Ecological Succession Test Study Guide

➢ Ecological succession- is the observed process of change in the species structure of an ecological community over time
➢ The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community.
➢ It is a phenomenon or process by which an ecological community undergoes more, or less orderly and predictable changes following a disturbance or initial colonization of new habitat.
➢ succession may be initiated by either formation of new, unoccupied habitat(a law or serve landslide) or by some form of disturbance (fire, severe windthrow, lodging) of an existing community
•What is ecological succession?
➢ Pioneer Species- pioneer species are species which are the first to colonize previously disrupted or damaged ecosystems, beginning a chain of ecological succession that ultimately leads to a more biodiverse steady- stare ecosystem
➢ Since some uncolonized land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, roots containing nitrogen-fixing bacteria, and leaves that employ transpiration.
➢ Pioneer species will dies creating plant litter, and break down as “leaf mold” after some time
o Purpose is to grow and die to create fertilized soil
•What is a pioneer species? Examples of pioneer species?
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➢ Primary succession- is one of two types of ecological succession of plant, occurring in tan environment usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited
➢ In other words, it is the gradual growth of an ecosystem over a longer period of time.
➢ Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession
➢ In primary succession pioneer species like lichen, algae and fungi as well as other abiotic factors like wind and water start to “normalize” the habitat.
➢ Primary succession starts to begin on rock formations, such as volcanoes or mountains, or in a place with no organisms or soil.
➢ This creates condition nearer optimum for vascular plant growth
• What is primary succession?
➢ Secondary succession- is a process stared by an event that reduces an already established ecosystem to a smaller population of species, and such secondary succession occurs on preexisting soil whereas primary succession usually occurs in a place lacking soil.
➢ Whereas succession that follows disruption of a pre-existing community is called secondary succession.
➢ Simply put, secondary succession is the succession that occurs after the initial succession has been disrupted and some plants and animals still exist.
➢ It is usually faster than primary succession as:
o Soil is already present, so there is no need for pioneer species;
o Seeds, roots and underground vegetation organs of plants may still survive in the soil
• What is secondary succession?
➢ Climax Community- is a historic term that expressed a biological community of plants and animals and fungi which, through the process of ecological succession, and the development of vegetation in an area over time, have reached a steady state.
➢ This equilibrium was thought to occur because the climax community is composed of species: best adapted to average conditions in that area
• What is a climax community?
➢ Although primary and secondary succession require different amounts of time, the changes in species diversity are very similar.
➢ Why?
➢ The “outcomes”/ecosystems the same for both types of succession.
➢ Both grow a complex community/ecosystem
• Are the ending outcomes of primary and secondary succession similar? Why?
• Community:
➢ Community changes during succession include increases in species diversity and changes in species competition
➢ Perrenial plants replace annual plants
➢ Introduction of animals
• Ecosystem:
➢ In photosynthesis and respiration
➢ In resources
➢ Ecosystem changes during succession include increases in biomass, primary production, respiration, and plant production.
➢ As succession changes communities, the overall ecosystem us affected as well
• What are some community and ecosystem changes that occur during succession?
➢ Facilitation Model-proposes that many species may attempt to colonize newly available space, but only certain species, with particular characteristics, are able to establish themselves
➢ Why?
o The most fit pioneer species will colonize
➢ These species that are able to establish themselves are the pioneer species.
➢ According to the facilitation model, pioneer species modify the environment in such a way that it becomes less suitable for themselves and more suitable for species of later successional stages
o Pioneer species facilitate succession
➢ In other words, these early successional species “facilitate” colonization by later successional species.
➢ Early successional species disappear as they make the environment less suitable for themselves, and more suitable for others.
➢ The replacement of less suitable species by more suitable species continues until resident species are established
o Live & last forever
• What is the facilitation model?
➢ Tolerance model- suggest that the initial stages of succession are not limited to pioneer species
➢ Juvenile or young versions of species are present from the earliest stages of succession until the community has reached the climax.
➢ These species do not modify the environment in such a way that makes it more suitable for later successional species.
➢ Later successional species are simply those “tolerant” of environmental conditions.
• What is the tolerance model?
➢ Inhibition model- this model assumes that any species that can survive in any area as an adult can colonize the area during the early stages of succession.
➢ The inhibition model proposes that early successional species modify the environment in such a way that makes it less suitable for both early and late successional species.
➢ The model assume that late successional species come to dominate the area simply because they live a long time and resist damage by physical and biological factors
• What is the inhibition model?
➢ Community stability may be due to a lack of disturbance or community resistance or resilience in the face of a disturbance
➢ Stability- the absence of change.
➢ Communities can be stable due to:
o No disturbances
o Endless resources
• What is stability?
➢ Resistance- the ability of community or ecosystem to maintain structure and or function in the face of potential disturbance
• Not change at all in the face of disturbance
o Hurricane
o Tsunami
o Tornado
o Earthquake
o Forest fire
o Disease
• What is resistance?
➢ Resilience- the ability of a community to bounce back after a disturbance
o Bounce back right after disturbance
➢ A resilient community or ecosystem may be completely disrupted by a disturbance but quickly return to its former state.
• What is resilience?

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