What is Natural?

Complexity in the Field
by J.B. Ruhl

In the November 24 issue of Science, researchers K.J. Willis of Oxford and H.J.B. Birks of the University of Bergen (in Norway--a very nice city by the way) discuss the advances that have been made in paleoecology, moving from a largely descriptive and imprecise discipline to one they believe offers much for the future of conservation practice.

Paleoecological records include fossil pollen, seeds, and fruits, animal remains, tree rings, charcoal, etc. Descriptively, they can provide a snapshot of what ecological conditions were like well before human intervention. Willis and Birks argue, however, that the real value in paleoecology is in helping us understand how natural systems behave over long terms in response to natural perturbations--i.e., the natural variability of the environment. One of the challenges of modern conservation, which frequently relies primarily on observed conditions playing out over short terms, is that it is exceedingly difficult to disentangle the natural cause-effect relationships from the human-induced effects based on observations of the short-term dynamics of complex ecosystem behavior.

Particularly as more and more conservation practive involves active management toward some defined goal (e.g., to modify preserve boundaries to adjust for global climate change; to maintain biodiversity; to sustain a "natural" ecological system in situ), paleoecological studies can help form dynamic models of the natural component of ecological systems (e.g., understanding the long term effects of implementing different fire regimes on public lands; understanding the long term effects of species introduction).

In my view this is a healthy trend in terms of policy. On too many occasions conservation policy has been set by a static vision of what is "natural," based on conceptions (in many cases formed by descriptive uses of paleoecology) of what conditions prevailed at particular times in the past. In rare cases it may be possible to manage a particular ecosystem so as to maintain our best understanding of a state of nature from the past, though global climate change will complicate that strategy in any corner of the world. Far more frequently, particularly with the effects of global climate change starting to surface in significant ecological shifts, it will be more important to understand how natural systems respond to perturbations such as biological invasions, wildfire regime shifts, and climate variability. With better understanding of nature's past as it played out, rather than simply as it appeared at points in times, we will have a better set of tools for managing nature's future.

This is not to suggest that conservation policy should give up on the quest for sustaining the natural, but rather that we might want to reconfigure our conceptions of what is natural. Naturalness is a process, not a static state.