New Zealand Journal of Agricultural Research abstracts
The response of a shrub-invaded grassland on the Inner Mongolia steppe to long-term grazing by sheep
Zhen Guo Liu1,2
Zhen Qing Li1,*
Ming Dong1
Bill Johnston3
1Laboratory of Quantitative Vegetation Ecology
Institute of Botany
The Chinese Academy of Sciences
Beijing 100093, China
2Graduate School of Chinese Academy
of Sciences
Beijing 100039, China
3NSW Department of Natural Resources
P.O. Box 189
Queanbeyan, NSW 2620
Australia
*Author for correspondence.
lizq@ibcas.ac.cn
Abstract The diversity of a degraded grassland community on the Chinese Inner Mongolia steppe dominated by Artemisia frigida
(Asteraceae) subject to a range of grazing treatments (zero, and light,
medium and heavy grazing) for 13 years was studied from July to August
2002. Under zero grazing, percentage total vegetation cover was
significantly (P < 0.05) less than under light, medium, and heavy grazing. Although not dominant in any treatments, percentage cover of Carex duriuscula
(Cyperaceae) was higher than other species in the zero, light, and
medium grazed treatments. Its cover tended to decline as grazing
intensity increased (P = 0.49). Aneurolepidium chinense (Poaceae) reasserted its dominant status in the zero grazed grassland; A. frigida remained dominant under light and medium grazing. Under heavy grazing, Potentilla acaulis
(Rosaceae) was the dominant species and it provided the highest
percentage cover. Zero and heavy grazing resulted in fewer
(three–four) species contributing most of the total cover
(cf. six–seven species for light and medium grazing). This
was reflected by indices of diversity and evenness, which were highest
for light and medium grazing. The Simpson Dominance Index was highest
for the zero and heavily grazed treatments, indicating that at the
extremes of the grazing spectrum, single species tended to exclude
potential co-dominants more effectively than at intermediate levels of
grazing. Selective grazing was a key process. Grazing increased the
proportion of unpalatable and grazing resistant species, and species
that although palatable, were relatively inconspicuous. These findings
are discussed in terms of their impact on the productivity and long
sustainability of grazing. The need to develop a better understanding
of underlying processes, and more sustainable forms of grazing
management are highlighted.
Keywords species diversity; grassland degradation; grassland succession; sustainable grazing
A05025; Received 17 June 2005; accepted 18 January 2006; Online publication date 9 May 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49: 163–174
0028–8233/06/4902–0163 © The Royal Society of New Zealand 2006
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