Do not disturb?

In ecological circles, when there is a shake up of the natural order of things, we call this a disturbance. This natural process can be biological in nature - such as disease, beavers taking out trees or flooding areas through their dams, buffalo pushing down small trees or cattle pushing through hedges, boar turning over turves of grass or woodland litter - or more elemental in nature - pollution, storms creating gaps in the canopy, wildfires stimulating new growth, landslips, floods, coastal erosion, even earthquakes, tsunamis and volcanic eruptions! You get the picture.

These events, I'm sure you'll appreciate, occur at different frequencies and likelihood. If they are fairly regular and predictable, then the ecosystem is probably pretty used to coping with them, and may even depend upon them for habitat maintenance (as with fires on heathland, and in certain pinewoods). The great advantage of these kind of relationships is that they allow pioneer species to get a foothold and suppress over dominant species.

The result is that you get more diversity in the species that an area holds, and therefore you are likely to see a richer variety of natural processes. The locality can become more dynamic. This is especially true where the disturbance itself varies across an area, so the degree of change mirrors this and varies across the patch - some bits become more diverse and some don’t. If you like, there is variation in the amount of variation.

More wholesale destruction, as caused by natural disasters, could press reset on an entire ecosystem or landscape, whereupon most species have to recolonize and compete from scratch. And the results can be markedly different than what was previously there. Ecologically it could be seen as catastrophic or an intriguing opportunity, but either way, there is little you can do but shrug, move on and respect such planetary forces. Naturally we humans ourselves have always been a source of disturbance, but through active suppression of unwanted flora and fauna, or just a by-product of our ever increasing drive for fuel, food and society. And our influence has usually had a negative impact on species richness and hence natural processes.

So what is the role of disturbance, if any, in nature recovery or rewilding schemes? Well firstly, remember disturbance is an essential part of the natural order of things, and I would therefore be cautious not to overmanage your project to prevent it. Conversely, major natural disasters are rare, so think very carefully about your goals, and your modus operandi before removing a forest wholesale due to that fictional mudslide. A happy medium would be to either welcome or turn a blind eye to a naturally occurring disturbance, or to encourage through some set-up or maintenance actions, a gentle disturbance regime of your own.

Where to draw the line is really up to your nature recovery ethics. Rewilding purists would find initial work to kick start disturbance acceptable, such as introducing a couple of pigs to plough up the damper parts of the plot to benefit wildflowers and invertebrates. However, they may be troubled by plans to fell a tree every few years to allow light into a woodland. That is more active (ongoing) management, and rewilding is focused on setting nature up to become self-sufficient. In this example, some would point out that the odd tree may fall over time due to winter storms, so is there a place for our intervention?

What happens when you don't have the time or money to manage some pigs though? Do you do without disturbance? Well personally, I feel here there is a good argument for a bit of active management, and turning over some random bits of grassland or woodland each autumn and winter.

Either way, when habitats are altered in this way by nature, whilst some plants and animals become destitute (or worse), the new system often creates opportunities for many others. Disturbance, far from being a dangerous risk to ecosystems, is an essential and very normal part of nature's equilibrium.