Results
Diversity index calculation results and analysis of
variance
The Simpson index analysis results show that compared with the control
group sample, the test group showed a decline in the overall decline
(Table 1) as the test group increased, and the differences between
different gradients were significantly (Table 2). The differences
between different research sites are significant, but the differences
between seasons are not significant, and the laws of different research
sites on gradients are different. Simpson of DL and HL showed a trend of
first decreasing and then increasing on the grazing gradient, Simpson of
EE showed an overall decreasing trend on the grazing gradient, Simpson
of WA showed an overall fluctuating trend on the grazing gradient, and
Simpson of SP showed an increasing trend on the grazing gradient,
especially in the rainy season. Shannon index analysis showed that
Shannon of WA showed the maximum value, while Shannon of SP showed the
minimum value. In the study of grazing gradient, Shannon’s change
characteristics were consistent with Simpson’s, that is, diversity index
showed a significant negative correlation with grazing time, but the
difference between seasons was not significant, and different research
sites had different change rules on grazing gradient. For Simpson and
Shannon indices, the interaction between the study site and grazing
gradient, the study site and seasonal factor, and the seasonal factor
and grazing gradient were all significant. In addition, the Pielou index
of sites fluctuated across grazing gradients, but the differences
between gradients were significant, while the differences between
seasons were not significant. For Pielou index, the interaction between
site and grazing gradient and seasonal factors and grazing gradient were
significant. The interaction of the three factors of the study site,
grazing gradient and seasonal factors had significant effects on the
three diversity indexes.
Table1 Simpson, Shannon and Pielou index of each study sites
along grazing gradients for dry season and rainy season. DL (Duo lun),
EE (Er er duo si), HL (Hai La er), SP (Sha po tou), WA (Wu lan aodu).