Exploring the potential of native plants in restoration projects

Parthenium weed (Parthenium hysterophorus L.) is amongst the worst weeds in the world. Parthenium weed is an Alien Invasive Species (IAS) harmful to human beings, crops and animals, and a curse to bio-diversity. Parthenium weed is already close to being out of control around most of the northern cities in Pakistan, particularly in the outer city suburbs and into the underutilized lands around the cities, and into forests and crops. Several methods have been recommended in containing the growth of P. hysterophorus. However, none of these appear to be satisfactory, as each method suffered with one or the other limitations such as inefficiency, high cost, impracticability, polluting the environment, temporary relief etc. During field surveys, it was noticed that some competitive native plants viz, Chamaesyce hirta, Dicanthium annulatum and Senna occidentalis replacing P. hysterophorus gradually in patches. Aqueous extract of C. hirta, D. annulatum and S. occidentalis in different ratios were tested to check the germination and early growth of P. hysterophorus. All the three test plants at different concentrations showed least germination of P. hysterophorus and a significant gradual depression in fresh biomass accumulation with increasing extract concentration. Seed bank analysis of the selected sites showed that after one growing season parthenium seeds very significantly less in native plant dominated sites. On the basis of this study, it is probably advisable to promote native plants competition to suppress the alien invasive species.