Effects of different trample intensities on quantitative characteristics and physiology indices of Thymus mandschuricus

Thymus mandschuricus, as an endemic species, is a kind of perfect wild fragrant ornamental ground cover plant with water-saving and drought-resistance characteristics. The plant has a wild prospect at the aspect of landscaping and the restoration of vegetation in arid areas. T. mandschuricus was introduced and planted by Northeast Forest University with the necessary of popularizing and applying new cover plant species. Trample device was employed to simulate human trample on T. mandschuricus. The results showed that low frequency and light trample intensity had less effects on biomass of T. mandschuricus. Moderate and severe trample intensity had significant effects on the aboveground biomass and ornamental characteristic. Light trampled plots were not different with the control plots and recovered within 4~7 days. However, moderate and severe trampled plots were significantly different with the control plots. The moderate trample plants plots were recovered within 30 days. The malondialdehyde (MDA), soluble carbohydrate, soluble protein, and proline of T. mandschuricus increased with the increase of trample intensity which suggested that T. mandschuricus has strong tolerance to trample. However, plant physiological indices increased significantly under severe trample stress and the branches suffered heavily damage which could not be recovered in one year. Light trample intensity had less effects on quantitative characteristics and physiology with increase of trampling circulation. Moderate and severe trample had significantly effects (P<0.05) on quantitative characteristics and physiology with increase of trampling circulation. The flexibility of T. mandschuricus branches provided strong tolerance to trample which was different with general woody ground cover plants.