Conclusions
The conclusion of this study is that the inter-specific relationship of
dominant grass species is not only affected by grazing intensity, but
also by initial population density and sampling scale. There are three
results. First, the increase of grazing intensity generally increased
the density of S. breviflora and C. songorica populations
in a Inner Mongolian desert steppe. We also noted that this relationship
was particularly sensitive to spatial scale, and observed that ‘density’
increased with the increase of our sampling scale (moving from 5 cm×5 cm
to 100 cm×100 cm sampling quadrats). Secondly, with the increase of
grazing intensity, the affinity of S. breviflora and C.
songorica increased greatly at the small scale, though this affinity
was not obvious when observing the entire plot, further suggesting that
sampling size may induce bias in these measurements. Finally, with the
increase of grazing intensity, the competition between S.
breviflora and C. songorica increased first and then decreased,
that is, heavy grazing led to the decrease of inter-specific competition
between the two species. Inter-specific relationship is the basis for
exploring the stability and evolution of plant communities. The change
of inter-specific relationship of dominant grass species in desert
steppe may further affect the stability and sustainability of grassland
ecosystem, and our observations provide a theoretical basis for
formulating reasonable and scientific grazing practices in S.
breviflora desert steppe.