Ecological Succession 3

Recently cleared ground to the front of the log cabin. The bare ground is now covered by a great variety of different grass species and  other  herbaceous flowers.


By the time two years have passed, succession has already taken place on our bare patch of ground. A new community of plants, animals, fungi and micro-organisms has largely replaced the earliest pioneer species which first colonized the bare ground.

The environmental conditions on the same patch of ground are considerably different to the conditions present when the first pioneers arrived.

'Cuckoo Spit' (froghopper nymph home) on Bird's-foot Trefoil - Lotus corniculatus. By now, a variety of longer-lived, slower colonizers have displaced many of the species in the early pioneer community. These include grasses and flowering herbs such as dock, clover and Bird's-foot Trefoil. The ground is almost completely covered in plants.

The plants are not the only species to have colonized the area. Along with the plants have come the herbivorous invertebrates which feed on those particular plant species. The presence of the herbivores then attracts a range of carnivorous invertebrates to feed on them.

Left: 'Cuckoo Spit' - the foamy home of the young stage of a herbivorous insect known as a Froghopper. On Birds's-foot Trefoil.     See inside the 'spit'.

Roe Deer droppings. Larger herbivores such as rabbits and deer will also graze such an area.

Their dung provides another wonderful microhabitat for many different species of fungi and invertebrates. Nothing is wasted in nature and one animal's waste is another's food source!

The soil will be enriched as the dung is recycled by the dung-dwelling community. Interestingly, the dung community also goes through a succession of its own as the droppings age.

Left: Roe Deer droppings

Pilobolus fruiting bodies. Image courtesy of Jeff Benn. One of the fungi occurring in various types of animal dung is called Pilobolus. The fruiting bodies are produced on the surface of the dung (left). It has a fascinating method of ensuring that it is always in the right place at the right time.

The fruiting bodies are only 3mm high, with a little black   packet of spores on the top. The bulb beneath the spore packet explodes shooting the packet of spores out onto surrounding grass. Another animal will come along and eat the grass together with the spores. These then pass through the gut of the animal and out in the dung, where the fungus can then develop all over again.

Shrews have arrived and will eat invertebrates.  

A number of small mammals will also now be present, including shrews (left), voles and mice. These will attract carnivores such as owls and foxes to feed on them.

Because there are now many more species of plants and animals in the area, the number of possible interactions between species has greatly increased.

The simple food chains of the eariest pioneer stage, when few species were present, have developed into more complex foodwebs.       

Many, if not all of the environmental changes which have taken place on our original bare area have actually been brought about by the communities living there. This is because in the processes of living, growing and reproducing, species interact with and modify their habitat. 

Shield Bug on butterup.


Using our previous example to illustrate this, the grasses and small flowering herbs have by now bound the bare soil with their network of roots, preventing erosion and soil loss. The soil has been somewhat enriched through the addition of dung and the decomposition of dead plants. Legumes such as the clover and trefoil will also have helped to add nutrients to the soil through nitrogen fixation in their root nodules.

The cover provided by the vegetation has affected the microclimate of the ground surface, while also providing a great variety of microhabitats for invertebrates.

Left: Shield Bug on buttercup

Rhododendron ponticum seedlings growing in a moss base. The environmental changes brought about by organisms often result in their subsequent elimination from the area.

For example, pioneering mosses may grow into thick cushiony carpets with great water-holding capacity, which act like sponges. These provide an ideal new environment for the germination and establishment of the seeds of other competing plants, which otherwise might die from lack of water.

These rhododendron seedlings (left) will eventually grow into tall, tangled, dark thickets which will shade out and displace the moss which enabled them to survive in the first place. (Note : Rhododendron ponticum is not native to Britain and causes great ecological damage.)

In the space of two years, the biodiversity (variety of life) on our bare patch of ground has soared, as it has been colonized by fungi, plants and animals. The ecosystem has developed from a very simple one with few interactions, to a much more complex system with a staggering number of interactions going on between individuals, species and the habitat itself.  

If left undisturbed, the area will pass through a number of further different successional stages, each with its own characteristic mix of species. All of these different successional stages are known collectively as a sere.

Each new community will be better adapted to the changed environment which has been provided by the previous community.

Eventually, a climax or 'final' community is reached. At this point, the succession will not go any further. However, this does not imply that there will be no further change.

Woodland, the climax community for our original bare patch of ground. The climax community for our original bare patch of earth would be oak woodland.

As part of the natural sequence of life, trees mature and eventually die. When they fall to the ground, an opening is provided in the woodland and the process of succession will start all over again on this new opening.

The species which colonize the opening will be different to the original bare ground pioneers because the environmental conditions have been altered.

Because there is a different starting point, this cycle of succession would be known as a secondary succession.

It differs from the succession which first started on our original bare patch of ground, because this had never been colonized before. This first succession is therefore known as a primary succession.


Follow a succession starting in water, otherwise known as a


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Succession Contents