Impact of plant invasion on soil nutrient parameters
Analysis of soil physicochemical properties revealed that pH, EC, TDS and WC differed significantly (p <0.001) between plots (Table 1). Soil pH, TDS, SAL and WC values were higher in the invaded plots as compared to uninvaded, whereas EC showed the opposite trend. Furthermore, pH, EC, TDS and SAL were highest at KZ site and showed a gradual decrease along the increasing altitude, while WC revealed the opposite trend (Table1). Significant differences were found in TOC, N and P between the plots at all the sites except KD site where P did not show any significant difference (p = 0.9). TOC and N were higher in the invaded plots at all sites and P showed an opposite trend. Between the plots, K differed significantly and showed progressively increasing trend from KZ to KU followed by decline at KD site. Furthermore, micronutrients were lower in concentration in the invaded plots as compared to uninvaded plots and increased gradually along the altitude (Table 1).
PCA analysis illustrated that first two axes (PC1, 52.4% and PC2, 32.4%) explained approximately 85% of total variance (Fig. 5). There was a striking pattern for soil physicochemical properties observed at different sites with invaded and uninvaded plots separated distinctly. WC, TOC, K, N and Cu were positively related with invaded plots at the higher-altitudinal KU and KD sites whereas Fe, Zn, Mn and P were strongly associated with uninvaded plots at these two sites. Similarly, pH, TDS and SAL were positively related with invaded plots at the lower-altitudinal KZ and TM sites but negatively associated with invaded plots at KU and KD sites. EC was strongly associated with uninvaded plot at KZ site, but negatively related to uninvaded plots at KU and KD sites (Fig. 5).