What do plants tell us
about places? Ecological
Design October 03
Describe the simplest plant. What is
the primary design constraint on the most rudimentary plant-like organism?
·
surface/volume (explain using cubes)
·
discuss exchange of
energy and materials with surroundings.
Consider plants in general.
What does a plant need
to do to survive and reproduce? ·
photosynthesize ·
take up water ·
take up mineral
nutrients ·
transport
throughout plant ·
etc. |
What parts does it have
to perform these functions? ·
leaves, other
structures ·
roots ·
roots etc. ·
stems, vascular
tissues ·
etc. |
How are these plant parts
modified to alter their function?
·
Leaves: large,
small; thick, thin; simple, compound; entire, lobed; glabrous, pubescent;
·
Roots: deep,
shallow; storage; fire resistant
·
roots: dense, sparse
(nutrients e.g. nitrate vs. phosphate)
·
stems, vascular
tissues: herbs, grasses, trees, vines, lianas
(vessel size, investment in support)
·
etc.
Any given feature has more than one effect. For example:
·
Thick leaves provide
a) water storage capacity,
b) heat storage capacity, and
c) organic acid storage capacity (CAM plants)
·
Fuzzy leaves:
a) reflect radiation input à cooling effect
b) reflect PAR à
reduce photosynthesis
c) increase boundary layer à reduce water loss
d) increase boundary layer à reduce heat loss by convection/conduction
·
Sun/shade
adaptations
a)
Light response curve
of individual leaves
b)
Plant architecture
and adaptation to light
·
Roots
a)
Fine roots good for
uptake of phosphate
b)
More widely-spaced
roots are good for uptake of water, nitrate
Consider your plant from Pojar and MacKinnon.
·
What adaptations to
its environment are evident?
·
How would you expect
your plant to interact with others in the community?
Static vs. dynamic: Pattern vs.
process
What can you infer about process just by looking at a group of plants
sitting there? Some questions to ask:
·
Do you know the
species? Are they weedy or do they prefer undisturbed sites?
·
What adaptations to
their environment do they show? Is it consistent with the present environment?
·
Are the adaptations
consistent with a narrow range of environmental conditions, or do the species
in the community show a range of adaptations? (heterogeneity or seasonality)
·
Phenology: Are the plants primarily evergreen, or
deciduous? Or, coriaceous,
sclerophyllous leaves vs. thinner,
less durable leaves (a clue about seasonal variation in resource availability)
·
Population
structure: are the small plants juveniles of the large plants? Or, are some species replacing the others?
K.P.
Hogan, The Evergreen State College, October 2003.