Soil factors influencing juvenile growth of Liriodendron chinense × tulipifera

Key words: 
• silviculture /
• Liriodendron chinense × tulipifera /
• growth /
• soil factors /
• hydrolyzed N /
• available K

Abstract: To determine the impacts of soil factors on juvenile growth in years 1 through 8 for Liriodendron chinense tulipifera, thirty 8 m 8 m plots from 3 plantations having dozens of interspecies crosses were sampled for 9 soil characteristics including soil bulk density, pH, total and hydrolyzed N, total and available P, total and available K, and organic matter. Growth （height and DBH） of trees within a plot were also measured followed an random complete block （RCB） design with 3－4 replications. A correlation analysis and a （duncans multiple range test） were conducted. Results revealed differences of soil factors existing among the sites, slope positions, and soil layers in a site. Juvenile growth differed significantly among the sites （P＜0.05） and blocks in a site （P＜0.05）. No significant correlation existed between ground diameter and available K （r =0.287－0.323, P = 0.081－0.124） during the first and second year; but height and DBH were significantly （P＜0.05） and positively correlated （r = 0.369－0.711） with soil hydrolyzed N and available K for years 3 through 8 showing that hydrolyzed N and available K were the two critical soil indexes for growth. Thus, enhancing hydrolyzed N and available K could promote juvenile growth of Liriodendron chinense tulipifera and could provide guidance for tree selection and soil nutrition management in the juvenile stage of large scale afforestation projects.［Ch, 6 tab. 20 ref.］