桂西北西南桦人工林生长规律和生物生产力

以广西天峨县林朵林场12年生西南桦人工林为研究对象,研究其生长过程和生物生产力特征。结果表明:西南桦在桂西北具有较强的生长适应性,12年生平均胸径(去皮)、平均树高和平均蓄积量分别达到15.6 cm,16.8 m,170.10 m3/hm2; 西南桦树高和胸径生长均以前5 a最快,随后随林龄的增长而下降; 材积生长在8年生时达到峰值,之后开始下降但仍然保持较高的年生长量。12年生西南桦人工林林分生物量为130.86 t/hm2,其中乔木层、灌木层、草本层和凋落物层生物量依次为122.38,2.35,1.87和4.26 t/hm2,分别占93.52%,1.80%,1.43%和3.26%。林分乔木层年净生产力为10.20 t/(hm2？ a),不同器官净生产力大小次序为树干、树叶、树枝、树根、树皮。
In order to understand the growth regularity and biomass productivity of the Betula alnoides plantation, the 12-year-old B. alnoides plantation was studied in Linduo Forest Farm of Tian'e County in Northwest Guangxi, China. The results showed that the growth of B. alnoides trees presented a strong adaptability in Northwest Guangxi. Its average diameter at breast height(DBH), height and volume of stand were up to 15.6 cm, 16.8 m and 170.10 m3/hm2 respectively. Both the tree height and the DBH were grow fastest in the initial 5 years. The growth of DBH and height represented declining trend after the age of 5 years. The annual volume growth would achieve the peak at 8 years. After 8 years, it's annual volume growth still maintained a higher growth tendency. The biomass of stands of 12-year-old B. alnoides plantation was 130.86 t/hm2, in which the biomass were 122.38, 2.35, 4.26 and 1.87 t/hm2 for the arbor layer, shrub layer, herb layer and litter layer, accounting for 93.52%, 1.80%, 3.26% and 1.43% respectively. The annual net productivity of arbor layer was 10.20 t/(hm2？a). The net productivity of different organs were in order of trunk>leaves>branch>root>bark