The relationship between the atmospheric SO₂ pollution and the decline of the masson pine forest located in Nanshan on the south bank of Yangtze River near Chongqing was studied. This work included SO₂ pollution monitoring, SO₂ fumigation, filtered air experiment in situ,and analysis of sulfur content in needles. The results of air monitoring indicated that the SO₂ pollution in this area was heavy, and the SO₂ concentration in air was 0.35 mg/m3 averagely, with maximum 1.30mg/m3. The fumigation tests showed...