Populations in ecosystems Typeit

Every organism has its own , which describes its role and how it fits into its environment. This, along with the abiotic and biotic conditions, determines the of a species, which is the maximum population size of the species that the ecosystem can support. Before this level is reached, population size may often increase exponentially if the correct conditions are met, meaning that for organisms such as bacteria, a scale needs to be used to measure their population growth. Conditions which may affect population size can include:

temperature and pH, which are particularly important for to catalyse important reactions

light intensity, which is important in determining the rate of in plants, algae and cyanobacteria

water/humidity levels for transpiration and evaporation

These are all , or non-living, factors.

competition (competition within a species), or interactions between different species involving food or predation, breeding sites, disease, etc., can also have an impact on population size.

To determine the abundance of a plant species, , which are frames containing several pins, can be dropped into various locations in a sampling area, and the results extrapolated. To measure the distribution of organisms in an area, a systematic sample can be taken along a . The cover of species in each frame can be recorded along the line to get an idea of how the distribution changes within an area.

Systematic samples often work well when studying , the change in species over time in an area as a result of changes to the landscape. When a pioneer species first attempts to modify an inhospitable environment, this is known as . Eventually, as more organisms come and go from the area and change the environment, a may be reached, in which the ecosystem becomes stable.