Modelling habitat preferences of water hyacinth (Eichhornia crassipes) in some wetlands of Guilan province

8 sites were selected in different wetlands of Guilan province to survey the habitat preference of invasive water hyacinth (Eichhornia crassipes). At each site, a set of environmental variables (physico-chemical and structural variables in the given ecosystems) was seasonally and simultaneously sampled with 32 biological instances (16 presence samples and 16 absence samples of water hyacinth) during one year study period (2016-2017). The results of Mann-Whitney test showed that there was a significant difference between presence/absence of water hyacinth and electric conductivity, flow velocity, turbidity and bicarbonate (p < 0.01 for the first three variables and p < 0.05 for bicarbonate), while no significant difference was observed between the presence and absence of water hyacinth and other variables (p > 0.05 for all variables). Based on the results of the principal component analysis, electric conductivity, water turbidity and flow velocity were the most influential varaibles in the first to third components (more than 82 % of the total variations were related to these three components) so these variables had the major effect on the habitat suitability of water hyacinth in the wetlands. The results of generalized linear model showed that there was a significant difference between the presence and absence of water hyacinth in the sampling sites and electric conductivity, flow velocity, water turbidity and bicarbonate (p < 0.05 for bicarbonate and p < 0.01 for other 3 variables).