The
environment can be thought of as a series of interconnected cycles;
Any
change in one cycle will affect all the others and alter the total
environment;
The
cycles which make up the physical environment exert considerable
influence over plant and animal distributions;
The
physical environment operates at three different scales or levels.
At each level the impact and its implications differ;
At
the individual level, the physical environment controls the existence
of the organism;
At
the species level, the physical environment controls the distribution
of the population;
At
the community level, the physical environment controls the composition
of the ecosystem;
These
physical factors can be translated into a series of key concepts
which help explain plant and animal distributions;
It
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).
Puts
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.
Demonstrates
that to best understand the changes in a dynamic system like tidal
marshes one needs to look at both positive and negative elements e.g.
plants and physical factors.
It's
well known that the physical environment affects species distribution
but the rise of desertification means that the importance of this
paper could go beyond a mere US example.
The
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
warming calculations.