environment can be thought of as a series of interconnected cycles;
change in one cycle will affect all the others and alter the total
cycles which make up the physical environment exert considerable
influence over plant and animal distributions;
physical environment operates at three different scales or levels.
At each level the impact and its implications differ;
the individual level, the physical environment controls the existence
of the organism;
the species level, the physical environment controls the distribution
of the population;
the community level, the physical environment controls the composition
of the ecosystem;
physical factors can be translated into a series of key concepts
which help explain plant and animal distributions;
is usually assumed that the physical environment is in equilibrium
with plants and animals. When changes occur through time there are
two responses that can be made: organisms change their responses
(evolution) or their locations (succession).
forward a viable explanation of interaction between early lifeforms
and the considerable changes in climate in the Pre-Cambrian especially
those in in the Cryogenian when the Earth went from ice to warmer.
This also has astrobiological implications.
original idea was that above ground biomass (NPP) would respond to
rain according to the species. This suggests that NPP at low rain
levels converges to a mean wioth important impliocations for global