Abstract:

In order to understand the short-term(one year after fertilization) growth effects of compound fertilizer(including slow- release fertilizer,SRF) and phosphate(P) fertilizer on a 12-year-old Pinus yunnanensis plantation,the L₉(3 ⁴) orthogonal design was employed to implement the trial.At one year after fertilization,the growth rates of diameters at breast height(DBHs),tree height(THs) and individual tree volumes(ITVs) of treatment combinations(TCs) were 4.29%~12.37%,7.96%~22.58% and 20.13%~38.39%,while numbers of control were 3.80%,10.21% and 15.76%,respectively,which was of significant difference between the TCs(P<0.01).The dominant factor affecting growth rate of the DBH was the type of fertilizer,while which of the TH and ITV was the amount of the P fertilizer.The growth rates of the THs went up with the increase of P fertilizer application,while DBH was opposite.The interaction of fertilizer types and P fertilizer amount had significant difference effects on the DBH and TH growth rates(P<0.01 or P<0.05).The demand of nutrient types and quantity for the DBH and TH growth of juvenile P.yunnanensis was different,and the fertilization of the forest primarily focuses on promoting the DBH growth.Suitable types of compound fertilizer and P fertilizer amount could significantly improve the growth of trees.Accurate fertilization could be achieved by taking every 5cm diameter of the DBH as the calculation unit of fertilization.The combination of the 0.75 and 0.50 kg/5 cm of 9-month SRF and diammonium phosphate could promote the growth of juvenile P.yunnanensis plantation and increase the stand volume in a short period of one year after fertilization based on comprehensive results of the optimal combination of theory and practice,the interaction results of compound fertilizer types and P fertilization amount,and the dominant factors affecting the timber volume of the stand.

Key words: pinus yunnanensis, orthogonal design, forest tree, growth rate, short term, interaction, forest fertilization