Succession

Succession in Communities Succession is the process by which communities develop through a series of stages. New communities replace one another through time in predictable stages. There are two main types: 1)primary succession 2)secondary succession.

Primary succession: Growth of a community in an area where there was no previous vegetation. Occurs wherever a volcanic island forms or a glacier melts. Soil development must happen first and can take many centuries!

Primary Succession There are three types of stages that take place during primary succession: Pioneer species – colonizers, the first to grow. They survive on very little biomass. They change the conditions of the community so now others can survive. Ex) lichens, moss, grasses Seral species – specific intermediate stages of succession identified by the dominant species (always changing). Ex) grasses, shrubs, pioneer & intermediate trees Climax community – Stable community of plants and animals with dominant species that maintain dominance.

Label: Pioneer community Seral community Climax community Increasing biomass & biodiversity until levels off in climax community Decreases temperature and increases fertility of soil Stabilize environment Enriches soil, crowds out pioneer species Shade causes shrubs to die and prevents growth of saplings

Secondary succession Growth of a community after the previous one was destroyed (through fire, forestry, farming) Soil is already formed, so succession happens much more quickly.

Primary succession: Growth of a community in an area where there was no previous vegetation. Occurs wherever a volcanic island forms or a glacier melts. Soil development must happen first and can take many centuries!

Using Non-native species as biological control When pest species overtake an ecosystem, governments try to reduce the population. One technique is biological control – introducing natural predators to kill the pest Although biological control can work, sometimes it can get out of control….let’s take a look!

Example of Biological Controls that have gone out of control Cane Toads introduced in Australia for pest control in sugar cane - 100 toads (first shipment) became 10 000 of thousands -They ate everything (small mammals, bugs, other frogs, etc) but the beetles they were brought over to eat

Out of Control Species