The idea of the term “succession” has been around since the 18^th Century. Its importance is undeniable – it underpins modern ecology theory and application. Taken at its most basic level, ecological succession explains how one habitat changes over time to be replaced by an entirely new habitat.

The time scale in which habitats change is variable, but how they change can be quite accurately predicted. This is because the change in both aquatic and terrestrial habitats is directional – meaning that habitat changes are progressive and take place in an orderly fashion.

To visualise this process, imagine a grassland field in which management completely stops i.e. no mowing.

Now imagine that field two years down the line from that moment – the blackthorn hedges lining the field have started creeping into the field, birch and oak saplings have appeared amid the wildflowers.

Then imagine 20 years down the line – the blackthorn is now fully established and ever creeping to the centre of the field in dense patches, the wildflowers in those areas have been shaded out, the birch saplings are now over 15m tall. Suddenly an area of woodland and scrub has replaced what once was an open grassland field.

Why is succession important for reserve managers?

Succession is a natural process and is self-sustaining when areas are large enough. Remember that we’ve defined succession as being progressive? Well now we have to introduce disturbance. Disturbance effectively knocks back succession.

Again to visualise this, imagine a beautiful oak woodland in the middle of summer – clusters of oak trees soaring above your head. The sunlight is dappled through the tree canopy.

Take that woodland and imagine a harsh thunderstorm ripping through the tress – the aftermath being one of the older oak trees has fallen to the floor. Suddenly an area of the woodland is flooded with bright sunlight come Springtime. Plants that were shaded out, can now flourish and bloom. The habitat has been “knocked back” to grassland in that area, making a glade.

As we are all aware, Britain has lost a lot of its wild spaces. Our habitats are now constricted into smaller spaces where the process of succession has less room to continue naturally as it has done in the past. As custodians of wild spaces, reserve managers now must think about maintaining and balancing habitats so that more species can thrive in the spaces we have left.

Imagine that woodland again – now imagine that the thunderstorm has no effect. The trees do not falter against natural processes as they once did. Without human intervention, succession is inevitable on most of our reserves. We now rally against succession in order to maintain those precious habitats – we have become the disturbance - we are now the storm.