Effects of Spacing and Fertilization on the Growth of Eucalyptus urophylla × E. grandis Plantation in Southern Yunnan

Taking Eucalyptus urophylla × E. grandis clone plantations in Xiaoheijiang of Yunnan Weiguo Forestry Bureau as the research object, the growth level and benefit of E. urophylla × E. grandis plantations were compared and analyzed by using the 4.5-year investigation data under 5 densities and 4 fertilization treatments. The differences among different treatments and the optimization model of treatment combinations were evaluated to reveal the effects of different spacing and fertilization treatments on the growth of plantation. The findings indicated that the effects of the growth level and benefit according to different fertilization and spacing management on stand were significantly different. The highest volume/hm² was fertilization 4, and the best benefit of 1 hm² was spacing 5 and fertilization 4; on the whole, the volume/hm² of fertilization experiment was better than those of spacing experiment. For the same spacing of fertilization 1 and spacing 2, the growth level and benefit of fertilization 1 in 1 hm² was better that of spacing 2, and the main reason might be related to slope position; through the single factor growth and benefit analysis, the treatment of fertilization 4(adding peat soil to basal fertilizer) and spacing 5(2.5 m×4 m) are the best. If there is interaction effect between fertilization and spacing management, we need to pay attention to the combination treatment among fertilization 4, fertilization 2, spacing 5 and spacing 4, and verify the interaction, so as to obtain the optimal combination under the interaction and find the mode worthy of promotion.