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9 Cards in this Set
- Front
- Back
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Equilibrium and succession |
• Most natural ecosystems are in a state of equilibrium • Their biotic and abiotic features are constant over time • Changes do occur but they happen slowly and are normally caused by climate changes |
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Succession |
Succession: The process of establishing and replacing a community following a disturbance – Ex. Fire, geological event, human activity • Primary succession occurs on newly exposed ground where no life previously existed. – Ex. On a rock • Secondary succession follows a disturbance that disrupts but does not destroy a community – Ex. Regrowth of an area after a forest fire |
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Benefits of succession |
• Succession helps ecosystems be sustainable while also allowing them to recover from natural and human-caused disturbances providing that they are not extremely harmful and damaging. • Society relies heavily on the notion that ecosystems will bounce back regardless of the disturbance and the intensity. But the reality is that not all disturbances can be repaired through natural succession. • This is where society needs to become aware of their actions and contribute to the process |
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Biodiversity |
• the variety of life found in an area and is measured by counting the number of species on an ecosystem – This measurement of species numbers is called species richness – A diverse ecosystem will have high species richness |
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Fragmentation |
• Fragmentation is the dividing up of a region into smaller parcels, or fragments. • Fragmented ecosystems are less sustainable because more of the habitat is exposed to damaging outside influences, such as pollution. |
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Invasive species |
Invasive Species • Occasionally, an introduced species is successful in the new environment. The new ecosystem may lack predators or diseases to control the population of the new species. • The population of the new species may increase rapidly and become invasive. • Invasive species are introduced species with growing populations that spread and have a negative effect on their environment. • There are over 3000 invasive species in Canada, including several species of carp and the European earwig. |
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Clear cutting |
CLEAR CUTTING: the removal of all or most of the trees in an area Takes the shape of large blocks, strips or small patches. Meant to simulate forest fire conditions From a business perspective, this method is the most economical and efficient Regeneration can occur naturally or artificially by planting seedlings. Both of these methods however, result in a forest where all the trees are the same age. Most clear cutting worldwide happens in Canada and more specifically in Ontario, accounting for 90% of harvested tress. Most common method in Canada |
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Shelter wood cutting |
2. SHELTERWOOD CUTTING:mature trees are harvested in a series of two or more cuts which allows regeneration to occur under the shelter of remaining trees. takes the shape of long, narrow, parallel strip cuts. |
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Selective cutting |
• 3. SELECTIVE CUTTING: the forest is managed as an uneven aged system. Foresters come in periodically and harvest only those trees that are selected. Economically speaking, this is the most costly type of cutting as it takes planning and time and does not yield as many trees; however, environmentally it has the least impact on the forest and its ecosystem |
