桉树人工林近熟林密度调控及施肥试验

Eucalyptus Plantation Density Regulation and Fertilization Experiment in Near-Mature Stands

摘要: 为提升桉树胸径、单株材积以及单位面积蓄积量，本项目于2021~2025年在广西国有六万林场高岭分场开展桉树近熟林密度调控和施肥试验。采用标准地对比法进行试验。(1) 2021年在2016年种植密度为每公顷1665株的DH32-28、DH32-29林分中分别设立标准地，2022年根据设计要求伐除标准地内被压木、风倒木、病死木等，最终保留密度为900~1350株/hm²，然后每株树施复合肥1000克，每隔6个月测定树高、胸径1次。2024年调查结果表明：在DH32-28近熟林中，每公顷保留1050株的胸径、单株材积、单位面积蓄积量、年均单位面积生长量的增加值最大，每公顷保留1200株的增加值次之，每公顷保留1350株的增加值最小；在DH32-29近熟林中，每公顷保留1200株的树高、胸径、单株材积、单位面积蓄积量、年均单位面积生长量的增加值最大，每公顷保留1050株的增加值次之，每公顷保留1350株的增加值最小。这表明近熟林最佳保留密度为1050~1200株/hm²，不同品种间有差异。(2) 2022年在2016年种植林分中设立标准地和对照地，试验林每株树施复合肥1000 g，对照不施肥。据2024年测定数据，试验林平均树高、平均胸径明显高于对照，中大径级树比对照高8%，这表明对近熟林施肥能够促进林木生长，提高林分质量。

Abstract: In order to improve the DBF, individual tree volume, stand volume per unit area in eucalyptus plantations, the paper studied the density regulation and fertilization experiments on near-mature eucalyptus forests in Guangxi state-owned Liuwan Forest Farm from 2021 to 2025. The experiment was conducted using the standard comparative method. In 2021, some standard sample plots of DH32-28 and DH32-29 were set up, which the stand were planted in 2016 at density of 1665 tree/hm². In 2022, according to the design requirement, the suppressed, windblown, and diseased trees were removed within the standard area. The final retaining density was 900 to 1350/hm² and 1000 gram fertilization per trees. The tree height and DBF were measured biannually. The survey results in 2024 were as follows: (1) In Near-Mature Stands of DH32-28 (retaining density 900~1350 trees/hm²), the maximum diameter at breast height, individual tree volume, and growth per unit area was achieved by retaining 1050 trees/hm², the second by retaining 1200 trees/hm², the minimum value by retaining 1350 trees/hm². In Near-Mature Stands of DH32-29 (retaining density 900~1350 trees/hm²), the maximum diameter at breast height, individual tree volume, and growth per unit area was achieved by retaining 1200 trees/hm², the second by retaining 1050 trees/hm², the minimum value by retaining 1350 trees/hm². (2) In 2022, the sample and control plots were established within the forest planted in 2016. 1000 gram of fertilizer per tree was applied in the experimental forest in 2022. According to the 2024 survey data, the tree height and diameter at breast height in the experiment forest was significantly greater than those in the control forest. Medium and large diameter timber trees were 8% higher than the control group. This shows that fertilization can improve the growth of near-mature of Eucalyptus plantation and improve stand quality.