Abstract: The damage and impact of acid rain and sulfuric dioxide exposure alone and in combination on several woody young trees were described in the paper. The exposure tests in open top field chambers were carried out in four kinds of acid rain, pH=2.0, 3.0, 4.5 and 6.6, and in two groups of SO₂ concentrations(mg穖^-3), 1.5, 1.0, 0.5, 0.03 of first and 3.0, 2.0, 1.0, 0.03 of second respectively. The results showed that blade damage degree was closely related with level, pattern and time of pollution exposure. The difference in sensitivity and reaction to complex exposure was obvious among the trial young trees. When the exposure to acid rain(pH=3.0)and SO₂(1.0mg穖^-3)for two days had not aroused blade damage of the resistion trees, the exposure only for one day in same level mentioned above had led to obvious damage of the sensitive trees. In addition, the feedback action to complex exposure was antagonistic and synergistic reaction in resistive and sensitive trees, respectively.

Key words: rotation, Loess Plateau, wheat, protein quality, nutritional quality.