One might reasonably ask: why protect habitats? After all, wetlands are drained, lowlands diked, rivers dammed, deserts irrigated and so on, all the time. The overall environment does not seem drastically affected by all this human activity. So why exert time, money and policy initiatives to protect natural habitats, or attempt to repair those that have been changed, to protect their productive potential to meet human needs?
The answer has to do with the character of natural systems. All natural systems are complex, and intertwined in ways both visible and invisible. The various parts — plants, bacteria, animals, water, air, soil and trees — each have a biological role and depend on one another. Overall, this is the “biological-physical (biophysical) system,” the basic support system that supports all life on earth.
This may seem counterintuitive, because there appear to be so many unnecessary parts to an ecosystem. If we cut all the Western Red Cedars in a coastal forest, a forest is still there in some form, and appears to function as it did before. But in reality, all species in an ecosystem are essential to it; none are useless or expendable. If human activity reduces one or more species to a minimal level, or extirpates them entirely, this reduces the complexity of the system. The ecosystem’s integrity depends on having all its parts intact. It is like a fishing net: cutting a few strands does not destroy the net, but cutting too many strands makes large holes, destroying the net’s use completely. As Aldo Leopold said, “The first rule of intelligent tinkering is to save all the pieces.”
We don’t know which piece of a biophysical system is the most important at any given time. Each part has a corresponding relationship with every other part of the system. They provide stability only by working together within the inviolable biophysical limits of their design. Thus, any biophysical system is defined by how it functions, not by its pieces in isolation. The system’s behavior depends on how its individual parts interact as components of the whole, not on what an isolated part is doing. The whole, in turn, can only be understood through the relationships, the interaction of its parts. A so-called “independent variable” — an isolated fragment — exists only on paper as a figment of the human imagination.
A biophysical system has both integrity and resilience. After a major disturbance, such as an earthquake, volcanic eruption or tsunami, natural systems re-establish themselves because of resilience. Resilience consists of the many species, all deeply interconnected, that create the whole. Thus even if some are temporarily reduced or eliminated, the entire system has strength to heal after a major trauma. Its so-called feedback loops are strong, and the system remain productive even under severe stress. But when species go extinct and the natural system is too heavily altered, it becomes fragile. Such a system is easily affected by slight changes. It does not have backups — meaning, more than one species able to perform a similar function. What to a person may look like a “useless” species is actually an integral part of the ecosystem, providing part of its sustainability through the strength of its resilience.
Biological diversity buffers an ecosystem against severe disturbance. Diversity needs to be protected because without it the biological systems humans depend on no longer have resilience. Nature is not stable and unchanging, but its equilibriums are dynamic. Therefore, change and recovery from disturbance depends on resilience.
This is the key to sustainability. Notoriously difficult to define, ‘sustainability’ simply means the ability of a biological system to maintain its critical functions — and thus continue to produce whatever it does, whether salmon, acorns, cedars or clams and sea anemones. If a system is simplified by human intervention, it is more fragile and easily disrupted. Unable to return to its pre-disturbance state, because nothing is reversible, it cannot easily re-establish a new healthy equilibrium. Obviously, humans have many choices to make in terms of how we treat natural systems, all of which we depend on for the necessities of life. We can treat them so they hopefully remain productive, resilient and sustainable. How we do this is complex, but the steps for protecting habitats are fairly well known.
There is an increasing number of books that discuss these issues. What the River Reveals by Valerie Rapp looks at the “ecosystem services” provided by rivers. A comprehensive, well-written and coastal-focused study is by Oregon scientist Chris Maser, entitled Interactions of Land, Ocean and Humans published by CRC Press in 2014. Maser details the connections, many of them little known, and the effects they have on biological functioning. A good background book is Aldo Leopold’s classic A Sand County Almanac. Finally, the Millenium Ecosystem Assessment is a recent large scale attempt to weigh the consequences of ecosystem change for human wellbeing, involving the work of more than 1,300 experts worldwide. Their findings are a state-of-the-art scientific appraisal of the conditions and trends in the world’s ecosystems. Click here for further reading.
Several recent books describe the methods of defining sustainability and the concrete steps leading to policy-making for sustainability. Two are by Chris Maser, Ecological Diversity in Sustainable Development and Decision-Making for a Sustainable Environment: A Systemic Approach, both published by CRC Press. Another excellent work is Nature’s Services: Societal Dependence on Natural Ecosystems, edited by Gretchen Daily. This book gives an overview of several major ecosystems and how they support human economies through soil, pollinators, wetlands and other components.
For a good overview of the relationship between biological systems and sustainability, see the video here of a University of Missouri presentation by Chris Maser in 2009.