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

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Grasslands of the world
mention over-seeding for the revegetation of abandoned cropland – a subject
discussed below.
Attitudes to over-seeding and the introduction of exotic pasture plants to
natural grassland ecosystems are changing. The ability to spread and colonize
in a grazing situation used to be a desirable characteristic of plants for pasture
improvement – now such plants may be regarded as invasive aliens.
Fertilizer may be used, with or without reseeding if the botanical composition
of the sward is appropriate and economics warrant it, and slashing is
sometimes used to reduce coarse vegetation .
Grassland rehabilitation
Degraded grassland is a symptom of weakness in the pastoral production
system and these weaknesses have to be identified and dealt with before further
action can be taken. Where rehabilitation of grassland is desirable it should
be through management methods, with or without water-spreading. Overseeding
degraded rangeland is rarely an attractive option and reliance has to
be put on making the most of the recovery of the natural vegetation . Assuring
even grazing over an area, keeping stock numbers within reasonable limits, and
avoiding localized overgrazing can all help.
Degradation of pasture can have effects more serious than reduction of
available grazing ; increased runoff can lead to flooding and siltation of more
valuable land and infrastructure lower in the catchment. In such cases action
may have to be taken to reduce runoff; in severe cases grassland that is a focus
for runoff and erosion may have to be closed, temporarily or permanently, with
or without forestation – this is being done on a large scale in China , notable in
the Yellow River and Yangtze catchments. Many grasslands are very resilient
and will recover from serious misuse through resting; if, however, change and
degradation has been very serious, the grassland may have passed the point of
recovery, and while rest will allow some sort of vegetative cover to develop, it
will not be as the original grassland.
Two situations closely allied to grassland rehabilitation are old mining and
industrial sites and cropland that is being removed from cultivation . Treatment
of mining sites is a specialized matter. Marginal cropland going out of cultivation
is mentioned in East and South Africa , North America and Russia . Where
adapted grasses are available, reseeding may be a better option than relying
on tumble-down fallow since old crop land may not turn spontaneously to a
grassland but to weeds or thicket.
HERD MANAGEMENT
In commercial systems management generally aims at improving animal
status and usually concentrates on one, or at the most two, species. Common
management practices to that end include: dividing herds into categories so
that they get the appropriate treatment, avoiding underage and unseasonable