2. Stratification in the field of ecology refers to the
vertical layering of a habitat; the arrangement of
vegetation in layers.
It classifies the layers (sing. stratum, pl. strata) of
vegetation largely according to the different heights
to which their plants grow. The individual layers are
inhabited by different animal and plant communities
(stratozones).
Stratification
3. ✓ Natural climax communities usually exhibit some
form of stratification, by which the populations that
make up the community are distributed into defined
vertical or horizontal strata.
Stratification
4. For example, the bottom-up stratification of a forest
community could be
divided into:
o The subterranean layer
o The forest floor
o The herbaceous vegetation
o The shrub layer
o The canopy layer
5.
6. Organisms may not occupy only one stratum, moving
between the layers often on a diurnal basis.
For example, a bird that feeds on the forest floor
during the day but roosts within the canopy.
7. A community may occur along a horizontal stratification
where there is transition between successional stages and
ecotones.
8. Ecotone
Communities occur in a range of different sizes,
and the boundaries of each are often not well defined.
An ecotone is the transitional area
between two biomes, where communities meet and
may integrate.
9. The word Ecotone was coined by Alfred Russel Wallace, in
1859 who first observed the abrupt boundary between two
biomes. This word is formed as a combination of Ecology
plus tone, from the Greek tonos or tension, which means a
place where ecologies are in Tension.
10. Many organisms may be part of several different
communities because they have various geographic
ranges, and density peaks; if these boundaries are wide, it
is known as an open community.
A community in which the species all have similar
geographic ranges and density peaks, resulting in a
discrete unit where the boundaries are well defined, is
called a closed community.
11. Open communities tend to occur where there is a long
environmental gradient, such as that of soil moisture content or the
altitudinal slope of a mountain. Organisms with different tolerances
to the conditions occur at different spatial scales along the gradients.
12. Closed communities occur where there is a sharp change in the
vegetative structure or the physical environment, for example, an area
of a beach, which separates the water from the land.
13. Ecotones are generally very hard to
define because within an ecosystem
there are usually organisms, which can
disperse between both open and
closed communities.
