Grasslands of the World.pdf - Disasters and Conflicts - UNEP

The Russian Steppe 391
pratensis dominant. 6. Association group: various admixtures of Alopecurus
pratensis. 7. Associations.
Sukachev’s classification is “phytocoenological”, whereas Ramenskii’s is
“phytotopological”, and the latter’s example was followed by Dmitriev (1948)
and Chugunov (1951). However, the distinction is often blurred. Ramenskii’s
seral stages of plant succession, although not coined as such by him or his successors,
are classical examples of linear Clementsian succession.
Conversely, bare ground is colonized by ruderals, which give place to
seral grassland stages as organic matter accumulates and these are eventually
replaced by taller bunch grasses. Clements (1916) ideas proved applicable not
only in USA , but also in Canada (Coupland, 1979, whose work used to be
quoted in Russia ) and in East and South Africa (Phillips, 1929). It is doubtful
if it ever was Clements’ aim to apply the succession model to all situations
liable to transition, or to claim that climax vegetation was the most desirable
or most productive from the agricultural point of view in all situations. Plant
succession can be studied with the aim of identifying the preferred seral stages
with desirable composition. As we will see in Russia, many instances can also
be found in which some of the seral stages (fallow land) are considerably more
diverse and productive in herbage than the climax vegetation itself. It goes too
far, however, to regard this as counter-evidence for the succession model. As in
the Great Plains of USA, the climax grasses of the Russian steppe are productive
and acceptable to livestock; they provide ground cover to protect soil and
are effective plants in utilizing environmental growth factors to fix carbon and
to cycle nutrients.
The interplay of biotic, climatic and edaphic components of the environment
is relevant, as these modify the dynamics of grassland communities . Efforts at
grassland improvement are directed at manipulating the botanical composition
to encourage the more desirable species and suppress those less desirable. A basic
thrust in current grassland improvement has been the comparison of the current
site condition with what it ought to be, i.e. site potential . Acknowledgement of
various stable vegetation states at a particular site widens the scope for opportunistic
management that is responsive to abiotic events and that is not bound
under all circumstances by doctrines that abhor fire or that only value stocking
rates that are moderate.
BOTANICAL CONDITION (ECOLOGICAL MONITORING )
Few are the instances where ecological techniques can have such an impact
on practical management decisions in agriculture as those developed in
grassland science. Botanical assessment has proved a more reliable and efficient
criterion of condition , and, therefore, of productivity of grassland, than yield
measurements themselves. Given the enormous tasks of natural resource
management ahead, it is appropriate here to draw attention to new techniques
of botanical grassland surveys.