Species turnover or process modification may not have immediately visible consequences, but they decrease ecological resilience to disturbance or disruption. For example, the loss of large birds from the forests of New Brunswick may reduce the scale range over which budworm predation is resilient, producing outbreaks at lower budworm densities. The loss of species or processes produces ecosystems that are more vulnerable to ecological collapse, and reduces the variety of possible alternative ecological organizations . The loss of species that represent functional groups, especially large species that generate mesoscale vegetative patterns such as elephants, moose or tapirs, may eliminate possible types of ecological organization. There are suggestions that this may have occurred during the Pleistocene extinctions of mega-herbivores, and such losses appear to be particularly difficult to reverse, even if large scale ecological engineering projects are undertaken.
Conclusions Translating either data or understanding across scales is often difficult.
It shifts the focus of scaling from looking solely at how change is transmitted across scales, to looking at what are the situations in which reorganization within a scale can occur, or entirely new levels of organization may form. Doing this provides a framework to identify what types of qualitative change are possible and plausible. One thing that is virtually certain about the consequences of global change is that, both to citizens and to scientists, its consequences are going to be surprising. When the resilience of existing systems is overwhelmed, processes and events that have never happened before will happen. Formerly unimportant processes or species will become important, and formerly fundamental things will lose their importance.