Lecture 6: Rangeland Ecology/Succession Flashcards
Ecology
The study of relationships among organisms, and between organisms and their environment
Population ecology
Autecology, individual organisms and populations
Community ecology
Synecology, deals with complex groups of organisms, for example the plant community, and their relationship to other organisms, for example herbivores, as well as their environment.
Population
A group of individuals of the same species living in a given area at the same time
Species
A population or group of populations whose members have the potential in nature to interbreed and produce fertile offspring
Environment
Total surroundings of an organisms, including other plants and animals, and those of its own kind.
Habitat
Place where a plant or animal can live
Community
A group of interacting plants and animals inhabiting a given area
Association
A kind of plant community represented by stands that occur in places where environments are so similar that there is a high degree of floristic uniformity in all layers of the plant community
Dominant
Plant species or species groups, which by means of their number, coverage, or size, has considerable influence or control upon the conditions of existence of associated species
Ecosystem
The biotic community and its abiotic environment functioning as a system
Four characteristics of ecosystems
- web of interactions and interdependencies
- synergy
- stability
- diffuse boundaries
Abiotic components
Non living components of the ecosystem on which living organisms depend. This includes parent material, climate, topography, and natural disturbances
Biotic components
The living organisms in an ecosystem. Producers, consumers, decomposers, and manipulators.
Succession
Implies a sequence in time or space. Directional change in species composition, community structure, and function over time and space
Primary succession
Sequence of plant communities on a new site, previously devoid of plants. Examples include volcanic eruptions, glacial retreat, sand dunes. Grasses are common in early succession.
Secondary succession
Describes the change in plant communities after a disturbance, on a site which already had plants and soil. For example, grazing and fire. This is the progressive modification of soil, micro-climate, and vegetation. Plant traits and dominance play a key role.
Primary succession graph
Bare ground–> serial stage–> serial stage–> climax
Secondary succession graph
Seral stage–>earlier serial stage–> serial stage–> climax
Autogenic (biotic) succession
Vegetation changes due to the activities of the organisms themselves
Allogenic succession
Vegetation change due to environmental conditions and environmental change or external factors
Stress gradient hypothesis
Facilitation occurs in stressful environments. Competition occurs in productive environments,
Stability: Resistance
The ability of the system to withstand a perturbation
Stability: Resilience
The speed at which a disturbed system returns to equilibrium after a perturbation
Stability: Inertia
The tendency of s community to continue to occupy a specific range site, even after conditions have changed to favour a new community
Seres
Intermediate stages in the development of a climax plant community
Retrogression
Changes within the plant community away from climax due to a disturbance
Community unit hypotheses
Clements,
Individualistic hypothesis
Gleason
Facilitation
Each seral community changes the site for the next community, similar to relax fluoristics
Tolerance
Which species have the ability to survive the longest
Inhibition
Some species will inhibit the development of others
Clements 6 stages of primary succession
Nutation, migration, establishment, competition, reaction, stabilization
