Effects of the Invasive shrub, Chromolaena, odorata on Soil Properties in the Atharamura forest ecosystem: Indian Himalayan state of Tripura, North East India

Invasion of alien species is modifying attributes of soil to facilitate a further invasion of other invasive species, which is one of the major threats to biodiversity and ecosystem stability. The species Chromolaena odorata is one of the most hazardous invaders in Indian subcontinent. It alters under-story native vegetation in tropical forests. In this comparative investigation, we assessed the soil properties (soil physiochemical and microbial) of C. odorata invaded forest and in an adjacent natural forest in the three topographic strata of Atharamura hill range of Tripura. Soil samples were collected from the top layer (0-20cm) of both invaded (C. odorata) and non-invaded forest of different topographic locations in the month of August. Our results showed, soils that were collected from C. odorata invaded forest had significantly reduced moisture content, WHC, soil porosity, texture, total C, N, P, Ca, Fe, Mg, and microbial colony, compared to the soils in the adjacent natural sites; while, bulk density, pH, K and Cu are significantly higher in invaded ecosystem compared to the soil in three adjacent topographical natural sites in the forest range. Significant differences (t-test) were found among the invaded and non-invaded natural sites in various strata. ANOVA also shows the significant difference between the three invaded and non-invaded sites. Pearson's correlation was done to identify the correlation between the variables. To know the status of strongly correlated variables (C, OM, P and Conductivity) in the invaded and non-invaded sites of three altitudinal strata, PCA was applied. These results indicate that the species C. odorata have an overall negative impact on the functioning of this entire forest ecosystem. Therefore, management of this invasive species is necessary to prevent the invasion in the natural forest.