History of Succession

Succession Changes that forests undergo are part of a process

Change in forests can be caused by the natural aging and dying of plants or can be caused by Disturbances Disturbances- forces that affect the structure and composition of a forest. (Fire, wind, logging, floods, drought, insect infestation, disease, animal browsing, etc)

Large-scale forces Both social and environmental are exerted over large areas for long periods of time and shape events and ultimately, disturbances Includes: climate change, evolution, plate tectonics, human population growth and expansion, industrialization, and glabalization Natural: volcanic eruptions, glaciations, earthquakes, extreme weather patterns Human: war, social movements, migration, and settlement

Two Types of Succession Primary- establishment of vegetation in an environment that lacks biologic communities, soil, and immediate sources for plant reproduction (may occur after: glaciations, lava flows, or any event that eliminates all reproductive sources of plants) Secondary- occur on sites that have some plant and animal remnants. (may occur after: disturbance or set of disturbances that affect forest structure such as fire, logging, insect infestation, animal browsing, wind, and flooding)

Secondary succession can also occur in the absence of major disturbances. TIME is a major factor for succession Succession can occur with shade, density of the understory, soil conditions, and moisture levels.

SUCCESSION OVERVIEW History of Succession

When did plants first appear? The earliest plant fossil are about 400 million years old.

Which Came First? herbaceous plants or trees Herbaceous plants came first. Trees evolved from herbaceous plants as a result of competition for sunlight

The earliest fossil of conifer trees (gymnosperms) are 250 million years old, and the earliest fossil of deciduous trees (angiosperms-or flower bearing trees) are 100 millions years old.

Have Trees Changed Since Then? Yes, trees have adapted to changing conditions and many more species of trees are present today.

How have forests changed? Forests have spread across the landscape and can now be found from coastlines to mountains, deserts to rainy climates, and bordering ear of our polar ice caps. Many new species have evolved and many plants, animals, insects, fungi, and microorganisms have adapted to live in forest ecosystems.

Forests change because the have the ability to regenerate or renew themselves after plants, animals, and other organisms die.

Working with a partner identify forces, actions, or events that you can think of that causes trees and other organisms to be injured and/or die and subsequently causes forests to change. ***Largest accurate list wins

My list Fire Severe wind Flood Drought Climate Animal population Insects Disease Soil erosion Soil deposition Glaciers Logging Land development Agriculture Introduction or removal of species Air pollution and smog Water pollution Competition from other plants Dams and wetland draining Solid waste pollution