Soil sampling
For soil microbiome and nutrient pool studies, we collected soil samples from the four sampling sites along the altitudinal gradient during the peak vegetation season (June-July 2019). At each site, we collected soil samples in triplicates from the invaded (IN) plot and one sample from uninvaded (UN) plot which served as a control. To maintain the viability of the soil microbiota sampled at each site, we employed proper soil collection and storage protocols (McPherson et al., 2018). For each sample, we collected ca. 1000g of soil using sterilized gloves and placed them in sampling bags. Digging equipment was also sterilized with bleach and ethanol after each soil sample collection to avoid any possible cross-contamination of soil biota. The collected samples were immediately transported to the laboratory and processed in less than 6 hours after collection from the field. All the visible macrobiota and roots were removed from the soil and sieved using a mesh of 2mm pore size. The sieved soil samples for the microbiome studies were stored in 50 ml tubes and kept inside deep freezer at -80ºC, while as, for nutrient studies all the soil samples were air dried and stored at -4ºC till further analysis.