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

360
6 000
4 000
2 000
0
(a) Queensland
Area of
pasture
Area
fertilized
1950 1960 1970 1980 1990
Grasslands of the world
Figure 9.4
Changes since 1950 in the area of sown pastures and the area of pasture fertilized.
(a) Queensland. This area is mainly tropical pastures and includes most of the tropical
pastures sown in Australia . (b) Remainder of Australia. This area is almost all temperate
pastures and occurs mainly in Western Australia, New South Wales, Victoria and South
Australia.
SOURCE: Data from the Australian Bureau of Statistics and ABARE.
30 000
20 000
10 000
(b) Australia - remainder
of these have been intentional introductions, but others are local strains of
accidental introductions, such as many Trifolium subterraneum cultivars.
Although the native communities described in the section on natural vegetation
still remain important, introduction of exotic pasture species commenced
at or soon after European settlement. The poor quality of pastures near Sydney
was soon recognized and requests for pasture legumes and grasses were made
before 1800, and lucerne and clovers were among the non-indigenous plants
growing in the Colony in 1803 (Davidson and Davidson, 1993). By the early
twentieth century, many of the pasture plants currently used were already
being exploited, although on a much smaller scale than at present (Lolium perenne
, L. multiflorum , Dactylis glomerata , Medicago sativa , Trifolium repens ,
T. pratense , T. fragiferum , Paspalum dilatatum , Panicum maximum ) (Davies,
1951). In addition, there had been a number of accidental introductions that
were to be of great importance, although their potential had not been recognized
(e.g. Trifolium subterranean, annual Medicago spp., Cenchrus ciliaris and
Stylosanthes humilis ).
There have been considerable differences between the development of
temperate and tropical pastures and these are considered separately in the following
sections.
Figure 9.4 shows the changes in the area of sown pastures from 1950
onwards for Queensland (mainly tropical pastures) and the remainder of
Australia (mainly temperate pastures).
Temperate pastures
During the first 50 years of the twentieth century, much information was
gathered on temperate pasture species and their growth requirements: A.W.
Howard had actively promoted subterranean clover; the superphosphate
responses by pastures had been documented; and the role of trace elements
0
1950 1960 1970 1980 1990