Ecological Succession

Questions for Today: What is Ecological Succession and what are the two types of succession? What is Ecological Succession and what are the two types of succession? Distinguish between Primary Succession and Secondary Succession. Distinguish between Primary Succession and Secondary Succession. Explain environmental inertia, resilience and tipping point. Explain environmental inertia, resilience and tipping point.

Ecological Succession Ecological Succession is the gradual change in species composition over time. Ecological Succession is the gradual change in species composition over time. –Some species colonize an area and their populations become more numerous. –Other populations decline or disappear completely. In this process, pioneer species come first and colonize rapidly and then are replaced by other species. In this process, pioneer species come first and colonize rapidly and then are replaced by other species.

Primary Vs. Secondary Two main types of succession: Two main types of succession: –Primary Succession involves the gradual establishment of biotic communities in lifeless areas where there is no soil or no bottom sediment. –Secondary Succession is when a series of communities or ecosystems with different species develop in places containing soil or bottom sediment

Primary Succession Primary succession starts with an essentially lifeless area. Primary succession starts with an essentially lifeless area. –Can be caused naturally or by man Primary Succession starts when a pioneer species or early succession species arrive and start growing on the inhospitabile, no-soil area. Primary Succession starts when a pioneer species or early succession species arrive and start growing on the inhospitabile, no-soil area. –Usually Lichen, algae or moss. –They start breaking down the rock and capture soil particles to create soil –Takes hundreds to thousand of years.

Primary Succession After the early succession period, we enter the midsuccessional plant species period. After the early succession period, we enter the midsuccessional plant species period. –Herbs, grasses, and low shrubs grow. –They create shade which kill off the lichen, algae and moss. After the midsuccessional plants, late successional plant species arrive. After the midsuccessional plants, late successional plant species arrive. –Mostly trees –Trees help overturn soil and hold soil to protect from erosion.

Secondary Succession Similar to primary succession, but soil is present at the beginning. Similar to primary succession, but soil is present at the beginning. –Abandoned farmland, burned or cut forests, areas that have been flooded. Succession cannot be predicted. Nature is random and chaotic and systems can restart itself due to cataclysmic events. Succession cannot be predicted. Nature is random and chaotic and systems can restart itself due to cataclysmic events. Does succession only occur in plant species? How do animals show succession traits? Does succession only occur in plant species? How do animals show succession traits?

How do living systems respond to change? Remember that all systems must respond to change. Remember that all systems must respond to change. –Feedback loops –Homeostasis –We want balance in our lives!

How do living systems respond to change? Two aspects of stability in living systems: Two aspects of stability in living systems: –Inertia  The ability of living system to survive moderate disturbances. –Resilience  The ability of living system to be restored through secondary succession after a moderate disturbance. A tipping point can be reached where a system, due to environmental pressures, can crash and irreversible change can occur. A tipping point can be reached where a system, due to environmental pressures, can crash and irreversible change can occur. –No way back!