Multivariate impact analysis of Parthenium hysterophorus invasion on above-ground plant diversity in Pothwar region of Pakistan.
Phytosociological studies help to understand extent of biological invasion. Multiple analyses of ecological parameters at different locations derive general explanations of impact on species diversity in plant communities. Current study assessed the impact of Parthenium hysterophorus (an annual weed of great significance in Pakistan and worldwide) invasion on native vegetation in Pothwar region of Pakistan. The approach used for the study was random samplings with two categorical factors: invaded and non-invaded under same habitat conditions. Differences in number of species (S), abundance (N), species richness (R), evenness (J′), Shannon diversity index (H′) and Simpson index of dominance (λ) were compared between invaded and control plots by t-test series. Control plots harbored by average of 0.9 more species per 10 m2. The control category was more diverse (H′=1.73) than invaded category (H′=1.53). The higher value of species richness in control plots shows the heterogeneous nature of communities and vice versa in invaded plots. The lower value of index of dominance in invaded plots shows less sample diversity than in the control ones. At multivariate scale, ordination (nMDS) and ANOSIM showed significant magnitude of differences between invaded and control plots in all sites. The most effected site by Parthenium invasion was Jhelum followed by Attock, Rawalpindi, Chakwal and Islamabad. The decrease in diversity indices in invaded over control sites indicated less productive plant communities due to Parthenium invasion. This makes Parthenium a candidate of consideration for appropriate control measures.