IN YOUR BACKYARD
• with martyn robinson
THE MORE MOVING PARTS THE BETTER... One of the interesting differences between human-designed systems and natural ones is the inverse effect of increasing complexity. With human systems, tools and machines, the more complex they are, the more likely they are to break down. One tiny factor or faulty component can cause an entire system to grind to a halt, and fixing the problem usually calls for replacement of parts rather than repair. Similarly the more refinement, or work, needed to produce the device, the more quickly it will fail or need maintenance. Each component of a system depends on the others, rather than functioning in isolation – and there is often very little ‘give’ in the more complex systems. A hammer is less likely to fail than a hand drill, which is less likely to fail than an electric drill, and so on. In a complex machine like a computer, one tiny fault can (and often does) stop work until a specialist can come to adjust an electronic feature, reinstall software or replace some component. Yet the home handyman can hammer away for weeks or months until the head falls off the hammer! In natural systems too, each component depends on others, rather than functioning in isolation. Simple systems are prone to failing as too few components are involved, and there is little ‘give’ or resilience. Consider, say, a temporary puddle consisting of five species – one plant, three herbivores and a carnivore. If the plant should go, the herbivores starve and die out, shortly followed by the carnivore.
Explore 35(3) Summer 2013
Left Rainforests are among the most diverse habitats on Earth. Photo by Stuart Humphreys.
If we compare the puddle to a more complex system – say, a river or lake – there are many more species, niches and diets involved. If one species of plant disappears, the herbivores can turn to others. Similarly, the predators can prey on the herbivores or on other carnivores, and the diversity and populations ensure they won’t eat out their food supply completely. The system is far more stable if it has developed all together in a natural system over a long time. So why then are so many natural systems in trouble right around the world? The answer is, predictably, us in most cases. We now have inputs into most, which tends to make them ‘smaller’
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(think of land clearing and swamp draining) or less complex by reducing key species and populations (overfishing, clear-felling trees etc). With fewer species, systems become less stable. When we add other decidedly unnatural inputs, like pollution, pest species and climate change, it is not surprising that many natural areas are struggling to survive. Left to their own devices, some natural systems have run, and may continue to run, more or less unchanged for thousands of years. Will any humanmade systems last as long?
