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

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Grasslands of the world
Young fallow
In the first year, botanical composition is little different from the previous
arable weed composition, which reflects preceding crops and their husbandry.
The commonest plants are annuals such as Chenopodium album , Salsola kali ,
Setaria spp. , Artemisia absinthium , A. sieversiana , Brassica campestris , Sonchus
arvensis , Polygonum aviculare , P. convulvulus , Avena fatua , Camel ina spp. ,
Thlaspi arvense , Lappula spp. , Sisymbrium spp. , Berteroa spp. , Lactuca spp. ,
various thistles, Erigeron canadensis , Urtica cannabina , Crepis tectorum , Bromus
tectorum , and Cannabis sativa . Perennials develop and begin to predominate:
Cirsium arvense , Sonchus arvensis, Artemisia campestris , A. frigida , A. austriaca ,
Melilotus alba , Gypsophila spp. , Achillea millefolium , Falcaria vulgaris , spurge
(Euphorbiaceae) and Potentilla argentea , together with rhizomatous grasses
such as Agropyron repens , A. racemosum , Calamagrostis epigeios and Bromus
inermis .
Much higher herbage yields are obtained in the fallow phase. Larin (1956)
speaks of 4 000–8 000 kg/ha of fresh and 1 000–2 000 kg/ha of dry matter,
whereas the steppe produces no more than 800 kg/ha of hay ! Low productivity
of the virgin steppe itself, in comparison with high productivity of (unsown)
green fallow on top of intermittent crop yields, has no doubt been a major
incentive to plough virgin steppe, at least on the richer and better watered
soils.
However, green fallows are heterogeneous and many of the herbaceous
weeds are ignored by the grazing animal, such as Chenopodium album ,
Artemisia spp. , Thlaspi spp., Salsola kali and other thistles. Herbs are grazed
highly selectively, not least because of the wide range in date of flowering and
maturity. This is an advantage in summer , when the virgin steppe itself has
dried off. Hay is then a better alternative and many Russian authors claim that
when the mixed herbage is turned into silage, the rate of utilization is higher
than when grazed. Conversely, Agropyron repens , Avena fatua , Bromus spp.
and Setaria spp. , together with herbs such as Sonchus arvensis , Polygonum
convolvulus , Polygonum aviculare and Brassica campestris provide relatively
good pasture , with 2 500–3 500 kg/ha of edible fresh matter.
As the fallow period develops, rhizomatous perennials take over in about
the fourth to fifth year: Agropyron repens on chestnut soils, A. racemosum on
lighter soils, and Bromus inermis and Calamagrostis spp. This is the most valuable
fallow phase from the herbage point of view. Agropyron hay is highly valued.
Patches with Achillea spp., Artemisia austriaca and A. frigida may still be
much in evidence. In the final stages of return to the virgin steppe, rhizomatous
grasses and Artemisia spp. begin to give way to Festuca sulcata and Stipa spp.
Avenues of steppe improvement
Land and grass resources in the steppe zone are grossly underutilized. Most
farms are overstocked, yet even on the better farms in favourable areas, yields