Fig. 3. Seasonal variations in diversity indexes of FFG of macroinvertebrates in Jingui River.
3.4 Relationship between species diversity and functional diversity
Using stepwise regression analysis to study the impact of species diversity on functional diversity, the lowest values of FEve and RaoQ were observed in wet season, and those of FRic and FDis were in normal season and dry season, respectively. FEve, FDis, and RaoQ showed the highest values in normal season, and FRic showed it in dry season (Fig. 4). Species richness varied greatly among Jingui river, ranging from 53 to 96 in each season, and FRic varied even more profoundly, ranging from 0.01 to 80.544 in each season (Fig. 4a). Moreover, species richness was significantly positively related with functional richness (R2 = 0.344, p < 0.001; Fig. 5a). In addition, it indicated a rather strong correlation between FEve and Margalef index (R2 = 0.366, p< 0.001; Fig. 5b). FDis was strongly correlated with Simpson index (R2 = 0.208, p < 0.01; Fig. 5c). FDis varied between 0.066 and 0.271, and RaoQ varied between 4.294 and 13.445. Although RaoQ was also significantly positively related with Simpson index (R2 = 0.234,p < 0.01; Fig. 5d), FDis was on average lower than RaoQ.