B1 - Species Interactions

direct effects

Impact of the presence of species A on species B in a two species interaction.

indirect effects

Impact of the presence of species A on species C via an intermediary species. (A—>B—>C)

cascading effects

impacts extend across three or more trophic levels and can be top-down. (predator—>herbivore→ plant) or bottom up (plant—>herbivore—>predator)

keystone species

profoundly affect other species in the community. no or limited functional redundancy.

foundational species

define and structure certain forest ecosystems. typically physically modify the environment.

indicator species

measure of environmental conditions.

mutualism

+,+

commensalism

+,0

facilitation

0,+

competition

both partners are negatively affected. -,- or +,-

predation

consumption of one species, usually bigger than the other. +,-

parasitism

one benefits, the larger organism is usually negatively affected. +,-

inhibition

one species inhibits the growth of the other organism. +,-

alleopathy

chemical inhibition from one organism to another

mechanisms

physical interactions and biochemical interactions

responses

resource substitutions, spacial seperations, temporal differentiation

changes in single plants

phenology, plant shapes

changes in plant communities

different species after a disturbance, patchiness that reflects moisture, nutrient moisture