Abstract: With its age increasing, A. adsurgens population obviously leads to soil aridification,which is represented by the tendency of moisture content reduction on each horizon of 5m soil layer.In forest-grassland zone,A. adsurgens population of 5—6 years old can reduce the moisture content of 1—3m soil layer nearly to wilting point; 7 years old population can reduce it of whole seil profile to wilting point. In shrub-grassland zone, 4 years old population can reduce the moisture content of whole soil profile to wilting point. The 1—3m soil layer forms a "low moisture horizon". To reduce the unfavorable ecological effect, it is necessary to suitably adjust A. adsurgens population, such as control the growth density, harvest timely and practise stripped resowing etc.

Key words: marigold, drought-resistance, principal component analysis, subordinate function, cluster analysis