bare ground conditions favour pioneer plant species.
Species which grow best where there is little
competition for space and resources. (moss)
moss are low growing, carpeting the ground
and with little height. Mosses are unable to successfully
compete for space amongst taller, dense
often have light seeds, which are easily
transported by the wind.
seeds which rapidly germinate and do not require
grow quickly, reproducing themselves before slow other slower-
colonising species arrive to out compete them.
often ‘opportunist’ species which are able to rapidly
exploit a sudden new opening in ground plant
How would bare ground which has just started to be
colonised by pioneer species diﬀer after 2 years in:
competition, soil structure, ground temperature and
In the process of succession, the
species present in an area will
Bare ground Two years later
No plant competition for light, space, nutrients or water. Intense plant competition for space and other resources.
Soil mobile and liable to erosion and loss. Soil bound by roots and plant cover
A more extreme surface microclimate because the bare The plant cover provides a certain amount of ground
soil both absorbs and reﬂects heat more than soil covered insulation from extremes of temperature. There are now
in vegetation also a variety of microclimates within the vegetation.
A drier environment because there is no plant cover to
Plant cover and increasing humus levels help to retain
hold moisture above ground and little humus to hold it in
Lower nutrient levels in the soil. The nutrient levels in the soil will have increased.
environmental conditions on the same patch of ground are very diﬀerent to the
conditions when the ﬁrst pioneers arrived.
a variety of longer-lived, slower colonisers have displaced many of the species in the
early pioneer community.
plants are not the only colonisers. Herbivorous invertebrates which feed on those
particular plant species have arrived. These then attract a range of carnivorous
invertebrates to feed on them.
larger herbivores such as rabbits and deer will also graze this area.
the soil will be enriched as the dung is recycled by the dung-dwelling community.
the simple food chains of the earliest pioneer stage, when few species were present,
have developed into more complex foodwebs.
many, if not all of the environmental changes have been brought about by the
communities living there. During the processes of living, growing and reproducing,
species interact with and modify their habitat.
in 2 years, the biodiversity (variety of life) on the bare patch of ground has soared,
as it has been colonised 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
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 n these
diﬀerent successional stages are known as a collectively as a
Each new community will be better adapted to the the
changed environment which has been provided provided by the by
the previous community.
Eventually, a climax or ‘ﬁnal’ community is reached. At
reached. At this point, succession will not er
Climax community is in a stable equilibrium
with prevailing climate. Abiotic factors such as
climate determine dominant species of that
In the UK, this is most likely to be deciduous
is found on a new land surface or in water and various
seral stages are passed through before climatic climax is
reached. It is an orderly sequence of events where one
community is replaced by another. Biomass is created
via decomposition and provides more nutrients for the
soil allowing for greater and variety of plants and
animals to exist at each successive seral stage:
if succession is halted before reaching dynamic
equilibrium a secondary succession occurs.
Interruptions include ﬁre, disease, climate change and
more rapid - spores and seeds remain in soil.
does not begin with pioneer species, but one of the
subsequent successional stages.
land alteration will mean some of the species in the
climax community will be diﬀerent.
If sub-climax is due to local variations in soil etc.
If sub-climax is a consequence of human activity.
Management practices of humans (burning, clearing
and grazing of land, urban and transport
Succession which starts in fresh
A wetland, which is a
transitional area between open
freshwater and dry land,
provides a good example of this
and is an excellent place to see
several stages of a hydrosere at
the same time.
starts in salt water.
A salt marsh
Succession which starts on
newly exposed rock surface.
Examples, one left bare as a
result of glacial retreat or
starts on sand surface.