In natural selection, disturbance are important aspects in the water biological evolution as they modify the environment in which every living being perm vital functions.
Ecological disturbances is an event or force of non-biological or biological origin that brings about mortality to organisms.
Ecological disturbance are of two types:
- Natural disturbances
- Anthropogenic disturbance
1. Natural disturbances:
It includes fires, flood extreme weather, earthquakes , and severe storms affecting the whole ecosystem.
2. Anthropogenic disturbance:
It includes animal grazing, human food path on vegetation deforestation etc. Some cause harmful effects in a very short period of time and some cause harmful extinction species only at the local level.
Disturbance of species along dual characters, low level and disturbance favor slow growing species with high resilience to competition. Increasing disturbance frequency favors species with more rapid life cycle.Even the composition of a highly disturbed community can be influenced by additional disturbance.
IDH is a non- equilibrium model used to describe the relationship between disturbance and species diversity.
I = low level of ecological disturbance species richness decreases as competitive exclusion increases.
II = Intermediate levels of disturbance.
III =N High level of disturbances.
Species richness is the number of different species represented in an ecological community landscape or region. It is simply a count of species and it doesn’t take into account the large sample.
Species diversity differs from species richness in that it takes into account both the no. of species in relation to one another.