Change and restoration

Upland rivers are fascinating places that possess a raw quality. Full of rapid change, violent spates to low flows in quick time, they pose challenges to people and nature. It is this rapidity of change that keeps them alive, keeps people drawn to them and puts their ecosystems on a knife edge of existence. One severe flood, drought, landslip or pollution event can alter their ecology for years. And when a natural system flips between threshold states dragging it back to its original condition is complex and challenging, beset with frustrating feedbacks and full of unexpected consequences. The new science of restoration ecology has discovered this time and again. What has appeared to be an obvious intervention can force a natural system to skew off towards some other state not accounted for during intervention planning. This has resulted in more measured approaches to reverse interference and has revealed that ecology does not exist in easily flipped parallel states but occurs in complex dimensions of interacting multivariate factors that we can never fully understand.

But not fully understanding something does not mean that we cannot understand it enough. Beneath the aesthetics of these places lie scale upon scale of interacting processes within and between both the living and non-living components of a system that create forever fluctuating conditions. However, even though they fluctuate, under prevailing conditions they are always pulled back towards some unknown average. In order to understand enough we need to simplify these interactions down to basic assumptions that explain them in as much detail that is required in order to predict the outcome of an intervention. This is not a magical process and can only come from experimentation both in laboratories and natural systems. And we are beginning to understand enough though it would be arrogant to suggest that we will never make mistakes during restoration efforts, but with restoration ecology it is the mistakes that guide learning.

The biggest experiment (and probably mistake) we are undertaking is one we have not planned but has come as a consequence of modern economies and lifestyles. An article published in 2007 in Global Change Biology by Durance and Ormerord showed that upland stream macro-invertebrate assemblages may decline by 21% for every degree centigrade rise in water temperature. This is of concern to freshwater ecologists as after primary production these are the most important components of upland river systems. What we have learned in recent years is that such a change would be difficult to reverse and as future temperatures are forecast to increase for sometime it may be that these upland river systems are destined to become shadows of their present selves.