Abstract:

Soil physi-chemical properties and the tree growth were compared in successive rotation plantations of Cunninghamia lanceolata (CR Chinese Fir) in tree different ages(8-year-old, 11-year-old and 14-year-old), and Taiwania flousiana plantations with the same age pattern which were afforested in previous slash of Chinese Fir. The results showed that soil bulk densities were 0.893-1.112, 0.797-1.256 and 0.598-1.211 g·cm^-3 respectively in 8,11,14-year-old Taiwania flousiana plantations soils (0～100 cm), which were lower 0.9％-6.9% than those in CR Chinese Fir plantations. Total soil porosity in the three ages of Taiwania flousiana plantations was respectively 45.69％-65.33％，46.45％-68.74％ and 39.82％-68.26％，and all higher 6.6％-8.7％ than that in the CR Chinese Fir plantations. The soil ventilation degree was respectively 49.57%-59.71％, 44.55%-66.68％ and 42.38%-66.16％，and also higher 14.2 %-24.4% than that in the CR Chinese Fir plantations. The soil saturation moisture capacity was respectively 3.43％-11.43％，4.15％-19.73％ and 2.28％-12.23％, and higher 12.4％-14.9％ than that in the CR Chinese Fir plantations; The saturated water contents were 46.89％-66.50％, 40.90％-68.09％ and 42.36％-98.15％ respectively，and higher 12.4％-14.9％ than that in the CR Chinese Fir plantations. pH values of forest soil (0-40 cm layer) were 4.30-5.10，4.40-4.80 and 4.13-4.55 respectively in 8,11,14-years-old of Taiwania flousiana plantations, which were lower 1.3％-6.3％ than that in the CR Chinese Fir plantations , and the organic matter contents were 46.03-71.45，34.96-68.67 and 25.59-79.38 g·kg^-1 , and lower that in CR Chinese Fir plantations in the 8-year-old, however higher 23.4％-77.1% than that in the 11, 14-years-old. Total nitrogen and hydrolysis nitrogen contents were 1.78-3.55，1.97-3.04，2.01-3.12 g·kg^-1 and 146.9-355.3，185.0-370.5，136.6-365.9 mg·kg^-1，and slightly lower than that in 8-year-old is and higher 20.1％-35.6％ in the 11, 14-years-old. Available P contents were 0.5-2.7，0.6-1.5 and 0.6-2.8 mg·kg^-1 respectively， and higher than that 11.1％-54.5％ in the CR Chinese Fir plantations. Available K contents were 15.4-137.5, 34.5-115.5 and 18.7-89.1 mg·kg^-1，and lower 23.6％-47.6% than that in the CR Chinese Fir plantations. In the 8,11,14 years-old of Taiwania flousiana plantations, the average diameter was 10.70 , 12.67 and 14.13 cm respectively, and higher 12.4%-36.7% than that in the CR Chinese Fir plantations. The average tree height were 8.63, 11.47 and 13.33 m respectively, and higher 11.7%-30.2% than that in the CR Chinese Fir plantations. Tree stands volumes were 93.308, 153.418 and 203.824 m³·hm^-2 respectively, higher 37.7%-117.5% than that in the CR Chinese Fir plantations.

Key words: continuous planting Cunninghamia lanceolata, Taiwania flousiana introduction experiments, soil physi-chemical properties, tree growth, Nandan County of Guangxi