New Zealand Journal of Agricultural Research abstracts
Influence of grazing intensity on performance of perennial grass mixtures
in the alpine region of the Tibetan Plateau
Dong Shikui1,3
Long Ruijun2,3
Hu Zizhi3
Ding Luming3
Xu Meiyong3
1Institute of Environmental Science
State Joint Key Laboratory of Environmental Simulation and Pollution Control
Beijing Normal University
Beijing, 100875, PR China
email: DSK@irs.bnu.edu.cn
2Northwest Plateau Institute of Biology
The Chinese Academy of Science
Xining, 810001, PR China
3Grassland Science College
Gansu Agricultural University
Lanzhou, 730070, PR China
Abstract Effects of grazing intensity on leaf photosynthetic
rate (Pn), specific leaf area (SLA), individual tiller density, sward leaf
area index (LAI), harvested herbage DM, and species composition in grass
mixtures (Clinelymus nutans + Bromus inermis, Elymus nutans
+ Bromus inermis + Agropyron cristatum and Elymus nutans
+ Clinelymus nutans + Bromus inermis + Agropyron cristatum)
were studied in the alpine region of the Tibetan Plateau. Four grazing intensities
(GI), expressed as feed utilisation rates (UR) by Tibetan lambs were imposed
as follows: (1) no grazing; (2) 30% UR as light grazing; (3) 50% UR as medium
grazing; and (4) 70% UR as high grazing. Leaf Pn rate and tiller density
of grasses increased (P < 0.05), while sward LAI and harvested herbage
DM declined (P < 0.05) with the increments of GI, although no effect of
GI on SLA was observed. With increasing GI, Elymus nutans and Clinelymus
nutans increased but Bromus inermis and Agropyron cristatum
decreased in swards, LAI and DM contribution. Whether being grazed or not,
Elymus nutans + Clinelymus nutans + Bromus inermis +
Agropyron cristatum was the most productive sward among the grass
mixtures. Thus, two well-performed grass species (Elymus nutans and
Clinelymus nutans) and the most productive mixture of four species should
be investigated further as the new feed resources in the alpine grazing system
of the Tibetan Plateau. Light grazing intensity of 30% UR was recommended
for these grass mixtures when swards, LAI, herbage DM harvested, and species
compatibility were taken into account.
Keywords improved pastures; yields; leaf characteristics;
herbage DM yield; species composition
A02052; Received 12 August 2002; accepted 14 April 2003; online publication
date 9 September 2003
New Zealand Journal of Agricultural Research, 2003, Vol. 46: 175-183
0028-8233/03/4603-0175 $7.00/0 © The Royal Society of New Zealand
2003
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