternative state figure 1a. When the current state is deemed desirable, management focus will be on balancing feedbacks and avoiding runaway reinforcing loops, whereas when the current state is considered degraded or undesirable, the aim may be to reduce the effect of balancing loops that maintain the current state while searching for reinforcing loops that can quickly drive the system to a more desirable state.

For example, imagine a plant community in which an exotic species has recently been introduced figure 1b. If the community is intact, its current composition may be maintained by balancing feedbacks, such as high plant diversity and competitive exclusion, that slow the spread of the invasive species.

In a disturbed or fragmented community, balancing feedbacks may become weaker. As the invasive species establishes in the community, its spread and effects can escalate by way of reinforcing feedbacks, such as exponential population growth and invasional meltdown Simberloff and Von Holle In this case, a balancing-feedback loop maintains the native system relatively intact, whereas the initiation of a reinforcing-feedback loop results in runaway degradation as a result of invasion. In comparison, consider a situation in which overgrazing is thought to have placed a forest system in a degraded state with no regeneration figure 1c.

In this case, a balancing-feedback loop maintains the system in a degraded state i. Status quo management results in the maintenance of a degraded state, and active interventions are required to reestablish tree cover. Standard management approaches such as planting seedlings are unlikely to succeed if the key issue is overgrazing by deer or other ungulates.

In this case, fencing is a possibility, but more systemic treatment of the problem may be achieved by the reintroduction of predators, such as wolves, to reduce herbivore levels Beschta and Ripple and set up a reinforcing-feedback loop. This results in predator control of herbivores and enhanced tree regeneration.

Judicious management of balancing-feedback loops and the recognition of, and early intervention in, reinforcing-feedback loops may represent managers' main hope of being able to prevent rapid deleterious shifts in ecosystem state or to force beneficial shifts Suding and Hobbs In both examples, interventions focused on the socioeconomic and policy contexts may, in fact, be more effective than interventions in the ecosystem itself or may be a prerequisite for enabling effective ecosystem interventions.

In both hypothetical examples discussed above, changes in policy and regulations can significantly alter the parameters under which the actual ecosystem can operate: In the case of invasive species, for instance, tightening quarantine and trade regulations involving species transportation can significantly reduce the risk of problem species being introduced.

Introduction

Changing management goals as a result of new information or an altered understanding of system dynamics can also have a profound impact on the ecosystem. For instance, in the case of herbivore overabundance, hands-off management in a preserve may be replaced by an approach in which herbivore control is acceptable. The implementation of this goal may be intimately connected to shifting paradigms and philosophies.

Alchemy in the Rain Forest : Politics, Ecology, and Resilience in a New Guinea Mining Area

For instance, a switch to acceptance of some degree of nonnativeness in an ecosystem will reduce the management imperative to eradicate or control all nonnative species figure 1b. Shifting from a predator-eradication paradigm to the recognition of predators as important system components with cascading impacts on the system as a whole Terborgh and Estes similarly alters the goals and approaches likely to be used. Although the examples presented above primarily involve local ecosystem management, albeit set within the broader socioeconomic context, the same approach can be taken to larger-scale issues.

A recent prominent example is the Deepwater Horizon oil spill in the Gulf of Mexico, which resulted in major environmental pollution, ecological damage, and socioeconomic hardship. Clearly, interventions in this situation form a continuum from immediate reactive interventions to longer-term active interventions.

Reactive interventions are required in order to stop the flow of oil from the ruptured well: This intervention is more engineering than ecology. Further reactive interventions are required in order to limit the oil's damage to sensitive ecosystems, and these may be accompanied or followed by active interventions to attempt to repair the damage caused by the oil and to reinstate aquatic systems, fishery enterprises, and other human social and economic activities disrupted by the spill. Further proactive interventions could be envisaged that would be aimed at preventing such environmental damage from happening again; these proactive interventions could include rebuilding barrier islands and other coastal habitat, as is already advocated for the prevention of storm damage LCPRA Finally, proactive interventions in the broader socioeconomic sphere could be aimed at reducing society's oil dependence and fossil fuel use, thereby eliminating the need for ever-more-risky resource-development projects.

We recognize that proposing intervention ecology as an approach is not a panacea. There are counterarguments to all of the points we have raised above. In particular, the concept of intervention implies no specific management goal. Intervention could send the system in any direction; it would not necessarily return the system to or maintain the system at some preferred state.

However, this lack of de facto goals could and should give managers and society in general impetus to develop clear goals for any intervention plan with open discussion on the desirability of alternatives. Perhaps more importantly, the term intervention is itself loaded and has militaristic overtones as a result of recent popular usage. It is certainly not the nurturing term that restoration is, and it is hardly likely to engage communities in ecosystem management in the way restoration does. Maybe this connotation alone indicates that it would be wrong to advocate doing away with the idea of restoration altogether and that we should instead accept that it is one particular type of intervention that fosters community engagement with nature while, we hope, helping community members recognize the reality of what that nature is.

There is always uncertainty about the risks of interventions Matthews and Turner , but the degree of uncertainty is very variable within and often very different among the three categories of intervention. Direct deforestation is the most obvious immediate threat, but climate change is also a big issue for Amazonia. We have to deal with both if we want to safeguard the forest. Sulphate aerosol particles arising from the burning of coal in power stations in the s and s have partially reduced global warming by reflecting sunlight and making clouds brighter.

This pollution has been predominantly in the northern hemisphere and has acted to limit warming in the tropical north Atlantic, keeping the Amazon wetter than it would otherwise be. To improve air quality and safeguard public health, we must continue to reduce aerosol pollution, but our study suggests that this needs to be accompanied by urgent reductions in carbon dioxide emissions to minimize the risk of Amazon forest dieback.

Peter M. Cox, Phil P. Harris, Chris Huntingford, Richard A. Betts, Matthew Collins, Chris D. Jones, Tim E.

PUBLICATION TITLE:

Nobre Increasing risk of Amazonian drought due to decreasing aerosol pollution. Nature Journal external link - subscription required. Three of the authors of this Nature paper will publish a second paper on the Amazon basin later this month. Futher information can be found here external link. The full reference is Harris, Phil P. Daily Telegraph - 8 May Amazon doomed by too much clean air external link. Reuters - 8 May Clean air could kill the Amazon, researchers say external link.

Skip to main content. Additional information The research results referred to above are published in the following scientific paper: Peter M.