Ecological SuccessionEcological Succession

Questions for Today:Questions for Today:

What is Ecological Succession and What is Ecological Succession and what are the two types of what are the two types of succession?succession?

Distinguish between Primary Distinguish between Primary Succession and Secondary Succession and Secondary Succession.Succession.

Explain environmental inertia, Explain environmental inertia, resilience and tipping point.resilience and tipping point.

Ecological SuccessionEcological Succession

Ecological Succession is the gradual Ecological Succession is the gradual change in species composition over change in species composition over time.time.– Some species colonize an area and their Some species colonize an area and their

populations become more numerous.populations become more numerous.– Other populations decline or disappear Other populations decline or disappear

completely.completely. In this process, pioneer species come In this process, pioneer species come

first and colonize rapidly and then first and colonize rapidly and then are replaced by other species.are replaced by other species.

Primary Vs. SecondaryPrimary Vs. Secondary

Two main types of succession:Two main types of succession:– Primary Succession involves the gradual Primary Succession involves the gradual

establishment of biotic communities in establishment of biotic communities in lifeless areas where there is no soil or no lifeless areas where there is no soil or no bottom sediment.bottom sediment.

– Secondary Succession is when a series Secondary Succession is when a series of communities or ecosystems with of communities or ecosystems with different species develop in places different species develop in places containing soil or bottom sedimentcontaining soil or bottom sediment

Primary SuccessionPrimary Succession

Primary succession starts with an essentially Primary succession starts with an essentially lifeless area.lifeless area.– Can be caused naturally or by manCan be caused naturally or by man

Primary Succession starts when a pioneer Primary Succession starts when a pioneer species or early succession species arrive species or early succession species arrive and start growing on the inhospitabile, no-soil and start growing on the inhospitabile, no-soil area.area.– Usually Lichen, algae or moss.Usually Lichen, algae or moss.– They start breaking down the rock and capture soil They start breaking down the rock and capture soil

particles to create soilparticles to create soil– Takes hundreds to thousand of years.Takes hundreds to thousand of years.

Primary SuccessionPrimary Succession

After the early succession period, we enter After the early succession period, we enter the midsuccessional plant species period.the midsuccessional plant species period.– Herbs, grasses, and low shrubs grow.Herbs, grasses, and low shrubs grow.– They create shade which kill off the lichen, They create shade which kill off the lichen,

algae and moss.algae and moss. After the midsuccessional plants, late After the midsuccessional plants, late

successional plant species arrive.successional plant species arrive.– Mostly treesMostly trees– Trees help overturn soil and hold soil to protect Trees help overturn soil and hold soil to protect

from erosion.from erosion.

Secondary SuccessionSecondary Succession

Similar to primary succession, but soil is Similar to primary succession, but soil is present at the beginning.present at the beginning.– Abandoned farmland, burned or cut forests, Abandoned farmland, burned or cut forests,

areas that have been flooded.areas that have been flooded. Succession cannot be predicted. Nature is Succession cannot be predicted. Nature is

random and chaotic and systems can random and chaotic and systems can restart itself due to cataclysmic events.restart itself due to cataclysmic events.

Does succession only occur in plant Does succession only occur in plant species? How do animals show succession species? How do animals show succession traits?traits?

How do living systems respond How do living systems respond to change?to change?

Remember that all systems must Remember that all systems must respond to change.respond to change.– Feedback loopsFeedback loops– HomeostasisHomeostasis– We want balance in our lives!We want balance in our lives!

How do living systems respond How do living systems respond to change?to change?

Two aspects of stability in living systems:Two aspects of stability in living systems:– InertiaInertia

The ability of living system to survive moderate The ability of living system to survive moderate disturbances.disturbances.

– ResilienceResilience The ability of living system to be restored through The ability of living system to be restored through

secondary succession after a moderate disturbance.secondary succession after a moderate disturbance.

A tipping point can be reached where a A tipping point can be reached where a system, due to environmental pressures, system, due to environmental pressures, can crash and irreversible change can occur.can crash and irreversible change can occur.– No way back!No way back!