TOWARD UNDERSTANDING ECOSYSTEMS
31
is to formulate the analytical approach to the question of plant succession. Imagine that the model for a fairly simple plant community is
managsable. Introduce into the system at the seedling stage an additional species which, for example, has a great deal of shade tolermce
and has physiologica1 and physical propertim which will permit it to
grow hi the shade of the other species making up the simple community.
It is understood that the climate at all levels of the stand is speoified
as a function of time of day, month and season, etc. The output from
the program may be rate of growth for each species. As the shade
toleraat species begins to top out the shade intolerant species, the
climate for each species will change and the relative rates of growth
will change drastically. If the proper physiological responses are put
into the program for each species then the results of the competition
will show up in a realistic manner in terms of species dominance, vegetation structure and composition, etc. When a suitable model is formulated the properties, both physical and physiological, of a plant can
be ‘chenged and the model run using various values of the plant
properties.
It is very difficult to be convincing that a mathematical model ia
useful when it comes to treating a problem as complex and diverse as
competition and succession within a plant community. Some will argue
that JOU get out of the analysis only as much aa you put into the formulation 3f the model. This is indeed true. Yet what one does derive from
such tx model system is the ability to test the sensitivity of the whole
system to certain specific factors, or to predict relative rates of change
within the system. A model is useful for testing the system to stresses
in a way which is very difficult to do in nature. One can change the
pattern of climate put into the model syetem and compute what might
happen to the species density, or to the productivity. A mathematical,
analytical model is not a substitute for or replacement of the real
system, it is a simulation of the real system in a way which should aid
us with the intricate “bookkeeping” of the complex, natural system.
E. PRODUCTION
Whtlt is the production of a given site with certain edaphic and
climatic charmteristica without management by man? To what extent
is this determined by the species available to it?
It is possible to simulate production of a plant community using the
storage capacity and data handling techniques of large computers. This
problem is not extremely different from the problem of computing the
water usage by a stand of p l a n k Following the same procedure outlined erxlier for following the relative metabolic activity of a plant leaf
during a diurnal cycle of climate one m n work out basic curves of
31
is to formulate the analytical approach to the question of plant succession. Imagine that the model for a fairly simple plant community is
managsable. Introduce into the system at the seedling stage an additional species which, for example, has a great deal of shade tolermce
and has physiologica1 and physical propertim which will permit it to
grow hi the shade of the other species making up the simple community.
It is understood that the climate at all levels of the stand is speoified
as a function of time of day, month and season, etc. The output from
the program may be rate of growth for each species. As the shade
toleraat species begins to top out the shade intolerant species, the
climate for each species will change and the relative rates of growth
will change drastically. If the proper physiological responses are put
into the program for each species then the results of the competition
will show up in a realistic manner in terms of species dominance, vegetation structure and composition, etc. When a suitable model is formulated the properties, both physical and physiological, of a plant can
be ‘chenged and the model run using various values of the plant
properties.
It is very difficult to be convincing that a mathematical model ia
useful when it comes to treating a problem as complex and diverse as
competition and succession within a plant community. Some will argue
that JOU get out of the analysis only as much aa you put into the formulation 3f the model. This is indeed true. Yet what one does derive from
such tx model system is the ability to test the sensitivity of the whole
system to certain specific factors, or to predict relative rates of change
within the system. A model is useful for testing the system to stresses
in a way which is very difficult to do in nature. One can change the
pattern of climate put into the model syetem and compute what might
happen to the species density, or to the productivity. A mathematical,
analytical model is not a substitute for or replacement of the real
system, it is a simulation of the real system in a way which should aid
us with the intricate “bookkeeping” of the complex, natural system.
E. PRODUCTION
Whtlt is the production of a given site with certain edaphic and
climatic charmteristica without management by man? To what extent
is this determined by the species available to it?
It is possible to simulate production of a plant community using the
storage capacity and data handling techniques of large computers. This
problem is not extremely different from the problem of computing the
water usage by a stand of p l a n k Following the same procedure outlined erxlier for following the relative metabolic activity of a plant leaf
during a diurnal cycle of climate one m n work out basic curves of