1.3 Statistical analyses
The mass ratio was used for the ratio C/N, C/P and N/P. Statistical analyses were performed with SPSS version 19.0 (SPSS Inc., Chicago, IL, USA). All results are presented as mean and standard deviations. One-way ANOVA and least significant difference (LSD) tests (P<0.05). The IV of each plant species was calculated by the following formula (Lindsey, 1956):
IV =\(\frac{relative\ coverage\ +\ relative\ height\ +\ relative\ density\ +relative\ dry\ weight}{4}\)
Plant diversity was estimated using the three standard multi-dimensional biodiversity indices, i.e., Pielou Evenness index, Shannon-Weiner (H’), and Simpson diversity index (D) was calculated based on the following equations.
H′=\(-\sum_{i=1}^{s}P\)i\(\ln P\)i
When H’ represents Shannon-Weiner index, Pi the total number of individual species proportion of ith species in the community and S represents encountered species number. the number of species encountered, Pi the proportion of the total number of individual species belonging to I th species in the community, lnPi means the natural logarithm of Pi.
D=1-\(\sum_{i=1}^{S}P\)i2
Where D reprensets Simpson diversity index, S represents encountered species number. Pi the total number of individual species proportion of i th species in the community.
J=H′/\(\ln S\)
Where J represents Pielou evenness index, H’ represents Shannon-Weiner index, S means the number of species
R=S
Where R represents richness index, S means the number of species.