- mass - kg
- distance - m(eters)
- velocity - ms-1 or m/s (meters / seconds)
- acceleration - m/s / s = m/s2
- power - J(oules) / S = watt
- Janzen-Connell model proposes the maintenance of this diversity is the result of two mechanisms: mortality of seeds and seedlings increases as seed/seedling density increases and survival of seeds and seedlings increases as distance from the parent tree increases. The hypothesis suggests that these two mechanisms are chiefly driven by the predation of natural enemies, particularly herbivores, insects, and pathogens, on seeds and seedlings. The Janzen-Connell hypothesis states that density-responsive and distance-responsive predation on seeds and seedlings promotes regular spacing of species and creates opportunity for colonization by other species, thus enhancing forest diversity.
- New Zealand has no native land mammals! they were all drowned before New Zealand rose again out of the water!
Plants - passive: wind water air
by animals carrying them away
ballistic dispersal expolsions
Animals - active (flying, walking)
passive (wind water)
"phorsey" - hitchhiking e.g. fleas
- Barriers to Dispersal:
- physical (mountains)
- Ecological succession, a fundamental concept in ecology, refers to more-or-less predictable and orderly changes in the composition or structure of an ecological community. Succession may be initiated either by formation of new, unoccupied habitat (e.g., a lava flow or a severe landslide) or by some form of disturbance (e.g. fire, severe windthrow, logging) of an existing community. Succession that begins in areas where no soil is initially present is called primary succession, whereas succession that begins in areas where soil is already present is called secondary succession.
Primary succession is one of two types of ecological succession and biological succession of plant life, and occurs in an environment in which new substrate, devoid of vegetation and usually lacking soil, is deposited (for example a lava flow).
Secondary succession is one of the two types of ecological succession of plant life. As opposed to primary succession, secondary succession is a process started by an event (e.g. forest fire, harvesting, hurricane) that reduces an already established ecosystem (e.g. a forest or a wheat field) to a smaller population of species, and as such secondary succession occurs on preexisting soil where as primary succession usually occurs in a place lacking soil.
the Eastern side of Lake Michigan is covered with sand... including sand dunes that are 200 ft. high!
edaphic refers to plant communities that are distinguished by soil conditions rather than by the climate. Edaphic plant communities include:
- Sandy soils: plant communities distinct to sandy, acidic, nutrient-poor soils include the tropical heath forests and restingas and temperate pine barrens.
- Ultramafic soils: plant communities distinct to soils derived from manganese and iron-rich ultramafic rocks include ultramafic woodlands and ultramafic barrens of the Appalachian mountains and piedmont, the "wet maquis" of the New Caledonia rain forests, the ultramafic forests of Mount Kinabalu and other peaks in Sabah, Malaysia, and the Serpentine soil plant communities of California.
Gleason began to express significant doubts on the usefulness of some of Clements's widely-employed vocabulary, especially the use of the organism metaphor to describe the growth of vegetation, and the treatment of the units of vegetation as including climaxes. (What units should be used in the analysis of vegetation was a widely disputed issue in early twentieth-century ecology.) In 1926, Gleason expressed even stronger objections to Clements's theory. First, he argued that Clements's identification of particular kinds of vegetation assumed too much homogeneity, since areas of vegetation are actually similar to one another only to degrees. Second, he argued that Clements's associating particular vegetation types with particular areas underestimated the real diversity of vegetation. These objections together cast doubt, for Gleason, on the "integrity of the association concept" itself—on identifying any grouping of species as amounting to a nameable association, like "oak-maple association," as botanists and ecologists (including Gleason himself) normally had.
As an alternative to describing vegetation in terms of associations, Gleason offered "the Individualistic concept of ecology," in which "the phenomena of vegetation depend completely upon the phenomena of the individual" species (1917), and plant associations are less structured than he thought Clements's theory maintained. At times, Gleason suggested that the distribution of plants approaches mathematical randomness.A superorganism is an organism consisting of many organisms. This is usually meant to be a social unit of eusocial animals, where division of labour is highly specialised and where individuals are not able to survive by themselves for extended periods of time. Ants are the best-known example of such a superorganism, while the naked mole rat is a famous example of the eusocial mammal. The technical definition of a superorganism is "a collection of agents which can act in concert to produce phenomena governed by the collective," phenomena being any activity "the hive wants" such as ants collecting food or bees choosing a new nest site.