ECEC - 6 Flashcards
what dictates plant distributions?
environmental conditions
what does cosmopolitan mean in terms of plant distributions and an example of a species?
it occurs everywhere - Daisy (Bellis perennis)
what are complementary distributions and an example?
opposite to each other -
Dogwood (Cornus sanguinea) = warmer drier climates Crowberry (Empetrum nigrum) = wetter colder conditions
what seems to determine the distribution of sea sandwort (Honckenya peploides)?
grows well in sand and shingle and is a halophyte (salt loving) - seen on coasts
plant distributions are explained in terms of three groups of factors, what are these?
1) climatic
2) physiographic
3) edaphic
what 2 things generally describe the global distribution of major biomes ?
temperature and precipitation
what are physiographic factors?
determined by the landforms of the landscape
- altitude
- directions of slopes
what are edaphic factors?
factor associated with the soil
what is the impact of insufficient and excess resources?
insufficient = poor growth (sub-optimal) excess = don't always results in increased growth sometimes detrimental (supra-optimal)
what is the difference between resources and conditions?
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
when species interact there are 3 possible outcomes what are they?
1) a species gains
2) a species loses
3) a species is unaffected
what are the 6 types of interactions between species?
1) competition
2) facilitation
3) parasitism
4) mutualism
5) commensalism
6) ammensalism
whats the difference between interspecific competition and intraspecific competition?
inter = different species intra = same species
describe indirect competition
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
between competing species the ones that put most resources towards reproduction are often first to decline why?
because it is a waste as there aren’t enough resources for offspring to grow in the surrounding area
describe direct competition
a form of direct antagonism between plant species - less common than indirect e.g. parasitism, strangulation and allelopathy
what is allelopathy?
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
what is the difference between hemiparasitic plants and holoparasitic plants?
Hemi = have chlorophyll but obtain carbon, nutrients and water from host holo = no chlorophyll - obtain all carbon from their host
describe facilitation
- occurs when a plant benefits from having a neighbour
- especially important in extreme environments
what did a test show about facilitation in high altitude harsh conditions?
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
what is aspect and what does it influence?
= direction of slope influences
irradiance(flux of radiant energy per unit area) received
what is sub-optimal and supra- optimal in terms of resources?
sub - optimal -Insufficient resources gives poor growth
supra- optimal - Excess resources not necessarily result in an increase in growth, and are sometimes detrimental
what is PH?
pH = effective concentration of hydrogen ions in solution.
- pH 4 has 10 times the effective concentration of H+ as pH 5
what is self thinning and the effects of high sowing densities?
– 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
how many species of parasitic plants are there and what percentage are hemiparasitic and holoparasitic?
3000 species in 17 families
80% hemi 20% holo
