Xerosere is the succession that occurs on bare substrates like rocks that have a deficiency of water. It begins with foliose and fruticose lichens attaching to the surface. Next, mosses like Polytrichum and Grimmia grow and their rhizoids penetrate the substrate and secrete acids. Annual herbs then invade and further weather the substrate with their roots. Eventually, shrubs develop which provide conditions for tree saplings to grow and a forest climax community can develop, with the type of forest depending on climate and soil conditions.

1. XEROSERE
" Succession initiated on bare rocks, Sand
dunes,rocky slopes(etc).where There is deficiency of
water,are termed XERARCH and different stages of
d evelopment are collectively called XEROSERE".

2. Xerarch Succession

3. Foliose AND Fruticose Lichens Stage
• Foliose lichens have leaf like thalli while Fruticose
Lichens are like small brushes.They are attached to
the surface of the substratum at one point only,
therefore, do not cover the soil important number
of this stage are Permelia and Dermatocarpom.

4. Moss Stage. Herb Stage
• spores of xerophytic
mosses, such as
Polytrichum, Tortula, and
Grimmia, are brought to
the rock where they
succeed lichens. Their
rhizoids penetrate soil
among the crevices,
secrete acids and corrode
the rocks. The bodies of
mosses are rich in organic
and inorganic compounds.
• Herbaceous weeds,
mostly annuals such as
asters, evening
primroses, and milk
weeds, invade the rock.
Their roots penetrate
deep down, secrete acids
and enhance the process
of weathering. Leaf litter
and death of herbs add
humus to the soil.

5. Shrub Stage. Tree Stage
• This results in dense
scrub growth shading
the soil and making
conditions unfavorable
for the growth of herbs,
which then begin to
migrate. The soil
formation continues
and its moisture
content increases.
• The tree saplings begin to
grow among the scrubs
and establish themselves.
The kind of tree species
inhabiting the area
depends upon the nature
of the soil. In poorly
drained soils oaks
establish themselves. Te
trees form canopy and
shade the area.

6. Climax Stage
• The succession culminates in a climax community,
the forest. Many intermediate tree stages develop
prior to establishment of a climax community. The
forest type depends upon climatic conditions.
• It is stage community stage . Ultimately,a forest
may develop.