ECEC - 6

Question 1

what dictates plant distributions?

Answer 1

environmental conditions

Question 2

what does cosmopolitan mean in terms of plant distributions and an example of a species?

Answer 2

it occurs everywhere - Daisy (Bellis perennis)

Question 3

what are complementary distributions and an example?

Answer 3

opposite to each other -

Dogwood (Cornus sanguinea) = warmer drier climates Crowberry (Empetrum nigrum) = wetter colder conditions

Question 4

what seems to determine the distribution of sea sandwort (Honckenya peploides)?

Answer 4

grows well in sand and shingle and is a halophyte (salt loving) - seen on coasts

Question 5

plant distributions are explained in terms of three groups of factors, what are these?

Answer 5

1) climatic
2) physiographic
3) edaphic

Question 6

what 2 things generally describe the global distribution of major biomes ?

Answer 6

temperature and precipitation

Question 7

what are physiographic factors?

Answer 7

determined by the landforms of the landscape

• altitude
• directions of slopes

Question 8

what are edaphic factors?

Answer 8

factor associated with the soil

Question 9

what is the impact of insufficient and excess resources?

Answer 9

insufficient = poor growth (sub-optimal) 
excess = don't always results in increased growth sometimes detrimental (supra-optimal)

Question 10

what is the difference between resources and conditions?

Answer 10

resources are consumed (essential for growth) and conditions are not rather plants respond to them however some conditions may help to regulate resources e.g. PH

Question 11

when species interact there are 3 possible outcomes what are they?

Answer 11

1) a species gains
2) a species loses
3) a species is unaffected

Question 12

what are the 6 types of interactions between species?

Answer 12

1) competition
2) facilitation
3) parasitism
4) mutualism
5) commensalism
6) ammensalism

Question 13

whats the difference between interspecific competition and intraspecific competition?

Answer 13

inter = different species 
intra = same species

Question 14

describe indirect competition

Answer 14

normal competition

• individuals attempt to obtain sam shared resource e.g light
• requires the resource to be of limited availability
• is dependent on the density of individuals

Question 15

between competing species the ones that put most resources towards reproduction are often first to decline why?

Answer 15

because it is a waste as there aren’t enough resources for offspring to grow in the surrounding area

Question 16

describe direct competition

Answer 16

a form of direct antagonism between plant species - less common than indirect e.g. parasitism, strangulation and allelopathy

Question 17

what is allelopathy?

Answer 17

the chemical inhibition of one plant (or other organism) by another, due to the release into the environment of substances acting as germination or growth inhibitors - can prevent by addition of activated charcoal to the soil

Question 18

what is the difference between hemiparasitic plants and holoparasitic plants?

Answer 18

Hemi = have chlorophyll but obtain carbon, nutrients and water from host 
holo = no chlorophyll - obtain all carbon from their host

Question 19

describe facilitation

Answer 19

• occurs when a plant benefits from having a neighbour

- especially important in extreme environments

Question 20

what did a test show about facilitation in high altitude harsh conditions?

Answer 20

you get a positive relative neighbour effect (RNE) as the neighbour is helping to protect the other plant from things like wind speed and high solar radiation etc. – still is competition but the positive benefits outweigh

Question 21

what is aspect and what does it influence?

Answer 21

= direction of slope influences

irradiance(flux of radiant energy per unit area) received

Question 22

what is sub-optimal and supra- optimal in terms of resources?

Answer 22

sub - optimal -Insufficient resources gives poor growth

supra- optimal - Excess resources not necessarily result in an increase in growth, and are sometimes detrimental

Question 23

what is PH?

Answer 23

pH = effective concentration of hydrogen ions in solution.

- pH 4 has 10 times the effective concentration of H+ as pH 5

Question 24

what is self thinning and the effects of high sowing densities?

Answer 24

– above a threshold of sowing density, no more individuals reach maturity.
At high sowing densities:
– there may even be a decrease in the total number of individuals reaching maturity
– or a reduction in their reproductive output (seed production).
– this can have important ecological and agricultural consequences

Question 25

how many species of parasitic plants are there and what percentage are hemiparasitic and holoparasitic?

Answer 25

3000 species in 17 families

80% hemi 20% holo