Plant Populations

Question 1

Why study plant populations

Answer 1

• primary producers = important to ecosystems

Question 2

The different ways to study populations

Answer 2

• density
• distribution
• structure
• growth

Question 3

What kind of info is studying plant pops aiming to find

Answer 3

• life cycles = aids describing populations
• influence of physical environment = how it affects growth and survival
• stresses on plants = how it affects growth and survival

Question 4

Modular growth

Answer 4

Plants have intermediate growth and grow by adding modules

Question 5

Vertical growth

Answer 5

Leaves, buds, twigs, branches, flowers, fruits

Question 6

Horizontal growth

Answer 6

Clones

Question 7

Genets

Answer 7

Produced by sexual reproduction

Question 8

Ramets

Answer 8

Produced by asexual reproduction.

May be connected to a genet or independent

Question 9

Clone

Answer 9

A group of ramets arising from the same gent

• all the same genotype
• usually dominant species in terrestrial ecosystems; important to plant communities
• allows physical integration ( transporting resources across ramets) = successful colonisation across wide range of habitats

Question 10

Counting individual plants

Answer 10

Are to do if have runners/stolons or are clones

- w/ clones, genet may be very old but ramets young = ramets counted as separate individuals

Question 11

Ubiquitous species

Answer 11

Broad, widespread range made up of many populations

Question 12

Endemic species

Answer 12

Narrow range, containing a few populations

Question 13

How can plant ranges be shifted

Answer 13

• global change e,g, some species expanding to cold regions, whilst others reducing distributions
• human influence e,g, transporting seeds = broken dispersal barriers

Question 14

What are the different types of distribution

Answer 14

Random
Clumped
Uniform

Question 15

Random distribution

Answer 15

Rare
Position of each is independent of the others
May occur in wind-dispersal
Requires uniform environment

Question 16

Clumped distribution

Answer 16

Most common
Influenced by propagation type and environmental requirements
E.g. asexual reproduction

Question 17

Uniform dispersal

Answer 17

No as common

Influenced by intraspecific competition due to scarcity of resources

Question 18

Propagules

Answer 18

Vegetative structure that detaches from plant and forms new one 
Mostly by vectors:
- biotic e.g. animals 
- abiotic e.g. water
- other e.g. ballistic

Question 19

Population structured by age

Answer 19

3 basic categories

• pre-reproductive
• reproductive
• post-reproductive

Question 20

How to measure a plants age

Answer 20

• growth rings
• bud scars
• tracking through time (but may live longer than researcher)
  Modular structure and asexuality can make it difficult

Question 21

The Rauniker system

Answer 21

Alternate way of categorising population structure for plants
Via position of perennating buds in relation to ground surface
- phanerophytes
- chamaephytes
- hemi-cryptophytes
- cryptophtes
- therophytes

Question 22

Phanerophytes

Answer 22

Dormant buds on branches which project freely into the air

Question 23

Chamaephytes

Answer 23

Buds/short-spices on the surface of the ground or just above it

Question 24

Hemi-cryptophytes

Answer 24

Resting buds at or near soils surface

Question 25

Cryptophytes

Answer 25

Resting buds beneath the surface

Question 26

Therophytes

Answer 26

Live through unfavourable season as seeds

Question 27

Annuals/biennials

Answer 27

Often have Long-lived seed and significant seed bank - opportunists - their habitat changes unpredictable

Question 28

Major problem with studying plant age

Answer 28

Seed bank in soil - seeds can be dormant for many years - plants may germinate at same time but aren’t from the same time - do you factor in seed age?

Question 29

The affect of competition on population structure

Answer 29

- older plants often exclude younger age classes - younger trees my become larger = size cant always indicate age - plants normally stage structured rather than age; but plant size often indicates reproductive potential Complicated to sort out

Question 30

Influences on popualtion growth

Answer 30

``` Extrinsic - density dependent - density independent Intrinsic - births and immigration - deaths and emigration ```

Question 31

Negative density-dependence

Answer 31

Resource competition = plants slow growth - increased mortality and reduced fecundity Self thinning = progressive decline in density and increase in biomass of remaining individuals in a population

Question 32

Positive density-dependence

Answer 32

Allele affect = increase in reproduction/survival with increasing density May increase seed production per plant..perhaps due to increased mate availability and pollinator attraction

Question 33

How life histories may affect pop growth

Answer 33

- variation in age and frequency of reproduction (mono or polycarpic) - variation in offspring number and size - R or K selected lifestyles

Question 34

E.g. monocarpic bamboo

Answer 34

- fastest growing on the planet - flower en-mass = whole pop at same time (not every year) - major animal food source - economically important to humans; building and food - on every continent except Europe and America - 1,500 spp

Question 35

E.g. offspring number/size variation

Answer 35

Orchids = 1billion seeds the size of fungal spores | Vs. Sea coconut takes 6-7 years to mature + 2 to germinate. 1 seed per year produced

Question 36

Grimes triangular model

Answer 36

``` Created by Philip Grime 3 strategy scheme to refine R and K selection theory for plants Split plants into either: - competitors - stress-tolerators - ruderals ```

Question 37

Competitors in grimes triangle

Answer 37

Fast growing Inhabit high fertility, low disturbance sites Maximise captured resources

Question 38

Stress tolerators in grimes triangle

Answer 38

Slow growing Inhabit low fertility, low disturbance sites Conserve captured resources

Question 39

Ruderals in grimes triangle

Answer 39

Fast growing Inhabit high fertility, high disturbance sites High seed production