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Nurse plant association
is a phenomenon that occurs mostly only in
desert
environments. A nurse plant is a
plant that
creates an
environment that is less severe for young
seedlings
growing underneath it to
survive in
a harsh desert environment. The importance of nurse plant
associations ranges from providing
shade
to providing the only means of seedling
establishment. |
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Seedlings of
Pelecyphora aselliformis at the base of the mother
plant. |
The
seedlings of many
succulent plants are found only in sheltered
microhabitats, nearly all occurring under the
canopy of a
desert grass,
shrub or
under the mother
plant its self.
Seedlings were generally located near the
base or on the
northern side of the nurse plant this because the
soil surface temperatures can reach 71°C in
exposed
areas.
A seedling is
vulnerable
to
desiccation when
fully exposed
to the heat of the desert sun, but when growing in the shade of
a larger plant, has more of a chance of
survival.
The larger plant also protects seeds from
predation
from birds and rodents, allowing them a chance to
germinate.
Seedlings in harsh environments are often more dependent on a
nurse relationship than seedlings in more benign environments |
In other environments, growing
under the shade of a larger plant may be detrimental to a
seedling's
growth, reducing the amount of
sunlight available for
photosynthesis, but the harsh desert environment makes this
protection more beneficial. Thus, although the nurse plant
facilitates seedling establishment by reducing maximum
soil surface temperatures and provides a
microhabitats with higher soil
nitrogen levels, its
shading and
competition for
water reduce
seedling growth.
Addition to benefits provided by a nurse, seedling performance
in unfavorable environmental conditions can be aided by
mycorrhizal
relationships. |
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