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.