Lecture 1 CM Flashcards
What are spatially biomes not in uniform with?
their composition or productivity
What causes spatial variation in biomes?
- topography (mountains, river valleys, plains)
- soil type (nutrient content, drainage, depth, structure, microbial activity)
- exposure (proximity to dominant rain belts)
What are temporal changes?
type of change that will occur over a certain period of time to affect the stability of an ecosystem or habitat
Temporally, ecosystems are in a…
constant stae of flux due to micro and macro scale changes
Micro-scale changes
- local extent
- the duration is short-term, annual/seasonal cycle or longer
- e.g. local flood
Macro-scale changes
- regional extent
- geological scale processes measured over > 10^5 or 10^6 years
- e.g. climate change
Disturbance frequency
- consistent over time
- inversely proportional to magnitude
- small disturbances are more frequent that larger disturbances
What do plants vary in and what does this determine?
plants vary in their ability to exploit the environment and this determines their relative competitive strength (r/K)
What do organisms with good/high K have?
- very strong competitive ability
- can dominate habitats (if you don’t disturb it at all)
- e.g. oak (Quercus spp.)
What do organisms with good/high r have?
- rapid intrinsic reproductive rate
- e.g. dandelion (Taraxacum spp. )
Equation of intrinsic rate of growth
R = rN (K-N)/K
What is facilitation?
the dominance of one species provides ideal circumstances for other species to become newly established, including species whose competitive advantages are now ideally suited to the habitat.
What is succession?
a process where one group of organisms is gradually replaced by another due to biotic interactions between species and environmental changes
What dominates the 1st phase of succession?
species with optimal dispersal/colonisation (‘r’) traits
What dominates the later stages of succession?
species with optimal competitive (‘K’) traits.
