Zonation/Succession Flashcards
What are Biomes?
Biomes are collections of ecosystems that share distinctive abiotic factors, species and climatic conditions.
Each biome has unique limiting factors, diversity and productivity.
Climate determines the type of biome in a given area. It determines its characteristics, therefore what grows and lives there.
What is Climate determined by?
Temperature, Isolation and Precipitation.
Examples: high isolation + precipitation= more photosynthesis = more productivity
Very low temperatures = less productivity.
How does Climate Change Affect Biomes?
Changes in global patterns and distribution.
Latitudinal Shifts → From North to South (Biomes Near the equator)
Altitudinal Shifts → Move up slopes
Low lying biomes can be lost due to changes in sea level.
Can also affect rain patterns → Can affect productivity and population.
What is Zonation
Changes in an ecosystem along an environmental gradient due to abiotic factors such as altitude, latitude, tidal level or distance from the shore.
What is Succession?
Succession is the change overtime in an ecosystem that involves pioneer, intermediate and climax communities. Succession explains how ecosystems develop overtime.
Each community represents a stage in the succession process.
Overtime we get more matter or productivity growing and when these die the soil is built.
As succession develops, not only the species present change. The productivity and diversity do too.
What is the pioneer community?
First inhabitants of the area. First stage of succession.
Resilient organisms → Reproduce a lot and quickly + Are able to withstand difficult conditions.
eg Lichen and Mosses
Mutualism
What is the intermediate community?
Middle stage of succession.
Competition → Species replace each other through competition
eg Grasses, Small Herbs, Shrubs and Coniferous Trees
What is the climax community?
Final stage of succession
More Stable + Has an equilibrium
Diverse and Mature
eg Stable Large Trees and Complex Food Chains
Gross Productivity in Succession
In the early stages of a succession, the gross productivity is low because of the low density of producers. The density of producers is low because of the lack of soil, water and nutrients.
In time, as the succession progresses, gross productivity starts increasing.
In the later stages of a succession (climax), the gross productivity is high as there is an increased consumer community
Net Productivity in Succession
In the early stages of a succession, the proportion of energy lost through community respiration is relatively low and so net productivity is high.
When net productivity is high, the ecosystem is growing and biomass is accumulating
In the later stages of a succession (climax), the gross productivity is balanced by respiration, and so the net productivity of the system approaches zero.
Diversity in Succession
Early in the succession, there is low biomass and few niches.
Over time, the plant community changes leading to larger plants and greater complexity.
As the plant community grows and complexity increases, the number of niches increases.
As the number of niches increases, the food webs become more complex and both habitat diversity and species diversity increase.
Primary Succession
Takes place in areas that have never previously supported life. Bare ground. Slow succession.
Occurs in new lakes, ponds, cooled lava, sand dunes and bare rock
Secondary Succession
Occurs where soil already exists but vegetation has been removed. Faster succession.
Happens because of Human Activities: Cutting for timber, clearing for farming, construction, overgrazing animals.
